METHODS FOR DESCRIBING DISTRIBUTION OF SOUNDWOOD
IN MATURE WESTERN HEMLOCK TREES
by
DONALD D. MONRO
B.S.F„, University, of British Columbia, 1960 M.S., Oregon State University, 1964
A THESIS SUBMITTED IN PARTIAL FULFILMENT OF
THE REQUIREMENTS FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY
in the Department
of
FORESTRY
We accept this thesis as conforming to the
required standard .
THE UNIVERSITY OF BRITISH COLUMBIA
May, 1968 In presenting this thesis in partial fulfilment of the requirements
for an advanced degree at the University of British Columbia, I agree
that the Library shall make it freely available for reference and
Study. I further agree that permission for extensive copying of this
thesis for scholarly purposes may be granted by the Head of my
Department or by hiis representatives. It is understood that copying
or publication of this thesis for financial gain shall not be allowed
without my written permission.
Department of
The University of British Columbia Vancouver^ 8, Canada . ABSTRACT
Supervisor: Professor J. H. G. Smith
Estimation of soundwood volume and value is particularly
important in British Columbia because nearly half of the forests are
overmature or decadent. The objective of this thesis was to develop
-analytical techniques to define distribution of gross and net volumes within individual standing trees in order that appropriate reductions
for decay could be made for estimates of volumes of logs of specified
sizes and grades.
Relationships of heartr-ot to stand and tree characteristics and to external abnormalities were analysed for 369 western hemlock
(Tsuga heterophilla (Rafn.) Sarg.) trees from the Yale Public Sustained
Yield Unit in British Columbia. Comprehensive sorting, correlation and regression analyses were carried out on an I. B. M. 7044
electronic computer. One multiple regression equation provided
estimates of total decay volume within individual trees from DBH, total
height and external indicators of decay. It had a standard error of
estimated decay volume of 18.7 cubic feet (19.5 per cent). A second
equation estimated decay volume within individual logs in standing
trees from the above variables and from section height. It had
standard errors of estimate ranging from 13.7 cubic feet (31.6 per cent)
in butt logs to 0.1 cubic feet (2.9 per cent) in top logs. The best
taper function which could be derived to estimate upper stem diameters
inside bark had a standard error of estimate of 1.29 inches using
measures of DBK and total height. Combination of the log and tree decay estimating functions and the taper function facilitated complete description of.the soundwood volumes in the sample of 369 trees.
A graphical analysis was developed whereby percentages of trees in a stand with more or less than specified decay volumes could be estimated.
Preliminary chemical studies of western hemlock wood infected with Echinodontium tinetorium E. and E. indicated that cellulose yields were slightly less than those from soundwood. Such partly decayed wood might be used for the manufacture of pulp without serious reductions in yield on a volume or weight basis.
Further research is needed to substantiate the possible cyclic nature of decay losses and to determine the influence of bark thickness and natural pruning on the distrubution of decay within individual trees. Application of the analytical techniques developed for western hemlock to other species should result in more precise estimates of soundwood volumes and values, thereby contributing to improved management planning and utilization. Ill
ACKNOWLEDGEMENTS
The author wishes to express his thanks and appreciation to the following:
The late Dr. J. E. Bier for helpful suggestions during the planning stages of the study. Dr. Bier was to have served as Co- chairman of my Supervising Committee.
M.W. Bradshaw for assistance in providing data and for many hours of patient explanation and discussion.
The British Columbia Forest Service, Inventory Division, for provision of the basic stem analysis data used herein.
The Computing Centre, University of British Columbia, for provision of computing facilities.
The Faculty of Forestry, University of British Columbia, especially Dean J. A. F. Gardner, for financial assistance and pro• vision of office and laboratory space.
Dr. R.E. Foster for helpful analytical advice and review of the manuscript.
Dr. R. W. Kennedy for advice in experimental design and chemical analyses of decayed wood and review of the manuscript.
J. Kiss for cheerful assistance and guidance during field observations near Blue River, B.C..
Dr. A. Kozak who regularly acted as my statistical ''sounding board" and who, from time to time, extricated me from seemingly unresolvable computer programming difficulties.
MV Lambden for draughting the figures.
The National Research Council of Canada for financial assistance for a field trip. Dr. Vidar J: Nordin for provision of listings from the
INTREDIS Register System for Literature Retrieval in forest pathology.
Dr. J. H. G. Smith for inspiration, encouragement and
constructive criticism throughout the study.
Dr. R. W. Wellv/ood for suggestions during the preparation
of the literature review and for review of the manuscript.
E. L. Young for permission to use the data collected by the
-Inventory Division of the British Columbia Forest Service.
F. Adams, M. Jackson and G. Plester for assistance in data
coding and laboratory analyses.
T. Bapty, D. MacLelian and L. Polonich for typing the
manuscript.
Numerous North American forest pathologists who so kindly
responded to my mail survey of the status of work in this field.
Finally, I wish to express my special appreciation to my wife
Nona, and to my sons Lance and Deane for their patience, understanding,
encouragement and sacrifice throughout this study, particularly during
the latter stages of manuscript preparation. TABLE OF CONTENTS
ABSTRACT
ACKNOWLEDGEMENTS...
TABLE OF CONTENTS
LIST OF TABLES......
LIST OF FIGURES ... . .
LIST OF PHOTOGRAPHS ...... • .
CHAPTER I INTRODUCTION ......
CHAPTER II LITERATURE REVIEW......
Important Heartrot Fungi in British
Columbia's Forests......
Echinodontium tinctorium E. and E. .
Fomes pini (Thore) Lloyd
Important Heartrot Fungi in Western Hemlock
Environmental Conditions Required For
Fungal Establishment and Growtb.
Food
Air .
Temperature
Moisture
Decay Resistance
Regional variation
Sapwood-heartwood relationships . . . ©
vi
Page
Position in tree '.' 26
Effects of Decay on Wood Quality. . 26
Chemical 26
Mechanical ...... 27
Specific Gravity ...... 29
Color...... 29
-Moisture-holding-capacity 30
Utilization of Decayed Wood ...... 31.
Pulp . 31
Other manufactured products. . 34
Relationships Among Tree and Stand Age, DBH, Site Quality and Decay. . . 35
External Indicators of Decay. . 40
Distribution of Log Size and Gross ,
Volume Within Trees . 50
Conclusion 53
CHAPTER III DATA COLLECTION AND INITIAL;,
SUMMARIZATION . 55
CHAPTER IV DEVELOPMENT OF TREE DECAY .
FACTORS 93
Selection of Equation Form 93
Results and fiiscussion. 94
Conclusion 101
CHAPTER V DEVELOPMENT OF LOG POSITION
DECAY FACTORS 108
Selection of Equation Form 108
Results and Discussion • Ill vii
Page
Conclusion...... 119
CHAPTER VI DEVELOPMENT OF TAPER.FUNCTION ...... 120
Derivation of Basic Function 120
Results and Discussion. ' 122
: Conclusion. . 131
CHAPTER VII ESTIMATION OF VOLUME AND VALUE OF
SOUND AND DECAYED WOOD...... 136
Estimation of Tree and Stand Volumes
and Values. . ... '." ...... 136
Estimation of Log Volumes and Values 142
Estimation of Cellulose Quantity and
Quality in Decayed Wood. . . . 146
Laboratory procedures 147
Results and discussion 148
Conclusion 153
CHAPTER VIII SUMMARY AND SUGGESTIONS FOR
FURTHER RESEARCH 154
LITERATURE CITED . . 158
APPENDIX I Log position decay factors for
western hemlock 169
APPENDIX II Comparison of estimated per cent,
of gross tree volume decayed 'from
tree decay equation (A) and log ;
' position decay equation (B) for ' .
several suspect classes'. . ." ..• v '. 1178
APPENDIX III Taper table for'western hemlock• 180 APPENDIX IV Tabulation (Part I) and explanation
(Part II) of values derived during
calculation sequence for estimation
oof gross and net cubic foot volumes
by log position within a tree . . .
APPENDIX V Tree stem and decay profiles for
three western hemlock trees . . . . ix
LIST OF TABLES able . Page
f
1 Area classification .of British Columbia...... 1 2 Volumes in British Columbia forests 3 3 Gross volumes of commercial species on commercial forest land in British Columbia...... 4 4 Total volume of accumulated decay in trees 10 in. DBH+ in forests in British Columbia 5
5 Soundwood, decay and gross volume in coast and interior forests 5
6 Average annual decay losses in forests in British C O XllTTlL) 13. • • • • • . • • • • • • . • • • • • 7
7 Comparison of annual decay loss and annual growth
in the forests in British Columbia 7
8 Common butt rots and host species...... 10
9 Common trunk rots and host species . 11 10 Relative infections and decay volumes for important heartrots of western hemlock in several geographic locations 19
11 Pathological age classes defined by the British Columbia Forest Service 37
12 Influence of age and site on the proportion of trees with visible indications of defects • 41
13 Distribution of tree classes by DBH classes for western hemlock in five Public Sustained Yield Units (P. S. Y. U.) in British Columbia 42
14 Per cent decay in western hemlock trees having varying numbers of sporophores ...... 46
15 Distribution of decay volumes associated with sporophores of F. pini and E. tinctorium on western hemlock 47
16 Regression equations for estimation of per cent decay for individual trees 49
17 The frequency and occurrence and relative importance of abnormalities of decay significance on living western hemlock in the upper Columbia region .... 50 Table Page
18 Number of trees, site index, per cent merchantability and average age by sample number. . 57
19 Classification of stands sampled by sample number and area 58
20 External abnormalities tabulated and analyzed in relation to tree decay 60
21 Distribution of basic data by DBH classes...... 63
22 Heartrot identifications, descriptions and frequency of observation in 369 western hemlock trees.. 64
23 Summary of sound and decayed trees by tree class. . 67
24 Basic data summary for all (369) western hemlock trees 68
25 Basic data summary for 97 sound western hemlock trees 69
26 Basic data summary for 272 decayed western hemlock trees 70
27 Summarytof average statistics for 272 decayed western hemlock trees for various kinds of external abnormalities 71
28 Basic data summary for 111 "residual" western hemlock trees ' 72
29 Basic data summary for 278 "suspect" western hemlock trees 73
30 Frequencies and relative frequencies of occurrence of numbers of trees having varying numbers of external abnormalities. 75
31 Frequencies and relative frequencies of occurrence of external abnormalities and associated decay in 369 western hemlock trees 76
32 Distribution of trees with various external abnormalities 77
33 Frequency of occurrence and maximum, minimum and average heights of external abnormalities in 369 western hemlock trees.. . 78 xi
Table Page
34 Frequency of occurrence and maximum, minimum and average heights of external abnormalities in 97 sound western hemlock trees 79
35 Frequency of occurrence and maximum, minimum and average heights of external abnormalities in 272 decayed western hemlock trees...... 80
36 The frequency of occurrence of external abnormalities, singly and in combination, on 97 sound western hemlock trees. . 81
37 The frequency of occurrence of external abnormalities, singly and in combination, on V272 decayed western hemlock trees 82
38 Summary of relative numbers of trees with varying amounts of decay by tree class 86
39 Summary of percentages of trees with varying proportions of decay for various external abnormalities.. . 87
40 Numbers of trees, actual' percentage merchantability and percentage merchantability as predicted through British Columbia Forest Service (1966) loss factors for 369 western hemlock trees 91
41 Simple coefficients of correlation for variables / considered for use in development of tree decay factors 95
42 Some preliminary regression equations and statistics for use in the estimation of per cent decay volume in individual trees with from 1 to 10 independent variables 99
43 Some preliminary regression equations and statistics for use in the estimation of cubic foot volume of decay in individual trees with from 1 to 9 independent variables 100
44 Some regression equations and statistics for use in the estimation of per cent decay volume in individual trees with various groups and combinations of external abnormalities 102
45 Trial results for selected equation used to predict decay volume in individual trees 106 xii
Table - Page
46 Estimated decay volume expressed as a percentage of total tree volume by DBH classes for several external abnormality groupings.. 107
47 Summary of basic data by log position for 369 western hemlock trees...... 109
48 Simple coefficients of correlation for variables considered for use in development of log -.position decay factors...... 112
: 49 Some preliminary regression equations and statistics for use in estimation of per cent decay volume to specified heights (h) in individual trees with from 1 to 10 independent variables...... 114
50 Some regression equations and statistics for use in estimation of per cent decay volume to .specified heights (h) in individual trees with various groups and combinations of external abnormalities...... 115
51 Summary of actual and estimated decay volumes by log position within trees.. . 117
52 Summary of average diameters inside bark (d) and heights (h) at various cut sections for 369 western hemlock trees 123
53 Simple correlation coefficients for variables considered for use in development of a function to estimate upper stem diameters (d) . 124
54 Some preliminary regression equations and statistics for use in estimation of (d/DBH) with from 1 to 9 independent variables 125
55. Comparisons of actual and estimated stem diameters inside bark at various tree heights for several estimating equations 127 2 56 Regression equations for estimation of (d/DBH) for polynomials from degree one to five ' 130 57 Comparisons of actual and estimated values (d/DBH) from the independent variable h/H for polynomials from degree one to five 132
58 The extent of bias in the estimation of stem diameters from 5th degree polynomial equation for several DBH classes 133 XI11
-Table Page 2 59 Estimating equation for (d/DBH) incorporating variables and interactions as suggested in method proposed by Bruce et al. (1968)...... 134 60 Two equations for use in estimation of cubic foot tree volume between a 1-foot stump height and a 4-inch top diameter. 137
61 Analysis of variance for physical yields from western hemlock wood with various -stages of heartrot caused by Echinodontium tinctorium 149
62 Analysis of variance for holocellulose yields from wood of western hemlock with various stages of heartrot caused by Echinodontium tinctorium.. . . 149
63 Comparison of average physical yields and holo and alpha cellulose yields from western hemlock wood with various stages of heartrot caused by Echinodontium tinctorium...... 150
64 Analysis of variance for alpha cellulose yields from western hemlock wood with various stages of heartrot caused by Echinodontium tinctorium.... 151
65 Specific gravity of western hemlock wood infected with various stages of heartrot caused by "Echinodontium tinctorium.. 152 xiv
XIST OF FIGURES Figure Page
1 Relative cumulative frequency of decay percentages in individual western hemlock trees by British Columbia Forest Service (1966) tree classes. .... 89
2 Relative cumulative frequency.of decay percentages in individual western hemlock trees with various types of external abnormalities. 90
3 Scatter diagram showing per cent merchantability. and site index for 14 sample locations ...... 97
4 Relationship between estimated accumulated decay volume percentage and relative height for 20-inch DBH class trees for several external abnormality groupings, with an adjustment for other DBH classes. 118 2 5 The relationship between (d/D) and h/H showing a 5th degree polynomial curve fitted to average values of the basic data 129 6 Tree value (quality) and DBH relationship by site index classes for British Columbia interior Douglas fir 140 XV
LIST OF PHOTOGRAPHS
Photograph Page
I Typical old growth stand of western hemlock, Blue River, B.C...... 59
II Portion of a western hemlock tree sectioned for decay measurement 62
III Stump and top sections of western hemlock tree. • " ' "Heartwood destroyed by Echinodontium tinctorium. 65
IV Sporophores of Echinodontium tinctorium on western hemlock felled for decay measurement . . 74
V Small scars do not indicate significant amounts of decay in western hemlock 84
VI Frost cracks do not indicate significant amounts of decay in western hemlock 85
VII Large open scars indicate significant amounts of decay in western hemlock. 103
VIII Broken tops indicate significant amounts of - dec.ay in western hemlock 104
IX Dead tops indicate significant amounts of decay in western hemlock 105 1
CHAPTER I
INTRODUCTION
Probably mensurationists have devoted more time to the study of tree volume than to any other topic (Spurr, 1952) yet there is increasing concern now for improved determinations of log sizes and volumes as they are distributed within trees. Modern manufacturing methods, coupled with the multiplicity of possible end-uses of a single log in an integrated operation, require that the forester provide detailed information regarding the raw material supply. Data for the modern forest inventory must be collected in a manner that permits flexible and comprehensive analyses. Estimates of total volume per acre no longer suffice. Now the volume of material available in certain sizes and qualities must be estimated with high standards of precision and accuracy.
The ultimate success of any forest inventory depends upon the accuracy of estimation of • soundwood volume. No matter how accurate estimates of gross volume may be, predictions of soundwood volume will be in error unless reliable methods for estimating decay volumes have been developed and applied. In British Columbia, where forestry is the major industry and 136.7 million acres or 58 per cent of the land area is classed as commercial forest land (Table 1), the estimation of soundwood volume is particularly important.
British Columbia's forests contain a gross volume of 495 billion cubic feet in trees 4 inches DBH and larger and 403 billion cubic feet in trees'10 inches DBH and larger (Table 2). Approximately Table 1. Area classification of British Columbia.
Class of land and forest Millions of acres
Forest land Bearing commercial forest Productive 110.1 Low site 7.9 Total 118.0 Not bearing commercial forest Non-commercial cover 12.0 Not satisfactorily restocked 6.4
Total 18.4
Selectively logged forest 0.3
Total forest land 136.7
Non-forest land 91.3
Water 6.1
Total area in province 234.1
Source: British Columbia Forest Service^ 1957 3
Table 2.^ Volumes in British Columbia forests.
,_ . Gross volume (billions of cu. ft.) Class of forest , . -.„„• -in • n-6nj. 4m. DBH+ 10 in. DBH+
Commercial forest Productive site 442 365 Low site 27 23 Total 469 388
"Non-productive forest 16 10
Not satisfactorily restocked 10 5
Total 495 403
^ Source: British Columbia Forest Service, 1957
96 per cent of the volume or 388 billion cubic feet is located on commer•
cial forest land. Spruce species (Picea spp.) , western hemlock (Tsuga
heterophylla (Rafn.) Sarg.), lodgepole pine (Pinus contorta Dougl.) and balsam species (Abies spp.) are the most abundant (Table 3). Together
they account for nearly 72 per cent of the gross wood volume in trees
4 inches DBH and larger in the province.
Average decay percentages vary widely among species (Table 4),
ranging from 2 per cent in alder (Alnus rubra Bong.) to 57 per cent in
cottonwood (Populus trichocarpa Torr. and Gray). Western red cedar
(Thuja plicata Donn.) and balsam species are the most seriously defec•
tive conifers with average decay percentages of 32 and 19 per cent,
respectively. The total volume of decay in all living trees 10 inches
DBH and larger is 63.4 billion cubic feet (Table 5) and the annual decay
loss is approximately 681 million cubic feet (Table 6). In mature Table 3-.1 Gross- volumes of commercial species on commercial forest land in British Columbia.
Species Gross volume (billions of cu. ft.) 4 in. DBH+ 10 in. DBH+
Spruce species 130 107 Hemlock 80 73 Lodgepole pine 72 46 Balsam species 55 45 Western red cedar 48 46 Douglas fir 38 35 Aspen 17 13 Cottonwood " 10 8 Birch 6 4 Yellow cedar 4 4 Larch 3 2 Yellow pine 3 2 White pine 2 2 Alder 1 1 Maple 0.1 0
Total 469 388
Source: British Columbia Forest Service_, 1957 Table 4.^ Total volume of accumulated decay in trees 10 in. DBH+ in forests in British Columbia.
2 3 Total volume decay Average per cent Species /4, . , , • (thousands cu. ft.) decay
Western red cedar 13,046,831 32 Hemlock 12,399,435 18 Spruce species 11,685, 157 11 Balsam species 8,087,461 19 Aspen.. 5,371,602 42 Cottonwood 4,685,775 57 Douglas fir 3, 163,654 9 Lodgepole pine 2,871,349 6 Birch 890,336 24 Yellow cedar 731,707 23 Larch 216,587 10 White pine 157,506 9 Yellow pine 125,814 5 Maple 21,607 14 Alder 16,959 2
Total 63,471,780 17
Source: British Columbia Forest Service, 1957
Basis: live merchantable trees in commercial forests
Average percentage decay in gross cub'ic foot volume to close utilization standards.
Table 5. Soundwood, decay and gross volumes in coast and interior forests.
Volumes in billions of cubic feet 10 in. DBH+ Location . , , soundwood decay gross
Interior 216.9 39.5 256.4 Coast 89.5 23.9 113.4
Province 306.4 63.4 369.8
Source: British Columbia Forest Service, 1957 • -6 forests, annual decay losses amount to 583 million cubic feet or 316 per cent of estimated net'growth. In immature forests, however, decay losses are only 98 million cubic feet or 4.6 per cent of net annual growth (Table 7).
Regional average decay percentages are of little or no prac• tical use on a local basis. Often, the variability in decay in one species from different areas is greater than the decay variability among several species from the same area. Browne (1956) reported that analyses carried "out by the British Columbia Forest Service indicated that each tree species requires separate consideration within a forest region and a particular forest site. Foster, Thomas and Browne (1953) observed that decay loss factors within local areas in the Upper Columbia region ranged from 39 to 74 per cent of total gross volume. Foster
(1957) reported that decay in western red cedar ranged from 24 per cent in coastal regions to 47 per cent in interior regions. Western hemlock has been reported to be 7 per cent defective on" the Queen Charlotte
Islands (Foster and Foster, 1951), 10 per cent defective in western
Oregon and Washington (Englerth, 1941), 18 per cent defective near
Alberni (Foster, 1946) and 31 per cent defective in the Kitimat area
(Foster, Browne and Foster, 1958).
Although reasonably.reliable estimates of decay volume per• centages are available for inventory zones (British Columbia Forest
Service, 1966) in British Columbia, there is a scarcity of reliable information for local-areas. Comparisons of statistics reported often are complicated because of the fact that methods of calculating decay volumes have not been standardized. The need for such standardization was clearly illustrated by Foster (1958) who proposed standards of procedure and measurement for decay investigations„ Table 6. Average annual decay losses in forests in British Columbia.
Location Volume in cubic feet 4 in. DBH+
Coast 127,114,000 Interior 553,838,000
Province 680,952,000
Source: British Columbia Forest Service, 1957
Table 7.^ Comparison of annual decay loss and annual growth in the forests in British Columbia.
Description , Volume in millions of cubic feet
Immature forests Growth 2,127 Decay . 98
Mature forests Growth 184 Decay 583
All forests Growth 2,311 Decay 681
Source: British Columbia Forest Service, 1957 8
Most existing decay loss tables and equations are premised on
gross tree volume inside bark with some modification for age class,
diameter class, site class or external abnormality groupings. A mail
survey of nearly 100 forest pathologists in North America, a compre•
hensive search of the literature, and' electronic computer listings from
INTREDIS (Hepting, 1967) which covered pathology articles abstracted
in Forestry Abstracts, Review of Applied Mycology, Biological Abstracts
-and-Air Pollution Abstracts during the period 1958 to 1966 revealed no
equations which could be used to provide information on the amount or
extent of decay in individual logs within trees. Such information
could be of.value to foresters in valuation, scheduling of harvests and
planning for integrated forest operations. The major objectives of
this thesis, therefore,, are to develop and test analytical techniques
that will permit the determination' of the distribution of gross and net
volumes within individual standing trees in order that appropriate
reductions for decay can be made for estimates of volumes of logs of
specified sizes and grades. Western hemlock data were chosen for the
study because the species exhibits a wide variability in decay volume
percentage and hemlock is exceeded only by spruce species in gross
cubic foot volume of the forest resource in British Columbia.
Although this study is most concerned with distribution of
soundwood volume, some aspects of log value will be discussed in
relation to tree grades. Because of the very large volumes available,
utilization of decayed wood for pulp is considered briefly. 9
CHAPTER II
LITERATURE REVIEW
Important Heart Rot Fungi in British Columbia's Forests
Although decays can be, and often are, described according to"their pos'ition in" the" living tree, the same species of fungi" can - cause decay in roots, butts and stems of living trees. The decays commonly associated with butts and stems of living trees listed in
Tables 8 and 9 respectively,are considered to be the most important in the Pacific Northwest region of the United States and Canada (Bier,
1949; Baxter, 1952; Boyce, 1961).
Excellent illustrations and descriptions of most of these decay-causing fungi were reported by Bier (1949). Two species of fungi listed in Tables 8 and 9 are responsible for a significant proportion of the total decay volume in British Columbia conifers, particularly western hemlock. These are Echinodontium tinetorium E. and E. and
Fomes pini (Thore) Lloyd. Kinsman (1964) examined 235 western hemlock
trees in the Kitwanga Public Sustained Yield Unit (P0S.Y„U.) and reported that F_. pini and E. tinctorium were the cause of all decay observed in a total of 60 trees containing measurable amounts of decay. Foster _et al. (1954) found that E. tinctorium and F. pini accounted for 60 per cent and 16 per cent respectively,of gross volume of decay in western hemlock in the Big Bend area of British Columbia. Thomas and Thomas
(1954) reported that F_. pini was associated with nearly half of the decay volume in coastal Douglas fir (Pseudotsuga menzies.ji (Mirb.) Franco) 10
Table 8. Common butt rots and host species.
Fungus Important host(s)
Armillaria me Ilea (Vahl.) Quel. spruces, pines, oaks, (shoestring fungus, honey mushroom) chestnuts
Fomes annosus (Fr.) Cke. old growth western (white stringy root rot) hemlock, most conifers
Fomes applanatus (Pers.) Gill, hardwoods, most (shelf fungus, artist's conk conifers polyporus Schweinitzii Fr. Douglas fir, spruces, (velvet top fungus) larches, pines
Polyporus balsameus Pk. true firs, western red (balsam conk, brown butt rot) cedar
Poria We ir i i Murr . western red cedar, (yellow ring rot) Douglas fir
Poria albipellucida Baxter western red cedar (laminated rot, paper rot)
Por ia as.iatica (Pilat) Overh. western red cedar (brown cubical rot)
Poria subacida (Pk.) Sacc. true firs (feather rot, stringy butt rot) • 11
Table 9. Common trunk rots and host species.
Fungus Important host(s)
Echinodontium tinctorium E. and E. western hemlock, true firs (brown stringy trunk rot)
Fomes pini (Thore) Lloyd Douglas fir, larches, (ring scale, pecky rot) pines, western hemlock, spruces, western red cedar
Fomes pinicola (Swartz) Cke. Douglas fir, Sitka (red belt fungus) spruce, western hemlock, true firs
Fomes laricis (Jacq.) Murr. Douglas fir, Sitka spruce (quinine fungus) western hemlock, yellow pine, western larch
Hydnum sp. western hemlock, true (long pitted trunk rot) firs
Lentinus Kauffmanii Smith Sitka spruce (brown pocket rot)
Polyporus sulphureus (Bull.) Fr. Douglas fir, western (sulphur fungus) hemlock, Sitka spruce, true firs
Polyporus abietinus Dicks, ex Fr. dead sapwood of most (pitted saprot, hollow pocket rot) conifers
Polyporus volvatus Pk. most conifers (pouch fungus)
Poria tsugina (Murr.) Sacc. and Trott. western hemlock, true- (white trunk rot) firs
Poria monticola Murr. Sitka spruce
Stereum sanguinolentum A. and S. (red heart rot) true firs, pines, spruces
Stereum abietinum Pers. (brown cubical pocket rot) western "hemlock, true firs
Trametes serialis Fr. Sitka spruce, Douglas fir (dry rot) 12
Nearly 30 per cent of the decay volume of all species in Ontario is caused by F. pini (Basham and Morawski, 1964) and about 74 per cent of decay in Engelmann spruce (Picea Engelmanni Parry), lodgepole pine and subalpine fir (Abies amabilis (Dougl.) Forbes) in Colorado (Hornibrook,
1950). Nearly half of the decay in balsam in the upper Fraser region of British Columbia is caused by -F. pini (Bier et_ al., 1948). Because of the importance of these two species of fungi, they are discussed in more detail in the following sections. •
Echinodontium tinctorium E. and E.
Echinodontium tinetorium, commonly called the Indian Paint
Fungus, causes a brown stringy rot in the heartwood of living coniferous trees throughout North America. According to Thomas (1958) it has been reported to commonly attack western hemlock and most species of Abies and to occasionally attack Engelmann spruce and western white spruce
(Picea glauca (Moench) Voss). The western North American genera
Chamaecyparis, Juniperus, Larix, Pinus, Taxus and Thuja appear to be either non-susceptible or only very slightly susceptible to E. tinctorium.
Spores are produced on basidia in a hymenium which extends over a spiny structure on the lower side of the fruiting body. The sporophores are perennial and by adding a new hymenium annually can remain active for several years. The spores are airborne to potential infection courts, commonly branch stubs and open scars (Thomas, 1958).
In appearance, the sporophores or conks, are black and rough or cracked on the upper surface. The lower surface is a dull grey and is charac• terized by hard coarse spines. When broken open, the interior exhibits a rusty red color (Boyce, 1961) . Fruiting bodies as wide as one foot 13
have been reported (Baxter, 1952).
Incipiently decayed wood is characterized by light-brown areas of discoloration, sometimes associated with small radial pockets. As decay progresses, reddish streaks follow the grain, the wood becomes soft and separates along the springwood in the annual rings. In the final stages, the wood is reduced to a brown, fibrous, stringy mass
(Boyce, 1961). (Despite the brown color of the rotted wood, this fungus has been categorized pathologically as a "white-rot" fungus (Nobles,
1948; Gross, 1964; Maloy, 1967. See page 26 of this thesis.) The rot is not generally confined to any portion of the tree stem but some investigations have shown it to be more prevalent in the middle section
(Kinsman, 1964).
Thomas (1958) surveyed the occurrence of this fungus throughout
British Columbia and concluded the following:
1. The distribution and abundance of the fungus closely follows
the occurrence of specific forest types. Maximum infection
levels are associated with trees of low vigor, particularly
those trees which retain dead branches for long periods of
t ime.
2. Maximum infection potential occurs when high summer tempera•
tures and sustained high humidities are present in combination.
3. The presence of the fungus in individual stands is determined,
in part, by the proportion of the stem length over which
favourable temperatures and humidities prevail.
4. Within local climatic regions, altitude has an important
effect on the fungus because of its influence in the deter•
mination of rainfall and temperature. -14
5. Different host species may have inherent susceptibilities to
infection.
The requirements of high temperature in combination with high humidity for maximum infection potential are substantiated in part by Miller's (1962) findings that, in culture, the basidiospores have stringent moisture requirements and may even require an aqueous solution before germination-can occur.
The extremely large amounts of decay caused by this fungus in western hemlock in the. upper Columbia region, contrasted with negligible amounts in coastal areas, led Foster and Craig (1957) to hypothesize that
"...certain of the excessive cull associated with hemlock may be attributed to unfavourable site conditions." and to suggest that:
"...consideration should.be given in future management to the encouragement on some sites of species other than hemlock in order to minimize future losses from disease."
After a thorough and comprehensive review of the literature
Maloy (1967) stated: •
"Despite the many and varied studies on E_. tinctorium, 'information on this fungus and its activities is still fragmentary. There is little doubt that E. tinctorium is a major cause of decay in true firs and hemlock, but is it the only cause? It is difficult to reconcile the very slow growth of the fungus in culture and its slow rate of growth in inoculated wood blocks with the exten• sive decay columns found in relatively young trees. The consistent recovery of several imperfect fungi and the occasional isolation of other decay fungi leads to the tentative conclusion that E. tinctorium may be merely the climax species of a succession of fungi colonizing .the heartwood of these tree species."
There is an obvious need for further research regarding this fungus if adequate and efficient control measures are to be developed. 15
Fomes pini (Thore) Lloyd
Fomes pini, commonly called red ring rot, ring scale, red heart or conk rot causes a white pocket rot, usually confined to the heartwood, in almost all North American coniferous tree species with the exception of Cupressus spp. Economic losses caused by this fungus reportedly exceed those from any other wood-decaying fungus (Boyce,_ .
1961).
Spores are produced on basidia in a hymenium which lines numerous tube-like structures on the lower side of the fruiting body.
The sporophores are perennial and extremely variable in size and shape
(Baxter, 1952). They range from 1 inch to more than 12 inches in width, but usually average about 6 inches in width and are commonly hoof- shaped. The upper surface is dull grey or brownish and is characterized by circular furrows parallel to the margin., The lower surface is usually brownish in color with tube mouths ranging from small and circular to large and irregular (Boyce, 1961). The interior is yellowish brown and punky in-texture.
Incipiently decayed wood is characterized by a pronounced reddish discoloration in the heartwood. As decay advances, elongated whitish pockets develop parallel to the wood grain and sometimes become filled with resin. Zone lines are often distributed irregularly through• out infected wood. In the final stages of decay, the white pockets may merge and become indistinguishable so the entire decayed area is reduced to a mass of white, fibrous material (Boyce, 1961). -Usually the decay is confined to the heartwood but in Douglas fir particularly, it also attacks sapwood and kills the host in a relatively short time
(Boyce and Wagg, 1953) . Infections are not confined to particular 16 sections of the bole, but are usually less prevalent in butt logs than in top logs (Boyce, 1961)...
Swollen knots or punk knots are often formed at points where old conks have deteriorated or fallen off. These, along with blind conks, which are-punk knots overgrown by sapwood, are useful external indicators of decay in Douglas fir (Boyce and Wagg, 1953).
Some investigators have observed that rot caused by this fungus extends much farther in the tree above the sporophore than below it. Bier and Foster (1944) reported that rot in Sitka spruce rarely extended appreciable distances below the lowest visible sporophore.
Analyses of 354 trees in the Queen Charlotte Islands indicated that this fungus was confined almost entirely to the upper portions/ of the bole.
Kinsman (1964) on the other hand, found this fungus to be more prevalent on the lower third of stems of western hemlock in the Kitwanga P.S.Y.U. f
Ohlmann (1959) observed that the moisture content of wood of Pinus Syl- vestris' L. infected with F. pini was higher than healthy wood and hypothesized that wood moisture content variability might account for the fact that the fungus progresses faster up the stem than down.
Bratus and Kirilenko (1960) suggested that differences in natural resin content, not moisture content, explained differential growth rates of ' the fungus. Boyce and Wagg (1953) conducted one of the most extensive and thorough investigations of F. pini in Douglas fir. The concluded that:
1. The development of conk rot in individual trees increases
with treei age.
\ 2. The development of conk rot in stands is cyclical. 17
.3. Infection and decay development is greater on good sites
than on poor sites.
4. Extensive rot development is associated with areas of higher
temperature and that temperature may be a controlling
factor in the growth of the fungus.
Important Heartrot Fungi in Western Hemlock
In addition to Fomes pini and Echinodontium tinctorium discussed in the previous section, there are other heartrot fungi which cause significant amounts of decay in western hemlock. Kimmey (1964) estimated that the total volume of decayed wood in commercial sawtimber stands of western hemlock throughout its geographic range amounts to
120 billion board feet (roughly 25 per cent of gross volume). He reported that approximately 50 species of fungi cause heartrot in west• ern hemlock but that only 13 species produce significant volumes of decay. Some of * these fungi, are abundant, absent from, or insignificant in certain areas in the range of western hemlock. A knowledge of their distribution is important because many species differ considerably in the amount and type of decay they can cause. Foster and Foster (1951) conducted an excellent review of the literature on studies pertaining to decay of x^estern hemlock in British Columbia, Washington, Oregon and
Alaska and concluded:
"From this review of literature, it is evident that significant differences on a regional basis are to be anticipated in the complex of decay-producing fungi, and their associated volumes of cull. In view of the apparent lack of information relating to the analysis of factors contributing to excessive variations of the nature mentioned, it is evident that regional boundaries cannot, at present, be defined with any degree of accuracy." 18
Decay-causing fungi in table ID are listed in order of importance for white-rots and brown-rots, respectively, in the central coastal region of Oregon, Washington and British Columbia reported by
Kimmey (1964). As is evident from table 10, the relative amount of heartrot caused by any one fungus species varies markedly in different geographic areas. For example, no volumes of decay caused by Echino• dontium tinctorium are reported for the Queen Charlotte Islands and
Franklin River area on Vancouver Island. In the Upper Columbia region in the interior of British Columbia, however, it is by far the most important decay-causing fungi, accounting for 62 per cent of the total decay volume in western hemlock. Fomes pinicola, on the other hand, is of minor importance in the Upper Columbia, accounting for only 4.8 per cent of decay volume, but in the Franklin River Area it accounted for
40.8 per cent of total decay volume.
It is important to consider the location of the decay within the tree caused by different species of fungi. Some of the root and butt rots, such as Fomes annosus, Polyporus schweinitzii and P. sulphureus may extend a considerable distance up the tree bole, thus causing high decay losses in wood of high quality butt logs. Others, such as
Armillaria meIlea, Poria subacida and Fomes applanatus usually decay only roots or butts. Rots caused by Fomes pini and Echinodontium tinctorium often enter the bole through branch stubs but decay caused by these fungi can affect the entire tree bole. Table 10. Relative infections and decay volumes for important heartrots of western hemlock in several geographic locations.
Geographic Location
Organism Queen Charlotte Franklin Kitimat3 Is lands River2 Infections Decay (per cent Volume I D I. D of total) (per cent of total) White-rots (I) (D) Fomes annosus (Fr.) Cke. 10.3 11.2 6.9 7.3 1.6 1.1 Poria subacida (Pk.) Sacc. 10.7 4.8 20.6 10.2 0.3 0.6 Fomes pini (Thore) Lloyd 6.3 12.9 9.1 12.8 24.1 47.9 Fomes robustus Karst. - - 3.4 2.6 - Armillaria me Ilea (Fr.) Quel. 6.8 7.1 14.0 6.4 4.1 . 2.6 Fomes applanatus (Pers.) Gill. 3.1 .4.0 1.4 Trace - - Stereum sanguinolentum A.& S. ex Fr. 0.4 Trace - - 18.1 V 6.6 Pholiota adiposa (Fr.) Quel. - - - - ' - Echinodontium tinctorium E.& E. - - . - - . 17.5 19.8 Brown-rots Fomes pinicola (Sw.) Cke. 12.1 14.6 20.0 40.8 6.3 4.6 Polyporus sulphureus (Bull.) Fr. 5.7 9.4 1.8 0.8 0.5 0.3 Stereum abietinum Pers. 8.2 5.4 5.7 3.0 11.8 5.8 Polyporus schweinitzii Fr. 0.9 1.3 - - - .Other or unknown 35.5 29.3 .21.5 18.7 12,3 9.1
Infected Trees (per cent of total) 48.3 32.5 66.0 Decay volume (per cent of gross vol.) 10.6 25.0 31.0
£ Foster and Foster, 1951. ' Buckland e_t al., 1949. 3 Foster et al., 1958. Table 10. Relative infections and decay volumes .for important heartrots of western hemlock in several geographic -locations (cont'd.).
Geographic Location- Western Wash, Organism and Oregon4 Upper Columbia-*
I D I D White-rots Fomes annosus (Fr.) Cke. 17.7 22.8 0.8 0.2 Poria subacida (Pk.) Sacc. - 2.8 1.4 Fomes pini (Thore) Lloyd 19.1 15.8 12.6 25.2 Fomes robustus Karst. - - - - Armillaria mellea (Fr.) Quel. 7.2 3.9 - - Fomes applana.tus (Pers.) Gill. 9.2 15.8 - - Stereum sanguinolentum A.& S. ex Fr. - - '2.0 0.2 Pholiota adiposa (Fr.) Quel. - - • - - Echinodontium tinctorium E.& E. 8.3 4.9 56.8 62.4 Brown-rots Fomes pinicola (Sw.) Cke. 12.6 4.9 4.4 4.8 Polyporus sulphureus (Bull.) Fr. 1.5 3.9 - - Stereum ab'ietinum Pers. • - - 2.8 1.9 Polyporus schweinitzii Fr. 2.3 1.0 - - Other or unknown 22.1 25.0 17.8 3.9
Infected Trees (per cent of total) 60.1 Not available Decay volume (per cent of gross vol.) 10.1 50.8
4 Englerth, 1942. 5 Foster et al., 1954. 21
In dense stands of coastal areas, growth of branches which contain significant amounts of heartwood to act as avenues of infection is prevented by natural pruning,and decay caused by these fungi is often confined to upper portions of the tree bole.
Many heartrots are associated with trunk wounds and the location of the rot is therefore dictated by the location of the wound.
Western hemlock has a particularly thin bark and the bole is susceptible to scarring from falling trees (Englerth, 1942). Many such scars are superficial and heal over quickly. Large scars, however, do not heal over rapidly because of the inability of western hemlock to produce resin in large quantities and they often serve as entrance courts for decay-causing fungi (Kimmay, 1964).
It appears that fungal activity in a given area is governed to a large extent by environmental considerations (Boyce, 1961) and, therefore, a knowledge of environmental conditions required for fungal establishment and growth should aid in developing methods to describe decay distributions within tree stems. 22
Environmental Conditions Required for Fungal Establishment and. Growth
In common with other members of the plant kingdom to which they belong, fungi require suitable environmental conditions for growth.
The main factors involved - food, air, temperature and moisture - were reviewed in detail by Munro (1967a) and are therefore considered only briefly here.
Food
With the exception.of the mould and staining fungi, all fungi which infect, wood require wood, or at least some of the components of wood, as food. Very broadly, wood-destroying fungi can be separated into two distinct classes. The first class consists of those which de• compose all components of wood, including lignin. These are called white- rot fungi. The second class consists of those which decompose only cel• lulose and its associated pentosans, leaving lignin relatively unchanged until decay is well advanced. These are called brown-rot fungi. Wood affected.'by white-rot fungi is generally white in color although it may be yellow to light brown. It may be completely reduced to a spongy, stringy or fibrous condition, or portions of undecayed wood may bo separated by white pockets or streaks of rot. Wood affected by brown- rot fungi is eventually reduced to a brownish-colored crumbly mass.
Both classes of wood-destroying fungi feed on components of the cell wall. Various types of fungi attack different cells and different cell wall components. Depending on the fungi, holocellulose or lignin may be equally affected or one or the other may be attacked preferentially. The actual decay of the wood is caused by fungal enzyme secretions which transform the various components' of the cell 23
walls into substances of nutritive, value to the fungus. It is thought
that the primary chemical reactions involved are oxidation and hydrolysis
(Findlay, 1932, 1940, 1956). The secreted enzymes can affect wood
components even if the fungal hyphae are not in direct contact with
the wood.
Decay progresses as the fungal hyphae grow and find their way
through the wood. The hyphae generally adhere closely to the inner walls of cells and progress along the long axis of the cell. They pass from cell to cell, either directly through the cell wall or through
the pit membranes. Passage of hyphae through cell walls is accomplished by the chemical reaction of hyphal secreted enzymes on the cell wall.
A portion of the cell wall is chemically dissolved by these enzymes to
facilitate passage of the hyphae.
As decay advances, the hyphae and hyphal holes in the cell walls become more numerous. In brown-rotted wood, diagonal or spiral
shrinkage cracks' may appear in the cell walls. Cells may become filled with irregularly deposited decomposition products; secondary cell walls
may become uneven in thickness; the middle lamella may dissolve; pit
cavities may become enlarged or destroyed; or the entire cell wall may
disintegrate. In some cells, resin deposits may occur (Boyce, 1961).
Elongated, crystal-like cavities in the secondary cell walls, oriented
to the angle of the cellulose fibrils, are associated with the soft rot
fungi (Duncan, I960). They are thought to be enzymatically produced
and caused by the longitudinal penetration of the cell walls by the
fungal hyphae (Boyce, 1961; Cartwright and Findlay, 1958). Wood decayed
by soft rot fungi usually retains its shape, but becomes extremely soft
when wet and brittle when dry.
When all material nutritive to either class of fungi has 24
been exhausted from the wood it is thought that the hyphae themselves disintegrate (Boyce, 1961). At this point, the infected wood has been greatly reduced in strength and in most instances will consist of nothing more than a crumbly mass of fungal decomposition products.
Air
As far as can be determined, all wood-destroying fungi require free oxygen in order to maintain life. According to Boyce (1961), an amount of air equivalent to more than 20 per cent of the volume of a piece of wood is necessary before decay can occur.
Temperature
Tests of fungi in culture have provided some information on temperatures requisite for growth' of wood-destroying fungi. Cartwright and Findlay (1958) reported optimum temperatures ranging from 20° to
36°C (68° to 97°F) for most fungi. They also reported that the optimum temperature for 147 species tested at the University of Michigan was between 76° and 86°F. The lowest optimum recorded was 68°F and the highest 94°F.
Moisture
Fungal spore germination and growth require moisture and it
is generally recognized that wood in a partially air-dry condition
(i.e. below about 18 per cent moisture content) is immune (Fritz, 1952).
If wood is infected and then air-dried, fungal growth will cease, but
the fungi will not be killed. They may remain inactive for many years and when sufficient moisture is later obtained, revive and continue to 25
grow (Baxter, 1952; Fritz, 1952).
Of considerable importance, is the balance between moisture and air, because both are required for growth. Since air is necessary for wood-destroying fungi, the more wood substance in a given volume of wood, the less free water it will hold before the air supply is reduced below the minimum requirement.
Decay Resistance
Regional variation
Baxter (1952) prepared an abbreviated list of the natural durability of common North American woods. Duncan and Lombard (1965) classed western hemlock as non-resistant and stated that:
"...the local climate, site and availability of favorable host species are probably the dominant distribution factors for the majority of fungi."
Sapwood- •- .heartwood•'.relationships..
The sapwood of nearly all species, even in those which have highly durable heartwood, is susceptible to infection by wood-destroying fungi. The greater durability of heartwood is mainly due to the presence of extraneous materials, some of which are toxic to fungi. Other factors which may explain the greater durability of heartwood are lower moisture content, lower rate of diffusion, and blocking of cell cavities by gums and resins which affect the air-moisture, balance necessary for fungal growth. Various fungicidal extractives are common in coniferous woods, but none have been isolated from western hemlock wood (Panshin, deZeeuw and Brown, 1964). 26
Density
Cartwright and Findlay (1958) cited seven authors, all of whom conducted extensive research into the correlation of wood density and durability and concluded that it was not statistically significant.
Even within species or individual trees, variations in density were not shown to be related to durability. -
Position in tree
The durability of wood from various positions in the tree is determined largely by the extractive distribution, the relative amounts of sapxtfood and heartwood and the specific fungal organisms. There seems to be no general relationship between durability and the position of the wood in the trunk for all woods. Durability differences among individual trees are as great as those from the same positions in different trees '(Baxter, 1952).
Effects of Decay on Wood Quality
Chemical
As mentioned on page 22, the wood-destroying fungi are commonly classified into two groups - the white-rots and the brown-rots. Accord• ing to Findlay (1949) these groups can be defined as:
"...those fungi which produce hydrolyzing enzymes and • attack cellulose and associated pentosans, bringing about "brown" carbonizing rots which leave the wood in a friable powdery condition and those which produce oxidizing as well as hydrolyzing enzymes, attacking all the constituents of the wood, including lignin, and bring about white or light-colored rots." 27
Garren (1-938) detected a total of 20 different enzymes pro• duced by wood-destroying fungi.
Although most fungi can be classified in one of the above groups, there are some so-called brown-rots which are capable of eventu• ally destroying all the wood constituents.
Cartwright and Findlay (1958) reviewed the progress of research on the chemical processes involved in the decay of wood and . stated that the general decay process is fairly well understood but that little information is available about intermediate products formed during decomposition. They also stated:
"The successive degradation of cellulose and of the other polysaccharides in the wood appears to begin with a shortening of the cellulose chains, and this, with in• creasing hydrolysis of the polysaccharides, leads to the breakdown of the condensation products of the various wood sugars with formation of the corresponding hexoses and pentoses, which at certain stages in decay are formed more rapidly than the fungus can utilize them, so that an extract from decayed woods shows strongly reducing properties when tested with Fehling's solution....when the structure of this substance (lignin) is better under• stood it will be possible to find out how closely the residual lignin left after fungal decay resembles the original material as it occurs in the cell walls of the wood."
Mechanical
In the advanced stages of decay, it is obvious that decayed wood is softer, more brittle and not as strong as sound wood. In the incipient stages, however, the effect of fungal infection may not be readily apparent.
According to Cartwright and Findlay (1958), Longyear (1926) was the first researcher to publish the results of a careful series of mechanical tests on samples exposed to decay. His results showed 28
considerable strength losses before weight loss occurred. These results
have been confirmed by several investigators (Cartwright e_t al., 1931;
Mulholland, 1954).
Cartwright and Findlay (1958) stated that more severe and
rapid reductions in strength properties are caused by brown-rot fungi
than by white-rot fungi. Loss in strength'caused by white-rot fungi is
due mainly to "the depletion and alteration of the cellulose and its associated pentosans." The eventual depletion of lignin apparently
only adds to an already well advanced mechanical breakdown. From a
comprehensive literature review on this topic, Cartwright and Findlay
(1958) concluded that:
1. "Fungi causing brown-rots (in which attack is mainly directed against the cellulose) bring about a fairly rapid drop in strength properties of wood."
2. "Fungi causing white-rots (in which all constituents of the wood are attacked) may also, in the case of certain species, bring about a rapid drop in toughness, but probably less rapidly than by brown rots."
3. "Toughness, or resistance to impact, as measured by impact, bending or the "Izod" test, is the strength quality which is most rapidly affected by fungal infection - followed in approximate order of susceptibility by ben• ding strength, compressive strength, hardness and elasticity."
4. "The strength properties of infected wood must not be
assumed to be unimpaired, even if it is hard and firm."
Kennedy (1961) investigated the influence of incipient decay
caused by two white-rot fungi and two brown-rot fungi on the micro-
tensile strength of several woods. He concluded that the amount of
tensile strength reduction before measurable weight loss was signi•
ficantly different from the rate of tensile strength reduction per
unit of weight loss for various combinations of fungi and woods tested. 29
..Specific gravity ~
The loss in dry weight expressed as a percentage of original dry weight can provide a statistic which is useful in comparing amounts
of decay in wood. In some instances, however, it may not be reliable.
In brown-rots, for example, where lignin is usually not decomposed until decay is well advanced, the maximum weight loss that can occur is
_about 70 per cent (Cartwright and Find lay, 1958). In other cases,
serious strength losses may occur before appreciable changes in density
can be detected (Scheffer, 1936) .• Glennie and Schwartz (1950) pointed
out that in some cases the difference in density between decayed and
sound wood, is not greater than the normal variation in density between different samples of sound wood from any one species.
The loss of wood weight provides a statistic which indicates
the direct loss of wood substance due to volatilization of the end products of decay, but does not reflect the degeneration of nonvolatile
intermediate products (Glennie and Schwartz, 1950). However, because
of the simplicity of determining weight loss, it is the most common
laboratory method used as a measure of the extent of decay.
Color
As decay progresses in wood it is sometimes accompanied by
color changes. In the incipient stages, these are often difficult to
detect. Because one fungus can cause the formation of different colors
in different host species, and heartwood in many species has natural
color variations, it is difficult to diagnose decay in wood on the
basis of color alone. MacLean and Gardner (1956) observed that color
variations in the heartxv'ood of western red cedar were related to the 30 concentrations of thujaplicins and water-soluble phenols - both natural fungicides. A change from a light to a darker color coincided with a decrease in fungicidal concentrations. Roff, Whittaker and
Eades (1962) carried out comprehensive studies on the relationship between color and decay in logs from three western red cedar trees.
They showed that, in general, brown heartwood from logs which contained obvious rot was low in decay resistance. From similar positions in the tree, straw-colored wood was most resistant and tan-yellow wood was least resistant.
With the possible exception of the spruces and true firs, western hemlock wood is unlike other important coniferous species in
British Columbia in that it exhibits very little natural color varia• tion. The wood is generally a uniform whitish to yellowish brown color.
The heartwood is not distinct from the sapwood and without the aid of magnification or sensitive color tests it is difficult to distinguish any transition line separating the two.. (Brown, Panshin and Forsaith,
1949). In many instances small white chemical deposits called floccosoids, which occur naturally, are easily confused with coloration caused by white-rots (Barton, 1963).
Moisture-holding capacity
Decayed wood absorbs and loses water more rapidly than sound- wood, probably because the hyphal bore holes allow rapid entry and dissemination of moisture throughout the decayed wood (Panshin, deZeeuw and Brown, 1964). Although the equilibrium moisture content of decayed wood may differ from that of soundwood in a given relative humidity, the difference is generally small and of little practical significance. If 31
-decayed" wood is subjected to alternate periods of wetting and drying,
however, it retains moisture for a longer- period of time than does
soundwood subjected to the same treatment. It appears, therefore,
that once.wood is infected, moisture conditions favourable for fungal
growth will be retained for a longer time than in soundwood (Cartwright
and Findlay, 1958).
.Utilization of Decayed Wood
Pulp .
Creamer (1950) summarized literature up to 1949 regarding the
use of decayed wood for pulping and pointed out that although decay
does not affect the gross volume of wood, the density can be greatly
reduced and with it the yield of pulp per unit of wood volume. In
addition to cellulose losses due to decay, excessive chip losses caused
by brashness of the partially decayed wood are common. Mechanical or
hydraulic debarking of decayed wood also results in higher than normal
wood losses. Creamer stated:
"It is extremely difficult to correlate the degree of decay with changes in the chemical or physical properties of wood or pulp but most work in this field is in general agreement with the following effects of decay:" 'Groundwood Pulp - Use of decayed wood causes lower yields, lower strength, darker color, more dirt and shives, and less permanency, the only advantageous effect being lower power consumption. The features, of course, depend on the extent of the decay.-' 'Sulphite Pulp - Lower yields, darker color, lower strength, dirt arid shives, higher bleach consumption and higher chipping losses follow the use of decayed wood. Although a shorter cooking time is required, it is not possible to take advantage of the slight change unless an entire di• gester charge of uniformly decayed wood is accumulated. Since grading of decayed wood is very difficult, chips of varying degrees of soundness usually find their way into the same digester and the result is overcooking for the decayed chips or undercooking for the sound chips.•" 32
Alkaline Pulps - Use of decayed wood causes lower yield, higher consumption of chemicals and higher chipping losses. Dirt and dark colors make little difference in unbleached kraft grades and the alkaline cooking liquor dissolves degraded carbohydrates, thus guaranteeing a fairly high alpha-cellulose content and a fair strength for the resulting pulp. For these reasons the kraft process is best suited for the utilization of partially decayed pulpwood."
Glennie and Schwartz (1950), after a comprehensive search of the literature on the effects of decay in pulpwood on pulp quality, stated: N
l "Although decayed wood may give lower yields of sulphite pulp than sound wood, in general it can be said that this pulp suffers only slight loss in quality when the decay is not far advanced."
After an extensive series of pulping tests of Douglas fir wood { v. decayed by F. pini, Martin (1949) concluded:
"A possible composition containing decayed (Douglas fir) wood and a minimum amount of the associated species that would produce a sulphate pulp having the same qualities as one made entirely from sound Douglas fir might be made up of 65 percent sound wood, 25 percent incipient-decayed wood, and 1C* percent associated species."
Bjorkman e_t al_. (1964) carried out extensive sulphate and sulphite pulping tests on spruce (P.abies(L). K) and pine (Pinus silvestris).
A linear relationship between pulp yield and the proportion of decayed wood included was observed in all cases. Firm dark and firm light rot types usually caused only small reductions in pulp yields, even when included in relatively high proportions. On the other hand, soft light and soft dark rot types reduced pulp yields in approximately direct proportion to the percentage of rot included in the test cooks. i ^ \ Statistical analyses of sulphate pulp strengths indicated that in almost all instances there was no significant difference between pulp from soundwoodd and pulp from mixtures of sound and decayed wood. 33
It was observed, however, that bursting strength and tear factor were slightly lower when higher proportions of decayed wood were included.
Bjorkman e_t a_l. (1964) concluded the following regarding the production of pulp from coniferous species investigated:
1. "Soft dark and soft light rot proved to result in a great increase in wood consumption and impairment of the quality of the pulp. When bleaching of the pulp takes place, such rot may, however, be admitted. . A volume deduction of 100 percent for the damaged volume of such decay is suggested."
2. "Firm dark rot, apart from its impairment of quality, also gave a lower yield than the corresponding soundwood. A certain proportion might therefore be included in pulp wood provided that some deduction is allowed for. A deduction of 100 percent for the volume of decayed wood seems unneces• sarily high but might be justified by the need for the maximum simplification of the assessment in practice."
3. "Firm light rot did not cause an appreciable Impairment of the pulp, whatever proportion was included. Although there was undoubtedly some initial breakdown and loss of strength, this type of decayed wood may conveniently be included without deduction and thus counted as a "tolerance defect". Some compensation for the too great deduction for the firm dark rot is thereby obtained."
Since 1948 in Sweden, wood containing top rot caused by
Stereum sanguinolentum has been used in the manufacture of pulp. Scaling regulations in that country do not permit deductions for this defect because it has been shown that pulp quantity and quality is not signi• ficantly impaired by inclusion of this material when mixed with sound- wood (Bjorkman e_t a_l., 1964).
Sheridan (1958) summarized information provided by pulp mills represented in the Technical Section of the Canadian Pulp and Paper
Association regarding the use of decayed wood for pulping. Two mills,
(Mill B and Mill C) reported on studies of sulphate pulping of decayed wood. In one instance, the decay organism was positively identified as 34
Fomes pini, in the other, the fungus was not positively identified, but
the rot description was similar to that of rot caused by F. pini.
Mill B concluded:
"...the heavy culling of punky wood is a wasteful practice because most of the infected wood produced a fair yield of suitable pulp."
Mill C concluded:
"Pulpwood infected with Fomes pini should not be culled in its early stages of decay because it only attacks the cellulose " in the more advanced stages of rot."
Other manufactured products
The use of decayed wood for the manufacture of products other than pulp is limited. For example, the scaling regulations* of the British
Columbia Forest Service (1963) require that logs of most tree species with less than one-third of their gross scale in soundwood content
(less than one-half for some species) be classed as culls. It is only rarely that culled material is removed from the forest and converted into useful products.
In most instances, decayed wood that reaches a manufacturing plant is eliminated during the manufacturing process. Peeler log grade rules are strict in specifications concerning permissible decay allow• ances. Usually only a minor amount of heartrot is allowed, and this must be small enough in size to enable the log to be securely held in a lathe chuck (Plywood Manufacturers Association of British Columbia).
No decay is permitted in plywood (Canadian Standards Association, 1961,
1961a). \ • \ ' Lumber grades in use in British Columbia (British Columbia
Lumber Manufacturer s'Association, 1959) do not permit the use of decayed
/ 35
wood in any but the. lowest grades. "Utility" grades permit the use of
unsound wood "in small spots and streaks wall scattered." "Economy"
grades, generally suitable for use as crating, bracing, cribbing or
dunnage, permit the use of decayed wood in lumber lengths longer than
eight feet provided that "at least 75 percent of the piece is usable
after it has been cut into two or three pieces."
The use of decayed wood in the manufacture of poles and
piling is generally not permitted.
Relationships Among Tree and Stand Age, DBH, Site Quality and Decay
Incidence of infections and volumetric decay losses in trees
are often observed to increase progressively with tree size as measured by DBH. Probably more decay studies have been summarized and presented
on a diameter class basis than any other (e.g. Bier, Salisbury and Waldie,
1948; Waldie, 1949; Thomas and Thomas, 1954; Etheridge, 1958; Estep
and Hunt, 1964; Aho, 1966).
For western hemlock in the Kitimat region of British Columbia,
infections increased from 31 per cent in 15-inch DEH trees to 100 per
cent in 50-inch DBH trees,while decay volumes increased frcm 4 per cent
to 47 per cent for the same DBH range (Foster ejt a_l., 1958).
For the Queen Charlotte Islands, Foster and Foster (1952)
reported that relative frequencies of infections in hemlock trees
increased from 19 per cent in the 15-inch DBH class to 100 per cent in
the 60-inch DBH class. Decay volume losses increased from 1.5 per cent
to 30.9 per cent of gross volume in the same DBH classes. The British
Columbia Forest Service analysed about 32,000 trees throughout British
Columbia and concluded that decay is closely correlated with DBH for 35
-all commercial species. Decay loss factors, segregated by DBH classes
and provincial forest inventory zones, have been prepared for all
commercial tree species in British Columbia (Forest Club, 1959; British
Columbia Forest Service, 1966).
Auckland et al_. (1949) found that DBH was more useful in the
estimation of volumes of decay in Douglas fir, western hemlock, western
red cedar and Abies species near Franklin River than either age or
—external indicators of decay.
In general, it can be concluded that increases in the decay
volume of trees are almost always associated with increases in DBH.
This author was able to find only one report in the literature where
attempts to correlate decay volume and tree DBH were unsuccessful.
Aho (1966) reported no correlation of DBH and decay volume in western
larch in Washington and Oregon.' It should be pointed out that although
tree DBH and decay volume are usually significantly correlated, the
precision with which amounts of decay in individual trees can be
estimated from DBH is usually low and extremely variable. A wide range
of decay percentages among individual trees of the same DBH class is
common, therefore recognition of other factors is necessary.
Numerous studies have shown that increases in the incidence
and volume of decay are often associated with increases in the age of
trees and stands (e.g. Bier and Foster, 1944; Foster, 1946; Bier, Foster
and Salisbury, 1946; Foster, 1947; Bier, Salisbury and Waldie, 1948;
Morawski jst a_l., 1958). The British Columbia Forest Service (1966)
reported age to be a significant factor in decay estimation and
published decay loss factors for several "pathological" age classes
(Table 11). 37
Table 11. "Pathological age classes defined by the British Columbia Forest Service.
„ Aga e class Stand type _ n,. Immature Older immature Mature
Deciduous 1-20 yr. 21-40 yr. 41 yr. + Lodgepole pine 1-60 yr. 61-80 yr. 81 yr. + Other coniferous 1-80 yr. 81-120 yr. 121 yr. +
^ Source: British Columbia Forest Service, 1966
Although numerous authors have found correlations between decay volume and tree and stand age, there are several reports of unsuccessful attempts (Waldie, 1949; Loman and Paul, 1963; Hinds and
Hawksworth, 1966; Aho, 1966). According to Foster, Browne and Foster
(1958), the practice of demonstrating increasing decay with increasing age has:
- "apparently developed from a concept of forest growth and mortality which recognizes that tree species live for a maximum period and may deteriorate with increasing rapidity during a period of decline."
They pointed out that in some stands this assumption may not be valid and that:
"it may be necessary to consider that cyclic mortality depreciates most stands and consequently that percentage of decay and net volume fluctuate with advancing stand age."
Decay in western hemlock and amabilis fir in the Kitimat area showed some cyclic trends with advancing age,, however, these trends were not significant enough to enable the formation of valid conclusions
(Foster, Browne and Foster, 1958). 38
Thomas and Thomas (1954) reported that percentage decay-
volumes in Coastal Douglas fir increased to a maximum with increasing
age and then declined. They attributed this irregularity to influences
of site quality, latitude and stand history.
In subalpine fir in Colorado Hinds, Hawkswofth and Davidson
.(1960) found that decay volume.per acre increased with age to a peak
in the 150 to 200 year age class, then declined to a minimum in the
250 to 300 year old age class, then increased again to a second peak
in the 350 to 400 year age class. They suggested that factors con•
tributing to this relationship were :
"1. some of the trees infected with decay early in life are killed directly by parasitism of the decay fungi or indirectly by windthrow or wind breakage. 2. growth of the remaining trees is enhanced by the
release due to the loss of the more decadent trees."
Boyce and Wagg (1953) studied decay caused by F_. pini in
mature Douglas fir in Oregon. Their analysis of individual trees and
stands indicated a cyclical behavior of decay. Decay volume per acre
was minimal at ages 120, 250 and 350 years and maximal at ages 200 and
320 years. Sampling was not sufficient in stands older than 360 years
to enable the recognition of pronounced trends. According to Boyce
and Wagg (1953), the factors controlling cycles of F. pini decay are
difficult to ascertain because little is known about the actual growth
of F. pini in heartwood. They suggested however, that decay was cycli•
cal because: "the weakening action of F. pini and the competitive action of associated trees causes the death of many infected trees., thus affording release to the remainder. This has a twofold influence on the volume of decayed wood in the stand. The decay volume is reduced by death of infected trees, and at the. same time, the rate of growth of sound trees increases." 39
It has been suggested (Foster, Browne and Foster, 1958)
that in uneven aged stands of tolerant species, rapid decay need not
necessarily be associated with advancing, age, but that decay volume
per acre might be more or less constant for considerable periods of
time.
Investigations of the relationship of site quality to decay
for a number of species have failed to give consistent results (Boyce,
1961) . For some fungi, decay has been found to increase with increasing
site index; for others the opposite has been observed. Weir and
Hubert (1918) found that decay caused by E. tinctorium on western
hemlock was more severe and infections occurred at an earlier age in
river bottom types than on slope types. Foster et_ a_l. (1954) noted a
definite increase in the incidence of infections caused by this fungus
with decreasing site index. In the same stands however, decay caused
by F. pini was observed to decrease with decreasing site index. Boyce
and Wagg (1963) noted a similar relationship with F. pini and Douglas
fir in stands over 110 years of age. They stated:
"there is no obvious explanation for the greater incidence of conk rot on better sites."
Thomas (1958) noted that poor vigor was usually associated
•with increased infections of JS. tinctorium on western hemlock but Bier
et al. (1948) were not able to detect any influence of site on this
fungus in Abies species. Smith et a_l. (1961) reported Sis' observations
on the influence of age and site on the proportions of residual (TCI)
and suspect (TC2) (therefore probably more decayed) trees in stands of
western hemlock, western red cedar and Douglas fir. Although the
relative number of suspect trees increased with age, no relationship 40
could be detected for site quality (Table 12)-.
Hamilton (1967.) summarized relative numbers of residual (TCI),
suspect (TC2) and dead (TC4) trees by diameter classes for western
hemlock in five Public Sustained Yield Units in British Columbia
(Table 13) but was not able to discern significant differences in
proportions of suspect or dead trees among units.
The influence of climate, topography, altitude, air moisture
_and' humidity, aspect, host vigor and natural resistance appear to
interact with site index in. the determination of fungal activity in a
given area.
External Indicators of Decay
Individual trees in mature coniferous stands may be easily
-segregated into recognizable classes by their possession or lack of
certain visible abnormalities indicative of decay (Foster, Thomas and
Browne, 1953). Increased precision in defect estimation is often
obtained when trees are classified according to the presence or absence
of such abnormalities.
The late Chief Justice Gordon Sloan (1956) was impressed by
the relative amounts of decay associated with residual and suspect
classes of trees in several areas of British Columbia. After con•
sidering the much larger percentages of decay volume in the suspect
trees than in the residual trees he stated:
"...comparisons could be made to support my conclusions that the estimated amounts of accumulated decay and yearly losses due to incidence of diseases are not extravagant, but conservative."
Analysis of trees of all commercial species in British
Columbia (British Columbia Forest Service, 1966) showed that classi- Table 12. Influence of age and site on the proportion of trees with visible indications of defects.
Species Douglas fir Western hemlock Western red cedar No. %T.C.l %T.C2 No... 7.T.C.1 7.T.C.2 No. 7.T.C.1 .%T.C.2
Number and proportion of trees by age classes Under 100 1,311 85 15 2,561 73 27 1,409 81 19 years Mixed young 172 87 13 664 77 23 129 72 28 and old Mature 112 73 27 1,381 72 28 461 41 59
Number and proportion of trees by site classes Site index 21-40 142 71 29 80 60 40 41-60 199 86 14 434 71 29 197 51 49 61-80 138 84 16 266 60 40 548 85 15 81-100 266 90 10 688 71 29 647 71 29 101-120 138 86 14 1,677 74 26 323 67 33 121-140 378 79 21 1,222 79 21 141 70 30 141-160 295 81 19 59 53 47 161-180 153 85 15 - — 4 75 25 181-200 28 100 0
Source: Smith et al., 1961 42
1 2 Table 13. Distribution of tree classes by DBH classes for western hemlock in five Public Sustained Yield Units (P.S.Y.U.) in British Columbia.
Dean P .S.Y.U. DBH Tree class 1 Tree c la s s 2. Tree class t :lass N.T. % • N.T. % N.T. %
4 - 16523 63.6 -7562 29.2 •-• 1880 7.2 8 6696 61.8 2918 26.9 1214 11.2 12 2535 54.1 1796 38.4 351 7.5 16 1086 45.8 1041 43.9 245 10.3 20 .578 40,2 676 47.0 184 12.8 24 279 31.4 493 55.5 116 13.1 28 138 23.5 364 62,1 84 14.4 32 99 29.0 166 48.5 77 22.5 36 28 16.2 77 44.5 68 39.3 40 21 20.2 • 58 55.8 25 24.0 44 6 14.3 27 . 64.3 9 21.4 48 6 20.7 16 55.2 7 24.1
Harrison P.S.Y.U. DBH Tree class 1 Tree class 2 Tree class 4 class N.T. % N.T. 1 N.T. %
4 6412 61.0 3714 35.4 380 3.6 8 2230 48.0 1975 42.5 438 9.5 12 1117 41.4 1325 49.1 258 . 9.5 16 747 35.8 1145 54.8 197 9.4 20 521 33.2 865 55.2 182 11.6 24 267 21.8 798 65.2 158 13.0 28 145 17.6 547 66.4 132 16.0 32 63 13.1 351 73.1 66 13.8 36 24 8.1 221 74.2 53 17.7 40 18 9.8 129 69.7 38 20.5 44 6 4.3 101 72.7 32 23.0 48 3 3.9 48 63.2 25 32.9 Table 13. (Continued)
Chilliwaclc. P.S.Y.U. Tree class 1 Tree class 2 Tree class 4 N.T. % N.T. % N.T. %
4 1695 57.8 1147 39.1 92 3.1 8 558 51.9 422 39.3 95 8.8 12 198 45.2 217 49.5 23 5.3 16 109 43.1 129 50.9 15 6.0 20 79 40.3 96 49.0 21 10.7 24 37 22.8 109 67.3 16 9.9 28 58 29.9 117 60.3 19 9.8 32 24 18.2 86 65.2 22 16.6 36 19 14.2 82 60.7 34 25.2 40 8 10.3 53 67.9 17 21.8 44 3 5.1 42 71.2 14 23.7 48 5 11.6 34 79.1 4 9.3 52 2 6.7 24 80.0 4 13.3
Terrace P •S.Y.U. DBH Tree class -1 Tree class 2 Tree class < :lass . N.T. % N.T. N.T. 7»
4 17680 62.7 7853 27.8 2674 9.5 8 8376 55.4 5281 34.9 1454 9.7 12 3505 46.8 3434 45.8 556 7.4 16 1742 38.2 2438 53.5 375 8.3 20 953 29.0 2015 61.2 323 9.8 24 466 21.3 1455 66.5 266 12.2 28 173 12.8 993 73.7 182 13.5 32 110 12.2 645 71.4 148 16.4 36 48 10.5 345 75.0 67 14.5 40 27 11.7 174 75.3 30 13.0 44 2 1.7 107 89.2 11 9.1 48 3 5.2 41 70.6 14 24.2 Table 13. (Continued)
Shuswap P.S.Y.U. DBH Tree class 1 • Tree; class 2 Tree class < :lass N.T. % N.T. % N.T. %
4 6713 68.8 2819 28.9 299 2.3 8 1825 63.5 887 30.8 164 5.7 12 610 52.6 503 43.4 46 4.0 16 445 48.5 408 44.4 65 7.1 20. 209 35.2 322 . 54.2 63 10.6 24 116 32.1 209 57.9 36 10.0 28 • 60 24.3 165 66.8 22 8.9 32 16 14.4 80 72.1 15 13.5 36 2 4.6 30 69.8 11 25.6 40 6 27.3 14 63.6 2 9.1 44 3 23.1 14 63.6 2 9.1 48 0 0.0 2 100.0 0 0.0
Source: Hamilton, 1967
Tree class 1 is residual. Tree class 2 is suspect. Tree class 4 is dead standing.
No. of trees. 45. fication of trees as residual and suspect was of practical significance in decay estimation.
Investigations have shown that basal and trunk scars provide entrance courts for decay-causing fungi and that they are often useful as indicators of internal decay in the tree (Nordin ej^ al., 1955;
Nordin, 1958; Parker, 1958; Thomas, 1958; Aho, 1966). Kinsman (1964) reported that small, medium and .large open scars were associated with decay 64, 77 and 100 per cent of the time respectively in western hemlock in the Kitwanga P.S.Y.U. Closed scars were associated with decay less frequently - the percentages being 23, 23 and 33 for small, medium and large scars. Open scars were associated with an average decay volume of 5.8 cubic feet and closed scars were associated with an average decay volume of only 1.6 cubic feet.
Shea (1960) observed evidence of decay in 91 per cent of the logging scars on 90-year-old western hemlock. After 17 years from the date of logging, decay losses averaged 0.9 per cent of gross merchantable tree volume. In a 114-year-old stand of Douglas fir and western hemlock in western Washington, decay was associated with 92 per cent of 10-year- old logging scars on western hemlock (Shea, 1961). In the older stand, decay volumes averaged 6.0 per cent of gross merchantable hemlock volume.
The fruiting bodies or sporophores of fungi, when present, are virtually certain indicators of decay. The absence of sporophores is, of course, no guarantee that decay is absent. Some species of fungi do not produce fruiting bodies until decay is well advanced, others only produce sporophores occasionally, still others produce fragile sporophores which last for only a short time. 46
Foster e_t a_l. (1954) reported that the only external indicators of significance in decay estimation in western hemlock in the Big Bend area were sporophores. of Echinodontium tinctorium and
Fomes. pini. A total of 60 per cent, of the trees containing measurable decay volumes had one or more sporophores visible from the ground.
Table 14 indicates volumes of decay associated with varying numbers of sporophores on individual trees. They concluded:
"...the entire decay volume is not necessarily associated with sporophores when they are present. Despite the preceeding qualifications, the relative decadence of individual trees may be estimated through the occurrence and location of sporophores and a more accurate inven• tory of diseased stands of the nature sampled may be realized.".
Table 14. Per cent decay in western hemlock trees having varying numbers of sporophores2
Number of sporophores Per cent gross per tree volume decayed
0 57.2 1-2 71.5 3-4 76.9 5-6 88.3 7+ 93.3
Source: Foster et al., 1954
Including sporophores of E. tinctorium, F. pini and F. pinicola. 47
Kinsman (1964) reported that decay volumes in western hemlock in Kitwanga were closely associated with visible sporophores. Kis results are summarized in Table 15.
Table 15. Distribution of decay volumes associated with sporophores of F. pini and E. tinctorium on western hemlock.
Average decay Average distance Average distance volume per of decay below r , , Decay fungi , , off decay above sporophore sporophore sporophore (ft.) (cu. ft.) (ft.)
F. pj.ni 9.89 11 22
E. tinctorium 19.41 16 20
^ Source: Kinsman, 1964
Numerous attempts have been made to associate various other external abnormalities such as forks, crooks, frost cracks, mistletoe infections, rotten branches, branch stubs, dead or broken tops, cankers and galls with decay in the living tree. The usefulness of these abnormalities for the estimation of defect varies with the species of fungi, the host species and the local area.
It is usually common to find more than one kind of external abnormality or decay indicator on a single tree. When the significance of these abnormalities is assessed singly and in various combinations or groups, increased precision in defect estimation is often possible. 48
The total number of indicators, irrespective of their type, was signi• ficantly related to per cent decay of western hemlock trees in the
Kitwanga P.S.Y.U. (Kinsman, 1964). A simple linear regression of per cent decay and number of indicators present accounted for 52 per cent of the variability, in decay volume -in single trees.; The standard error of estimate of per cent decay was + 16 per cent. The addition of
DBH as an independent variable in the regression equation only accounted for an additiona1 -5 per cent of the variability in decay percentage in single - trees.
Aho (1966) derived regression equations based on various external indicators for several tree species in Washington and Oregon
(Table 16). His best equation accounted for nearly 58 per cent of the variability in decay volume in individual trees. He used several external indicators and values for substitution in multiple regression equations for the determination of per cent decay in individual trees.
Foster, Thomas and Browne (1953) reported that swollen knots and sporophores were the most significant external indicators in western hemlock in the upper Columbia region. The relative importance of various indicators in that area are listed in Table 17.
Analysis of trees throughout British Columbia by the British
Columbia Forest Service (1966) showed that in addition to sporophores, scars, forks, crooks, frost cracks, mistletoe, rotten branches and dead or broken tops were useful as indicators of decay.
In general, it can be concluded that external abnormalities are useful aids in the estimation of decay volumes in living trees.
One notable exception occurs, however, when the decay-causing fungi enter through the roots and provide no visible evidence until decay is Table 16.* Regression equations for estimation of per cent decay for individual trees.
Coefficients for external indicators
Species fist. 2 A B C D E I L T R frees Term: Grand fir •
1 .049 6.410 27.222 -.271 4 .123 -1.805 •579 679 2 7.918 28.. 170 -.128 5 .376 3.276 .560
Engelmann spruce 1 .046 13.126 .139 .1.798 6.150 -5.108 212 151 2 13.696 .324 2.032 5.587 -1.124 .169
Douglas fir 1 7.679 25.316 .082 .771 X 6.027 - .745 2 25.010 .098 . .690 . 835.X 5.9 20 - .893 .501 160
Larch 1 4.150 10.833 7.178 .578 °350 go 2 9.828 22.910 8.176 2.002 .283
^ Source Aho, 1966 . l A = tree age in years E - 1 if top injury present; B = 1 if one or more basal injuries present > 0 if no top injury present 0 if no basal injury present I = 1 if one or more top or trunk injuries present; C = 1 if one or more conks present; 0 if no top or trunk injuries present 0 if no conks present L = basal scar length, rounded to the nearest foot D = tree DBH in inches T = 1 if one or more trunk injuries longer than one foot present; 0 if no trunk injuriis< present. 50 well advanced.. It is important to note, also, that the usefulness of any abnormality for decay estimation varies significantly with the species of fungi, the host species and the local area.
Table 17. The frequency and occurrence and relative importance of abnormalities of decay significance on living western hemlock' in the upper Columbia region.
Frequency of Per cent of affected.trees occurrence - with decay Abnormality per cent of living In direct In close trees affected association association
Sporophores 47.9 .100 100 Frost cracks 30.4 62 78 Scars 11.6 60 65 Dead tops 8.5 80 80 Rotten branches 7.1 90 90 Forked trees 3.6 60 71 Swollen knots 2.2 100 100 Mistletoe 0.8 75 75
Source: Foster, Thomas and Browne, 1953
Distribution of Log Size and Gross Volume Within Trees
Despite the large amount of research devoted to tree volume estimation, development of flexible methods for estimating the distri• bution of volume in standing trees has been slow. Spurr (1952) stated:
"As in medicine, where the large number of remedies proposed for the common cold indicates the ineffectiveness of any one, so the large number of approaches to the problem of volume estimation may be taken as an indication that no one approach has received more than partial recognition." 51
Log position volume tables'(e.g. Mason, Bruce and Girard,
1949; Skinner, 1955; British Columbia Forest Service, 1959; Bones,
1963) which are designed for 16-or 32-foot log lengths are restricted
in present day applications because of their fixed log length and their
lack of diameter information for various logs, Honer and Sayn-
Wittgenstein (1963) stated:
"We must develop a mathematical tree volume expression which can be efficiently programed for generally available electronic computing equipment to yield tree and stand volumes from inputs of tree diameter outside bark and total heights (form estimates optional) and for any demanded stump height and top diameter."
In the light of present day requirements the above statement should be revised to include log volumes and log sizes in addition to tree and stand volumes.
Several authors have attempted to describe tree form and taper and to develop mathematical formulae for the determination of tree volume between specified stump heights and top diameters.- Wright (1927) was the first Canadian forester to prepare general taper curves for
Canadian trees. Depending on species examined and analytical techniques used, tree form has been shown to resemble a quadratic paraboloid
(Gray, 1956; Newnham, 1958), a cubic paraboloid (Metzger, Busgen and
Munch, 1929), a hyperbola (Before, 1923) or some form intermediate between a paraboloid and hyperbola (Grosenbaugh, 1954, 1967). Multivariate methods have been used to describe tree form (Fries, 1965; Fries and
Matern, 1965; Kozak and Smith, 1966, 1967).
Comprehensive regression methods have been used in the
development of taper and volume tables for red alder (Bruce jet al.,
1967; Curtis and VanCoevering, 1967). These were based on the work of Matte (1949) who found that stem profile of loblolly pine above breast height could be described by the equation
\n
y » x \ ax + bx + c where i
"y" was ratio of diameter inside bark at point of measurement to diameter inside bark at breast height.
"x" was ratio of distance from tip to measurement point, to total height of tree above breast height,
a + b + c = 1 and
• "a" "b" "c" were coefficients found by least squares analysis.
The British Columbia Forest Service (1962) has developed
taper curves for the commercial tree species of British Columbia, However
these were constructed by the method of harmonized curves and it is not
easy to find a mathematical function which adequately describes, them.
Burstall and Duff (1959) prepared combined taper and volume tables for
]?. radiata B - and Douglas fir in New Zealand. These tables too, are
limited in application. They are restricted to 10-foot log lengths
(or multiples thereof) and are based on harmonized curves.
The tarif tables of Turnbull et'al. (1963) are designed
specifically for electronic computer applications and are-probably the- most flexible volume tables available. Volumes can be obtained for
4, 6, or 8-inch top diameters in cubic feet or in board feet. They do
not however, provide the information needed on the distribution of log
size and volume within trees.' Fries (1965) used Eigenvector analyses i . \
to show that birch and pine have similar form in Sweden and in British
Columbia. He did not attempt to define log volumes, sizes or distri•
bution of logs within tree stems. y' ; 53
-Honer (1964, 1967) developed a system of equations which permitsan estimation of volume of any portion of the tree stem defined by.two measures of merchantable height and determination of merchantable volume to any specified top diameter and stump height. He found that ratios of merchantable volume to total volume are proportional to the ratios of merchantable height to total height and of the square of diameter at merchantable height to diameter at breast height. He derived equations which, according to a preliminary analysis based on
11 trees, adequately described tree volume to various utilization standards. His equations can be manipulated through a series of successive subtractions to provide estimates of individual log volumes within trees. It is also possible to specify a log length or a log diameter and obtain log volumes. His selection of variables does not however, permit the specification of both a diameter and a length at the same time. An ideal method would permit the determination of log volumes for specified log lengths and diameters.
Conclusion -
From this review of literature, it is apparent that although much is known about decay-causing fungi and their effect on wood, further research is needed to provide information necessary for the development of forest management methods by which decay losses can be reduced.
Much good quantitative information is available regarding relationships betx^een external abnormalities and decay within living, standing trees. However, there is no quantitative information available on the distribution of decay within tree stems and the relationship of this distribution to tree size and external abnormalities. Similarly, 54 ho.flexible methods are available to enable the prediction of volumes of individual logs of specified lengths and diameters in standing trees.
There is clearly a need for the development of an efficient quantitative method to describe the distribution of soundwood and decay volumes within tree stems. 55
... CHAPTER III
DATA COLLECTION AND INITIAL SUMMARIZATION
Since 1952, the Inventory Division of the British Columbia
Forest Service has been engaged in a program to collect stem analysis data from trees throughout the province to provide reliable information for volume tables, decay loss factors and site index curves. By 1966, analyses were completed for 32,056 trees of 15 commercial species in all forest zones of British Columbia (British Columbia Forest Service, 1966).
These analyses were carried out in accordance with strict standards and procedures (British Columbia Forest Service, 1954, 1967) and were similar to those which the author had the opportunity to observe near Blue River,
B.C. in July, 1967. Individual tree records are maintained in a well organized and efficient filing system in Victoria, B.C.
It was recognized early in this study that data such as the above would be ideal for use in the development of methods to assess distribution of soundwood volume in trees. To enable a complete and exhaustive analysis in a resonable time period, it was necessary to restrict the data to a relatively small number of trees. Consequently, a sample of 369 western hemlock trees was selected from 14 sample plots established in 1965 in the Yale P.S.Y.U. (situated in the Cascade-Coast mountain region of Thomas' (1958) classification at approximately 121°
15' west longitude and 49° 30' north latitude).
Approximately 15 computer programs were written by the author to facilitate analyses of the data. Computer programs for multiple regression analysis (Kozak and Smith, 1965) and analysis of variance were obtained from the Faculty of Forestry, University of British 56
Columbia, and modified where necessary. All computing was carried ' out on an IBM 7044 in the computing centre of the University of
British Columbia.
Numbers of trees, site index, per cent merchantability and average stand age are summarized for each sample identified by region, compartment and sample number in Table 18.
Species composition, height class, site class and gross cubic foot volume per acre in stems 5.1 inches DBH and larger are tabulated- in Table 19.. (Unless specified otherwise in this study, gross volume means total wood volume inside bark between a 1-foot stump height and
4-inch top diameter inside bark.) No samples were available from immature stands, therefore all samples used for this study were esta• blished in old growth or overmature stands (Photograph I). Sample 16. originated in the youngest stand with an average age of 196 years.
Each sample consisted of a total area of one acre and was composed of four subplots, each of which was one-quarter acre in size.
All trees 11.1 inches DBH and larger were marked for felling and sectioning for decay analysis. Trees 7.1 inches to 11.0 inches DBH were measured and marked for felling and sectioning on subplots one- twentieth acre in size situated at the centre of each one-quarter acre plot. All plot boundaries were carefully established with tape and compass, blazed, and marked with string. Before felling, diameters inside bark were measured at 1, 1.5, 2, 3, 4.5 and 5 feet above the assumed point of germination. Notes were taken regarding tree quality and tree class, and the type and position of all external abnormalities
(Table 20) were recorded. After the above measurements were completed, each marked tree was felled and sectioned at 16-foot intervals above a 57
Table 18. Number of trees, site index, per cent merchantability and average age by sample number.
Site index height at . Per cent Average Area and sample no. No. trees 100 yrs. merchantable age (yrs.) (ft.)
R 10 C6A S5 10 89 86.05 250 R 10 C6A S6 17 87 70.90 389 R 10 C6A S12 21 106 77.69 299 R 11 C4J S34 11 103 69.61 267 R 12 C3 S16 21 113 91.72 196 R 12 C3 S17 19 109 80.27 256 R 12 C3 S18 18 112 75.72 228 R 12 C3 S19 10 115 96.65 254 R 12 C3 S20 14 107 94.14 254 R 12 C7 S16 39 98 77.32 289 R 26 C2 S40 10 71 98.38 266 R 26 C2 S41 6 78 64.94 252 R 26 C2 S42 13 136 83.63 258 R 26 CIO S61 160 71 95.18 259 Table 19. Classification of stands sampled by sample number and area.
, .a _• . .,_. 1 Height class Site Volume per acre Area and sample no. Species composition % , ,c ... „„TT , . . v • * (ft.) class (5.1" DBH + gross c.f.)
RIO C6A S5 B H3 (Cy) 156 -• 185 poor 12,290 6
RIO C6A S6 H B4 (Cy) 96 -- 125 poor 9,471 5
RIO C6A S12 H B3 (C) 126 -• 155 poor 12,281 5
Rll C4J S34 H B 126 -• 155 medium 13,442 7 3
R12 C3 S16 H C2 (B) 156 -• 185 med ium 10,387 6
R12 C3 S17 H C B 126 - 155 medium 11,099 4 4 2 •
R12 C3 S18 B 126 -• 155 medium 9,078 5 H4 (C) R12 C3 S19 (H) 156 -• 185 medium 14,262 B8
R12 C3 S20 B H 126 -• 155 good 11,237 8 2
R12 C7 S16 H C3 (B) 126 -• 155 medium 13,428 6
R26 C2 S40 B Cy3 H3 96 -• 125 poor 8, 150 4
R26 C2 S41 H 96 -• 125 poor 10,074 5 \ (Cy)
R26 C2 S42 B H 156 -• 185 good 18,778 6 3
R26 CIO S61 H B2 (Cy) 96 -• 125 poor 9,521 7
Subscripts denote species present to nearest 10 per cent. Photograph I. Typical old growth stand of western hemlock. Blue River, 3- C. Table 20. External abnormalities tabulated and analyzed in relation to tree decay.
External abnormality Code no.
Echinodontium tinctorium conks 1 Fomes pini conks 2 "Blind" conks of Fomes pini 3 Conks of all other fungi 4 Small open scars (less than 5 feet in length) 5 Med. open scars (from 5 to 10 feet in length) 6 Large open scars (longer than 10 feet) 7 Small closed scars (less than 5 feet in length) 8 Med. closed scars (from 5 to 10 feet in length) 9 Large closed scars (longer than 10 feet) ' 10 Small frost cracks (less than 5 feet in length) 11 Med. frost cracks (from 5 to 10 feet in length) 12 Large frost cracks (longer than 10 feet) 13 Mistletoe infection 14 Rotten branches 15 Dead or broken tops 16 Small forks 17 Crooks 18 Other 19 61 one-foot stump height. Diameters inside bark at each cut section were recorded to the nearest 1-inch class and lengths were recorded to the nearest one-tenth foot. In addition to the above cuts and measurements at regular intervals, a cut was made at each external abnormality to determine if the abnormality was an entrance court for decay. When decay was encountered at any cut section, additional cuts were made at approximately 2-foot intervals until the maximum diameter of the decay column and the beginning and ending points of the column could be deter• mined within plus or minus one foot of height above ground level
(Photograph II). Characteristics of the decay were noted and described and, if field identification of the fungus was not possible, additional descriptions of the rot were recorded. In some instances, samples of decayed wood were collected for culture to permit accurate identifi• cation of the decay-causing fungi in the laboratory. No attempt was made during the field work to separate, for recording purposes, the presence or absence of wood in severely decayed sections, incipient, advanced stages or intermediate stages of decay. For the purpose of this study, the term "decayed wood" includes all wood which has been visibly infected with wood rotting fungi.
The first step in the analyses was to assess and summarize the trees by various classes and to segregate the types of decay to enable graphical examination of trends and the postulation of analytical techniques that might prove to be useful in the development of decay estimating equations. Distribution of the 369 trees by DBH classes, with numbers of samples, average height, average cubic foot volume and average per cent merchantability is presented in Table 21. The majority of samples is located in the DBH range from 11 to 24 inches. A slight Photograph II. portion of a western hemlock tree sectioned for decay measurement. Table 21. Distribution of basic data by DBH classes.
DBH class No. Avg. ht. Average vol. (c.f.) Avg. per cent (inches) trees (ft.) Gross Merch. merch. vol.
8 5 44.0 5,. 0 4.8 96.0 9 3 55.0 7 .5 6.9 92.0 10 9 67.2 14 .4 12.8 88.9 11 24 63.7 15,. 7 14.7 93.6 12 36 70.1 20 .6 18.7 90.8 13 33 74.2 24,. 4 23.5 96.3 14 31 80.1 30,. 7 29.0 94.5 15 28 80.9 35,. 2 33.6 95.4 16 21 86.8 44 .6 40.6 91.0 17 18 93.5 50 .4 45.6 90.5 18 16 85.4 55,. 1 53.5 97.1 19 8 98.8 73,. 0 63.7 87.3 20 13 97.2 75,. 1 64.4 85.7 21 11 98.5 85,. 0 76.3 89.8 22 9 102.3 91,. 9 77.6 84.4 23 10 121.7 121 .5 104.2 85.6 24 7 111.6 129,. 5 112.4 86.8 25 5 122.4 145,. 4 124.0 85.3 26 6 122.7 164, .7 130.4 79.2 27 8 123.6 173 .0 136.5 78.9 28 9 128.1 198 .5 157.1 79.1 29 8 142.4 217 .4 197.2 90.7 30 8 123.5 211,. 9 187.0 88.2 31 5 133.2 246, .2 .198.1 80.5 32 7 136.0 272 .2 183.5 67.4 33 3 124.7 232 .4 192.1 82.6 34 5 143.4 297 .5 272.1 91.5 35 5 136.6 308 .9 223.1 72.2 36 4 153.3 359 .4 293.2 81.6 37 2 .147.5 368, .6 293.3 79.6 38 3 152.3 376 .5 294.4 78.2 39 3 146.0 383 .2 299.3 78.1 40+ 6 157.0 522 .2 379.3 72.6 64 trend, of decreasing per cent merchantability is evident with increasing
DBH and height. This trend is not well defined, however, and the variability from DBH class to DBH class is large. For example, five trees in the 34-inch DBH class average 91.5 per cent merchantable while nine trees in the 10-inch DBH class average only 88.9 per cent merchant• able.
Summarization of the heartrot identifications and descriptions made'by British Columbia Forest Service personnel (Table 22) reveals that E. tinctorium and F. pini were positively identified.either from
Table 22. Heart rot identifications, descriptions and frequency of observation in 369 western hemlock trees.
Item Frequency of observations'
Identification (positive) Echinodontium tinctorium 32 Fomes pini 37 Stereum sp. 4
Description Early stages Brown columnar 27 Advanced stages
Brown columnar^ 253 Brown cubical 21 Brown stringy^ 212
White pitted 28
All brown stringy rots were also described as brown columnar. 65
Photograph III. Stump and top sections of western hemlock tree. Heartwood destroyed by Echinodontiraa tinctoriun-.. 66 sporophores or culture in nearly equal proportions (32 E. tinctorium infections versus 37 F. pini infections). In the rot descriptions, however, where all rots were described according to appearance, the majority were described as brown stringy and columnar, rather than white or white pitted which is typical of F. pini. It would appear from the rot descriptions that very little rot caused by F. pini wa-s present without sporophores to aid in positive field identification.
The author has conferred with personnel of the British Columbia Forest
Service responsible for the field analysis of these trees and it is their opinion that probably the majority of the rot was caused by
E. tinctorium, with only a minor amount caused by F. pini. Unfortunately, most of the culture tests of the samples taken were not successful.
Without positive identification from culture or from the presence of sporophores, it is not possible to state positively the species of fungi in the trees examined. This is particularly true of rot caused by E. tinctorium (Photograph III) which is often and easily confused with that caused by Stereum sanguinolentum (Maloy, 1967). Unless posi• tive field identification was made from the presence of sporophores, the heart rot was described according to appearance and the causal organism recorded as species unknown. In the total sample, 272 trees or nearly 74 per cent contained measurable amounts of decay, but, only
209 of these trees had external abnormalities which could be regarded as possible indicators of decay in the tree stem (Table 23). Basic data are summarized by several tree class groupings in Tables 24, 25,
26, 27, 28 and .29. In Table 27, data are summarized for each suspect abnormality class and ranked in increasing order of decay volume
expressed as a percentage of gross tree volume. 67
Table 23. Summary of sound and decayed trees by tree class.
„ , Number of trees Tree class Decayed Sound Total
Resldua'l1 63 48 111 Suspect2 209 49 258 All 272 97 369
I ^ Trees with no external abnormalities 2 ' ' • Trees with one or more of the external abnormalities listed in Table 20. /
Many trees bore more than one external abnormality. Table 30
indicates the frequency with which more than one external abnormality was observed on decayed and sound trees. Considering all trees with measurable decay volume, nearly 64 per cent had two abnormalities or
less (23.2 per cent had none, 23.2 per cent one and, 18.0 per cent two abnormalities). This is in contrast to the "sound; trees where 85 per cent of the trees had one abnormality or less." The difference in
incidence of two or more abnormalities between sound and decayed trees
suggests that certain combinations of external abnormalities might be more useful than individual abnormalities in the estimation of decay
volume within standing trees. The relative usefulness of external abnor- malities as decay indicators can be inferred from Table 31 where the
absolute and relative numbers of trees with abnormalities associated r • • • with decay are tabulated. Where the number of trees with decay in a i • • \ .• I •. specific abnormality class approaches 100 per cent, then that abnormality may be useful as an indicator of decay. It is also important to Table 24. Basic data summary for all (369) western hemlock trees.
Variable Average Minimum Maximum Stan, dev. No. obs,
Tree DBH (inches) 19.07 7.5 55.1 8.11 369 Height (feet) 94.63 29.0 178.0 29.89 369 Age (years) 265.38 109.0 512.0 63.20 369 Gross vol. (c.f.) 94.92 2.6 912.0 112.28 369 Merch. vol. (c.f.) 79.20 2.6 519.9 88.83 369 Net vol. (c.f.) 73.85 2.6 510.6 85.00 369
First decay column Low height (feet) 14.90 1.0 70.0 16.76 272 High height (feet) 46.96 2.0 160.0 28.19 272 Ht. of max. dia. (feet) 25.15 1.0 81.0 20.00 272 Max. dia. (inches) ' 8.90 1.0 35.0 6.55 272
Second decay column Low height (feet) 44.48 8.0 124.0 28.55 48 High height (feet) 66.60 16.0 148.0 29.16 48 Ht. of max. dia. (feet) 53.67 13.0 130.0 27.85 48 Max. dia. (inches) 5.88 1.0 21.0 4.25 43
oo 69
Table 25. Basic data summary for 97 sound western hemlock trees.
Variable Average Minimum Maximum Stan.dev. No.obs.
Tree
DBH (inches) 15.2 7 .5 39.9 5.98 97 Height (feet) 81.80 29 .0 172.0 : 25.63 97 Age (years) 242.39 109 .0 318.0 42.09 97 Gross vol. (c.f.) 52.67 2 ,6 472.4 74.26 97 Merch. vol. (c.f.) 52.67 2 .6 47214 74.26 97 Net vol. (c.f.) 52.59- 2 .6 472.4 74.28 97
know what volume of decay is associated with each of the above indicators.
It is possible that,, although decay is consistently associated with a particular abnormality, the actual decay volume is relatively small.
For those decay columns in which entrance courts were confirmed by sectioning, scars were associated with the largest decay volumes and forks with the least. The distributions and frequency with which external abnormalities appear on sound and decayed trees are summarized in table 32. The mpst frequently occurring abnormality in both sound and decayed trees is small frost cracks. These appear on 12.4 per cent of the sound trees and 29.4 per cent of the decayed trees.
A wide difference between the percentage of sound trees with a particular indicator and decayed trees with the same indicator could point to potentially useful decay indicators. As an obvious example, conks were associated with decay 100 per cent of the time and can therefore be considered reliable indicators of decay (Photograph IV).
On the other hand, mistletoe occurred with almost equal frequency on
sound and decayed trees, thus suggesting that the presence of mistletoe does not indicate decay within the tree stem. Similarly small forks are Table 26. Basic data summary for 272 decayed western hemlock trees.
Variable Average Minimum Maximum Stan. dev. No. obs.
Tree DBH (inches) 20.30 7.6 55.1 8.41 272 Height (feet) 99.21 42.0 178.0 30.02 272 Age (years) 273.58 125.0 512.0 67.38 272 Gross vol. (c.f.) 109.99 5.4 912.0 119.58 272 Merch. vol. (c.f.) 88.66 5.4 519.9 •91.77 272 Net vol. (c.f.) 81.43 3.9 510.6 87.39 272
First decay column Low height (feet) 14.90 1.0 70.0 16.76 272 High height (feet) 46.96 2.0 160.0 28.19 272 Ht. of max. dia. (feet) 25.15 1.0 81.0 20.00 272 Max. dia. (inches) • 8.90 1.0 35.0 6.55 272
Second decay column Low height (feet) 44.48 8.0 124.0 28.55 48 High height (feet) 66.60 •16.0 148.0 29.16 48 Ht. of max. dia. (feet) 53.67 .13.0 130.0 27.85 48 Max. dia. (inches) 5.88 1.0 21.0 4.25 48
o Table 27. Summary of average statistics for 272 decayed western hemlock trees for various kinds of external abnormalities.
First decay column Second decay column Code Per cenc Decay DBII Tota 1 Total Low High Mid Max. No . of low High Mid Max. No. of No. decay volume (in.) height age height he ight height diameter trees height he ight height d ia'meter trees (c.f.) (ft. ) (yrs.) (ft. ) (ft. ) (ft. ) (in. ) (ft. ••) (n.. ) (ft. ,) (in .) 14 5.. 3 6.7 22., 4 115 .5 234 '5 .2 '26 .0 13 .0 8 .2 4 33 .0- 50.• P 37 .6 5 .3 3 19 6.. 9 23.8 34,. 3 174 .0 233 1 .0 .0 1 .0 25 .0 1 0,. 0 ' 0 ,0 0.. 0 0 .0 0
9 14.. 9 37 .5 29,. 5 138 .5 266 1 .5 43 . 1 8 .8 15 .3 12 47.. 4 . 66.. 0 53 . 2 7 .8 5 5 L7.. 7 21.6 21 , 3 102 . 1 260 13 .3 43 .0 22 .0 9 .3 42 40.. 0 64 ,. 0 50. 1 6,. 0 13
18 13, 1 13.5 18,, 5 89 .3 238 17 . 1 41 .6 25 .9 7 .6 45 44,, 5 59,, 0 5 1. 5 4.. 5 12
11 19. T 28.4 '23.. 0 109 .4 277 11 .4 46 .3 21 . 4 10 .2 80 47:. 3 • 69,.2 . 56. 1 5;. 2 ' 22
12 . 19 ,9 25.2 21,. 6 108 .6 255 11 .0 44 .3 18 .9 10 .0 34 40,. 1 . 60,. 9 49 .2 6.. 5 12
6 20,, I 46.5 • 29,. 1 130 .8 277 5 .7 -50 .0 19 . 1 • 16 . 1 8 27 .5 53,. 5 41 . 0 10 .0 2
15 20.. 4 38.1 26,, 3 117 .0 237 L . 7 36.. 7 ' 8 .3 14 0 8 38,. 5 57. 5 44 . 7 5'.. 0 , 4 17 2 1., 1 . 1.8.9 20.. 0 88 .5 304 17 .0 51,. 8 ' 29 .6 • ' 9. 5 8 52,; 0 85 .0 66. 0 9 ,.0 1 C u 22.. 8 37.8 25,. 3 1 19 .0 2S6 S .6 49.. 4 19 .3 1 1 .8 17 48.. 1 •73.. 1." 60. 7 7. 9
8 ' 25,, 8 34.1 21.. 3 100 .4 270 13 .4 52 .9 23 .0 10 . 1 41 ' 54 .,0 67.. 0 59 . 1 4 .3 6
10 27,, ? 89.1 32,. 1 137 .8 271 2 . 1 54 .'3 10 .3 19 .0 . 8 66 . 2 . 82.. 5 7 1.. 7 • 5,. 5 4
16 27.. 3 23.4 17., 8 86 .3 273 . 12 .S 48,. 1 23 .6 8 .8 33 32, 5 ;• 52. 8 ' 40. 3 3.. 5 6
4 28,, 3 64.4 28,. 9 126 .0 253 1 .0 55,. 6 6 .3 17 .3 3 ' 102.• 0 ; • 138.,0 1.13. 0 6.. 0 I
1 JO,. 6 23.7 18,. 3 87 .4 305 '11 .9 52 .0 26 .6 10 .0 27- 34,, 0 66,, 3 45. 0 5,,6 7 3
7 .36 , 2 75.8 24 .9 108 .4 2S9 1 I. 4 51 , 2 16 . 1 12 .5 7 11.. 6 23,. 6 15 ,6 3,. 6 3
2 36 .5 59.6 24 .7 113 .7 2 SO 3 .9 71 . 2 18 . 6 14 . 7 33 ; 85 .0 108 .5 94,. 5 6 .0 2
_ 0 3 39 .7 61.1 23 .7 112 . 1 303 2 ' 64 .3 15 .3 14 . 7 17 . 102 .0 138 .0 113 .0 6 .0 1
abnormality code No.; see table 20 Lor key. Table 28. Basic data summary for 111 "residual" western hemlock trees.
Variable Average Minimum Maximum Stan. dev. No. obs.
Tree DBH (inches) 15.97 7.5 40.1 5.84 111 Height (feet) 86.00 29.0 150.0 23.42 111 Age (years) 260.62 109.0 472.0 54.38 111. Gross vol. (c.f.) 55.81 2.6 444.3 66.22 Ill Merch. vol. (c.f.) 52.75 2.6 349 .9 60.30 111 • Net vol. (c.f.) 51.11 2.6 326.8 58.92 111
First decay column Low height (feet) 23.03 1.0 61.0 17.49 63 High height (feet) 47.41 2.0 77.0 19.98 63 Ht. of max. dia. (feet) 33.48 1.0 65.0 19 .09 63 Max. dia. (inches) 5.68 1.0 21.0 3.93 63
Second decay column Low height (feet) 51.00 28.0 88.0 32.35 3 High height (feet) 77.67 55.0 99.0 22.03 3 Ht. of max. dia. (feet) 63.00 49.0 91.0 24.24 3 Max. dia. (inches) 3.67 2.0 7.0 2.88 o Table 29. Basic data summary for 258 "suspect" western hemlock trees.
Variable Average Minimum Maximum Stan. dev. No. obs.
Tree DBH (inches) 20.40 7.6 55.1 8.58 258 Height (feet) 98.35 41.0 178.0 31.60 258 Age (years) 267.43 125.0 512.0 66.64 258 Gross vol. (c.f.) 111.75 5,. 4 912.0 123.41 258 Merch. vol. (c.f.) 90.57 5,. 4 519.9 96.50 258 Net vol. (c.f.) 83.64 3,. 9 510.6 92.41 258
First decay column Low height (feet) 12.40 1.0 70.0 15.77 209 High height (feet) 46.78 2.0 160.0 30.32 209 Ht. of max. dia. (feet) 22.45 1.0 81.0 19.40 209 Max. dia. (inches) 9.87 1.0 35.0 6.87 209
Second decay column Low height (feet) 44.04 8.0 124.0 28.64 45 High height (feet) 65.87 16.0 148.0 29.62 45 Ht. of max. dia. (feet) 53.04 13.0 130.0 28.20 45 Max. dia. (inches) 6.02 1.0 21.0 4.31 45
—J u> 74
Photograph IV, Sporophores of Echinodontiutn tinctoritna on western hemlock felled for decay measurement. 75
Table 30. Frequencies and relative frequencies of occurrence of numbers of trees having varying numbers of external abnormalities.
Number of 272 decayed trees 97 sound trees abnormalities Number Per cent Number Per cent
0 63 23.2 48 49.5 1 63 23.2 33 34.0 2 49 18.0 12 12.4 3 38 13.9 3 3.1 4 25 9.2 1 1.0 5 14 5.1 0 0.0 6 6 2.2 7. 7 2.6 • 8+ 7 2.6
of no value as decay indicators - they occur more often on sound trees than on decayed trees. - Table 33, 34 and 35 show for all trees, sound trees and decayed trees respectively, the frequency of occurrence of each external abnormality, the maximum and minimum heights within which
it occurred and the average height above the ground at which it occurred
Correlation coefficients between height of abnormality and location of decay column as defined by maximum, minimum and average height were
.170, .295 and .232 respectively. Although statistically significant, such low values indicate a poor association between position of external abnormalities and decay columns within tree stems. Generally, conks
occurred most often near the top portion of the first butt log, small
scars and frost cracks occurred nearer to the ground and larger scars and other defects were most prevalent in the centre portions of the bole. The occurrence of each abnormality singly and in combination
•with every other abnormality is summarized for sound trees in table 36
and for decayed trees in table 37. Examination of these tables reveals
'that nearly any indicator can be associated with any other, and, as 76
Table 31. Frequencies and relative.frequencies of occurence of external abnormalities and associated decay in 369 western hemlock trees.
External Code Living trees Affected trees Affected trees abnormality No. affected V7ith decay with decay in association with abnormality
No. No. I'e r cent No Per cent Echinodontium conks 1 27 27 100.0 27 100.0 Fomes conks 2 33 33 10070 33 100.0 "Blind" conks 3 17 17 100.0 17 100.0 "Other" conks 4 4 4 • 100.0 4 100.0 Small open scars 5 47 42 89.4 13 27.6 Med. open scars 6 7 6 85.7 3 42.8 Large open scars 7 7 7 100.0 3 42.8 Small closed scars 8 50 41 82.0 5 10.0 Med. closed scars 9 14 12 85'. 7 4 28.5 Large closed scars 10 8 8 100.0 2 25.0 Small frost cracks 11 92 80 86.9 9 9.7 Med. frost cracks 12 39 34 87.2 2 5.1 Large frost cracks 13 19 17 89.5 5 26.3 Mistletoe 14 5 4 80.0 1 20.0 Rotten branches 15 8 8 100.0 1 12.5 Dead or broken tops 16 42 33 78.6 6 14.2 Forks (small) 17 12 8 66.7 2 16.6 Crooks 18 55 45 81.8 17 30.9 Other 19 1 1 100.0 1 100.0
External No. Entrance Courts Average Decay abnormalities abnormalities associ ated with ob served entrance >court s No. Per cent cu. ft. Per cent of of No. of grQss tree vo abnormalities Echinodontium conks 44 - - - - Fomes cOnks 91 - - -• Scars 176 21 11.9 31.5 24.3 Frost cracks 183 5 2.7 1.8 3.6 Mistletoe 5 1 20.0 1.6 1.4 Rotten branches 10 1 10.0 24.9 31.2 Dead tops 42 6 14.2 1.7 8.0 Forks 12 1 8.3 0.3 0.0 Crooks 59 13 22.0 6.9 15.8 77
Table 32. Distribution, of trees with various external abnormalities.
External Code 97 sound trees 272 decayed tr< abnormality No.
No. Per cent No. Per cen
Echinodontium conks 1 0 0 27 9.92 Fomes conks 2 0 0 33 12.13 "Blind" conks 3 0 0 17 6.25 "Other" conks 4 0 0 4 1.47 Small open scars 5 5 5.15 42 15.44 Med. open scars 6 1 1.03 6 2.20 Large open scars 7 0 0 7 2.57 Small closed scars 8 9 9.27 41 15.07 Med. closed scars 9 2 2.06 12 4.41 Large closed scars 10 0 o 8 2.94 Small frost cracks 11 12 12.37 80 29.41 Med. frost cracks 12 ' 5 5.15 34 12.50 Large frost cracks 13 2 2.06 17 6.25 Mistletoe 14 1 1.03 4 1.47 Rotten branches 15 0 0 8 2.94 Dead or broken tops 16 9 9.27 33 12.13 Forks (small) 17 4 4.12 8 2.94 Crooks 18 10 10.30 45 16.54 Other 19 0 0 1 0.36 78
Table 33. Frequency of occurrence and maximum, minimum and average heights of external abnormalities in 369 western hemlock trees.
External Code Frequency Max. ht. Min. ht. Avg. ht. abnormality No.
"Echinodontium conks 1 44 65 4 34.7 Fomes conks 2 91 75 7 30.2 "Blind" conks 3 29 51 3 21.6 "Other" conks 4 4 52 •11 35.5 Small open scars 5 61 .. 94 1 26.0 Med. open scars 6 9 59 3 21.1 Large open scars 7 7 79 2 36.4 i Small closed scars 8 71 134 i 18.4 Med. closed scars 9 ' 19 34 2 8.6 large closed scars 10 9 44 3 10.4 Small frost cracks 11 122 66 1 4.6 Med. frost cracks 12 41 72 3 12.1 Large frost cracks 13 20 78 6 21.0
Mistletoe 14 5 - 37 19 27.4 Rotten branches 15 10 113 11 45.5 Dead or broken tops 16 42 - - Forks (small) 17 12 107 2 47.3 Crooks 18 59 133 1 48.5 Other 19 1 - - - 79
Table 34. Frequency of occurrence and1 maximum, minimum and average heights of external abnormalities in 97 sound western hemlock trees.
External Code „ , , „ ' Frequency Max. ht. Mm. ht. Avg. ht. abnormality No. •
Echinodontium conks 1 0 - - -
Fomes conks 2 0 - - "Blind" conks 3 0 - - -
"Other" conks 4 0 - - - Small open scars 5 6 47 3 11.8 Med. open scars 6 1 21 21 21.0. Large open scars 7 0 - - - Small closed scars 8 11 50 3 14.4 Med. closed scars 9 4 9 3 5.0
Large closed scars 10 0 -' - - Small frost cracks 11 16 7 1 2.8 Med. frost cracks 12 5 16 4 6.6 Large frost cracks 13 2 25 10 17.5 Mistletoe 14 1 19 19 19.0 Rotten branches 15 0 - - - Dead or broken tops 16 9 - - - . Forks (small) 17 4 58 4 41.3 Crooks 18 11 99 2 40.0 Other 19 0 - - - 80
Table 35. Frequency of occurrence and'maximum, minimum and average heights of external abnormalities in. 272 decayed western hemlock trees.
External Code Frequency Max. ht. Min. ht. Avg. ht. abnormality No.
Echinodontium conks 1 44 65 4 , 34.7 Fomes conks 2 91 75 7 30.2 "Blind" conks 3 29 51 3 , 21.6 "Other" conks 4 4 52 11 35.5 Small open scars 5 55 94 1 27.6 Med. open scars 6 8 59 3 21.1 large open scars 7 7 79 2 36.4 Small closed scars 8 . 60 134 1 19.2 Med. closed scars 9 15 34 2 ' 9.5 Large closed scars 10 9 44 3 10.4 Small frost cracks 11 106 66 1 4.9 Med. frost cracks 12 36 72 3 12.9 Large frost cracks 13 18 78 6 21.4 Mistletoe 14 4 "37 21 29.5 Rotten branches 15 10 113 11 45.5 Dead or broken tops 16 33 - - - Forks (small) 17 8 107 2 50.4 Grooks 18 48 133 1 50.5 Other 19 1 - - Table 36. The frequency of occurrence of external abnormalities, singly and in combination, on 97 sound western hemlock trees.^
To read table select a column for an external abnormality and read down to find numbers of other external abnormalities found in combination. See Table 20 for key to external abnormality codes. Table 37. The frequency of occurrence of external abnormalities, singly and in combination, on 272 decayed western hemlock trees.1
External abnormality codes2 •• • > - • 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
No. of 2? 33 17 4 42 6 7 41 12 8 80 34 17 4 8 33 8 45 l\. trees • ; To read table select a column for an external abnormality and read down to find numbers of other external abnormalities found in combination. See Table 20 for key to external abnormality codes. 83
would be expected, none are mutually exclusive. For example, the most
common abnormalities, small scars (Photograph V) and frost cracks
(Photograph VI) and crooks are found in association with almost every
other abnormality tabulated. The absence of abnormalities on sound
trees is in marked contrast to the abundance of abnormalities on trees which are decayed. This points out in yet another manner the potential
usefulness of external abnormalities as indicators of decay. It must
be realized, however, that the trees which are decayed but do not have
external abnormalities are masked in this tabular presentation. From
table 23 previously discussed, it can be seen that of 111 residual
trees classed as having no abnormalities, 63 trees or more than half actually had measurable decay volumes.
The volume of decay actually associated with a particular abnormality or group of abnormalities is of great practical signifi•
cance (Table 31).. If a method can.be found to predict the amount of decay associated with important external indicators or groups of
indicators, then decay estimation in standing trees can be improved.
Table 38 shows relative numbers of trees having more, than specified
decay volume percentages for residual and suspect trees. The frequency with which specified decay volume percentages occur can be determined
from this table. For example, 72.1 per cent of residual trees had less
than 5 per cent of gross volume decayed, whereas less than 50 per cent
of the suspect trees had less than 5 per cent of gross volume decayed.
Similarly, almost 95 per cent of residual trees had less than 20 per
cent of gross volume decayed whereas only 78 per. cent of suspect trees
had less than 20 per cent of gross volume decayed.
Table 39 provides the same breakdown for- decay volume as
S3
Photograph VI. Frost cracks do not indicate significant amounts of decay in western hemlock. Table 38. Summary of relative numbers of trees with varying amounts, of decay by tree class.
Percentage of trees having less than Decay as per cent . ,° . , _ - , indicated amounts of decay of total tree volume (c.f.) "Residual" trees "Suspect" trees
0 ". 47.7 22.5 5 72.1 48.4 10 80.2 ,60.5 15 91.0 -^ 66.3 20 94.6 72.9 25 98.2 77.9 30 99.1 82.9 35 99.1 87.2 40 99.1 91.9 45 100.0 94.6 50 100.0 97.3 55 100.0 98.1 60 100.0 « 99.6 65 100.0 99.6 70 100.0 100.0 Table 39. Summary of percentages of trees with varying .proportions of decay for various external abnormalities.
External Percentages of trees having less than the percentage abnormality of decay volume indicated by column number
0 5 10. 15 20 25 30 35 40 45 50 55 60 " 6-5 70 Echinodontium conks 0 .0 3 .7 14 .8 29 .6 51, .8 66 .7 70 .4 74 .1 81 .5 92 .6 100 .0 Fomes conks 0 .0 0 .0 3 .0 6 .1 12 .1 18 .2 39 .4 57 .6 72 .7 .78 .8 87 .8 90. 0 97 .0 97 .0 100. 0 "Blind" conks 0 .0 5 .9 5 .9 5 .9 5 .9 11 .8 23 .5 47 .0 64 .7 76 .5 82 .3 88. 2 94 .1 94 .1 100. 0 "Other" conks 0 .0 0 .0 -33 .3 33 .3 33 .3 66 .6 66 .6 66 .6 66 .6 100 .0 Small open scars 17 .0 51 .1 61 .7 70 .2 78 .7 80 .8 87 .2 87 .2 91 .5 93 •6 95 .7 95. 7 97 .8 97 .8 100. 0 Med. open scars 11 .1 22 .2 44 .4 55 AJL 66 .6 77 .7 77 .7 88 .9 100 .0 Large open scars 0 .0 28 .6 28 .6 28 .6. 57 .1 71 .4 71 .4 85 .7 85 .7 85 .7 85 .7 100. 0 Small closed scars 20 .0 60 .0 64 .0 72 .0 78 .0 82 .0. 88 .0 94 .0 94 .0 96 .0 98. 0 100 .0 Med. closed scars 7 .1 50 .0 64 .3 64 .3 71 .4 71 .4 78 .6 85 .7 100 .0 Large closed scars 0 .0 0 .0 37 .5 50 ,0 62 .5 62 .5 75 .0 75 .0 75 .0 75 .0 75 .0 100. 0
Small frost cracks 17 .2 52 .7 62 .3 67 .7 70 10 77 .4 81 .7 87 .1 93 .5 96 .7 96 .7 98. 9 100 .0 Med. frost cracks 12 .8 41 .0 53 .8 64 .1 69 .5 76 .9 79 .5 84 .6 87 .2 89 .7 89 .7 92. 3 97 .4 97 .4..100 . 0 Large frost cracks 5 .5 33 .3 ^0 ,0 55 .5 61 .1 61 .1 66 .7 72 .2 77 .8 88 .9 94 .4 94. 4 100 .0 Mistletoe 20 .0 £0,0 60 .0 80 .0 80 .0 100 .0 Rotten branches 0 .0 25 .0 37 .5 37 .5 .62 jJL 75 .0 75 .0. 75 .0 87 .2 87 .2 87 .2 87-. 2 87 .2 87 .2 100. 0 Dead or broken tops 26 .2 59 .5 61 .9 71 .4 76 .2 78 .5 80 .9 83 .3 . 85 .7 90 .4 92. 8 100 .0 Forks (small) 41 .7 50 .0 58 .3 58 .3 66 .6 91 .7 91 .7 91 .7 91 .7 91 .7 100 .0 Crooks 20 .0 56 t3_ 74 .5 81 .8 85 .4 87 .3 87 .3 89 .1 96 .3 98 .2 98 .2 98. 2 100 •0 Other abnormalities 0 .0 0 .0 100 .0 Residual trees 47 .7 72 .1 80 .2 91 .0 94 .6 98 .2 99 .1 99 .1 99 .1 99 . 1 100 .0 Suspect class 1 13 .2 37 .7 .56 .8 60 .0 69 .7 77 .7 80 .8 85 .1 90 .2. 90 .5 93 .9 97. 2 98 .7 99 .5 ioo. 0 Suspect class 2 0 .0 2 .4 14 .2 18 .7 25 .8 40 .8 50 .0 61 .3 71 .4 87 .0 92 .5 94. 6 97 .8 97 .8 100. 0 All trees 20 .3 37 .4 -50 _-5_ 56 .6 63 .3 72 .2 76 .6" 81 .8 87 9 92 .5 95 .4 97. 3 98 .8 99 .9 100. 0
See text for explanation of underlining. 88
Table 38, but in detail for each external abnormality. The position
of the underlined figures in Table 39 are useful in assessing the impor-
tance of abnormalities as indicators of specified amounts of decay.
Each underlined figure indicates the column at which approximately 50
per cent of the trees will have less than the per cent decay indicated
by the column in which the underlining occurs. In the case of residual
trees, approximately half have decay and half have no decay. For trees with E. tinctorium conks, as many trees have less than 20 per cent decay
as have more than 20 per cent decay. From this table it is apparent
that conks, large open scars and rotten branches are the external
abnormalities which are associated with the largest amounts of decay
volume percentage. Figures 1 and 2 illustrate values from Tables 38 and
39 for several tree classes and selected abnormalities. The large dif•
ferences in decay volume percentages between residual trees and trees
with conks (suspect class "2") are clearly evident in these figures.
The lower decay volume percentages associated with dead or broken tops
compared to trees with conks are also evident. Comparisons of actual
percentage merchantability and estimated percentage merchantability as
predicted for this sample by the loss factors prepared by the British
Columbia Forest Service for this area (British Columbia Forest Service,
1966) are favourable for most tree classes (Table 40). With the excep•
tion of suspect class "2" in tree class II where difference between
actual and estimated decay volume percentage is 6 per cent and in the
smaller DBH class where the number of samples is small, the agreement
is excellent. It is probable that suspect class "2" would also be in
closer agreement had the sample been larger.
From these initial summaries it is apparent that certain 89
Figure !'• Relative cumulative frequency of decay percentages in individual western hemlock trees by British Columbia
Forest Service (1366) tree classes-
Abnormality residual trees suspect class "'" all classes suspect class "2"
20 30 40 60
Per cent of gross tres volume decayed 90
Figure 2- Relative cumulative frequency of decay percentages in individual western hemlock trees with various types of external abnormalities-
0 10 20 30 40 50 60
Per cent of gross tree volume decayed 91
Table 40. Numbers of trees , actual percentac; e merchantability. and percentage merchantability as predicted through British Columbia Forest Service (1966) loss factors for 369 western hemlock trees.
DBH limit Tree class "0" Tree class I (inches) No. Actual B.C.F.S. No. Actual B.C.F.S.
7.1-9.0 8 96 .98 5 95 99 9.1-11.0 12 94 97 5 90 99 11.1+ 349 83 83 101 95 93
Tree class IT. Suspect II ^II Suspect "2" No. Actual B.C.F.S. No. Actual BoCoFoS.
7.1-9.0 3 98 96 9.1-11.0 5 99 96 2 86 70 11.1+ 182 88 86 66 65 59
external abnormalities are potentially useful as indicators of decay within trees. Some abnormalities such as.small scars and large frost cracks are nearly always associated with decay, but the actual decay volume is usually small. On the other hand, other abnormalities such as conks, large open scars and dead tops are associated with larger volumes of decay. In some instances, combinations of abnormalities are potential decay indicators. It is clear that any technique developed to predict decay volume must provide for the incorporation of external abnormalities, both singly and in combination. One promising analytical technique is multiple correlation and regression analyses. The first use of this in forest, pathology was by Hepting (1935) who related the 92 height of decay above fire scars in Mississippi delta hardwoods to a
total of six independent variables. 93
CHAPTER IV
DEVELOPMENT OF TREE DECAY FACTORS
Selection of Equation -Form
The usefulness of tree decay factors depends to a great extent upon their accuracy, precision and ease of application. Tree decay factors are commonly expressed either in units of cubic feet or per cent of gross tree, volume. Both of the above measures have advantages and disadvantages. The cubic foot has the advantage that it is the primary unit of interest and does not require transfor• mation and decoding. The percentage unit must be decoded to cubic feet before answers can be obtained regarding volumes of wood decayed.
Mathematical manipulations carried out with percentage units often result in biased answers when decoded to natural units. Percentage transformations also may contribute to artificially high variation, especially when the base unit is small or approaches zero.
Analyses carried out with the cubic foot unit and conclusions reached therefrom, however, may be difficult to apply to other samples in similar areas. Variation in tree form, bark thickness and volume equations can be marked within a narrow geographic range. Decay factors developed on a cubic foot unit can be misleading and inaccurate because of' changes in tree form and resultant changes in gross tree volume from area to area. In many instances, decay loss factors developed on a cubic foot basis for one area could approach or even exceed gross tree volume for some trees in other areas. Factors expressed as a percentage of gross tree volume are not subject to these 94 disadvantages and can be applied with Consistency to a wide range of form classes. For the sake of this flexibility, it was decided to develop tree decay factors on a percentage basis and to attempt to minimize, if possible, any biases which might be introduced as a result of the percentage transformation. In the preliminary analyses, trials were duplicated for both cubic foot and percentage units for comparison purposes.
Results and Discussion -
The first step in the analysis was a correlation analysis to determine which tree variables were correlated with decay volume and decay volume percentage (Table 41). Variables most highly correlated with per cent decay were DBH, height, age, presence or absence of conks, gross tree volume in cubic feet and the combined variable DBH squared times total height. Grouping of similar single variables, specifically in the cases of conks and frost cracks, resulted in higher simple correlation coefficients.
Site index of each tree was not significantly correlated with percentage decay volume and was only barely correlated with cubic foot decay' volume (Table 41). In view of the accounts in the litera• ture of the relationship of decay to site index, particularly for
E_. tine tor ium, further analyses were deemed necessary.. Average heights and ages for all dominant and codominant hemlock trees on each plot, were calculated and site index for each plot was interpolated to the nearest foot from site index tables (Barnes, 1962). Per cent soundwood volume was plotted against site index (Figure 3) for the entire sample. No trends between per cent merchantability and site 95
- / Table 41. Simple coefficients of correlation :for variables" considered for use in development of tree decay factors.
Variable Decay ' volume (c.f.) (per cent)
simple correlation coefficients(r) 2 DBH (inches) ,654 .399
Total height (feet) .491 .278
Age (yrs.) .402 .343
Site index (ft.) - . 105 -.059
Gross vol. (c.f.) .719 .364
Merch. vol. (c.f.) ,478 .159
Echinodontium conks ~ .059 .259
Fomes conks .360 .539
"Blind" conks .261 .421
"Other" conks . 115 .092
Small open scars .036 .053
Medium open scars ..106 .056
Large open scars .219 .102
Small closed scars .127 .069
Med. closed scars .085 .036
Large closed scars .286 .123 96
Table 41. (cont'd). Simple coefficients of correlation for variables considered for use in development of tree decay factors.
Variable Decay vo lume (c.f.) (per cent)
simple correlation coefficients(r)
Small frost cracks .132 .084
Medium frost cracks .056 .125
Large frost cracks .118 .142
Mistletoe .032 - .018
Rotten branches .087 .118
Dead or broken tops .025 .117
Forks -.015 .027
Crooks - .051 -.040
Other .011 - .012 2 (DBH) (Total tree height) .714 .347 All conks .362 .649
Med. + large frost cracks .078 .137
external abnormalities assigned value of "1" if present, "0" if absent. "r" values larger than 0.100 are statistically significant at p.05 Figure 3- Scatter diagram showing per cent merchantability and site index for 14 sample locations-
100 X
X
90
~ 80
70
X
140 Site Index
' Site index after Barnes (1962)- 98
index could be discovered. Even in the multiple regression analyses, where site could have been significant after the interactions and
effects of age and tree size had been removed, it was usually among the
first group of variables to be eliminated. There is little doubt that
for this sample there is no significant relationship between percentage
decay and site index.
Regression analyses were used to assess all external abnormal•
ities and to single out those which could prove useful in tree decay-
functions. All variables with statistically significant simple correl• ation coefficients were analysed with a stepwise multiple linear regres•
sion program (Kozak, and Smith, 1965) to obtain various estimating
equations for tree decay volume percentages (Table 42). Statistically,
the "best" equation incorporated ten external abnormalities and tree
parameters and accounted for 57.9 per cent of the total variability in
decay volume percentage. The standard error of estimate was 9.46 per
cent. Similar preliminary regression equations for the estimation of
cubic foot volume of decay are presented in Table 43. The "best" of
these equations accounted for 68.6 per cent of the variability in decay
volume in cubic feet and had a standard error of 21.72 cubic feet.
All of the variables in equations presented in Tables 42 and
43 are statistically significant. The choice of predicting equation
for use must be made on the basis of practicability, precision and
accuracy desired. Even though more variability in decay volume was
accounted for by the use of the cubic foot estimating function rather
than by the percentage estimating function, subsequent analyses showed
that the standard errors, when recalculated as a percentage and decoded,
were actually less for the percentage estimating equations than the cubic Table 42. Some preliminary regression equations and statistics for use in the estimation of per cent decay volume in individual trees with 1 to 10 independent variables.1.
Regression coefficients Variable
Constant term 7.963 6.593 -3.157 -3.179 -4.131 -3.912 -16.43 -17.8.1 -13.23 -14.35 Fomes conks 27 .12 28.49 25.19 20.56 20.70 21.02 21.27 2\.22 21.15 21.24 Echinodontium conks 17.05 17.14 17 .53 17.10 17 .38 17.23 17.22 16.71 16.55 DR1-I (inches) .5264 .5068 .5261 .5033 .5848 .5785 .9130 ,9019 "Blind." conks 16.97 16.41 16.61 16.31 16.03 16.33 15.99 Dead or broken tops 5.516 5.102 5.081 5.089 4.507 4.689 Large open scars 10.82 11.09 10.06 9.493 8.628 Site index (ft) 3.970 4.441 4.168 4.561 Large frost cracks 4.744 5.057 5 .522 Total height (ft) -.1068 -.1057 Rotten branches 6.710
Coefficient of determination (R) .291 .386 .469 .522 .536 .547 .558 .563 .574 .579
Standard error of estimate, °L 12.1 11.3 10.5 10.0 9.86 9.76 9.65 9.23 9.49 9.46
all variables are statistically significant at p.05, regardless of the combinations in which they are used; external abnormalities assigned value of "1" if present, "0" if absent. Table 43. Some preliminary regression equations and statistics for use in the estimation of cubic foot volume of decay in individual trees with 1 to 9 independent variables.1
Regression coefficients Variable
Constant term -6.304 -7.781 -3.374 5.237 3.279 6.028 7 .109 7 .042 -13.96 (D.2,H) /100 .0438 .0411 .0375 .0594 .0573 .0579 .0580 .0589 .0599 Fomes conks 31.56 31.28 33.94 34.90 29.03 29.71 29.35 29.91 Age (yrs.) . 1048 .1144 .1136 : .1049 .0930 .0872 .0644 Total height (ft.) - .5576 - .5308 -.5435 - .5329 - .5137 - .4752 Large open scars 31.38 31.85 32.93 31.60 32 .71 "Blind" conks 21.45 22.36 22.so: 22.77 Echinodontium conks 12.26 ; 12.09 13.18 Med. closed scars -15 .31 -14.03 Site index (ft.) 8.208
Coefficient of determination (R2) .510 .563 .590 . 644 .657 .668 .675 .680 ; .686
Standard error of estimate, c.f. 26.84 25.36 24.62 22.94 22.58 22.23 22,04 21.89 21.72.
all variables are statistically significant at p.05, regardless of the combinations in. which they are used; external abnormalities assigned value of "1" if present; "0" if absent. 10 foot estimating equations.
In nearly all preliminary equations tested, the independent variables used in the equations tabulated in Table 44 were statistical!; significant. The "best" of these equations accounted for 52.6 per cent of the variation in decay volume percentage within individual trees and had a standard error of estimate of 9.95 per cent. This predicting equation was tested by estimating the volume of decay in the 369 trees used for the study sample. The decay volume within each tree was esti• mated by means of the equation, using as independent variables DBH in inches, the presence (1) or absence (0) of conks, large open scars
(Photograph VII) and dead or broken tops (Photographs VIII and IX).
A direct estimate of the standard error of estimate of decay volume in cubic feet within individual trees was obtained by solving the formula
SE = l/(actual decay volume - est, decay volume)^ V n - r - 1
Table 45 shows* the results of the comparisons of actual and estimated decay volumes.
These show that the equation is practically unbiased and has a standard error of estimate of 18.66 cubic feet which is less than the standard error of 21.72 cubic feet for the "best" predicting equation using cubic foot units rather than percentage units. Table 46 is a tabulation of this predicting equation for two-inch DBH classes from 8 to 50 inches for all possible combinations of the independent variables selected.
Conclusion
Analyses of multiple correlation and regression show that the Table 44. Some regression equations and statistics for use in the estimation of per cent decay volume in individual trees with various groups and combinations of external abnormalities.
Equation numbers and regression coefficients Variable 1 2 3 ' 4
Constant term 5.998 -3.452 -3.295 -4.136 All conks 24.18 22.19 22.56 22.26 DBH (inches) .5245 .4908 .5111 Large open scars 11.97 10.98 Dead or broken top 4.643
Coefficient of determination (R^) .422 .503 .516 .526
Standard error of 10.9 10.2 10.0 9.95 estimate, %
all variables are statistically significant at p.05, regardless of the combinations in which they are used; external abnormalities assigned value of "1" if present; "0" if absent. Photograph VII, Large open scars indicate? significant amounts decay in western hetolock.. 104
9 105
Photograph IX. Dead tops indicate significant amounts of decay in western hemlock. 106
Table 45. Trial results for selected equation used to predict decay volume in individual trees.
Variable Value
No. of trees 369 Total actual decay volume 5802.6 cubic feet Total estimated decay volume 5817.5 cubic feet Total bias (absolute) 14.9 cubic feet Total bias (relative) 0.25 per cent Average bias per tree 0.04 cubic feet Standard error of estimate of 18.66 cubic feet decay volume in individual trees (19.5 per cent)
decay volume in standing western hemlock trees.can be reliably estimated from DBH and the presence of absence of certain external abnormalities which indicate decay. Conks, large open scars and dead or broken tops are the most important external indicators of decay. An equation which includes DBH and the above abnormalities as independent variables, permits the estimation of decay volume in individual western hemlock trees with a standard error of estimate of 18.66 cubic feet or 19.5 per cent. Table 46. Estimated decay volume expressed as a percentage of total tree volume by DBH classes for several external abnormality groupings.1
External abnormalities DBH nil 1 2 3 1+2 1+3 2+3 1+2+3 (inches) Decay volume as per cent of gross tree volume 8 0.0 22.2 10.9 4.6 33.2 26., 8 15.6 37.8 10 1.0 23.2 11.9 5.6 34.2 27., 9 16.6 • 38.8 12 2.0 24.3 13.0 6.6 35.2 28.. 9 17.6 .: 39.9 14 3.0 25 .3 14.0 7 .6 36.2 29., 9 18.6 40.9 16 4.0 26.3 15.0 8.7 37 .3 30., 9 19.7 41.9 18 5.1 27 .3 16.0 9.7 38.3 32., 0 20.7 42.9 20 6.1 28.3 17.0 10.7 39.3 33., 0 21.7 44.0 22 7.1 29.4. 18.1 11.7 40.3 34., 0 22.7 45 .0 24 8.1 30.4 19.1 12.8 41.4 35., 0 23.7 46.0 26 9.2 31.4 20.1 13.8 42.4 36. 0 24.8 47.0 28 10.2 32.4 21.1 14.8 43.4 '••37. 1 25.8 48.0 30 11.2 33.4 22.2 15 .8 44.4 38.. 1 26.8 49.1 32 12.2 34,5 :. 23.2 16.9 45 .4 39., 1 27.8 • • 50.1 34 13.2 35.5 24.2 17 .9 46.5 40., 1 . 28.8. 51.1 36 14.3 36.5 25.2 18.9 47.5 41., 2 29.9 52.1 38 15.3 37 .5 26.3 19.9 . 48.5 42., 2 30.9 53.2 40 16.3 38.6 27 .3 20.9 49.5 43., 2 31.9 54.2, 42 17 .3 39,6 28.3 22.0 50.6 44.. 2 32.9 55.2 44 18.4 40.6 29.3 23.0 51.6 45., 2 34.0 56.2 46 19.4 41.6 30.3 24.0 52.6 46., 3 35.0 .57 .2 48 20.4 42.6 31.4 25.0 53.6 47., 3 36.0 58.3 50 21.4 43.7 32.4 26.1 54.6 48., 3 37 .0 59.3
Decay volume percentage = -4.136 + .511DBH + 22.258C + 10.976LOS + 4.643T. 2 "1" is conks (0), "2m is large open scars (LOS), "3" is dead or broken tops (T) 108
CHAPTER V
DEVELOPMENT OF LOG POSITION DECAY FACTORS
Selection of Equation Form
Examination of the position of- the decay columns within the
trees showed that for all decayed trees the average column of- decay was
situated in the middle portion of the trunk. Decay did not extend
downwards to the ground level or upwards to the point of merchantability which, for this study, was deemed to be a 4-inch top diameter inside
bark. Table 26 shows that the average decay column began at 14.9 feet,
reached maximum diameter at 25.1 feet and extended to a total height
of .46.9 feet above ground level. The maximum diameter for this average
column was 8.9 inches. Of the 272 trees which were decayed, a total of
48 or 17 per cent had a second but much smaller decay column above the
primary column. T*he location of the main decay column suggests that
logs in various positions within the tree would not have the same decay
volume or decay volume percentage. From the average location of the
rot columns it can be expected that logs in the mid-section of the tree
are the most defective, while butt logs and top logs are relatively
less decayed. Analysis of the individual 16-foot cut sections showed
this to be the case (Table 47). Decay percentage increased from the
butt logs to the third log, decreased from the fourth to seventh log
and then increased slightly to the tree tip. The third log in the
tree was the most defective averaging 21.4 per cent decay. However,
the second log contained the largest cubic foot volume of decay.
Attempts were made to develop an analytical technique that Table 47. Summary of basic, data by log position for 369 western hemlock trees.
Log position (numbered from ground) Variable 1 2 3.4 5 6 7 8 9 10 11 • •" • . • • — • » • »y ..... , . Diameter (inside 15.3 13.5 11.4 9.7 9.6 8.8 7.1 5.9 5.5 4.4 4.0 bark (inches).
Height 16.3 .31.6 47.0 61.0 75.5 91.9 107.8 123.9 141.0 157.3 171.0 above ground (ft.)
Average gross 28.8 21.7 17.3 13.8 13.1 11.7 8.8 6.5 5.3 3.4 1.8 vol. (c.f.)
Average decay 4.1 4.3 3.7 2.5 1.6 1.0 0.6 0.5 0.8 0.6 0.0 vol. (c.f.)
Average decay 14C2 19 i 8 21'A 1811 12 j 2 11'. 7 6'.8 7 57 15.0 17; 6 00 vol. (per cent of gross log vol.)
Number of 369 369 361 316 212 140 96 54 20 7 1 logs 110 would yield reasonable estimates of decay volumes for individual logs
in standing trees, much in the same manner that an equation was developed
to estimate decay volume percentage in the entire tree.' Phrased in another• manner, attempts were made to redefine the tree decay estimation equation to permit the estimation of decay volume for individual logs within trees.
At first consideration, it might seem logical to develop a
function to estimate log defect in terms of the top diameter of the
log. This is not sufficient, however, because the position of the log within the tree is an important criterion in the determination of the amount of defect likely to be present in any given log. A log with a
.small top diameter could originate from the top of a large tree, the middle of a smaller tree or the butt of an even smaller tree. As pointed out earlier, each of the above positions requires a separate decay loss factor. It is necessary, therefore, that any function deve•
loped must incorporate some measure of log position as an independent variable. The manner in which log position is indicated is also impor•
tant. In order to provide maximum flexibility, it is necessary that the equation be adaptable to provide estimates for logs of any given
length. A measure which determines log position relative to total height of the tree can be readily used to provide such flexibility.
The simplest and probably most efficient expression is h/H where"h'r is height above ground of the top of a given log and "H" is total tree height. This fraction can be used to specify the exact position of the
top of a log in any tree for which total height is available.
An additional measure needed to develop a predicting equation
is the DBH of the tree. The hypothesis then can be stated that the Ill
-defect percentage in any log is a function of the tree DBH and log
position expressed as h/H. To this must be added those external
indicators which proved to be significant in the development of the
tree decay factors. Utilization:of the log position indicator h/H
permits the estimation of percentage decay in a tree to any given height.
Results and Discussion
Multiple correlation and regression analyses were used to
consider those variables which could be of.importance in the estimation
of individual log decay volume. Table 48 shows simple con-elation
coefficients obtained for several dependent and independent variables.
In addition to significant external abnormalities, several transfor•
mations of h/H were included, some of which proved to be statistically
significant. Preliminary regression equations were developed from
stepwise regression solutions using some of the significantly correlated
variables (Table 49). Numerous other variables, transformations and
interactions were considered in addition to the ones presented in
Table 49, however, they were not significantly associated with log
position decay. Table 50 shows additional regression equations based
on grouped abnormalities plus several transformations of DBH and h/H
which were included because of high simple correlation coefficients.
Statistically, the "best" predicting equation in Table 50 accounted
for 51.8 per cent of the variability of decay within logs and had a
standard error of 9.10 per cent. Several of the equations in Table 50
were used to estimate the decay volume within the logs of the 369
sample trees in the basic data. Computer printouts of actual and
estimated decay volume for each log were examined for accuracy and bias. Table 48. Simple coefficients of correlation for variables considered for use in development of log position decay factors.
2
Variable X 1 X2 X3
simple correlation coefficients (r) DBH (inches) .6113 .397 - .432
Total height (H)(ft.) .452 .284 .322
Age (yrs.) .366 .321 -.324
Site index (ft.) -.074 . -.077 .099
Gross vol. (c.f.) .674 .354 -.390
Merch. vol. (c.f.) .430 .152 -.179
Echinodontium conks^ .032 .174 - .161
Fomes conks .347 .529 -.570
"Blind" conks .251 .408 - .442
"Other" conks - .013 - .007 .009
Small open scars .037 .091 - . 104
Medium open scars .122 .089 -.113
Large open scars .327 .120 -.128
Small closed scars .166 .100 -.106
Med. closed scars ,237 .074 -.086
Large closed scars .296 .108 - . 120 Table 48. cont'd. Simple coefficients of correlation for variables/considered for use in development of log position decay factors.
x Variable l x2 x3
s imp le correlation coefficient. Small frost cracks .118 .079 -.086
Medium frost cracks .015 .074 -.083
Large frost cracks .117 .152 -.166
Mistletoe -.042 -.025 .022
Rotten branches .054 .096 - . 109
Dead or broken tops • .006 .065 -.074
Forks -.044 - .021 .031
Crooks - .073 - .059 .060
Other .012 - .010 .000
Accum. gross vol.(c.f.) .720 .420 -.357
Accum. merch vol.(c.f.) .461 .203 -.143
Accum. height (ft.) .396 .356 --.189
Accum. ht./total, ht. .161 .24-3 -.041 2 .165 - .050 (Accum. ht./total ht.) .237 3 (Accum. ht./total ht.) .168 .231 -.057
(DBH)2 (total ht.) .671 .339 -.372
All conks .337 .599 NA
Med.+Large frost cracks .043 .096 NA
:1 external abnormalities assigned value of "1" if present; "0" if absent. 2 Xj is accumulated decay volume (c.f.) to a specified height.
X2 is accumulated decay volume as a percentage of gross tree volume, X3 is accumulated merchantable volume as a percentage of gross tree volume. 3 "r" values larger than 0.100 are significant at p.05. Table 49. Some preliminary regression equations and statistics for use in estimation of: per :cen decay volume to specified heights (h) in individual trees with 1 to 10 independent variables.1
Regression coefficients Variable
Constant term .6375 -.0497 -1.089 - 1.219 -5.177 .6783 .7288 .5949 .7429 -3.894 Fomes conks 21.91 20.48 21.36 17 .53 16.19 16.02 16.39 16.33 16.36 16.50 h . 1234 .1258 .1233 .0872 .1094 .1092 .1089 .1088 .1087 Echinodontium conks 12.38 17 .53 12.71 11.83 12.09 12.13 12.12 10.94 "Blind" conks 12.36 12.25 12.86 12.95 13.27 12.92 12.02 DBH (inches) .2824 .7577 .7057 .7052 .6972 0.622 Total height (ft.) -.1648 - .1569 - .1526 - . 1618 . 1530 Large open scars 9.160 8.869 8.617 8.031 Small open scars 2.922 . 3';044 3.257 Large frost cracks 4.125 4.276 Age (yrs.) .0207
Coefficient of determination (R2) .280 .368 .422 .460 .488 .521 .531 .537 .543 .552
Standard error of estimate, %. 11.11 10.41 9.96 9.63 9.38 9.07 8.98 8.93 8.87 8.79
All variables are statistically significant at p.05, regardless of the combinationsain which they are used; external abnormalities assigned value of "1" if present, "0" if absent. Table 50. Some regression equations and statistics for use in estimation of per cent decay volume to specified heights (h) in individual trees with various groups and combinations of external abnormalities.^
Equation number and regression coefficients Variable 1 2 3 4 5 6 7 8
Constant term 4.979 .5640 -5.626 -5.504 -5.840 -9.236 -9.383 -9.413 All conks 19.77 18.27 18.17 18.51 18.41 18.44 18.38 18.33 (DBH) .0088 .0086 . .0079 .0081 .0084 .0083 .0083 h/H 12.29 12.27 12.18 28.60 28.73 28.79 Large open scars 8.948 8.743 8.733 8.610 8.264 Dead or broken tops 2.813 2.906 2.881 2.845 (h/H)2 -16.11 -16.25 -16 .32 Med. + large frost 1.217 1.223 cracks Rotten branches 2.341
Coefficients of • determination (R2) .359 .;448 .499 .508 .513 .516 .517 .518
Standard error, % 10.5 9.73 9.27 9.19 9.15 9.12 9.11 9.10
all variables are statistically significant at p.05, regardless of the combinations in which they are. used; external abnormalities assigned value of "1" if present; "0" if absent. 116
Actual standard errors of estimated log decay volume were obtained for
each log position by solution of the equation on page 101. Each esti•
mating function proved to be biased for certain log positions. The
equation which combined best precision with least bias was equation
No. 6 in Table 50. ' This function is graphed for the 20-inch DBH class
in Figure .4 and tabulated for all. possible-abnormality groupings by
2-inch DBH classes from 8-50 inches and by log positions from 10 to
-100 per cent-of total tree height in Appendix I. If a wholly graphical
procedure is preferred, a correction for DBH other than 20 inches can
be made using- Figure 4. Predicted values from.the equation are compared with actual values for each log position in Table 51. Standard errors
of estimate which ranged from 13.7 cubic feet in butt logs to 0.1 cubic
feet in top logs are also given in this table. The equation has a
relatively large bias and low precision in the first 16-foot log in the
tree. Thereafter, however, bias is much less and precision improves.
Reasonable estimates of decay volume can be made with this equation for
the first 32-foot log in a tree but not for the first 16-foot log.
Comparisons of decay percentages for log position h/H equal to "1"
(which are estimates of total decay percentage in the tree), with total
decay percentages tabulated in Table 46, are favorable (Appendix II).
Since these two estimates are derived from least squares procedures which were not conditioned to identity, total agreement cannot be
expected. The most correct values are those estimated from the tree
decay equation ("A" group of Appendix II, and Table 46). Therefore,
Appendix II."revalues might be conditioned to identity with Appendix II
"A"values. The fact that agreement is close, however, indicates that
both estimating systems are mathematically stable and potentially Table 51. Summary of actual and estimated decay volumes by log position within trees.
Log position (numbered from ground) Variable
1 2 3 4 5 6 7 8 9 10 11
Top diameter inside bark 15.3 13.5 11.4 9.7 9.6 8.8 7 . 1 5.9 5.5 4.4 4. ,0 (inches) Log length (feet) 16.3 15.3 15.4 14.0 14.5 16.4 15. 9 16 .1 17 .1 16.3 13., 7 Cumulative log length 16.3 31.6 47 .0 61.0 75.5 91.9 107 . 8 123.9 141.0 157 .3 171., 0 (feet) Average gross vol./log 28.8 21.7 17 .3 13.8 13.1 11.7 8. 8 5.5 5.3 3.4 1.. 8 (c.f.) Cumulative gross vol. 28.8 50.5 67.8 81.6 94.7 106.4 115. 2 121.7 127.0 130.4 132. ,2
v.c . J- .) Average decay vol./log 4.1 4.3 3.7 2.5 1.6 1.0 0. 6 0.5 0.8 0.6 0., 0 (c.f.) Estimated decay vol./log 6.9 2.3 2.1 1.8 1.7 1.6 1. 2 . 0.8 0.6 0.2 0., 0 (c.f.) Cumulative decay vol. 4.1 8.4 12.1 14.6 16.2 17 .2 17 . 8 18.3 19.1 19.7 19., 7 (c.f.) Estimated cumulative decay 6.9 9.2 11.3 13.1 14.9 16.5 17. 7 18.5 19.1 19.3 19., 3 vol. (c.f.) Average standard error of 13.7 8.2 7^2 5.3 4.1 3.5 2. 8 2.6 1.4 0.1 0., 0 estimate of log vol..(c.f.) No. of logs 369 369 361 315 211 140 96 54 20 7 1 118
Figure 4- Relationship between estimated accumulated decay voiume percentage and relative height for 20-inch DB-M-class trees for several external abnormality groupings with an adjustment for other DBH classes- 35 f
DBH
to & CP
CD 6
50 i o CJ c o ft) 40
c o o o 30 - w. o u •o o 20 o o h/H -10- Estimated values obtained from equation No- 6, table 50-The first D CO ordinate axis can be used to adjust for D B H classes other than 20 inches- 119
useful as decay estimating equations.
Conclusion
As would be expected in trees with heart rot caused by
E. tinctorium, logs from mid-height positions were the most defective.
Analyses of multiple correlation and regression show that the distri• bution of decay volume in standing western hemlock trees can be esti• mated from a multiple regression equation incorporating as independent variables tree DBH, total tree height, specified merchantable height and the. presence or absence of the significant decay indicating external abnormalities, conks, large open scars and dead or broken tops. Standard errors of estimate of decay volume ranged from 13.7 cubic feet in butt
logs to 0.1 cubic feet in top logs. 120
CHAPTER VI
DEVELOPMENT OF TAPER FUNCTION
Derivation of Basic Function
Attempts were made to derive a mathematical function which would permit the development of an equation to provide estimates of stem diameter inside bark at specified heights in terms of the tree parameters DBH and total height.
The following theory is based on the assumption that tree form can be reasonably approximated by a quadratic paraboloid although some, authors have stated otherwise (see page 51). According to Newnham
(1958)^ who studied the form and taper of western hemlock in British
Columbia, a quadratic paraboloid is applicable to approximately 85 per cent of the total height of a tree. Only near the butt, which is neiloid, and the tip, which is conical, does tree form differ signifi• cantly from that of a quadratic paraboloid
If a quadratic paraboloid is rotated on its central axis, the square of the diameter at any point will be proportional to the distance from the point of diameter measurement to the point of truncation. Thus
D2 a H - 4.5 (1.1) where D is DBH, H is total tree height and denotes a linear relation• ship. Similarly
dob.2 a H - 4.5 - L. (1.2) i i where dob. is the diameter outside bark at point "i" and L. is the 121
distance from the point of truncation (i.e. tree tip) to "i".
For convenience and practicability it is better to deal
with portions of total tree height rather than distances measured
downward from the tree tip. The relationship
dob.2 a h. - 4.5 (1.3) J J where h. is tree height measured from ground level to point "j" is
simply the inverse of formula 1.2.
Formulae' 1.2 and 1.3 can be combined in ratio form to
2 dob. h - 4.5 (1.4) _ a _J D2 H - 4.5
Formula 1.4 can be further simplified to
d2 h.
D2 H
on the basis of the following assumptions:
(a) except in instances where h^ or H are small, the constant
"4.5" can be eliminated without significantly changing the
value of the ratio on the right hand side of formula 1.4.
(b) diameter inside bark (d^) can be substituted for diameter
outside bark (dob.) without significantly changing the value
of the ratio on the left hand side of formula 1.4.
To substantiate the foregoing algebra and assumptions it can
be shown-that formula 1.5 is a linear transformation of a quadratic
paraboloid by rearranging the variables to
I—~ d. a D \ /h. ' (1.6)
which is of the quadratic form. 122
A function of the form of formula 1.6 can be used to estimate diameters inside bark at specified heights above the ground, while a simple transformation of formula 1.6 to
h. a Hd2/D2 (1.7) facilitates estimates of merchantable.heights for specified upper stem diameters inside bark.
Results and Discussion
Attempts were made to fit the curve form postulated (formula
1.5, page 121) to the basic data from the sample of 369 western hemlock trees and to test the usefulness of the equation derived from both theoretical and practical viewpoints. Average diameters inside bark and heights for each section, together with transformations and combinations are tabulated in Table 52.
Correlation analyses were carried out to determine to what 2 extent variables other than h/H were associated with (d/D) . The simple correlation coefficients derived are given in Table 53.. As would be expected from the theoretical derivation, the variable most 2 highly correlated with (d/D) was h/H. This was followed closely by exponentiation of h/H to the 1.5, 2nd and 3rd powers. Further exponen• tiation also yielded significant simple correlation coefficients, as did some arbitrary combinations of variables.
Preliminary regression equations utilizing all of these variables, transformations and combinations were developed. Some equations were plotted and examined graphically for usefulness; others were tested by computing estimated diameters inside bark and comparing them with actual diameters for each section height. Table 54 lists 123
Table 52. Summary of average diameters inside bark (d) and heights (h) at various cut sections for 369 western hemlock trees.
No. of 0 obs. DBH Total • h. . d (d/DBH)~ (h/H) (in.) height(H) (ft,) (in.) (ft.)
369 19.1 94.6 1.0 : 18.0 .8881 .0010
369 19.1 94.6 16.3 15.3 .6416 .1723
369 19.1 94.6 31.6 13.5 .4996 .3340
361 19.2 95.7 47.0 11.4" .3525 .4911
315 20.2 100.2 61.0 9.7 .2306 .6088
211 23.2 112.4 75.5 9.6 .17 12 .6726
140 26.8 124.5 91.9 8.8 .1078 .7331
96 28.6 134.2 107.8 7.1 .0616 .8033
54 31.8 144.9 123.9 5.9 .0344 .8551
20 35.4 158.8 141.0 5.5 .0241 .8879
7 39.6 172.0 157.3 4.4 .0123 .9145
1 55.1 178.0 171.0 4.0 .0053 .9607 124
.Table 53. Simple correlation coefficients for variables considered for use in development of a function to estimate upper stem diameters(d)I.
Upper stem Variable (d/DBH)' diameter(d)
DBH .5191 - .067
Total height(H) .472 -.049
Merch. height(h) -.533 -.855
h/H -.756 -.963
2 (h/H) -.763 -.898
1 5 (h/H) " -.766 -.933
3 (h/H) -.742 -.830
4 (h/H) - .717 - .773
5 (h/K) -.692 - .727
(h/H) 10 -.610 - .595
(h/H)15 -.573 -.542
(h/H)20 - .555 -.518
(h/H)1'5-(h/H)20 ' -.274 - .538
(h/H)1-5-(h/H)1 0 . -.239 -.513
(DBH)(H) -.510 - .059
DBH(H)(h/H)1-5-(h(H)20) -.028 -.427
DBH(H)((h/H)1-5-(h/H)10) .026 -.409
20 Hah/ID^-Oi/H) ) -.161 -.514
^((hAO^-a/H)20) -.065 -.444
(h/H)1'5-(h/H) 3 -.048 -.325
H((h/H)1-5-(h/H)3) - .111 -.318
DBH ((h/H)1-5-(h/H)3) -.173 -.314
H2((h/H)1>5-(h/H)3) .206 -.271
-J1. :. "r" values larger than 0.100 are significant at p.05 Table 54. Some preliminary regression equations and statistics for use in estimation of (d/DBH)2 with 1 to 9 independent variables.1
Regression coefficients Variable
Constant term .8253 .8561 .8715 .8830 .3959 .8983 .3807 .8862 .8824
h/H -.8875 -.8641 -1.114 -1.114--: -2.567 -2.830 -2.949 -3.216 -3.469
DBH((h/H)1-5-(h/H)3) -.0160 -.0120 -.0148 - .0137 -.0281 . -.0329 -.0303 - .0418
(h/H)1'5 -.2378 1.527 4.201 5.375 5.871 6.626 7 .699
(h/H)2 -.8090 -2.689 -3.685 -4.064 -4.627 -5.547
(h/H) 10 .1625 .2431 .2441 .4928 .0549
DBH(H)X (h/H) -(h/H)1U) 383:io-3;' 384:10-A •'. 3 24.10 4"; 178.
DBH (inches) 949.10-3 .822.10" 4.113. 20 - .1779 - ."5415 (h/H)ZJ -.110. DBH(H)((h/H)1'5-(h/H)20)
Coefficient of determination(R2) .928 . 944 .945 .947 , 948 ,949 .949 .949 .949
Standard error of .0815 .0721 .0715 .0711 .0698 .0693 .0691 .0690 .0687 estimate
1 all variables are statistically significant at p.05, regardless of the combinations in which they are used. 126
equations developed from one such analysis where all variables included proved to be statistically significant.,
Comparisons of actual and estimated diameters for the simple 2 linear regression of (d/D) on h/H showed excessive bias and under- 2 estimation of diameters near tree tips. The term (h/H) was added to the equation in an attempt to remove this bias. Although this helped, it did not completely eliminate estimation of zero or negative diameters near the top of trees. Further modifications to the equation form were required, the first being to artificially restrict the function so that at 100 per cent of total tree height, zero diameter estimation would be ensured. This was accomplished by fitting the data to the same equation form by least squares methods conditioned to satisfy the above restric• tion. Conditioning calculation procedures followed were those recommended by Freese (1964). This conditioning eliminated zero and negative diameter estimation, but unfortunately resulted in unacceptable positive bias in tree diameters above 47 feet in height (see values from equation No. 1,
Table 55). Subsequent unpublished tests of this equation form by
Kozak and Smith (1967) for the commercial tree species of British
Columbia showed that, in most cases, this form was not biased.
In view of the success of Kozak and Smith, and of the reasonable estimated diameters obtained for this data from coefficients provided by them for western hemlock (see values from equation No. 2, Table 55), it was assumed that computer programming errors were the source of the excessive bias. After attempts to discover programming errors proved futile, the stem analysis sampling technique was examined and the reasons for bias became apparent.
Data used by Kozak and Smith were collected in the decile Table 55. Comparisons of actual and estimated stem diameters inside bark at various tree heights for several estimating equations.
Average Average No. Equation numbers and average height actual dia. of estimated diameters (in.) (ft.) (in.) obs. 1 2 3 4
1 I'..; 18.0 369 17.8 20.3 .17.8 17 .9
16.3 15.3 369 15.7 17.3 15.3 15.4
31.6 13.5 369 13.5 14.4 13.4 13.6
47 .0 11.4 361 11.4 11.6 11.2 11.4
61.0 9.7 315 10.1 9.9 9.6 9.8
75.5 9.6 211 10.3 9.9 9.4 9.5
9 it 9 8.8 140 10.3 9.4 9.7 8.9
107.8 7.1 96 9.3 8.2 7.2 7 .5
123.9 5.9 54 8.7 7.4 6.0 6.3
141.0 5.5 20 8.5 7 .0 5,3 5.4
157.3 4.4 7 8.3 6.6 4.6 3.3
171.0 4.0 1 7.7 5.8 3.4 -
Weighted average standard error of 1.59 2.06 1.29 1.20 estimated diameters
} d=DBHV 0.8812-1.283h/H+0.4018(h/H)2 2 d=DBHy 11152-2.057h/H+0.9046(h/H) see table 56, equation No.5.
;:see table 59. 128 system, where each tree was sectioned and measured in ten equal portions above breast height, whereas data for this study were collected from sections of approximately 16-foot lengths. The fixed length sampling resulted in a larger number of observations at lower heights than at higher heights. Table 52 shows that the number of sections and obser• vations decreased from 369 in the first three sections to 1 in the last section. In the decile sampling technique, an equal number of obser• vations was obtained at each section and, in the resulting analyses therefore, each section was accorded equal weight. In the fixed length sampling where the number of observations was large, the least squares solution provided a good curve fit but as the number of observations declined, so did the goodness of fit. In order to achieve comparable results with the conditioned equation for data collected on a fixed length format, weighting was necessary to artificially make the number of observations equal at each point. This was accomplished by averaging the data values for each of the 13 section heights (Table 52).
The conditioned equation fitted to the data averages did not provide a satisfactory curve fit near the tree butts and to remedy this, polynomial equations from the first to the fifth degree were fitted (Table 56) and examined by comparison of actual and estimated values (Table 57). The fifth degree polynomial proved to be the best fit when graphed against the average data values (Figure 5).
Estimated diameters were calculated from this equation for each cut section in each tree and the standard error of estimate of diameter inside bark in inches was determined with the formula on page 101. Average estimated diameters compared favorably with average Figure 5- The relationship between (d/D) and h/H, showing a fifth degree polynomial' curve fitted to average values of the basic data-
Legend
X average values
OO 0-2 0-4 0-6 0-8 1-0 h/H
1 See table 56 for equation- 130
2 Table 56. Regression equations for estimation of (d/DBH) for polynomials from degree one to five.
Variable Regression coefficients for polynomials of degree
1 2 3 4 5 Constant .81034 .88776 .87508 .88769 .89046 term h/H -.88932 -1.37294 -1.14849 -1.77777 -2.23409 (h/H)2 0.46073 -0.10388 3.01184 6.63776 (h/H)3 0.36488 -4.49652 -14.18542 (h/H)4 2.38232 12197729 (h/H)5 -4.08533
actual diameters (see values from equation No. 3, Table 55) throughout the diameter range of the basic data. The standard error of estimate, of 1.29 inches was lower than for previous equations. Further tests for bias in equation: No. 3 were made by drviding the basic data into three DBH class groups and preparing separate estimates of section diameters for each group (Table 58). Residuals in each group were larger than for the data as a whole and there was evidence of bias according to tree size as measured by DBH. A slight underestimation of diameter was noted for trees larger than 22 inches DBH while slight overestimates were observed,for trees between 14.1 and 22 inches DBH.
Standard errors of estimated diameter were higher for the largest DBH class group.
The tendency to underestimate diameters- in the larger tree sizes suggested that some interaction term involving DBH and tree height should be added to the estimating equation to eliminate bias associated 131
with tree size. Analyses by Bruce e_t a_l. (1967) of taper of red alder
indicated that interaction terms incorporating DBH and height with high exponentiation removed bias associated with DBH. Therefore,variable
combinations and exponents similar to those used by Bruce et_ a_l. (1967) were studied. Simple correlation coefficients calculated are included
in Table 53. Two such interaction terms are included in some of the multiple regression equations in Table 54. Although both terms were statistically significant, they added little to the usefulness of the equation from a predicting view point. Table 55 (equation No. 4)
includes estimated diameters from an equation (Table 59) developed by- procedures suggested by Bruce e_t a_l. (1967). Average actual and estimated diameters compare favorably except near the tips of larger trees.
The comparisons of the various taper functions indicate that estimates secured from the 5th degree polynomial equation are acceptable.
The complications introduced by the use of high exponentiation and inter• action terms makes their use unwarranted. Diameters estimated from the polynomial equation are tabulated by 2-inch DBH classes from 8 to 50
inches for deciles of height in Appendix III.
Conclusion
Although reasonable estimates of upper stem diameters inside bark can be obtained from equations based on the assumption that tree
form is paraboloid, more precise estimates are facilitated by expansion
of the basic paraboloid function to a 5th degree polynomial. The
equation developed and tabulated enables estimates of upper stem diameters
of western hemlock with an average standard error of estimate of 1.29 132
Table 57. Comparisons of actual and estimated values.of (d/DBH) from the independent variable h/H for polynomials from degree one to five.
2 2 Section. (d/DBK) (d/DBH) estimated from polynomials No. actual 1 2 3. 4 5
1 . .888 .809 .886-; .874 ,885 .888
2 .642 .657 .665 .676 .650 .641
3 .500 .513 , .481 .493 .492 .501
4 .352 .373 .325 .329 .347 .352
5 .231 .269 .223 .220 .234 .231
6 .172 .212 .173 .167 .174 .168
7 .108 .153 .125 .117 .115 .110
8 .062 .096 .082 .075 .064 .063
9 .034 .050 .051 .045 .032 .035
10 " .024 .021 .032 .029 .017 .021
11 .012 -.003 .017 .017 .008 .013
12 .005 -.044 -.006 .000 .002 .004
13 .000 -.079 -.025 -.012 .007 .001 133
Table 58. The extent of bias in the estimation of stem diameters from 5^. degree polynomial equation for several DBK classes..
Approx. DBH class (inches) height 7.5-14.0 14.1-22.0 22.1+ 7.5+ (ft.) ; actual diameter minus estimated diameter (inches) 1 -0.2 0.0 0.9 0.2
16 0.3 0.1 -0.4 0.0
31 0.4 0.1 -0.2 0.1
47 0.7 0.4 -0,5 0.2
61 1.2 0.3 -0.5 0.1
75 0.5 -0,4 0.1
92 0.5 -0.2 0.0
108 0.7 -0.2 0.0
124 -o.i 0.1
141 0.2 0.2
157 -0.1 -0.1
171 0.6 0.6
Average 0.88 1.09 1.60; 1.29 standard error of estimate in inches
No. trees 131 132 106 369 Table 59. Estimating equation for (d/DBH) incorporating variables and interactions as suggested in method proposed by Bruce et a_l. (1968).
Independent variable Regression coefficient
Constant term 0.873968
DBH (inches) 0.001589
b (ft.) -0.000343
h/H -3.500720
(h/H)2 -5.793200
(h/H)1*5 7.984210
(h/H)10 1.006370
(h/H)20 -0.568393
(DBH) (H)((h/H)1'5-(h/H)2°) -0.000117
(DBH) (H)((h/H)1'5-(h/H)10) 0.000198
(DBH)((h/H)1'5-(h/H)3) -0.045472 135 inches,. More complicated functions incorporating interaction variables and high exponentiation do not significantly improve the precision of estimates of upper stem diameters. 136
CHAPTER VII
ESTIMATION OF VOLUME AND VALUE OF SOUND AND DECAYED WOOD
Estimation of Tree and Stand Volumes and Values
The reliability of estimates of tree volume and value depends on three major factors: the gross tree volume estimation, the decay volume estimation and the valuation or grading system for assessing tree quality. Gross tree volume estimation is probably the simplest and most precise of the steps involved in determining tree volume and value. Numerous gross tree volume equations are available. In British
Columbia, equations for the commercial tree species have been prepared by Browne (1962). These make use of Schumacher's basic equation form
(Bruce and Schumacher, 1950), but other equations are also available
(Smith and Breadon, 1964; Smith and Munro, 1965; Munro, 1967). Gross tree volume equations can be developed simply and efficiently through the use of multiple regression analyses on electronic computers. Two such gross tree volume equations developed for the trees used in this study are listed in Table 60.
The most efficient decay factors are those which can be expressed in equation form and therefore incorporated in flexible computer applications. Most tables for the estimation of decay in trees have been developed by a freehand graphical basis and are therefore subject to personal bias. In the development of decay factors by graphi•
cal methods it is impossible to assess all the combinations and inter• actions which affect decay in trees. It is only recently that mathematical methods have been applied to develop functions for estimating decay 137
Table 60. Two equations for use in estimation of cubic foot tree volume between a 1-foot stump height and a.4-inch top diameter for western hemlock.
Dependent ndependent variables Constant R variable (DBH)2(H)/100 Log. DBH Log. H
Tree vol. (c.f.) 5.2619 .17838 .98 15.2 Log. tree vol. -2.7024 1.8957 1.0612 .99 11.9
within individual trees. Equations such as those published by Aho (1966) which permit decay estimation in board and cubic feet for several tree species with various abnormality and age classes are extremely useful.
The equation developed in this thesis for western hemlock offers flexi• bility to the extent that it can be used to estimate decay volumes for residual trees and for suspect trees with a total of seven different combinations of three suspect abnormalities. An important but easily overlooked advantage of this equation form which makes use of indepen• dent variable classification "present" or "absent" (i.e. "1" or "0") is the significance attached to the regression coefficients for each inde• pendent variable. Using the numerical values "1" to indicate the presence of an external abnormality and "0" to indicate the absence means that each regression coefficient in the equation is, in reality, the percent• age of gross tree volume decayed if that abnormality is present. The equation for decay in western hemlock (Table 46)
Per cent of gross tree volume decayed =
-4.136 + .511DBH + 22.258C + 10.976LOS + 4.643T can be interpreted as follows: 138
a) Minimum per cent of gross cubic foot volume decayed,
regardless of external abnormalities present, is
-4.136 + .511DBH
(It follows, therefore, that this equation is not useful for
trees less than 8.3 inches DBH).
b) If external abnormalities are present, decay percentage must
be increased from the minimum by 22.258 or 22 per cent for
conks, 10.967 or 11 per cent for large open scars and
4.643 or 5 per cent for dead or broken tops. External
abnormalities other than the above do not warrant any percent•
age deduction above the minimum as they are not included in
the equation.
Equations expressed in the above format are simple to interpret and can be applied as general "rules of thumb" for quick estimates on a reconnaissance basis.
In computer applications where it is desired to provide estimates of net volume directly, the gross volume function and the decay volume function can be combined into one equation to yield direct estimates of net tree volume.
Of equal importance with the estimation of gross volume and decay volume is the estimation of tree quality (Gaines, 1964). The estimation of tree value requires some system of classification of tree quality. Numerous qualitative classification methods are available, however, to avoid bias associated with personal judgement and to permit mathematical analysis it is necessary that a quantitative quality class system be developed. Smith _et a_l. (1961) presented several equations 139
which related tree quality to such characteristics as height to live crown, live crown width and length and branch size. The log and tree grade committee of the Society of American Foresters (Lockard, 1961) has outlined the general topics which need further research in the development of tree and log grades.
The studies of O'Regan and Savin (1964), Csizmazia e_t aJL, (1966) and Dobie (1966) are excellent examples of progress being made in this field. Analytical procedures using comprehensive regression analyses for the determination of gross tree quality classes for Interior Douglas fir were developed by Csizmazia et_ a_l. (1966). Figure. 6 shows these tree quality classes and their relationship to tree DBH and site index.
Dobie (1966) found that net tree value of coastal Douglas fir could be estimated most efficiently from combinations of DBH, butt log grade and crcwn class. In equation form, these quality classifications can be coupled with tree equations for gross volume and decay volume to provide estimates of value for individual trees.
Information useful for the determination of value on a stand basis, as opposed to a tree basis, can be obtained from Figures 1 and 2.
Relative numbers of trees free from decay or with less than specified amounts of decay can be estimated from these figures and such information may be useful in determining marginal tree sizes and allowable decay specifications for local areas. For example, of those trees with conks,
50 per cent will have more than one-third of their gross volume decayed, whereas of those trees with external abnormalities other than conks, only
18 per cent will have more than one-third of gross volume decayed. Assess• ment of number of dead standing trees per acre may also prove useful in estimating defective volume and value on a stand basis. Foster and 140
Figure 6- Gross tree value (quality) and D B H relationship by site index classes for British Columbia interior Douglas fir- '
JLto 20 22 24 26 28 30 32 34 36
DBH (inches)
Source: Csizmazia efof{\9G6)- 141
Foster (1952) found an excellent relationship between stand defect and volume of dead trees per acre. Their equation was
Y = 7.20 + 1.02X where: Y is stand decay volume expressed as a per cent of gross stand volume, and
X is volume of dead trees per acre expressed as a percentage.of gross stand volume.
Computer programs such as those developed by Henley and Hoopes
(1967) for the calculation of saw log lumber recovery and value are useful in the development of tree grades and quality and value classes.
Additional information may come from aerial photography.
•The use of low level helicopter photography holds promise in detecting suspect and dead trees in stands. The British Columbia Forest Service is currently engaged in active research regarding the usefulness of such photography for the assessment of decay and reported that: "results are encouraging and warrant further study." (3ritish Columbia Department of Lands, Forests and Water Resources, 1967) .
According to Boyce and Wagg (1953), development of rot caused by F_. pini may be cyclical and numbers of infected and dead trees increase and decrease with increasing stand age. They stated:
"Fomes pini is somewhat pathogenic, commonly encroaching on the sapwood, resulting either in the death of the tree directly or, as seems more likely, reducing its vigor so that it succumbs to competition. The most rapidly growing trees are infecLed first, their growth is reduced, and finally they drop out of the stand. Meanwhile, new infec• tions are occurring in the remaining trees, and the process is repeated."
Trees severely infected or decayed by other fungi such as
E. tinctorium which are not pathogenic, are often weakened to such an 142
extent that they are removed from the stand by windbreak.
It is conceivable that the use'of low level helicopter photography to detect trees and stands in early stages of decay may
enable foresters to develop management plans which provide for logging during low points of decay cycles, thus eliminating excessive decay
losses.
Estimation of Log Volumes and Values
Application of total tree decay factors such as those discussed earlier in this chapter can be misleading and may cause erroneous values when applied to individual logs. As illustrated with the trees in this
study, the amount of decay in butt and top logs would be overestimated while the amount of decay in mid-section logs would be underestimated,
if the average tree decay factor were to be applied to logs from each position in the tree. Where log quality is important, it may be highly misleading to state decay losses in terms of a percentage of gross merchantable volume in the tree. Investigations by Bier, Foster and
Salisbury (1946) and Bier (1946) on Sitka Spruce in the Queen Charlotte
Islands showed that high value, Grade No. 1 butt logs were actually among
the least decayed. Decay percentages by volume were 7.2, 7.1, and 23.4
for Grade Nos. 1, 2 and 3 respectively. However, similar investigations by Foster and Foster (1952, 1953) on western hemlock in the Queen
Charlotte Islands indicated that the average percentage of defect was greater in Grade No. 1 logs than in Grade No. 3 logs. They stated:
"within each diameter class and in relation to gross volume, decay was found to be of greater significance in Grade 3 than in Grade 1 wood. On the basis of the quality of wood affected, however, decay was of equal, if not greater, importance in the better grades. The average percentage of 143
"defect was greater in Grade 1 than in Grade 3 owing to the larger average diameter."
The taper function developed in this study is designed so that estimates of diameter inside bark can be made at any height above ground providing the DBH and total height of the tree are known. Pre• diction of a series of diameters at specified intervals along the stem enables the calculation of gross volumes of individual logs. It is important to realize, however, that volumes estimated from taper function may be biased (Grosenbaugh, 1954). Taper functions involve the grouping and averaging of diameters whereas volume functions involve the grouping or averaging of volumes. It is recommended, therefore, that in the estimation of gross volumes of individual logs, adjustments be made to correct for possible volume bias introduced by the taper function
Since reliable gross tree volume functions are readily available for most species, it is logical to adjust volumes derived from the taper function to equal those derived from the volume function. The simplest method of adjustment is to compute the gross volume of the tree to the standard of utilization of the tree volume function by accumulating all log volumes estimated by the taper function. This volume is then compared with the tree volume estimated from the volume function and any difference in the two volumes is pro-rated on a percentage basis over individual log volumes calculated from the taper function. This adjustment ensures that-the total volume calculated from the taper function will equal the total volume calculated from the volume function.
Such an adjustment, if based on reliable tree volume equation safely eliminates any volume bias present in the taper function. Furthermore, the need to prepare localized taper functions which are difficult and .expensive to derive, .is eliminated and at the same time, artificial
changes in volume due to arbitrary selection of log lengths cannot
occur.
Log volumes calculated with the aid of a taper function
should be reduced for estimated decay within each log. The log
position decay function is designed so that decay estimates can be
made for logs situated at any height in a standing tree. Estimation
of decay volumes to successive heights above ground followed by
successive subtractions of estimated decay volumes, can provide
estimates of decay volume within specified log lengths. The
expression of decay as a percentage of gross tree volume avoids the
necessity of localization of decay functions for different tree
volume equations. As pointed out in an earlier section, the log
position decay function results in unacceptably biased estimates of
decay volume for butt logs shorter than 32 feet. This is not a
serious limitation in assessing high quality butt logs however,
because such logs are usually cut in lengths of approximately 32 feet.
British Columbia log grading rules (British Columbia Forest Service,
1963) specify that Grade No. 1 hemlock logs must be at least 26
inches in diameter. For 32-foot butt logs and for logs of any
length above a height of 32 feet, acceptable estimates of decay can
be -made from the log position decay function.
Adjustments of estimated log position decay volumes should
be made in a similar manner to the adjustments made for the taper
function volumes. The log position decay function and the tree decay
function are derived independently by least squares procedures and
it cannot, therefore, be expected that total tree decay volumes
estimated from the two equations will be identical. Since tests proved that the tree decay function was practically unbiased (Table
45), it is recommended that decay volume estimated from the log position, function be adjusted to equal decay volume estimated from
the tree decay equation. Recommended calculation procedures for the estimation of log position gross and net volumes are illustrated by example in Appendix IV.
In assigning a value or quality class to individual logs in trees, it is necessary that some measure of log quality be available.
It is not necessary that log size be one of the quality parameters...
log size can be coupled with the quality classification system in the compilation with diameter estimates from the taper function. Quality or value assigned also depends on the methods of scaling. In British
Columbia, where several methods of scaling are used, it is important to realize that the functions developed in this thesis estimate volume of decay only. Such estimates are equivalent to cubic foot scaling to
"close" utilization standards. Revision-of these functions would be necessary if estimates were required for "intermediate" utilization standards where scaling may be either in board feet or cubic feet and deductions are permitted for waste and breakage in addition to decay.
Estimates of quality in standing trees should utilize such quantitative tree variables as length of clear bole, length of live crown or branch size. Csizmazia _et _al. (1966) reported that site index, height to first live limb and number of sides clear on the first 16 feet of bole, were the tree variables most significantly associated with quality expressed as gross dollar value per gross cubic foot. Such variables can be readily related to existing
British Columbia log grades (British Columbia Forest Service, 1963) for western hemlock which, in addition to size specifications, have
strict requirements concerning allowable heartrot percentages and number, size and spacing of knots. For example, Grade No. 1
specifications state clearly that "half the net contents of the log must be clears" and that "knots are tolerated only to the extent of
a few well-spaced ones on the upper 30 per cent of one quadrant or
on the upper 20 per cent of two quadrants on logs 36 feet and over
in length." Grade No. 2 specifications permit any number of sound,
tight knots provided not less than 20 per cent of the net contents
of the log yield clear lumber. Grade No. 3 logs include those which
contain more than 33 1/3 per cent of their gross volume as sound.wood,
but are lower in grade than No. 2.
The log position decay function facilitates the estimation
of decay within individual logs in trees. If this decay is expressed
as a percentage of gross volume of the log, additional measures of
quality regarding permissible amounts of decay in logs could be
developed.
Estimation of Cellulose Quantity and Quality in Decayed Wood.
In order to assess the possible value of decayed western
hemlock wood for pulp, wood samples from three western hemlock trees
near Blue River, B. C. with typical rot columns caused by E.
tinctorium were selected for cellulose determinations. Blocks
approximately two inches square were obtained at intervals of two feet
throughout the length of each tree, both inside and outside the decay
column. Where possible, samples were taken the same number of rings
from pith. All sample blocks were collected immediately after the
trees had been felled and allowed to air dry in the sun. Upon return 147 from the field, the samples were stored in a cold chamber at o approximately 33 F until they were required for analysis. A total of 21 of these wood blocks were selected for laboratory analyses.
The actual location and number of samples chosen from each tree are shown in Appendix V. Because the main objective of the laboratory analyses was to determine if the decayed wood had undergone any significant loss in holocellulose or alpha cellulose in relation to the soundwood, samples were taken from decayed wood in the intermediate to advance stages of decay, from transition zone wood and from soundwood.
Laboratory procedures
Each wood block was split into pieces of approximately match-stick size and air-dried in a normal laboratory atmosphere for two days. Each was then fed at a constant rate of speed into a
Wiley mill and ground to pass a 20-mesh screen. The wood meal was shaken by hand for 30 seconds on a 40-mesh screen and the 20 to
40-mesh and the 40+ mesh fractions (hereafter referred to as coarse and fine fractions, respectively) collected separately in glass petrie dishes. Both fractions were equilibrated in an atmosphere controlled at 73°F (+ 0.56F) and 50 per cent (+ 2.0 per cent) relative humidity.
The actual equilibrium moisture content (EMC) of the wood meal was determined by drying a portion of each meal fraction from decayed wood and soundwood to constant weight at 100°C. and solving the formula:
MC = meal weight at EMC - meal weight OP x 100% meal weight. OD where MC = moisture content in per cent OD is oven dry. 148
Possible screening losses in.decayed wood were evaluated by expressing the OD weight of the coarse meal fraction as a
i percentage of the OD weight of both meal fractions for each wood
sample. This proportion was termed "physical yield".
Chemical analyses for the determination of holocellulose and alpha cellulose were carried out in replications of two on the co• arse meal fractions for each sample. The procedure for holocellulose determination was the chlorite deiignification process of Wise et_ al.
(1946), as outlined by Kennedy (1961) while alpha cellulose determina• tions were made following procedures suggested by Erickson (1962).
Results and discussion
The physical yield was calculated to determine if there was any difference in the grinding properties in the Wiley Mill between decayed and soundwood. The literature review indicated that decayed wood is subject to excessive chipping and screening losses because of brashness. Physical yield was calculated for each of 21 wood samples, 13 of which came from soundwood, 5 from decayed wood and 3 from transition zone wood. Analysis of variance (Table 61) indicated no significant difference in physical yield between any of the wood types. Whether or not the grinding properties of the wood from which these samples came would differ in a commercial chipper is not possible to determine, and it would be dangerous to extrapolate on the basis of the results obtained from this test.
Analysis of variance of holocellulose content indicated a significant difference between trees and between wood condition
(Table 62). Mean values for yields from each wood condition were tested by Duncan's new multiple range test and the yield of 149
Table 61. Analysis of variance for physical yields from western hemlock wood with various stages of heartrot:: catised by PiChinodontium tinctorium.
Source of DF Sum Mean Variance Sig. ! variation . squares squares ratios level
Trees 2 10.303 5.15 0.33 NS Wood condition 2 14.187 7 .093 0.46 /NS Interaction 4 32.997 8.249 0.53 NS Error 12 186.61 15.55
Total 20 244.10
NS not significant at p.05;
Table 62. Analysis of variance for holocellulose yields from wood of western hemlock with various stages of heartrot caused by Echinodontium tinctorium.
~ ... Source of DF Sum Mean Variance Sig. ! variation squares squares ratios level
Trees 2 129.62 64.811 18.02 •JL. Wood condition 2 144.65 72.326 20.10 Interaction 4 12.973 3.2432 0.90 NS Error 39 140.30 3.5975
Total 47 427.55
* significant at p.05 NS not significant at p.05 150
holocellulose from soundwood was found to be significantly higher
at p.05 than the yield from decayed or transition zone wood. Although
these yields were statistically significantly different they were less
than 4 per cent higher than the yields from decayed wood (Table 63).
Table 63. Comparison of average physical yields and holo- and alpha cellulose yields from western hemlock wood with various stages of heartrot caused by Echinodontium tinctorium.
Variable Decayed Transition Sound wood zone wood -wood
Physical yield (%) 73.75 74.33 75.51
Holocellulose (%) 72.98 74.16 76.671
Alpha cellulose(%) 47.32. 48.29 48.50
1 Significantly different at p.05 from values shown for decayed wood and transition zone wood according to Duncan's new multiple range test.
Analysis of variance of alpha cellulose content (Table 64)
indicated significant differences between trees but no significant
differences between wood condition. The interaction of trees and
wood condition was significant, indicating that the relative order
of alpha cellulose yield in sound, transition zone and decayed wood was not consistent from tree to tree. It can be inferred from this
analysis that although cellulose quality as measured by alpha
cellulose yield is not significantly different in sound, transition
zone or decayed wood, the individual tree has some influence on the
quality of cellulose. It may be possible that decay-causing fungi act Table 64. Analysis of variance for alpha cellulose yields from western hemlock wood with various stages of heartrot caused by Echinodontium tinctorium.
Source of DF Sum Mean Variance Sig. l Variation squares squares ratios leve I
Trees 2 .40.986 20.493 9.45 Wood condition 2 12.922 6.4609 ' 2.98 NS Interaction 4 35.393 8.8481 4.08 Error 33 71.526 2.1675
Total 41 160.83
1 NS not significant at p.05 * significant at p.05
differently on alpha cellulose from tree to tree.
It is important to consider how the measures of physical yield, holocellulose and alpha cellulose are expressed. In this study, each was expressed as a percentage of the oven-dry weight, of the wood sample analysed. Ideally, yields should be expressed as a percentage of the original weight of soundwood, a measure not available for the decayed material used in this analysis. As the yields are expressed here, the possibility that decayed wood may be lower in specific gravity than soundwood is masked.
If it can be shown that the decayed wood has a lower specific gravity than the soundwood, then the yield of cellulose from the decayed wood is reduced on the basis of yield calculated from an original soundwood weight or gross volume. Since pulp yields from commercial digesters are limited by volume of wood rather than weight of wood which can' be pulped at one time, it is necessary to show that 152
equal yields can be obtained from decayed wood on a volume basis to prove that decayed wood can be used without yield reduction.
In an effort to estimate the amount of pulp yield that might be lost due to the lower specific gravity of decayed wood,
the specific gravity of several samples adjacent to those used for
chemical analyses was determined by water displacement. Results are
summarized in Table 65 and indicate a slight increase in specific
gravity of decayed wood rather than a decrease as might be expected.^
Table 65. Specific gravity of western hemlock wood infected with various stages of heartrot caused by EEchinddofttlumttincfcorium.
Wood type No. Obs. Specific gravity (oven-dry volume)
Sound sapwood 6 .431
Sound heartwood 4 .467
Decayed heartwood 6 .502
Transition zone 2 .536 heartwood
Although increases of specific gravity intdecayed wood have been
encountered by other investigators (Scheffer et al., 1941; Glennie and Schwartz,1950: Harris and Wayman, 1956), no proven reasons for
such a phenomenum exist. Harris and Wayman (1956) noted higher contents \ of ash, silica, and iron in decayed western hemlock wood than in \ '
soundwood. It also is possible that in response to fungal infection,
additional amounts of extractives are accumulated in the infected 153
areas, thus contributing to a higher specific gravity.
On the basis of these limited investigations, it appears that holocellulose and alpha cellulose yields from western hemlock wood decayed by E. tinctorium should be practically equivalent to yields obtained from equal volumes of soundwood.
Conclusion
Estimates of the distribution of soundwood volume within
individual standing western hemlock trees can be made from multiple regression equations developed in this thesis. Gross volumes of
logs of specified dimensions can be estimated from tree taper and volume equations and estimates of decay volume can be made from tree or logi'position decay equations. Estimates of log value can be made
from equations similar to those developed by Csizmazia (1966) and
Dobie (1966). Chlorite delignification experiments carried out on
samples from three trees indicate that yields of holocellulose and alpha cellulose from western hemlock wood decayed by E. tinctorium are comparable to those obtained from equivalent volumes of soundwood. 154
CHAPTER VIII
SUMMARY AND SUGGESTIONS FOR FURTHER RESEARCH ...
The purpose of this thesis was to develop analytical methods
to determine the distribution of soundwood volumes and values in order
that appropriate reductions for decay could be made for estimates of net volumes of logs of specified sizes and grades. This was done by
describing as completely as possible the distribution of decay within
369 individual western hemlock trees from the Yale Public Sustained
Yield Unit.
All analyses were carried out on an I. B, M. 7044 computer.
Initial summarization and analyses of the data required a total of 15
computer programs, all but two of which were written by the author.
Comprehensive analyses of the relationships of decay in tree stems to a total of 19 different classes of external abnormalities showed that
large open scars, conks and dead or broken tops were the external abnormalities most useful in improving estimates of decay. Multiple
regression equations which included provision for three external abnormality classes were developed to estimate decay within individual
trees. The final equation selected provided decay estimates with a
standard error of estimate of 18.66 cubic feet or 19.5 per cent in
individual trees.
Analysis of the distribution of decay within tree stems
showed that the greatest volume of heartrot:. was concentrated in the
second and third 16-foot logs above the ground. Decay percentage
increased from the butt log to the third log, then decreased to the
seventh log and increased again in higher logs. Regression equations 155 with provision -for recognition of significant external abnormalities were developed to describe percentages of decay volume to specified percentages of total tree height. The final equation selected provided estimates of decay volume within individual logs in standing trees with standard errors, of estimate ranging from 13.7 cubic feet (31.6 per cent) in butt logs to 0.1 cubic feet (2.9 per cent) in top logs.
A mathematical function was developed to describe the taper of western hemlock trees. Selection of independent variables was designed so that estimates of diameter inside bark at any specified height could be made for trees of known DBH and total height. A standard error of estimated diameter inside bark of 1.29 inches was obtained with a 5th degree polynomial function. Application of the taper equation to estimate upper stem diameters inside bark enabled the calculation of gross volumes of logs from any specified position in a tree. Combination of the log position decay estimating function with the tree taper function provided an equation "package" which permitted estimation /of gross and net volumes of individual logs within standing trees. «, . • -
A unique and useful feature of the decay estimating functions is the incorporation of the independent variable classification "1" and
"0" to denote the presence or absence, respectively, of specified external abnormalities which indicate decay. In the system developed, the regression coefficient for each external abnormality in the estimating equations is in reality, an estimate of the average ! ' \ percentage decay volume associated with that abnormality.
! •• - \ The importance of recognition of external abnormalities and I \ , i ' *• • their usefulness in estimating decay in trees and stands are pointed out in a new-graphical approach whereby the percentage of trees in a 156 stand with more or less than specified amounts of decay can be estimated.
Chlorite _ delignification of samples of western hemlock wood infected with E. tinctorium indicated that: such wood may be useful for the production of pulp. Holocellulose yields from decayed wood were reduced by about 4 per cent in comparison with yields from soundwood ,. and alpha cellulose yields are unchanged. Potential holocellulose and alpha cellulose quantities available from wood decayed by E. tinctorium warrant further investigation. In the future it may be necessary to develop methods to provide estimates of the portion of volume of wood decayed by various fungi that is suitable for pulp manufacture.
Although analytical techniques have been developed in this study to describe the distribution of soundwood volumes and values in western hemlock, there are many areas where research can lead to improvement of these methods. The work initiated by Csizmazia et al.
(1966) should be continued and expanded for other species. The relationships of natural pruning to position of the decay column have not been investigated. Most authors suggest that branch stubs are the most important source of infection of E. tinctorium in western hemlock.
Kimmey (1964) speculated that the natural pruning encouraged by keeping stands fully stocked would result in reduced amounts of decay. Stubs of branches pruned at early ages when branch heartwood has not formed in appreciable quantities will presumably heal quickly and minimize time of exposure to infection. Although loss factors are available for waste and breakage-associated with decay (British Columbia Forest
Service, 1966), the relationships of breakage to position of the decay column have not been investigated. The relationship of bark thickness at different heights above the ground to decay positions and amounts needs study. Intensive studies similar to those conducted on an 157
extensive basis by Smith and Kozak (1967) on thickness and percentage of bark are needed. They noted, for example, that suppressed western hemlock trees and trees of low vigor had thinner bark than dominant and ccdominant trees. It is possible that further, research might reveal relationships between bark thickness and . infection potential.
Studies reported by Hamilton (1967) indicated no difference in proportions of residual, suspect and dead trees in 5 different
P.S.Y.U.'s, and it is therefore possible that results obtained from intensive analysis of 369 trees in the Yale P.S.Y.U. may apply through• out much of the western hemlock in- the Cascade-Coast mountains in
British Columbia. Although further testing may be required to demon• strate the applicability of the results of this study to western hemlock outside, the Yale P.S.Y.U., the methods developed herein may be used to define the distribution of soundwood volumes for any of the commercial tree species of British Columbia.
Application of improved methods of estimation of the distribution of soundwood volumes within trees should contribute much to improved forest management, planning and better utilization of individual trees and stands throughout British Columbia. -158
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APPENDIX I. Log Position Decay Factors for Western Hemlock.
Basic estimating equation:
D^ = -9 .236+ IS .44C+ .0084DBH2+28 .60^+8 .733(L0S) + 2 .906T- 16 .11(J|) 2
where D^ = decay volume to height "h" as a per cent of gross tree
volume in cubic feet.
b/H= fraction of total tree height.
C "1" if one or more conks present: "0" if conks absent.
L0S= "1" if one or more large open scars present; "0" if .
large open scars absent.
T = "1" if top dead or broken; "0" if top not dead or
broken.
Suspect Class Key
Suspect External Abnormalities Present^ Class conks. large open scars dead or broken top
0 : o 0 0
1 l 0 0
2 0 1 0
3 0 0 1
4 l 1 0
5 l 0 1
6 0 1 1
7 1 1 1
"0" if abnormality absent: "1" if abnormality present Log Position Decay Factors for Western Hemlock Trees: Suspect Class 0
Fraction of total height - h/H DBH .1 . 2 .3 .4 .5 .6 .7 • 8 .9 1.0 (inches) Per cent of gross tree volume decayed
8 0.0 0.0 0.0 0.2 1.6 2. 7 3.4 3.9 4.0 4.0 10 0.0 0.0 0.0 0.5 1.9 3.0 3.7 4. 2 4.3 : 4.3 12 0. 0 0.0 0.0 0.8 2.2 3.3 4.1 4.5 4.7 4. 7 14 0.0 0.0 0.0 1.3 2.7 3. 8 4.5 5.0 5.1 5.1 16 0.0 0.0 0.0 1.8 3. 2 4.3 5.0 5.5 5.6 5.6 18 0.0 0.0 0. 6 2.3 3.8 4.3 5.6 6.0 6.2 6.2 20 0.0 0.0 1. 2 3-.0 4.4 5.5 6, 2 6.7 6.8 6. 8 22 0.0 0.0 1.9 3.7 5.1 6, 2 6.9 7.4 7.5 7.5 24 0.0 0.7 2. 7 4.4 5.9 6.9 7.7 8.2 8.3 8.3 26 0.0 1.5 3.6 5.3 6.7 7.8 8. 6 9.0 9. 1 9.1 28 0.0 2.4 4.5 6. 2 7.6 8.7 9.5 9.9 10.0 - 10.0 30 1.0 3.4 5.4 7. 2 8.6 9. 7 10.4 10.9 11.0 11.0 32 2.0 4.4 6.5 8. 2 9.6 10. 7 11.5 11. 9 12.0 12.0
34 3. 1 5.5 7. 6 (9.3 10.7 11.8 12.6 13.0 13.1 13. 1 36 4.3 6. 7 8.7 10.5 11.9 13.0 13.7 . 14.2 14.3 14.3 38 5.5 7.9 10.0 11. 7 13. 1 14.2 15.0 15.4 15.5 15.5 40 6.9 9.2 11.3 13,0 14.4 15.5 16.3 16. 7 16.8 16. 8 42 8.2 10. 6 12. 7 14.4 15.8 16.9 17. 7 •18. 1 18.2 18.2 44 9. 7 12.0 14.1 15. 8 17. 2 18.3 19.1 19.5 19.7 19. 7 46 11. 2 13.6 15. 6 17.3 18. 7 19. 8 20.6 21.0 .21.2 21.2 48 12. 7 15. 1 17.2 18.9 20.3 21.4 22.2 22. 6 22. 7 22. 7 50 14.4 16.8 18. 8 20. 6 22.0 23. 1 23. 8 24.3 24.4 24.4 Log Position Decay Factors for Western Hemlock Trees: Suspect Class 1
Fractions of total height - h/H DBH . 1 .2 .3 .4 .5 .6 .7 .8 .9 .1.0 (inches) Per cent of gross tree volume decayed
8 12.4 14.8 16.9 18. 6 20.0 21. 1 21.9 22.3 22.4 22.4 10 12, 7 15. 1 17.2 18.9 20.3 21.4 22.2 : 22. 6 22.7 22. 7 12 13. 1 15.5 17.5 19. 3 20. 7 21. 8 22.5 23.0 23.1 23.1 14 . 13.5 15.9 18.0 19. 7 21.1 22.2 23.0 23.4 23.5 23.5 16 14.0 16.4 18.5 20. 2 21. 6 22. 7 23.5 23.9 24. 6 24. 6 18 -14.6 17.0 19.6 20. 8 22. 2 23.3 24.0 24.5 24.6 24.6 20 15.2 17.6 19. 7 21.4 22-. 8 23.9 24. 7 25. 1 25.2 25. 2 22 16.0 18.3 20.4 22. 1 23.5 24.6 25.4 25.8 25.9 25.9 24 16. 7 19.1 21.2 22.9 24.3 25.4 26. 2 26. 6 26.7 26. 7 26 17.6 19.9 22.0 23. 7 25. 1 26.2 27.0 27.4 27. 6 27.6 28 18. 5 20. 8 22.9 24. 6 26.0 27. 1 27.9 28.3 28.5 28. 5 30 19.4 21.8 23.9 25. 6 27.0 28. 1 28.9 29.3 29.4 29.4 32. 20. 5 22. 8 24.9' 26.6 28.0 29. 1 29.9 30.3 30.5 30.5 34 21. 6 25. 1 27.2 28.9 30.3 31.4 .32. 2 32.6 ' 32.7 32. 7 36 22. 7 25. 1 27.2 28.9 30.'3 31.4 32.2 32.6 32. 7 32. 7 38 24. 0 26.4 28.4 30'. 2 31.6 32: 6 33.4 33.9 34. 0 34.0 40 25 .'3 27. 7 • 29. 7 31.5 32.9 34.0 34. 7 35.2 35.3 35.3 42 26. 7 29.0 31.1 32. 8 34.2 35,3 36.1 36.5 36. 7 36.7 44 28.1 30.5 32.5 34.3 35.7 36. 8 37.5 38. 0 38. 1 38.1 46 29.6 32.0 34.0 35.8 37. 2 38.3 39.0 39.5 . 39.6 39.6 48 31.2 33.6 35.6 37.3 33. 8 39.8 40.6 41.1 41.2 41.2 50 32.8 35. 2 37.3 39.0 40.4 41.5 42.3 42, 7 42. 8 42.8
r-1 Log Position Decay Factors for Western Hemlock Trees: Suspect Class 2
Fractions of total height - h/H DBH . 1 .2 .3 .4 .5 .6 . 7 .8 • .9 1.0 (inches) Per cent of gross tree volume decayed
"8 2.7 .5: i ' 7.2 8.9 10.3 11.4 12. 2 12.6 12.7 12.7 10 3.0 5.4 7.5 9.2 10.6 lli7 12.5 12.9 13.0 13.0 12 3.4 5.8 7. 8 9.6 11.0 12. 1 12. 8 13.3 13.4 13.4 14 3.8 6. 2 8.3 10.0 11.4 12. 1 12.8 13,7 13.8 13.8 16 4.3 6.7 8.8 10.5 11.9 13.0 13.3 14.2 14.3 14.3 18 4.9 7.3 :.9. 3 11.1 12.5 13.6 .14.3 14. 8 14.9 14.9 20 5, 5 7.9 10.0 11.7 13.1 14. 2 15.0 - 15.4: 15.5 15.5 22 6.2 8. 6 10. 7 12.4 13.8 14; 9 15.7 16. 1 16.2 16.2 24 '."7.0 9.4 11.4 . 13.2 14.6 15; 7 16.4 16.9 17.0 17.0 26 7.9 10.2 12.3 14,0 15.4. 16; 5 17.3 17. 7 17. 8 17.8 28 8. 8 11.1 13. 2 14.9 16.3 17.4 18.2 18. 6 18.8 . 18.8 30 9.7 12.1 14.2 15.9 17,3 18.4 19.2 19.6 19.7 19. 7 32 10. 8 13. 1 14.2 15.9 17.3 18,4 19.2 19. 6 19.7 19. 7 34 11.9 14.2 16.3 18.0 19.4 20, 5 21.3 21. 7 21.9 21.9 36 13.0 15.4 17.5 19.2 20. 6 21. 7 22.5 22.9 23.0 23.0 38 14.3 16. 7 18.7 20.4 21.9 22,9 23.7 24. 2 24. 3 24.3 40' 15.6 18.0 20.0 21. 8 23. 2 24.3 25.0 . 25.5 25. 6 25. 6 42 17.0 19.3 21.4 23, 1 24.5 25, 6 26.4 26. 8 27.0 27.0 44 18.4 20.8 22. 8 24. 6 26.0 27. 1 2.7. 8 28.3 28.4 28.4 46 19.9 22.3 24.3 26. 1 27.5 28, 6 29.3 29. 8 29.9 29.9 48 21.5 23.9 25.9 27. 6 29.1 30, 1 30.9 31.4 31.5 31.5 50 23. 1 25.5 27. 6 29.3 30.7 31.8 32.6 33. 0 33. 1 33. 1 Log Position Decay Factors for. Western Hemlock Trees: Suspect class 3
Fractions of total height - h/H DBH . 1 .2 .3 .4 .5 .5 .7 • 8 .9 1.0 (inches) Per cent of gross tree volume decayed
8 0.0 0.0 1.3 3. 1 4.5 5.6 6.3 6. 8 6.9 6.9 10 0.0 0.0 1.6 3.4 4. 8 5.9 6. 6 7.1. 7.2 7.2 12. 0..0 0.0 2.0 3.7 5. 1 6. 2 7.0 7.4 7.6 7,6 14 0.0 0.4 2.4 4.2 5.6 6.7 7.4 7.9 8.0 : 8,0 16 0.0 0.9 2.9 4.7 6.1 7.2 7.9 8.4 8,5 8.5 IS 0.0 1.5 3. 5 5.2 6. 7 7.7 8.5 9.0 9. 1 9.1 20 0.0 2.1 4.1 5.9 5.9 7.3 8.4 9.1 9.6 9.7 22 0.4 2.8 4.9 6.6 8.0 9. 1 9.8 10.3 10.4 10.4 24 1.2 3.6 5.6 7.4 8. 8 9.9 10.6 11.1 11.2 11.2 26 2.0 4.4 6.5 8. 2 9. 6 10. 7 11.5 12.8 12.9 12.9 28 2.9 5.3 7.4 9.1 10.5 11.6 12.4 12. 8 12.9 12.9 30 3.9 6.3 8.3 10. 1 11.5 12. 6 13.3 13.8 13.9 . 13.9 32 4.9 7.3 9.4 11.1 12.5 13.6 14.4 14.3 14.9 14.9 34 6.0 78.4 10. 5 12.2 13.6 14.7 15.5 15.9 16.0 16.0 36 7.2 9.6 11. 6 13.4 14.3 15.9 16.6 17.1 17.2 17.2 38 8.5 10.8 12.9 14. 6 16.0 17. 1 17.9 18.3 18.5 13.5 40 9.8 12.1 14.2 15.9 17.3 18.4 19.2 ' 19. 6 19.8 19.8 42 11. 1 13.5 15.6 17.3 18. 7 19.8 20.6 21.0 21.1 21.1 44 12.6 15.0 17.0 18. 7 20.1 21.2 22.0 22.4 22. 6 22.6 46 14.1 16.5 18.5 20.2 21.7 22. 7 23.5 24.0 24. 1 24.1 48 15. 7 18.0 20.1 21.8 23.2 24.3 25.1 25.5 25. 6 25.6 50 17.3 19.7 21.7 23.5 24.9 26.0 26. 7 27. 2 27.3 27.3 Log Position Decay Factors for Western Hemlock Trees: Suspect Class 4
Fraction of total height - h/H
Dim .1 .2 .3 .4 .5 .6 .7 .8 .9 1.0 (inches) Per cent of gross tree volume decayed
3 21.2 23.5 25. 6 27.3 28. 7 29. 8 30.6 31.0 31.2 31.2 10 21.5 . r '23.8 25.9 27. 6 29.0 30.1 30.9 31.3 31.5 31.5 12 21. 8 24. 2 26.3 28.0 29.4 30.5 31.3 31.7 . 31.8 31.8 14 22.3 24.7 26. 7 28.4 29. 8 30.9 31. 7 32. 1 32.3 32.3 16 22. 8 25.2 27. 2 28.9 30.4 31.4 32.2 32.6 32.8 32. 8 18 23.3 25. 7 27.8 29.5 30.9 32.0 32. 8 33.2 33.3 33.3 20 24.0 26.4 28. 4 30. 1 31.6 32. 6 33.4 33.9 34.0 34, 0 22 24.7 27.1 29. 1 30. 8 32.3 33.3 34. 1 34. 6 34. 7 34. 7 24 25.5 27. 8 29.9 31. 6 33.0 34. 1 34.9 35.3 35.4 35.4 26 26.3 28. 7 30. 7 32.5 33.9 35.0 35.7 36.2 36.3 36.3 28 27. 2 29.6 31. 6 33.4 34. 8 35.9 36. 6 37, 1 37.2 - 37.2 30 28.2 30.5 32.6 34. 3 35. 7 36. 8 37. 6 38.0 38.2 38. 2 32 29.2 31.6 33. 6 35.4 36. 8 37.9 38.6 39,1 39.2 39. 2 34 30.3 32. 7 34. 7 36.5 37.9 39.0 39. 7 40.2 40.3 40.3 36 31.5 33.9 35.9 37.6 39.1 40. 1 40.9 . 41.4 41.5 41.5 38 32. 7 35. 1 37.2 38.9 40.3 41.4 42. 1 42. 6 42. 7 42.7 40 34.0 36.4 38. 5 40. 2 41.6 42. 7 43.5 43.9 44.0 44. 0 42 35.4 37.8 39. 8 41.6 43.0 44. 1 44. 8 45.3 45.4 45.4 44 36. 8 39.2 41.3 43.0 44.4 45.5 46. 3 46.7 46. 8 46. 8 46 38.3 40.7 ". 42. 8 44.5 45.9 47,0 47. 8 48. 2 48.3 48.3 48 39.9 42.3 44.3 46. 1 47.5 48. 6 49.3 49.8 49.9 49.9 50 41. 6 43.9 46.0 47.7 49. 1 50.2 51.0 51.4 51,6 51. 6 Log Position Decay Factors for Western Hemlock Trees: Suspect Class 5
Fraction of total height - h/H
DBH .1 .2 .3 -4 • .5 .6 .7 .8 .9 1.0 (inches) Per cent of gross tree volume decayed
8 15.3 17.7 19.8 21.5 22.9 24.0 24. 8 25.2 25.3_. 25,3 10 15.6 18.0 20. 1 21.8 23.2 24.3 25. 1 25.5 25. 6 25.6 12 16.0 18.4 20.4 22. 2 23. 6 24. 7 25.4 25.9 26.0 26.0 14 16.4 18.8 20.9 22.6 24.0 25.1 25.9 26.3 26.4 26.4 16 16.9 19.3 21.4 23.1 24.5 25.6 26.4 26. 8 26.9 26.9 18 17.5 19.9 22. 0 23.7 25. 1 26. 2 26.9 27.4 27.5 27.5 20 18.2 20.5 22. 6 24.3 25. 7 26. 8 27. 6 28.0 28.1 28. 1 22 18.9 21. 2 23.3 25.0 26.4 27.5 28.3 28. 7 28.9 28,9 24 19. 6 22.0 24.1 25.8 27. 2 28.3 29.1 29.5 29. 6 29. 6 26 20.5 22.8 24.9 26.6 28.0 29.1 29.9 30.3 30.5 30. 5 28 21.4 23. 7 25. 8 27.5 28.9 30.0 30. 8 31.2 31.4 31.4 30 22.3 24.7 26. 8 28.5 29.9 31.0 31. 8 32. 2 32.3 32.3 32 23.4 25.8 27. 8 29.5 31.0 32.0 32. 8 33.3 33.4 33.4 34 . 24.5 • 26.9 28.9 30.6 32.1 33.1 33.9 34.4 34.5 34.5 36 25.7 28.0 30. 1 31. 8 33. 2 34.3 35. 1 35.5 35.6 35.6 38 26.9 29.3 31.3 33.1 34.5 35.6 36.3 36. 8 36.9 36.9 40 28. 2 30.6 32.6 34. 4 35.8 36.9 37. 6 38. 1 38.2 38.2 42 29.6 31.9. 34.0 35. 7 37.1 38. 2 39.0 39.4 39.6 39.6 44 3.1.0: 33.4 35.4 37.2 38. 6 39. 7 40.4 40.9 41.0 41.0 46 32.5 . 34.9 36.9 38. 7 40. 1 41.2 41.9 : 42.4 42.5 42.5 48 34. 1 36.5 38.5 40.3 41.7 42.8 43.5 44.0 44.1 44. 1 50 35. 7 38.1 . 40.2 41.9 43.3 44.4 45.2 45. 6 45.7 45.7 Log Position Decay Factors for Western Hemlock Trees: Suspect Class 6
Fraction of total height - h/H DBH .1 . 2 .3 .4 .5 . 6 .7 .8 .9 1.0 (inches) Per cent of gross tree volume decaye d
8 5. 6 8.0 10.1 11. 3 13.2, 14.3 15.1 15. 5 15. 6 15.6 10 5.9 8.3 . 10. 4 12.1 13.5 14.6 15.4 15.8 15;9 15.9 12 6.3 ' 8. 7 10,7 12.5 13.9 15.0 15.7 16.2 16.3 16.3 14 6.7 9. 1 11.2 12.9 14.3 15.4 16.2 16, 6 16.7 16.7 16 7.2 9.6 11. 7 13.4 14.8 15.9 16.7 17. 1 17.2 17.2 18 77.8 10.2 12. 2 14.0 15.4 16,5 17.2 17.7 17.8 17.8 20 8.5 10.8 12.9 14.6 16.0 17.1 17.9 18.3 18.. 4 18.4 22 9.2 XX. J 13.6 15.3 16. 7 17.8 18.6 19.0 19.1 19. 1 24 9.9 12,3 14. 4 16.1 17.5 18. 6 19.4 19. 8 19.9 19.9 26 10. 8 13. 1 15. 2 16.9 18.3 19.4 20. 2 20.6 20. 8 20.8 28 11. 7 14.0 "16. 1 17. 8 19.2 20. 3 21. 1 ' 21.5 21.7 21. 7 30 12.6 15.0 17.1 18. 8 20. 2 21.3 22.1 22. 5 22.6 22. 6 32 13. 7 16.1 18.1 19.8 21. 2 22. 3 23. 1 23.5 23.7 23. 7 34 14.8 17.2 19.2 20.9 22.4 23.4 24.2 24.7 24. 8 24. 8 36 15.9 18,3 20.4 22. 1 23.5 24. 6 25.4 25. 3 25.9 25.9 38 17.2 19,6 21.6 23.4 24. 8 25.9 26. 6 27. 1 27.2 27. 2 40 18.5 20.9 22.9 24. 7 26.1 27.2 27.9 28.4 28.5 28.5 42 19.9 22.2 24.3 26.0 27.4 28.5 29.3 29.7 29. 9 29.9 44 21.3 23. 7 25. 7 27.5 28. 9 30,0 30. 7 31.2 31.3 31.3 46 22.8 25. 2 27. 2 29.0 30.4 31.5 32. 2 32. 7 32.8 32. 8 48 24.4 26.8 28.8 30. 6 32, 0 33.1 33. 8 34.3 34.4 34.4 50 26.0 28.4 30.5 32.2 33, 6 34.7 35.5 35.9 36.0 36.0 Log Position Decay Factors for Western Hemlock Trees: Suspect Class 7
Fraction of total height - h/H DBH .1 .2 .3 .4 • .5 . 6 . 7 .8 .9 1.0 (inches) Per cent of gross tree volume de cayed
8 24. 1 26.5 28. 5 30. 2 31. 7 32. 7 33. 5 33.9 34.1 34. 1 10 24.4 26. 8 28. 8 30. 5 32. 0 33.0 33. 8 34. 2 34. 4 34. 4 12 24. 7 27. 1 29. 2. 30.9 32. 3 33. 4 34.2 34. 6 34. 7 34. 7 14 25. 2 27.6 29. 6 31.3 32. 8 33. 8 34. 6 35. 1 35.2 35. 2 16 25. 7 28. 1 30. 1 31.8 33.3 34. 3 35. 1 35. 6 35. 7 35. 7 18 26.3 28. 6 30. 7 32. 4 33. 8 34.9 35. 7 35. 1 36. 2 36, 2 20 26.9 29.3 31. 3 33.1 34. 5 35. 6 36. 3 36.8 36.9 36.9 22 27. 6 30. 0 32.0 33.8 35.2 36,3 37.0 37. 5 37.6 37. 6 24 28. 4 30. 7 32.8 34. 5 35.9 37. 0 37. 8 38, 2 38.4 38. 4 26 29. 2 31.6 33.6 35. 4 • 36.8 37.'9 38. 6 39. 1 39. 2 39. 2 28 30. 1 32. 5 34. 5 36.3 37. 7 38.8 39. 5 40. 0 40.1 40. 1 30 31. 1 33.4 35. 5 37. 2 38. 6 39, 7 40. 5 40.9 41.1 41. 1 32 32. 1 34.5 36. 5 38.3 39.7 40. 8 41.5 42.0 42. 1 42. 1 34 33. 2 35.6 37.6 39.4 40. 8 41.9 42.6 43. 1 43.2 43. 2 36 34.4 36. 8 38. 8 40.6 42,0 43. 1 43.8 44.3 44.4 44.4 38 35. 6 38.0 40. 1 41.8 43.2 44.3 45. 1 45. 5 45.6 45.6 40 36.9 39.3 41.4 43. 1 44.5 45.6 46.4 46.8 46.9 46.9 42 38.3 40. 7 42. 7 44. 5 45.9 47,0 47. 7 48.2 48. 3 48. 3 44 39. 7 42. 1 44. 2 45.9 47.3 48.4 49. 2 49.6 49.7 49,7 46 41.3 43. 6 45. 7 47.4 48. 8 49,9 50. 7 51.1 51.2 51. 2 48 42.8 45. 2 47.3 49.0 50.4 51.5 52.3 52.7 52.8 52.8 50 44.5 46.8 48.9 50.6 52.0 53.1 53.9 54.3 54,5 54. 5 Appendix II. Comparison of estimated per cent of gross tree volume decayed from tree decay equation (A) and log position decay equation (B) for several suspect classes.
Suspect class
DBH 0 1 2 3 (inches) A B A B A B A B 8 0.0 4.0 22.2 ' 22.4 10.9 12.7 4.6 6.9 10 1.0 4.3 23.2 22.7 11.9 13.0 5.6 7.2 12 2.0 4.7 24.3 23.1 13.0 13.4 6.6 7.6 14 3.0 5.1 25.3 23.5 14,0 13.8 7.6 8.0 16 4.0 5.6 26.3 24.0 15.0 14.3 8.7 3.5 18 5.1 6.2 27.3 24.6 16.0 14.9 9.7 9.1 20 6.1 6.8 28.3 25.2 17 .0 . .15.5 10.7 9.7 22 7.1 7.5 29.4 25.9 18.1 16.2 11.7 10.4 24 8.1 8.3 30.4 26.7 19.1 17 .0 12.8 11.2 26 9.2 9.1 31.4 27.6 20.1 17.8 13.8 12.0 28 10.2 10.0 32.4 28.5 21.1 18.8 14.8 12.9 30 11.2 11.0 33.4 29.4 22.2 19.7 15.8 13.9 32 12.2 12.0 34.5 30.5 23.2 20.8 16.9 14.9 34 13.2 13.1 35 .5 31.6 24.2 21.9 17 .9 16.0 36 14.3 14.3 36.5 32.7 25 .2 23.0 18,9 17 .2 38 15.3 15.5 37 .5 34.0 26.3 24.3 . 19.9 • 18.5 40 16.3 16.8 38.6 35.3 27 .3 25.6 20.9 19.8 42 17 .3 18.2 39.6 36.7 28.3 27.0 22.0 21.1 44 18.4 19.7 40.6 38.1 29.3 28.4 23.0 22.6 46 19.4 21.2 41.6 39.6 30.3 29.9 24.0 24.1 48 20.4 22.7 42.6 41.2 31.4 31.5 25.0 25.6 50 21.4 24.4 ' 43.7 42.8 32.4 33.1 26.1 27 .3 Appendix II cont'd. Comparison of. estimated per cent of gross tree volume decayed from tree decay equation (A) and log position decay equation (B) for several suspect classes.
Suspect class
DBH 4 5. . 6 __7_ (inches) A B A B A 3 A, B .8 33.2 31.2 26.8 25.3 15.6 15.6 37 .8 34.1 10 34.2 31.5 27 .9 25 .6 16.6 15.9 38.8 34.4 12 35.2 31.8 28.9 26.0 17.6 16.3 39.9 34.7 14 36.2 32.3 29.9 26.4 18.6 16.7 : 40.9 35.2 16 37 .3 32.8 30.9 26.9 19.7 17 .2 41.9 ' 35.7 18 38.3 33.3 32.0 27 .5 20.7 17.8 42.9 36.2 20 39.3 34.0 33.0 28.1 21.7 18.4 44.0 36.9 22 40.34 34.7 34.0 28.9 22.7 19.1 45.0 37 .6 24 41.4 35.4 35 .0 29.6 23.7 19.9 46.0 = 38.4 26 42.4 36.3 36.0 30.5 24.8 20.8 47.0 39.2 28 43.4 37 .2 37.1 31.4 25.8 21.7 48.0 • 40.1 30 44.4 38.2 38.1 32.3 26.8 22.6 49.1 41.1 32 45.4 39.2 39.1 33.4 27.8 23.7 50.1 42.1 34 46.5 40; 3 40.1 34.5 28.8 24.8 51.1 . 43.2 36 47.5 41.5 41.2 35 .6 29.9 25.9 52.1 44.4 38 48.5 42.7 42.2 36.9 30.9 27 .2 53.2 45 .6 40 49.5 44.0 43.2 38.2 31.9 28.5 5412 46.9 42 50.6 45.4 44.2 39.6 32.9 29.9 55.2 48.3 44 51.6 46.8 45.2 41.0 34.0 31.3 56.2 49.7 46 52.6 48.3 46.3 42.5 3.5.0 32.8 . 57.2 51.2 48 53.6 49.9 47.3 44.1 36.0 34.4 58.3 52.8 50 54.6 51.6 48.3 45.7 37 .0 36.0 59.3 54.5
VO Appendix III. Taper Table for Western Hemlock:
Fraction of total height - h/H DBH . 1 . 2 .3 .4 .5 .6 .7 . 8 .9 1.0 (inches) Diameter inside bark (dib) (inches)
8 6. 8 6.3 5.8 *5.3 4. 7 3.9 3.0 2.0 1. 1 0.0 10 8. 5 7. 8 7.3 . 6. 6 5.9 4.9 3.8 ' 2.6 1.3 0.0 12 10. 2 9.4 8. 7 8.0 7.0 5.9 4.5 3. 1 1. 6 0.0 14 11.9 11.0 10. 2 9.3 8. 2 6.9 5.3 3. 6 1.8 o:o 16 13. 6 12. 5 11. 6 10. 6 9.4 7, 8 5.0 : 4.1 2. 1 0.0 18 15.3 14. 1 13.1 12. 0 10. 5 8. 8 6. 8 4. 6 2.4 0.0 20 17,0 15. 7 14. 6 13.3 11. 7 9.8 7.6 5. i : 2. 6 0.0 22 18. 7 17.3 16.0 14. 6 12.9 10.8 8. 3 5. 6 2.9 0.0 24 20.4 18.8 17. 5 15.9 14.1 11.8 9.1 6. 1 3. 2 0.0 26 22. 1 20.4 18.9 17.3 15. 2 12. 7 •9.8 6. 6 3.4 0.0 28 23.8 22.0 20. 4 18. 6 16. 4 13. 7 10,6 7.2 3. 7 0.0 30 25.5 23.5 21.8 19.9 17. 6 14.7 11.3 •7.7' 3.9 0.0 32 27. 2 25. 1 23. 3 21.3 18. 7 15. 7 12. 1 8.2 4. 2 0.0 34 28.9 26. 7 24. 7 22. 6 19.9 16. 6 12,8 8. 7 ' 4.5 0.0 36 30. 6 28.2 26. 2 23.9 21.1 17.6 13.6 9.2 4. 7 0.0 38 32.3 29.8 27. 7 25. 2 22.3 18.6 14.4 9.7 .5.0 0.0 40 34.0 31.4 29. 1 26. 6 23.4 19.6 15.1 10. 2 5.3 0.0 42 35. 7 32.9 30. 6 27.9 24.6 20. 6 15.9 10.7 5.5 0.0 44 37.3 34.5 32.0 29. 2 25.8 21.5 16,6 11.2 5.8 0.0 46 39.0 36.1 33. 5 30. 6 26.9 22.5 17.4 11.7 6.0 0.0 48 40. 7 37.6 34.9 31.9 28. 1 23. 5 18.1 12.3 6.3 0.0 50 42.4 39.2 36.4 . 33. 2 29.3 24.5 18. 9 12.8 6. 6 0.0
Basic equation: dib=DBH \j . 89046 - 2. 23409^ + 6.63776(g)2 - 14. 18542(|)3 + 12.97729(|)4 - 4.08533(|)5 by definition: when h=H dib=»0.0 Appendix IV. Tabulation (Part I) and explanation (Part II) of values derived during calculation sequence for the estimation of gross and net cubic foot volumes by log position within a tree
Given: Western hemlock tree and the following observations: DBH 16 inches Total height 100 feet External abnormalities 1 large open scar
Required: Estimation of gross and net volume for each 20-foot section between a stump height of 1 foot and a top diameter inside bark of 4" inches. Part I: Tabulation of calculated'values .
Column No.
1 2 3 4 5 6 7 8 9 10 11 12
Sec tion Length Cumulative Diameter inside- Gross volume Cumulative Decay volume Net volume No. (feet) length bark (inches) (cubic feet) decay volume (cubic feet) (cubic feet) (feet) butt top unadj. adj . unadjusted unadj. adj.. adjusted % c.f.
_.. 1 1 1 16.0 16.0 1.40 1.36 ',-'.' - • 1.36
2 20 21 16.0 12.5 22.48 21.63 6.7 3.41 3.41 3.59 18.04
3 20 41 12.5 10.6 14.65 14.09' 10.5 5.35 1.94 2.03 12.06
4 2.0 61 10.6 7 .8 9.45 9.09 13.0 6.62 1.27 1.33 7.76
5 20 81 7J8 4.1 4.24 4.0.8 14.2 7.23 0.61 0.64 3,44
8 :. 19. 100G 4.1 0.0 0.70 0.68 14.3 7 .28 0.05 0.05 0.63
TOTAL Explanation of tabulation of calculated values .
Explanation
Identification and sequence number of sections in tree numbered in order from ground to top. Length in feet of each section Cumulative length in feet from ground to top of specified section number. Diameters inside bark in inches at butt and top of specified section. These diameters estimated through taper function tabulated in Appendix III. Gross cubic foot volumes calculated by Smalian's formula from diameters estimated in columns '"4" and "5".. First section volume calculated as volume of a cylinder; last section volume calculated as .4 times basal area of butt of top section times length of tip section. Gross cubic foot volumes adjusted to ensure that summation of section volumes are equivalent to total tree volume as estimated by tree volume function (table 46), Total cubic foot tree volume = 5.2619 + .17838(DBH)2H/100 = 50.93 cubic feet. Adjustment factor = 50.93/52.92 = 0.962. Adjusted gross cubic foot volumes = 0.962 times column "6" entries. 184
Part II: Explanation of tabulation of calculated values (cont'd).
Column Explanation no. 8 Cumulative unadjusted decay volume expressed as a percentage of total adjusted tree volume in cubic feet. These figures derived from log position decay estimating function tabulated in appendix I, 9> Cumulative unadjusted decay volumes in cubic feet calculated by multiplying column "8" entries by column "7" total entry, 10 Unadjusted decay volume in cubic feet calculated by successive subtractions of entries in column "9", 11 Cubic foot decay volumes adjusted to ensure that summation of section decay volumes is equivalent to total tree decay volume as estimated by tree decay function (table 46), Total tree decay•= 15 per cent of 50.93 ~ 7.64 cubic feet. Adjustment factor = 7.64/7/28 = 1.049. Adjusted decay volume - 1.049 times entries in column "10". 12 •, Net section volumes in cubic feet calculated by subtracting column "11" entries from column "7" entries. 185
Appendix V: Tree stem and decay profiles for three western hemlock
trees with heartrot caused by E. tinctorium. 186
Stem and decay profile showing sample locations,tree No-22- 196-
Legend
decayed wood
• sample locations and numbers
10 15 20 25 Diameter inside bark (inches) Stem and decay profile showing sample locations,tree NoU
35|-
Diameter inside bark (inches) cay profile showing sample locations, tree-No- 22-138-
Diameter inside bark (inches)