The ecology of curl-leaf mountain mahogany (Cercocarpus ledifolius Nutt.) in southwestern Montana with special reference to use by mule deer by Elizabeth Ann Duncan A thesis submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE in Fish and Wildlife Management Montana State University © Copyright by Elizabeth Ann Duncan (1975) Abstract: This study was conducted to obtain basic ecological information for curl-leaf mountain mahogany (Ceroocarpus ledifolius Nutt.) within its range in southwestern Montana. Intensive investigations were conducted on 21 stands. Mountain mahogany was distributed in isolated, typically small stands on steep southerly and westerly slopes with rather dry, rocky soils and sparse herbaceous cover. Total density of mountain mahogany in the stands ranged from 472 plants per hectare to 21,627 plants per hectare. Mountain mahogany was the dominant shrub on all but two stands, and had the highest importance value among shrubs on all stands. Importance values were significantly higher in stands of west exposure and on slopes greater than 40 percent. Two growth forms occurred; available plants were low and rounded while those escaping early browsing pressures tended to be "umbrella"-shaped. Plants in stands west of the Continental Divide averaged 16.7 decimeters in height and 16.5 decimeters in diameter with a mean live crown area of 1.54 square meters; while plants east of the Divide averaged 9.2 decimeters in height, 9.6 decimeters in diameter, and 0.52 square meters of live crown. Growth of current annual twigs from terminal and lateral portions of last year's wood occurred between late May and early July and averaged 29.2 millimeters in 1973 and 28.7 millimeters in 1974. Total production of current annual growth varied considerably between stands and between years and appeared to be enhanced by past utilization. Fall precipitation from the previous year was also positively correlated with better production. Total numbers of twigs produced per hectare varied among individual stands from zero to about 1.5 million in 1973 and from 43,000 to almost 2.0 million in 1974. Total utilization of current annual growth twigs by deer varied from zero to 54 percent among stands. Ocular estimates of the numbers of twigs used per plant showed from zero to 90 percent of the twigs were browsed. Stands were predominantly young to middle-aged (10 to 30 years) although older plants were often found, especially in stands west of the Continental Divide. Seed production was apparently sporadic. An average of 76 percent of the seeds collected in 1974 germinated in the laboratory. Conditions for seedling growth were harsh but survival, as indicated by the presence of young plants and mixed age structure in all stands, seemed to be sufficient to maintain existing populations. Crude protein values averaged 10.5, 10.4, 9.5, and 9.8 percent for the spring, summer, fall, and winter, respectively. STATEMENT OF PERMISSION TO COPY
In presenting this thesis in partial fulfillment of the require ments for an advanced degree at Montana State University, I agree that the Library shall make it freely available for inspection. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by my major professor, or, in his absence, by the Director of Libraries, It is understood that any copy ing or publication of this thesis for financial gain shall not be allowed without my written permission.
Signature
Date )9 7£ ~ THE ECOLOGY OF CURL-LEAF MOUNTAIN MAHOGANY • (CERCOCARPUS LEDIFOLIUS NUTT.) IN SOUTHWESTERN MONTANA WITH SPECIAL REFERENCE TO USE BY MULE DEER
BY
ELIZABETH ANN DUNCAN
A thesis submitted in partial fulfillment of the requirements for the degree
of ■
MASTER OF SCIENCE
- Fish and Wildlife Management
Approye
irman, Examining Committee
lead,. Major Department
Graduate Dean
.MONTANA STATE UNIVERSITY Bozeman, Montana
December, 1975 iii
ACKNOWLEDGMENT
To the following, the author wishes to express her sincere appreciation for the contributions to this study: Dr. Richard J . Mackie
Montana State University, who directed the study and aided in the preparation of the manuscript; Dr. Theodore W. Weaver and Dr. Don C .
Quimby, Montana State University, for critical reading of the manu-. script; Mr. Kenneth Greer, Montana Department of Fish and Game Research
Laboratory Supervisor, for use of laboratory facilities; Dr. John
RumeIy, Montana State University, for aid in identification of plant specimens; the following Fish and Game biologists who aided in distribution surveys: Howard Chrest, Frank Fiest, John Firebaugh,
John Ormiston,, and Joei Peterson; all .private individuals who allowed me to establish transects on their land; Dick Bucsis, for advice and assistance during the study; and to my many friends for their encourage ment and assistance. I was employed by the. Montana Department of Fish and Game under Federal Aid project W-I2O-R-5 and. 6; XV
TABLE OF CONTENTS
VITA ...... ii
ACKNOWLEDGMENT ...... iii
LIST OF TABLES . ; ...... ' v
LIST OF FIGURES' ...... ■■...... ' vii
ABSTRACT ...... ; ...... x
INTRODUCTION ...... ■ I
PROCEDURES ...... 6
RESULTS AND DISCUSSION ...... 11
Distribution ...... ■...... 11 Geographic...... 11 Physiographic...... 11 Edaphic.Characteristics ...... 23 Climatological Characteristics...... 26 Synecological Characteristics and Relationships ..... 3l Tree-Shrub Characteristics ...... 33 Grass., Forb, and Ground Cover Characteristics. . . . 37 Growth Characteristics and Relationships. 42 Growth Form...... 42 Annual Growth Chronology ...... 46 ’Browse Production and Utilization Characteristics .... .51
Browse Production...... 51 Utilization...... 57 Age Distribution...... 65 Reproductive Characteristics...... 68 Nutritional Characteristics and Relationships . . . I . . 72
LITERATURE CITED...... ' 75
APPENDIX . .■■...... 78 V
LIST OF TABLES
Table PnRe
I. EDAPHIC CHARACTERISTICS' OF 22 MOUNTAIN MAHOGANY STANDS INCLUDING TEXTURE, pH, ORGANIC MATTER, FIVE IMPORTANT ELEMENTS, AND SALT HAZARD v . . . 24
2. ■ IMPORTANCE VALUE, PLANTS PER HECTARE, CONSTANCY, AND MEAN AREA PER PLANT FOR SHRUBS' ON EACH OF 22 MOUNTAIN MAHOGANY STANDS . . . . ; . . '...... :
3. CANOPY COVERAGE, FREQUENCY, AND CONSTANCY OF LOW GROWING TAXA AS DETERMINED BY EXAMINATION OF TWENTY ' 2X5 DECIMETER PLOTS FOR EACH OF 21 MOUNTAIN MAHOGANY STANDS DURING . SPRING AND SUMMER (420 TOTAL P L O T S ) ...... 38
4. AVERAGE HEIGHT, DIAMETER, CORRECTED CROWN AREA, AND PERCENT OF CROWN DEAD FOR MOUNTAIN MAHOGANY, AND THE ■NUMBER OF DEAD PLANTS AND SEEDLINGS PER HECTARE ON EACH ■ OF 22 STANDS...... 44
5. PERCENTAGE OF PLANTS PRODUCING TWIGS, THE NUMBER.OF TWIGS PER PLANT, THE NUMBER OF TWIGS PER ONE SQUARE METER OF CORRECTED CROWN AREA, AND THE AVERAGE LENGTH . . OF TWIGS CALCULATED FROM PRODUCTION MEASUREMENTS DURING 1973 AND 1974 ...... 52
6. MEAN CORRECTED CROWN AREA, DENSITY, AND CURRENT ANNUAL GROWTH TWIGS PRODUCED FOR 21 MOUNTAIN MAHOGANY STANDS IN 1973 AND 1974 ...... 53
7. AVERAGE UTILIZATION OF MOUNTAIN MAHOGANY ON BROWSE TRANSECTS ESTABLISHED BY THE-.MONTANA. DEPARTMENT OF ■FISH AND GAME ...... 58
8. AVERAGE PERCENTAGE UTILIZATION AS DETERMINED BY SITE . OBSERVATIONS FOR THE WINTER OF 1973-1974 ON 21 MOUNTAIN ■ MAHOGANY STANDS ...... ■. '.. .-■ . '. 59
9. NUMBERS OF DEER PELLETS COUNTED WITHIN ONE METER OF-THREE 100 METER LINE'TRANSECTS ON 21 MOUNTAIN MAHOGANY STANDS FOR - USE AS A RELATIVE INDEX OF UTILIZATION DURING THE WINTER OF 1973—74...... : . . ■ ■ 60 vi
LIST OF TABLES (continued)
Table Page
10. MEAN DIAMETER AT BASE OF GROWTH (DBG) AND ESTIMATED TWIG LENGTH UTILIZED ON 21 MOUNTAIN MAHOGANY STANDS DURING THE WINTER OF 1973-74 ...... '...... 61
11.. MEAN DIAMETER AT THE POINT OF BROWSING (DPB) AND ESTI MATED TWIG WEIGHT UTILIZED ON 21 MOUNTAIN MAHOGANY STANDS DURING THE WINTER OF 1973-74 . . .. . '...... 62
12. AVERAGE AGE AND AGE RANGES FOR 21 MOUNTAIN MAHOGANY STANDS...... 67
13. AGE CLASS DISTRIBUTION FOR 1,221 MOUNTAIN MAHOGANY PLANTS; ...... P .... . 69
14. PERCENTAGE OF SEEDS' THAT.GERMINATED AND PERCENTAGE THAT.DEVELOPED COTYLEDONS 70
' 15. PERCENTAGE CRUDE PROTEIN, MOISTURE AFTER AIR DRIED, AND MOISTURE AFTER OVEN DRIED FOR EIGHT MOUNTAIN MAHOGANY STANDS DURING SPRING, SUMMER, FALL, AND WINTER. ....;,...... • 74
16. CLIMATOLOGICAL DATA FOR 1973 AND 1974 FOR THE TEN . WEATHER STATIONS NEAREST THE MOUNTAIN MAHOGANY ■ STANDS STUDIED '...... ' ...... 79
17. SPECIES' OCCURRENCE ON EACH OF 22; MOUNTAIN MAHOGANY . STANDS..- EXAMINED ...... •' i" ■ • 80
18. REGRESSION EQUATION VARIABLES FOR TWIG DIAMETER AND LENGTH, DIAMETER AND WEIGHT ...... 86
19. . DRAINAGE.AND EXACT- LOCATION- FOR THE 22 MOUNTAIN. MAHOGANY STANDS STUDIED ...... ' . , , . . .. • 87 vii
LIST OF FIGURES
Lgure Page
. I. General distribution of curl-leaf mountain mahogany in. Montana ...... 2
2. Location of 22 curl-leaf, mountain mahogany study sites in M o n t a n a ...... ; ...... 4
3. Site A on Axes Canyon Creek with N65°W exposurej 57 percent■slope, and 5,920 foot elevation. S23 T8S R8W. . 12
4. Site B at New Departure Mine on Cold Spring Creek. The stand of highest elevation (7,060 feet) is seen in the background with S3°W exposure and 25 percent. ' ■ slope. S27 T7S RllW 12
5. Site C on Scudder Creek with S81°W exposure, 43 percent slope, and 6,590 foot elevation. S21 T6S Rl2W . . . . . 13 ,
6. Site D on Big Sheep Creek with N83°E exposure, 39 percent slope, and 6,350 foot elevation. S36 T13S RlOW. 13
7. "Site E on the west fork of Little Sheep Creek with. S57°E exposure, 60 percent slope, and 6,880 foot elevation. S33 T14S R9W . ■ ...... 14
8. Site F, on the middle fork of Little Sheep Creek with N89°W exposure, 58 percent slope, and 6,840 foot elevation. •S34 T14S R9W ...... 14
9. Site H on Canyon Creek with NS2°E exposure, 43 percent - slope, and 5,510 foot elevation. S6 T2S R9W . 15
10. Site G on Camp Creek with N55°W exposure, 68 percent slope, and 5,640 foot elevation. S16 T2S, R8W. . . v . . 1 5
11. Site Q on Camp Creek with S60°E exposurei 57 percent slope, and 5,720. foot elevation-. S16 T2S R8W...... 16
12. Site R on Soap Gulch with N86°W exposure, 72 percent' slope, and 5,620 foot elevation. S12 T2S R.9W. '. . . . . 16
13. Site S oh Lime Gulch with S61°W-exposure, 48 percent slope, ■ and 6,050. fobt elevation. S2 TlS R9W . . . . 17 viii
LIST OF FIGURES (Continued)
Figure Page
14; Site I on Hell's Canyon Creek with S85°W exposure, 26 per cent slope, and 5,240 foot elevation. SB T2S R6W ...... 17
15. Site T o n Bear Gulch at the south end of the Tobacco . Root Mountains with SI2°W exposure, 55 percent slope, and 5,900 foot elevation. S3 T3S R5W ...... 18
,16. Site L on the Jefferson River at the north end of the Tobacco: Root Mountains with NS70W -exposure, 60 percent slope, and 4,560 foot elevation. S5 TlS-R4W...... 18
17. Site K on Pipestone-Dry Creek with S23°E exposure, 16 percent slope, and 5,120 foot.elevation. SlS T2N R2W . . . 19
18. Site U on Moore Creek with S21°E exposure, 23 percent . slope, and 5j400 foot elevation. S6 T5S R2W...... 19
19. Site J on Johnny Gulch with S31°W- exposure, 52 percent slope, and 5,24.0 foot elevation. S21 T5N RlW ...... 20
20. Site M at the Limestone Hills on. Indian Creek with NSJ0W' exposure, 38 percent slope, and 4,600 foot elevation. . S34 T6N R l E ...... 20
21. Site N at Haley's Chute on Trapper Creek, west of the Continental Divide. Tree-like mountain mahogany is seen in the background with SlS0W exposure, 45 percent slope, and 4,910 foot elevation.. S23 T2N R21W . . . ■. . . .' .
22. Site 0 at Robbins Gulch, west of the Continental Divide, with S57°E exposure, 39 percent slope,' and 4,150.foot elevation.' S17 T2N R20W
23. Site P oh Skalkaho Creek, west of the Continental Divide, with S40°E exposure, 79 percent slope, and.4,510 foot elevation! S'23 T5N R19W...... ; ...... ' ......
24. Average-and normal monthly temperature for the study areas.
25. Average and normal precipitation for the study areas east arid west of the Continental Divide. . .' . . . . ;...... 29 Ix
LiST OF FIGURES (Continued)
Figure Page
26. Phasic development and growth of mountain mahogany.on stands east and west of the Continental Divide as determined by spring and summer observations. 47
27. Growth curves of mountain mahogany as determined■by the measurement of. twigs greater than one centimeter, from 200 • tagged potential buds' per transect (number of twigs.read in parentheses)...... 48.
28. Age class frequency distribution of 210 randomly chosen mountain mahogany plants. ., .. ."...... 66 X
ABSTRACT
This.study was conducted to obtain basic ecological information ■ for curl-leaf mountain mahogany (Ceroocarpus IedifoZius Nutt.) within its range in. southwestern Montana. Intensive investigations were conducted on '2,1 stands. Mountain mahogany was distributed in isolated, typically small stands on steep southerly and westerly slopes with rather dry, rocky soils and sparse herbaceous cover. . Total density of mountain mahogany in the. stands ranged from.472 plants per hectare to 21,627 plants per hectare. Mountain.mahogany was the dominant shrub on all but two stands, and had the highest importance value among shrubs on all stands. Importance values were significantly higher in stands • of west exposure and on slopes greater than 40 percent. Two growth forms occurred; available plants were low and rounded while those escap ing early browsing pressures tended to be "umbrella"-shaped. Plants in stands west of the Continental Divide averaged 16.7 decimeters in height and 16.5 decimeters in diameter with a mean live crown area of 1.54 square meters; while plants east of the Divide averaged 9.2 decimeters in height, 9.6 decimeters in diameter, and 0.52 square meters of live crown. Growth of current annual twigs from terminal and lateral portions of last year's wood occurred between late May and early July and averaged 29.2 millimeters in 1973 and 28.7 millimeters in 1974. Total production of current annual growth varied considerably between stands and between years and appeared to be enhanced by past utiliza tion. Fall precipitation from the previous year was also positively,' correlated with better production. Total numbers of twigs produced per hectare varied among individual stands from zero to about 1.5 million ■ in 1973 and from 43,000 to almost 2.0 million in 1974. Total utiliza tion o f 1 current annual growth twigs by deer varied from zero to 54 per cent among stands. Ocular estimates of the numbers of twigs used per plant showed from zero to" 90 percent of the twigs were browsed. Stands were predominantly young to middle-aged (10 to 30 years) although older plants were often found, especially in stands west of the Continental Divide. . Seed production was apparently sporadic. • An average of 76 percent of the seeds collected in 1974 germinated in the laboratory. . Conditions for seedling growth were harsh but survival, as indicated by the presence of young plants and. mixed age structure in all stands, seemed to be sufficient to maintain existing populations. Crude protein values averaged 10.5, 10.4, 9.5, and 9.-8 .percent for the spring, summer, fall, and winter, respectively. !■ ' • INTRODUCTION
Curl-leaf mountain mahogany (Cereoearpus ledifolius Nutt.) occurs•
■over most of the western United States where it is recognized as an
important browse species for mule deer. Its range, centered in the
Great Basin region of Utah and Nevada * extends east into Colorado,
north into Montana, Idaho, and Washington, west into Oregon and
California, and south into Arizona (Kirkwood 1930). 'In Montana it is
found mainly in the southwestern portion of the state and in a small
area of southcentral Montana (Fig. I);
A paucity of ecological information for mountain mahogany has
hindered efforts of game and range managers to measure and interpret
range conditions and relationships and to develop effective management
plans on mahogany ranges. Two studies in Idaho by. Schedlt (1969) and
Claar (1973). and a study of the Scudder Creek mule deer winter range
by Allen (1967) provide the only information currently available on
the ecology and game use relationships of mountain mahogany in the
northern portion of its-range; ,
The current study was established in the summer of 1973 to obtain
basic ecological information for curl-leaf, mountain mahogany in south- •
western Montana. Specific objectives were: I) to determine general
distribution, edaphic, climatic, and synecological characteristics;
2) to determine and describe certain autecological characteristics such
as reproduction, growth and.development, forage production, and Missoulo
Homilton
Billings Bozeman
Lodge Grass
Legend Continental Divide
Figure I. General distribution of curl-leaf mountain mahogany in Montana. —3—
and nutritional values; and 3) to evaluate the inter-relationship
between mountain mahogany and mule deer in Montana. Field studies were
conducted.full time during the summer of 1973 and the spring and summer
of 1974. Additional'data were collected during the fall of 1974 and
winter of 1975. Intensive investigations were conducted in 21 mountain
mahogany.stands in southwestern Montana. Three of these were located
in Ravalli County, west of the Continental Divide; the remainder were
located east of the Divide in Beaverhead, Silver Bow, Madison, Jeffer-
' son, and Broadwater Counties (Fig. 2),
The genus .Cereocarpus' is a member of the Rosaceae (Rose) Family
and consists of 19 species, five of which are confined to Mexico. Curl-
leaf mountain mahogany was first described by Nuttal in.1840 in Flora
of North America (Torrey and Gray, 1840). The generic name.comes
from the Greek kerkos (a tail) and karpos (a fruit), referring to the
peculiar long styles of the seeds, which are characteristic of the
genus. The specific name ledifolius refers to the resemblance of the
leaf to that.of Laborador-tea (Ledwn). The common name, mountain
mahogany, refers to the mountainous habitat in which the genus is found
and the very hard and often reddish brown wood, suggesting that of true
mahogany, a tropical American tree (Swietenia rhahogoni). "Curl-leaf"
comes from the characteristic revolute leaf margins of the species'.
The species is an erect evergreen shrub usually three to fifteen feet
tall, though in some parts of its range it reaches tree-Iike heights of Missoula
Hamilton
Billings Bozemai
Dillon
Legend Vv e Transect Location - Continental Divide
Figure 2. Location of 22 curl-leaf mountain mahogany study sites in Montana. -5- up to 40 feet. The leaves are leathery, green, and shiny on top and whitish and hairy underneath. They are shed at the end' of their second summer,' The flowers are without petals. The calyx is densely soft hairy and flaring into a bell shape of five lobes with■the lower tube one-quarter inch, long and persistent-.. The color grades from pale, creamy white to pink. The stamens are numerous and inserted oh the calyx tube. The annual growth is reddish brown and at first covered , with pale, f ine hairs'but becomes hairless by the next summer and turns silver, gray or dark brown ( U. S. Forest Service 1937). PROCEDURES
The geographical distribution of curl-leaf mountain mahogany was determined by ground and aerial reconnaissance, and from Montana Depart ment of Fish and Game records.
Twenty-one stands located in southwestern Montana, were selected for intensive study on the basis of apparent differences in site characteristicsj plant condition, and.history of use by mule deer. One additional stand, located in southcentral Montana, was also visited to compare the density of mountain mahogany,species associates, and soil characteristics on that range with stands in southwestern Montana.
Exposure, and slope, for each stand were determined using a Brunton compass. Elevation was determined using an altimeter and checked against U. S . Geological Survey maps.. Soil characteristics including percent sand, silt, and clay, pH, organic matter content, salt hazard, and five important minerals were obtained from a :composite of ten soil samples taken to a depth of .15 centimeters (six inches) at each stand.
Precipitation and temperature data were taken from.the climatological records of the U. S. Department of Commerce weather station nearest ■
.each stand. • ' - .
Basic sampling of vegetation followed methods outlined by Cottom
and Curtis (1956) for trees and taller shrubs and by Daubenmire (1959)
for. low growing shrubs, forbs, and .grasses. Twenty points, spaced ten -7- ineters apart, were permanently established at each site in. a 5x4, 4x5, or 2x10 configuration depending upon the shape of the stand. At every point the nearest tree or shrub in each quadrant was measured following the point-center-quarter method (Cottom and Curtis 1956) and permanently tagged. Data recorded included: I) species; 2) distance from the . point to the center of the plant, to the nearest decimeter; 3) height,
to the nearest decimeter; 4) width of the major and minor axes of the crown, to the nearest decimeter; 5) percentage of dead crown; atid. 6) crown density (percentage of live crown within an imaginary circle around the outer edge of the plant). Age and form classes for each plant were recorded following Cole (1958).
The canopy coverage of low growing shrubs (less than two feet in height), forbs, and grasses was. recorded by; species using a. 2x5 deci meter frame placed in the second quadrant at each of the twenty points
(Daubenmir'e. 1959). Coverage of bare ground, rock, and litter was also recorded. . Canopy coverage measurements were made during both spring
(late May) and summer (mid July) periods. A species list was compiled : for each stand-.' Plant name's follow Booth (1950) arid',Booth and Wright
(1959).
Dates of phonological events including opening of flower buds,
formation and ripening of seeds, and initiation and termination of -
leader growth were recorded.
Twig growth rates and percent of potential twig buds that grew —8“
during 1974 were measured for the nearest mountain mahogany plant to
every other sampling point in each stand. Ten potential twig buds on
.two representative branches were individually marked on each plant in
early May, 1974j before growth began. Diameter and length of each twig were measured at approximately three week.intervals from the onset of growth until growth appeared to stop. Measurements were taken on all
twigs but not considered significant until the twig reached one
centimeter in length. . Only-those twigs which grew were considered in'
calculation of growth rates. 1 ,
Production of current annual growth (CAG) was determined at the
end of each summer by measurement of ten randomly selected mountain
mahogany plants in each stand. After the height and major and minor
diameters were measured, each plant was collected and all current
annual growth twigs (CAGT) one centimeter long or longer were clipped,
counted, dried for 24 hours at 90 degrees C, and weighed. Average twig
length was determined by measuring the length to the nearest 0.5 milli
meters of each twig in a sample of 100 from each plant. A subsample
of 25 twigs was then selected for measuring the diameter at. the base of
: " ' • . . . ' ■ ■. . ' . growth to the nearest 0.1 millimeter's and the weight to the nearest .
0.01 gram. ' ' •
Mule deer usage of each study site during the winter of 1973-74
was estimated on the basis of mountain mahogany utilization measure
ments and pellet group surveys made in the spring of 1974.. Utilization -9-
of- mountain mahogany was estimated as the percentage of the number of
available CAGT browsed on the nearest plant to every other sampling
point in each stand. Three browsed twigs were clipped from each quad
rant of the plant and dried in the laboratory for 24 hours at 90 degrees
C. An estimate of the average twig length utilized was predicted using
the method, described by Basile and Hutchings (1966) and Lyori (1970) .
The twig length before utilization was predicted using the diameter at
the base of current growth (DBG), and the regression equatiori developed
■from production studies in 1973. (y = bx + a, where b •= slope and a = y- .
intercept). . The percent of the twig browsed was then calculated as:
P = 100 — where T = the estimated average,length before browsing,,
and R = the average length of the unused portion of the twig (Basile ;
and Hutchings 1966). Due to an apparent malfunction in the balance,
used to determine, individual twig weights in 1974, the estimates of
weight utilization were based on the method described by Peek (1971).
The diameter at the point of browsing (DPB) was used in the regression
equation from 1973 to obtain directly the weight, of twig material '
.utilized, therefore avoiding weighing the unbrdwsed twig material.
Deer pellet-group surveys were conducted by placing 100 meter line .
transects, along the hill contour at the top, middle,, and bottom of
each stand. All pellets within one meter of either side of the
line were counted. -10-
The a g e •distribution, of mountain mahogany plants in each stand was estimated by determining the age of each plant collected during
1973. Cross sections of root, crowns were cut and sanded and growth rings counted following Lonner (1972).
Seeds.were collected at the end of..each season and viability and germination rates were measured. In 1973 seeds were stratified in moist sand for. 90 days at five degrees C (41 degrees F). Germination was attempted in a sand flat for 30 days (The Woody Plant Seedt Manual
1948). Due to the failure of this method, seeds collected in 1974 were stratified on moist filter paper in closed containers at five degrees C for 60 days and allowed to germinate in the same containers.
Nutritional values, based on the protein content of current annual growth twigs (CAGT), were obtained for each season of the year from eight stands with varying degrees of past use, topographic conditions, . arid production. Composite samples,of.complete CAGTs including leaves, were clipped from a fandom sample of plants in each stand. Protein and . moisture determinations were made by the Montana'Chemistry.Station,
Montana State University,- Bozeman. ... ' RESULTS AND DISCUSSION
Distribution
Geographic
Curl-leaf mountain mahogany occurs in scattered stands throughout
the southwestern portion of Montana,' west of a line extending, roughly '
from the Madison a n d .Bridget Ranges north through Canyon Ferry LakS and
south.of a line from Helena to Missoula. The species is also found
extending northward from Wyoming' into southcentfal Montana, along the
Bighorn and Little Bighorn Rivers south of a line from Lodge Grass to
Yeilowtail Dam (Fig. I). The highest concentration of stands occurs east of the. Continental Divide in Beaverhead County. : Locally, mountain mahogany occurs primarily in patch-like stands. Extensive, continuous ■
stands are fare, reflecting its restriction to. shallow, coarse soils and
cliffs and ledges on warm, dry,.rocky ridges or steep slopes. . '
Physiographic. -
' ' The 21 stands studied were extremely diverse in their physiographic
characteristics. ,The elevation, exposure, slope, drainage,- and exact
location.'for- each, stand are given in. the captions to .Figures 3-23.
Only foui of the 21 stands had slopes less than 30 percent,while nine
had slopes greater, than .55 percent ; the average slope was.. 48 percent
with 14 (67%) .Stands between 38 and 60 percent. Exposures were varied
with seven stands (33%) facing southwest, six (27%) facing northwest,.
six (27%) facing southeast, and two (9%) facing northeast. -12-
Figure 3. Site A on Axes Canyon Creek with N65°W exposure, 57 percent slope, and 5,920 foot elevation. S23 T8S R8W.
Figure 4. Site B at New Departure Mine on Cold Spring Creek. The stand of highest elevation (7,060 feet) is seen in the background with S3°W exposure and 25 percent slope. S27 T7S FllW. -13-
Figure 5. Site C on Scudder Creek with SSl0W exposure, 43 percent slope and 6,590 foot elevation. S21 T6S R12W.
Figure 6. Site D on Big Sheep Creek with N83°E exposure, 39 percent slope, and 6,350 foot elevation. S36 T13S RlOW. — I /# —
Figure 7. Site E on the west fork of Little Sheep Creek with S57°E exposure, 60 percent slope, and 6,880 foot elevation. S33 T14S R9W.
Figure 8. Site F on the middle fork of Little Sheep Creek with N89°W exposure, 58 percent slope, and 6,840 foot elevation. S34 T14S R9W. -15-
Figure 9. Site H on Canyon Creek with N82°E exposure, 43 percent slope, and 5,510 foot elevation. S6 T2S R9W.
Figure 10. Site G on Camp Creek with N55°W exposure, 68 percent slope, and 5,640 foot elevation. S16 T2S R8W. —16—
t Figure 11. Site Q on Camp Creek with S60°E exposure, 57 percent slope, and 5,720 foot elevation. S16 T2S R8W.
Figure 12. Site R on Soap Gulch with N86°W exposure, 72 percent slope, and 5,620 foot elevation. S12 T2S R9W. -17-
Figure 13. Site S on Lime Gulch with S61°W exposure, 48 percent slope, and 6,050 foot elevation. S2 TlS R9W. -18-
Figure 15. Site T on Bear Gulch at the south end of the Tobacco Root Mountains with S12°W exposure, 55 percent slope, and 5,900 foot elevation. S3 T3S R5W.
Figure 16. Site L on the Jefferson River at the north end of the Tobacco Root Mountains with N87°W exposure, 60 percent slope, and 4,560 foot elevation. S5 TlS R4W. -19-
Figure 17. Site K on Pipestone-Dry Creek with S23°E exposure, 16 per cent slope, and 5,120 foot elevation. S18 T2N R2W.
Figure 18. Site U on Moore Creek with S21°E exposure, 23 percent slope and 5,400 foot elevation. S6 T5S R2W. - 20-
Figure 19. Site J on Johnny Gulch with S31°W exposure, 52 percent slope, and 5,240 foot elevation. S21 TSN RlW.
Figure 20. Site M at the Limestone Hills on Indian Creek with N87°W exposure, 38 percent slope, and 4,600 foot elevation. S34 T6N RlE. -21-
Figure 21. Site N at Haley's Chute on Trapper Creek, west of the Con tinental Divide. Tree-like mountain mahogany is seen in the background with S13°W exposure, 45 percent slope, and 4,910 foot elevation. S23 T2N R21W.
Figure 22. Site 0 at Robbins Gulch, west of the Continental Divide, with S57°E exposure, 39 percent slope, and 4,150 foot elevation. S17 T2N R20W. -22-
Figure 23. Site P on Skalkaho Creek, west of the Continental Divide, with SAO0E exposure, 79 percent slope, and 4,510 foot elevation. S23 T5N R19W. -23-
Elevations ranged from 4,150 to 7,060 feet with five stands ho low 5,000 feet and three above 6,500 feet. The average elevation was 5,580 feet.
This conflicts with existing information (U. S. Forest Service 1937) indicating an altitudinal distribution between 2,000 and 4,500 feet in the northern part of its range. In the southern portions of its range curl-leaf mountain mahogany is found up to 9,000 feet. Exposure and soils may be more significant in determining local distributions than elevation '(Daubenmire 1943) . The stand examined in the Pryor Mountains
(V) was similar to those stands in southwestern Montana and had a S80°E exposure, 4 percent slope, and 4,680 foot elevation.
'Edaphic Characteristics
Mountain mahogany occurred on rocky sites with soils ranging from course sands intermixed with large rocks to gravelly sands. Six of the stands studied had bedrock slabs exposed with mahogany plants growing from cracks in the rock. Soils typically were shallow, often less than the'15 centimeters (six inch) depth to which soil samples were obtained. Overall they tended to be sandy loam in texture, slightly acidic, very low in phosphorus, intermediate in potassium content, normal in salt content, and variable in organic matter
(Table I).
Sandy loams, loamy sands, sands, and loams comprised 48, 28, 14, and 10 percent.of the stands, respectively. The average of all soil -24-
TABLE I. EDAPHIC. CHARACTERISTICS OF 22 MOUNTAIN MAHOGANY STANDS INCLUD ING TEXTURE, pH, ORGANIC MATTER, FIVE IMPORTANT ELEMENTS, AND SALT HAZARD.
Organic Phos Potas Cal Magne Sod Salt Tex Matter phorus sium cium sium ium Hazard Site ture1 pH Percent ppm2 ppm meq3 meq meq. mmhos1*
A SL 8.4 3.40(L)S 9 (VL) 236 (M) 40.15 3.51 • 0.33 0.4 B L 7.2 3.51(L) Il(VL)• 545(H) 42.00 4.96 0.33 0.8 C SL 7.7 6.56 (M) Il(VL) 196(M) 38.43 3.51 0.33 0.9 D S 7.9 . 4.66(M) Il(VL) 136 (M) 7.54 1.19 . 0.37 0.7 E S 7.2 I.35(VL) Il(VL) 67(VL) 5.63 0.70 . 0.33 0.6 . F S 7.3 I.62(VL) 11(VL) 67(VL) 3.74 0.70 0.33 0.6 G SL . 6.7 5.OO(M) 16(VL) 186 (M) 34.59 5.24 0.33 0.2 H ' SL 7.8 6.84(M) 35 (L) 565(H) 52.45 1.68 0.37 0.8 I LS 7.8 4.00(M) 32(L) 216 (M) 8.69 1.68 0.37 1.0 J L 7.8 5.88 (M) 16(VL) 385(H) 89.48 1 .19 0.42 0.42 ' K LS 6.8 2.96(L) 68 (M) 196 (M) 24.59 . 1.83 0.42 0.3 L SL 7.2 6.01(H) . Il(VL) 256(H) 39.29 5.67 0.33 0.7 'M SL • 7.8 6.15(H) 14(VL) 256(H) 70.40 4.81 0.42 0.8 N SL 7.8 6.84(H) 74 (M) 425(H) 16.12 3.06 0.37 0.9 O SL 6.7 4.66(M) 49 (L) 305(H) 11.40 3.06 0.37 0.6 . P LS 6.7 5.00(H) 14(VL) 196 (M) 9.47 1.52 0.33 . 0.3 Q SL 6.5 2.57(VL) 24(VL) 206 (M) 33.74 4.67 0.29 0.4 ■ R SL-' 7.8 3.51(L) 14(VL) 206 (M) ■' 36.71 4.09 0.33 1.2 - S LS 8.0 6.28(H) Il(VL) 166 (M) 42.00 1.68 0.33 0.6 T . LS 7.9 5.49(M) 2 (VL) 146 (M) 39.29 1.03 . 0.33 0.8 U LS 7.9 3.87(L) 4 O(L) 136 (M) 22.14 1.68 0.37 0.8 V LS 8.1 I.97(L) 14(VL) 117(L) 28.71 3.06 0.29 0.4
1 S = Sand:; SL = Sandy Loam; L = Loam; LS = Loamy Sand.. 2 ppm = pounds/one million pounds of soil. 3 Meq = Millequivalents/100 grams of soil. ^ mmhos = millimhos Imho = I/Ohm 5 Ratings from Montana Soils Testing Laboratory Report, ST-Form 2: VL - Very Low; L = Low; M = Medium; H = High. -25-
samples was a sandy loam (71% sand, 24% silt, and 5% clay). The sandi
ness of all these soils indicates a loose and open structure that would
allow mountain mahogany taproots to descend more rapidly than possible
in fine textured, more compact soils (Daubenmire 1943).
Soil pH varied from slightly acid (24% of the stands) to slightly
to moderately alkaline . (76% of the stands). The range was from 6.5 to
■ 8.4.
Organic matter is a source of plant nutrients and also is very
important as a soil stabilizer. Three stands (14%) rated very low,
five (24%) low, eight (38%) medium, and five (24%) high in organic
matter content. The overall average was 4.56 percent with a range of
1.35 percent (very low) at Lima to 6.84 percent (high) at Hamilton
where a pine overstory contributed to the vegetative litter.
Phosphorus, an essential element for plant energy transformations,
root development, and assimilation of other important nutrients
(Buckman and Brady 1969), was very low at 15 stands (71%), low at four
stands (19%), and. intermediate at two stands (10%). The mean was 23
ppm (very low) with a range of two to 74 ppm. All but one of the 11
stands in the Dillon-Lima-Melrose area were rated very low. At 90 per
cent of the stands phosphorus was rated low or very low. This plus the
fact that phosphorus is most readily available at pH 6.5 indicates that
this mineral could be limiting to mountain mahogany growth. — 26-
Potassium is essential to all cell metabolic processes. It also increases plant resistance to disease and encourages strong root systems (Buckman and Brady 1969). High levels were found in seven (33%) stands, medium levels in 12 (57%) stands, and very low levels in only two (10%) of the stands. The average potassium level was 243 ppm
(medium) with a range of 67 to 565 ppm.
Calcium is an essential nutrient for proper growth and functioning of root.tips and aids in controlling soil acidity (Buckman and Brady •
1969). It occurred within a range of 3.74 to 89.49 meq/100 grams.
Calcium levels seemed correlated with geographic area; the Lima area lowest, the Hamilton area low, the Dillon-Melrose area slightly above average, and the Townsend area highest.
Magnesium is needed by plants as a constituent of chlorophyll.
Soil levels ranged from 0.7 to 5.67 meq/lOO grams with an average of
2.7 meq/lOO grams for all stands. Sodium levels were stable ranging from 0.29 to 0.42 meq/lOO grams and with an average of 0.35 meq/lOO grams. All stands were normal in saltiness ranging from 0.2 to 1.2 miIlimhos and averaging 0.7 millimhos. .
Climatological Characteristics
Seasonal and annual mean temperatures'were quite similar through out the study area. Amounts and patterns of precipation varied only slightly. Due to these similarities, temperature data for the ten
J -27-
weather stations nearest the mountain mahogany stands studied were
combined while precipitation data were averaged for the eight stations
east of the Continental Divide and for the two stations west of the
Divide (Appendix Table 16).
Temperatures in 1973 closely followed the normal while those in
1974 were generally slightly higher than normal (Fig. .24). Monthly
temperatures west of the Divide tended to be warmer than those east of
the Divide. July is the warmest month with averages above 65 degrees F .
Maximum temperatures were between 90 and 105 degrees F. January is the
coldest month with averages around 20 degrees F. Minimum.temperatures were between -16 and -35 degrees F . The frost free period varied from
70 to 140 days depending on the year j whether east or west of the
Divide, and elevation.
Normal precipitation patterns differed between stations east and
west of the Divide. In both areas precipitation reaches a peak in
the spring (May-June), but winter drought occurs east of the Divide
from September through February while west of the Divide precipitation
increases from August through December (Fig. 25). Total precipitation
averaged 11 inches east of the Divide and 14 inches west of the Divide.
June is the wettest month and February the driest month in both areas.
Monthly precipitation totals for 1973 and 1974 at stations west of the
Divide seem to deviate more radically from the norm than those east of
the Divide. In 1973, precipitation was below normal during spring and N3 OO I
Figure 24. Average and normal monthly temperatures, bars and lines, respectively, for the study areas. iue 5 Aeaeadnra otl rcptto, asad lines, and bars precipitation, monthly normal and Average 25. Figure
INCHES INCHES J FM A M J J M A FM J FAJAOD FAJAOD JFMAMJJASOND JFMAMJJASOND JFMAMJJASOND epciey frtesuyae es n eto the of west and east area study the for respectively, Continental Divide. Continental 92 93 1974 1973 1972 JASOND J FM AM J J AM FM J -29- AOD JFMAMJJASOND JASOND Divide. at f the of East et f the of West Divide.
-30-
summer while in 1974 spring rains were nearly normal and summer precipi
tation was above average. The opposite occurred during fall and early
winter when precipitation was above normal in 1973 and far below normal
in 1974. Total precipitation was near average for both years. East of
the Divide, spring precipitation was below normal for both 1973 and
1974. Summer precipitation was below normal in 1973 and normal in 1974.
.Fall and winter precipitation was above and below average in 1973 and
1974, respectively. Total precipitation was near normal in 1973 but
below normal in 1974. ■
Because the weather stations ranged 100 to 1,500 feet lower in
elevation than the mahogany stands included in the study, temperatures and precipitation associated with the stands probably differ from the
stations. The summer temperatures might be expected to be warmer in
sparsely vegetated mountain mahogany stands having much bare ground and rock exposed to absorb heat. Night time temperatures could also be warmer due to cold air drainage from the steeply, sloping stands. Winter
temperatures may be colder due to elevational differences and the Open ness of the stands. Daily and seasonal temperature fluctuations are probably extreme due to the sparse vegetation and the fact that mountain mahogany stands are near no large bodies of water which .have a tendency
to moderate the climate (Caprio 1965). Precipitation tends to increase
. ' ■ with elevation throughout the study area; 12 of the 2I stands were locat ed in rainfall belts averaging three or more inches greater precipitation -31- than their corresponding weather station (U. S . D. A. Soil Conserva tion Service 1974).
Synecological Characteristics and Relationships
Mountain mahogany (Cercocarpus spp.) in association with oak
(Quevcus spp.) comprises one of the six vegetative zones described by
Daubenmire (1943) for the Rocky Mountain region. This zone occurs as a shrub ecotone between the coniferous forest and.the adjacent plains’ and plateaus. North of a line between Denver, Colorado and Logan, Utah,. oak disappears from the association and is replaced by other species including skunkbush sumac {Rhus tx“tlobata), antelope bitterbrush
(Purshia tvidentata), serviceberry (Ametanahiep spp.), and snowberry
(SymphovicaPpus spp.). In Idaho, curl-leaf mountain mahogany lies between the wheatgrass-bluegrass zone and the forest zpnes of ponderosa pine or Douglas fir (Scheldt 1969). It commonly occurs there in associ ation with the sagebrush-grassland and mountain brush or "snowbank" communities but it is also found in association with western.juniper
(Junipevus occidentalis) and antelope bitterbrush.
In Montana'curl-leaf mountain mahogany occurred on rocky inclusions in four of the 21 broad rangeland areas delineated by the Montana-
Agricultural Experiment Station (1973). These include the Foothills
Sagebrush area, the Intermountain Valley Grassland and Meadow, and.
the Teton River-Judith Basin Grassland areas in southwestern Montana -32-
and the Foothill Grassland area in southcentral Montana;
Mueggler (197.4) tentatively placed stands of mountain mahogany in .
a single, Ce'rcocarpus IedifoVtus/Agrojpyvon Spioatim3 habitat type. He
described these stands as usually occurring "in small patches only a.
few acres in size; restricted to southerly and westerly exposures on
rather dry, rocky soils"; and noted that, "in some instances, Cercooarpus
forms dense thickets, but usually it occurs in rather open stands,with
■ a somewhat sparse herbaceous cover and considerable bare soil. A.
■■ spioatum is.usually the dominant understory grass -with Oryzopsis
hymenoides and/or Stipa oomata as other distinctive graminoid species."
Stands studied east of the Continental Divide clearly belong to this
habitat type. • ' .
It is possible that other mountain mahogany habitat types exist in
Montana. Different climatic conditions west of the Continental Divide
are distinct and eight shrubs and forbs (described below).associated ■
with these stands were not found in stands east of the Divide. The
mountain mahogany occurred primarily on rocky outcrops.within, a ponder-.
osa pine (Piniis pondevosg)' forest. Although a few pine trees were found
scattered among the mountain mahogany, it seems unlikely that pine
could establish itself on the dry, rocky areas where the mountain
mahogany was concentrated. Because of this, I have tentatively con
cluded that the. association represents a,meeting of two different
habitat types and that the mountain mahogany stands were of the same -33-
habitat type as described by Mueggler. However, mountain mahogany lias
. been found in other forest types and placed in distinct habitat types
with the trees (R. D. Phister, 1975, personal communication)'. Thus, it
remains possible that more detailed study could show this to be. an
additional habitat type for Montana.
The high degree of site specificity, its dominance over other
shrubs, the sparse understory vegetation, and the evidence,of reprod
uction in most stands indicated that curl-leaf mountain mahogany. , 1
occurs as a climax: plant in most stands .in which it occurs. , .
Tree-Shrub'Characteristics.
Nineteen species of trees and shrubs., were identified in. the 22 3%
stands, including site V.in the Pryor Mountains (Table 2, Appendix
Table 17). No trees were actually encountered in the sampling plots,
though a few scattered, mature ponderosa pine, Douglas fir (Pseudotsuga
Tnenz1Le s H ) j and limber pine (P1Lnus ftexitis) occurred in some stands.
Total shrub densities.ranged from 1,487 plants per..hectare at Site
' N (Fig. 21) to 22,528 plants per hectare at site G (Fig. 10) (Table 2).
Mountain mahogany was the dominant shrub.in all stands;. At 70 percent .
of the stands mountain mahogany.was associated with either three or , . . . - ' - ' . ' - '. ' ' . . : . ' : .- . . , .. ... '. four other shrub species. The maximum number of associated species was
seven found at site K (Fig. 17). Broom snakeweed■(Gutiervezia Sarothnae)
occurred in all stands east of the Continental Divide; this plant is ■■
. . characteristic:of open rangeland (Booth and Wright 1959). and would not
' i ' TABLE 2. IMPORTANCE VALUE, PLANTS PER HECTARE, CONSTANCY, AND MEAN AREA PER PLANT FOR SHRUBS ON EACH OF 22 MOUNTAIN MAHOGANY STANDS.
Mean Area per Plant
Species A B C D E F G H I J K L M N= O P Q R S T U V Con- 3 stancy
Arar 1 23/ 65/ 38/ 7/ 8 / 4/ 27
7592 1993 898 288 81 6 8
Artr 13/ 18/ 46/ 19/ 59/ 70/ 38/ 32 415 679 1681 341 1129 854 738
Cele 245/ 2 2 2/ 189/ 154/ 161/ 192/ 282/ 241/ 2 0 1 / 199/ 1 0 1 / 234/ 129/ 286/ 167/ 244/ 257/ 273/ 289/ 234/ 146/ 185/ 1 0 0 6303 5894 9200 4636 4252 5863 21,627 5452 3387 4487 766 4490 7924 1442 472 1923 2333 5800 6 6 6 6 8105 2302 3973
Chna 4/ 77/ 17/ 58/ 18/ 8 / 23/ 1 2 / 35/ 5/ 1 1 / 50 76 3651 593 1922 901 136 591 147 298 127 360
Gusa + 23/ +* 17/ 93/ 76/ 13/ 32/ 8 / 91/ 27/ 4/ 62/ + 2 2 / 5/ 9/ 2 1 / 46/ 73 456 730 3864 3362 481 8 8 6 161 3894 324 60 4178 103 6 8 180 304 684
Juco 3/ 4/ 09 LO 144 43 I
Jusc 4/ 26/ + 6/ 1 0 / 31/ + 99/ 6 / 46/ 52/ 61/ 45 146 97 54 85 147 1873 6 8 360 347 1096
Putr 52/ 1 2 1/ 09 648 989
Rhtr + + n/ + 4/ 09
239 6 8
Rice 3/ + 7/ + + + 48/ 39/ 18 54 59 321 608
Syal 14/ 1 2 / 8 / 14 45 61 46 '
Teca + 13/ 9/ + 37/ 13/ + + 18 876 386 1346 299
Plants/ 7594 8302 14,604 9659 9888 9612 22,528 6816 5377 8466 2946 5986 14,407 1487 1521 2289 2713 6237 6802 9006 4343 6849 Hectare
Mean 1.31 1.20 0.68 1.03 1.01 1.04 0.44 1.46 1.85 1.18 3.39 1.67 0.69 6.72 6.57 4.36 3.68 1.60 1.47 1.11 2.30 1.46 Area/Plant (Square meters) TABLE 2. (Continued)
1Arar - Artemisia arbusoula Artr - Artemisia tridentata Cele = Cercocarpus ledifolius Chna = Chrysothaimus nausea sue Gusa * Gutierrezia sarothrae Juco = Juniperus eorrmunis Jusc = Juniperus seopulorum Putr = Purshia tridentata Rhtr = Rhus trilobata ■ Rice * Ribes aereum Syal = Symphoriearpus albus Teca = Tetradymia caneseens
^Importance value (relative frequency + relative density + relative dominance) XlOO/Number of plants per hectare. 3Constancy ■ percent occurrence among sites. 4Present but not encountered in density measurements. 5Transects N, 0, P were west of the Continental Divide. — 36—
be expected to occur in stands associated with the more forested habitat
west of the Divide. Rubber rabbitbrush (Ckpysotharmus nauseosus)3
another grassland species, and Rocky Mountain juniper (Junipevus soopu-
lomm) were found in 50 percent or more of the stands and also did not
occur west of the Divide. Shrubs occurring only in stands west of the
Divide included western serviceberry (AmetanohLev atnifptia)3 common
snowberry (Symphovioavpus albus)3 ninebark (Physocavpus malvaoeus)3 and
white spirea (Spivea betutifolia). These shrubs characteristically
occur on more mesic sites and/or forest habitat types. Other species
that occurred frequently included: low sagebrush (Avtemisia avbusoula)3
big sagebrush (Avtemisia tvidentata)3 and gray horsebrush (Tetvadymia
oanesoens )..
The density of mountain mahogany varied greatly between stands
(Table 2). The lowest density was 472 plants per hectare at site 0
(Fig. 22) and the highest density was 21,627 plants per hectare at site
G (Fig. .10). Stands with low density of mountain mahogany plants con
sistently had the largest individual plants and the largest mean area
per plant. Those with high density tended to have a small mean area per
plant. Overall^ mountain mahogany was the single most abundant shrub at
all.but two of the stands. Bitterbrush had a higher plant density than mahogany at site 0 . (Fig. 22), a stand on a grassy, southeast facing hill side of low slope. Bitterbrush occurred commonly throughout the area arid may have been better adapted to the site. Big sagebrush was more -37-
abundant than.mahogany at site K (Fig. 17), another stand of southeast
exposure and. low slope. . This stand had the highest number of shrub species present.for the stands studied suggesting a less than optimum site for mountain, mahogany and a situation where other species might eventually dominate.
Importance values indicated that mountain mahogany was the. dominant
shrub on all stands and was favored on steeper, warmer (more westerly)
slopes (Table 2). Some variation was evident by slope and exposure.
Importance values for mountain mahogany were significantly lower
(p < 0.05) in stands of east exposure and slope less than 40.percent
and significantly higher (p < 0.05) in stands of west; exposure and
slope greater than 40 percent.
The generally lower importance values for other species (Table 2)
suggested that mountain mahogany sites were sufficiently marginal for
most of these species that they could not compete effectively with
mountain mahogany. This supports the concept that mountain mahogany
is a climax species on most sites where it occurs.
Grass, Forb, and Ground Cover Characteristics
Sixteen species of grasses and grass-like plants and 128 forbs
were identified on the 22 stands (Table 3, Appendix Table 17). Because
canopy coverage and frequency values for the various species were gen-
eraliy similar between stands, data for all stands were combined
: . . ■ . . . .. ■ : (Table 3) . ' - -38-
TABLE 3. CANOPY COVERAGE, FREQUENCY, AND CONSTANCY OF LOW GROWING TAXA AS DETERMINED BY EXAMINATION OF TWENTY 2X5 DECIMETER PLOTS FOR ' EACH OF 21 MOUNTAIN MAHOGANY STANDS DURING SPRING AND. SUMMER (42.0 TOTAL PLOTS) . Spring Summer GRASSES AND SEDGES:. Agvopyvon spioatum 3/27/761 3/21/81 Avistidalongiseta tr2/tr/10 tr/tr/10 Boutelona gvgoilis tr/ 3/10 tr/ 2/10 Bvomus teotovum 1/10/29 I/. 5/24 Cavex filifolia I/. 4/10 tr/ 2/10 Cavex sp. tr/ 3/24 tr/ 3/19 Festuaa idahoensis 2/12/52 tr/: 3/ 5 Koelevia cvistata tr/ 3/ 5 tr/ 2/14 Ovyzopsis kyme:nbides I/ 8/24 I/ 8/43 Poa seounda 1/12/52 I/ 5/29 Poa sp. I/ 6/33 tr/tr/ 5 Stipa aomata ■ tr/ 2/10 I/ 5/29 Unidentified grass tr/ 4/29 “ Total Grasses & Sedges 12/70/100 8/48/100
FORBS: Aohillea millefolium tr/ 2/19 tr/ 1/14 Allium geyevi tr/ I/ 5 ■ - Alliim sp. tr/ 9/29 tr/ 1/10 Antennavig vosea tr/tr/. 5 Avabis holboellii . tr/ 1/14 Avabis miovpphylta tr/ 2/ 5 ■ Avabis s-p. tr/ 1/10 - Avtemisia dvanunaulus - tr/tr/10 Avtemisia fvigida ■ I/ 9/57 I/. 9/57 ' Balsamovvhiza sggittata tr/tr/ 5 Bevbevis vepens tr/tr/ 5 tr/tr/ 5 ■'Camelina.migvoogvpa . ■ ■ tr/ 3/10 tr/tr/ 5 Castelteya sp.,-' ' • . tr/ 1/10 — Centauvea vepens- tr/ 3/. 5 tr/ 2 / 5 ■Chenopodiim' fvemontii tr/ I/ 5 tr/ I/ 5 ; Civisium undulatum tr/ 1 / 5 tr/ I/ 5 Collinsia pawiflova . tr/ 6/19 . " - ■■ Comandva umbellata tr/ I/ 5 tr/ 1/14 Cvypianthe -celesoides tr/ 5/38 .tr/ 4/19 ■ Cymoptevus .bipinnatus tr/ 3/14 tr/ 3/14 ■Delphinium bioplov tr/ 1/19 - Desouvainia pinhata , I/ 9/48 tr/tr/10 Dvaba nemovdsd ' tr/ 1/14 tr/ I/ 5 -39 -
TABLE 3. (Continued) Spring Summer FORBS: (Con't.) Dvaba.oligosperma tr/ 4/24 tr/ 1/14 Er-igeron oompositus tr/ 1/10 tr/tr/ 5 Erigevon divergens tr/ I/ 5 tr/ 1/10 Erigeron tweedyi ■ tr/ I/ 5 Eriogomori Tnioroiheeion - tr/tr/ 5 Eriogoman striatum tr/tr/ 5 tr/tr/ 5 Erysimum asperum tr/tr/ 5 . - Ggliwn apdrine . tr/ 1/10 Geum. trifolium-. tr/tr/ 5 tr/tr/ 5 Haplopappus deaulis I/ 7/19 1/7/19 Lepidiumdensiflorum.. . tr/tr/ 5 Lesqiierilla dlpina tr/ 2/14 Lithophragma. parviflora tr/ 1 / 5 Lithospermum.'arvense tr/tr/ 5 Lithospermum inoisum tr/ 3/ 5 ' " — Lithospermon ruderale tr/tr/10 tr/tr/10 Lomatium triiernatum : tr/ I/ 5 Mertensia sp< tr/tr/ 5 • Miorosteris graoilis: tr/ 2/10 - Montia perfoHata tr/ 1/10 '-Opuritia polyogntha tr/ 2/19 tr/ 3/19 Penstemon .... tr/tr/ 5 Petrophytum oaespitosum tr/tr/ 5 .. tr/tr/ 5 Phaoeiiahastaia tr/tr/ 5; Phlox albomargindia tr/4/14 tr/ 1/10 Phlox' hoodii.. tr/ 4/29 tr/ 3/19 Phlox longifolia. tr/ 1/10 - Phlox musooides tr/tr/ 5 . tr/tr/ 5 Plantago patcugonica . — ■ tr/tr/ 5 Poteritilla glandulosa - tr/tr/ 5 ■ - . Ranunoulus glaberrimus tr/ 1 / 5 Sedion lanoeoiaium tr/tr/ 5 tr/tr/ 5 Serieeio oanus tr/ 2/19 tr/ 2/19 Solidago missouriensis - . tr/ 1 / 5 Sphaerdloea odooinea . tr/ 1/14 tr/ 1/19 Verbasoum thapsus. tr/tr/ 5 Moodsia soopulina tr/tr/ 5 Zygodehus veneosus tr/ I/ 5 tr/tr/ 5 Unidentified forbs tr/ 3/29 tr/tr/10 Total Forbs . 9/57/100 ' 6/39/95 -40 -
TABLE 3. (Continued) Spring ■ Summer SHRUBS: Artemisia arbuSeula tr/ 1/10 tr/tr/10. Artemisia tridentata tr/tr/ 5 tr/tr/ 5 Cercoaarpus ■ ledifolius 2/11/66 2/ 8/57 . Chrysothamnus nauseosus tr/tr/ 5 tr/tr/10 ' Gutierrezid sardthrae I/ 5/29 tr/ 3/24 Purshia tridentata tr/tr/ 5 tr/tr/ 5 Ribes oereum tr/tr/10 Spirea betulifdiia - tr/tr/ 5 . Symphoriearpus albus tr/tr/ 5 tr/tr/ 5 Tetradymia edneseens tr/tr/10 tr/ 1/10 Total Shrubs 3/18/81 3/14/76
MOSS AND LICHEN- 2/13/62 I/ 3/38 GRASS 11/70/100 8/48/100. FORBS 6/59/100 .5/40/95 SHRUBS 4/17/81 .2/14/76 BARE GROUND 27/79/100 25/73/100 ROCK 25/77/100 29/73/100 LITTER 29/92/100 37/94/100
1Canbpy coverage (percent of area covered)/percent frequency (percent occurrence among 420 plots/constancy (percent occurrence among 21 sites). • 2tr = trace - a value less than 0.5 percent.
The typical paucity, of understory vegetation in mountain mahogany
stands was evidenced by high percentages of bare ground and rock in
every frame of every stand. Bare ground and rock accounted for 49 per-
• ' • . •* . 1 • cent of the canopy, coverage (mean percent of total) in the spring plots and 50 percent in the summer plots. During spring total grass coverage
averaged 15 percent of the plots while total forb coverage was six — 41—
percent. Crass coverage'decreased to seven percent In the summer
measurements while forb coverage remained about the same at five percent.
Shrubs accounted for only two percent of the total coverage in measure ments for both seasons. Litter had a mean coverage of 28 percent among
plots measured in the spring and 36 percent for the summer.
Blue bunch wheatgrass (Agropyvon spiaatim) was present in every
stand (Appendix Table 17). This species occurred in canopy coverage plots on 76 percent of the stands in the spring and on 81 percent of the stands in the summer with overall mean coverage values of -four percent
for spring and three percent for summer. Other grasses which occurred
_ > •’ on more than 50 percent of the stands included Idaho fescue (Festuoa idahoensis); Prairie Junegrass (Koetevia evistata)3 Sandberg bluegrass
(Poa seounda)3 Indian ricegrass (Oryzopsis hymenoides)3 and needle-and- thread grass (Stipa aomata). Idaho fescue was recorded in the canopy coverage plots almost exclusively in the spring, occurring in only one stand during the summer reading. Sandberg bluegrass also occurred more often in the spring, readings. Prairie Junegrass, Indian ricegrass, and needle-and-thread grass occurred more often in summer readings.
Forbs varied considerably, with from two to 40 different species recorded in individual stands (Appendix Table 17). Almost all were of spring aspect and had completed their annual cycle and disappeared by summer. Fringed sagewort (Artemtsta frtgtda) occurred on all but three sites, two of which were west of the Divide and had a tree overstory -42-
(sites N and P ) . Mean canopy coverage values for this species were one
and two percent for spring and summer, respectively. Other important
forbs were miner's candle (Cryptdnthe oelesoides)3 pinnate tansymustard
(Descurainia p'innata)3 and Hood's phlox (Phlox hoodli). Pale bastard
toadflax (Comandva vmbeltata) and stemless goIdenweed (HapZopappus aaaulis) also occurred on a high number of stands but were not important in canopy coverage plots. Arrowleaf balsamroot (BaZsamorrhisa sagittata)3
Russian knapweed (Centaurea repens)3 shootingstar (Dodecatheon congugans)3 and Oregon grape (Berberis repens) were found in mountain mahogany stands only west of the Continental Divide, although they commonly occur through out most of western and southwestern Montana.
Growth" Characteristics and Relationships
Growth Form
Two different growth forms of mountain mahogany occurred in and
among the stands, apparently as a result of past browsing pressure.
Plants which appeared to have been heavily and persistently browsed
early in life were low and rounded or "basketball"-shaped, while those
which escaped early browsing and/or grew out of reach of browsing
animals tended to be "umbrella"-shaped and "highlined" leaving only a
small, generally none-forage productive, top canopy. Also, most low
growing plants were multistemmed, due either to intertwining of seed
lings into one plant or to branches being pushed under the soil and —43—
eventually becoming a "stem". Plants of taller growth form were gener
ally single stemmed.
Current annual growth occurred both terminally and laterally on
branches. Most twigs originated from the-previous year’s wood, though
twigs occasionally were found growing directly from the stem or main
branches. Flowers developed from both terminal and lateral buds located
between leaf axes on the. previous year 's wood. Consequently,. heavy ’
browsing resulting in utilization of most current growth stems may
directly reduce or eliminate flowering and seed production. This was '
dramatically demonstrated by partially available, "barbell"-shaped,
plants1 in which top crowns produced little or no current growth but were
covered with seeds while lower, available portions produced many long
leaders arid few seeds.
Plants in. stands west of the Continental Divide.were taller, and had
larger crown areas than those of stands east of the Divide ("Table 4).
Plants on the west side of the Divide averaged 16.7 decimeters iri height,
16*5 decimeters in diameter, and had a mean corrected or live crown
area (CCA) of 1.54 square meters, while plarits east of the Divide aver
aged 9.2' decimete.irs in height,. 9.6 decimeters in diameter and had a CCA
of 0.52 square meters. Mountain mahogany stands west of the,Divide were
at lower elevations'and on sites which were more moist and had longer -' '■ • *' ; I ; . . '' - . • ' growing seasons "than stands east of the Divide. Also, plants west, of
the Divide historically have received only light utilization by browsing -44-
TABLE 4. AVERAGE HEIGHT^ DIAMETER, CORRECTED CROWN AREA, AND PERCENT OF CROWN DEAD FOR MOUNTAIN MAHOGANY, AND THE- NUMBER OF DEAD PLANTS AND SEEDLINGS PER HECTARE ON EACH OF 22 STANDS. Percent Number of Number of Height Diameter CCA1 Crown Dead/ Seedlings/ (dm) (dm) (m2) . Dead Hectare , Hectare
A 7 , 7.6 ' .19 31 630 • B . 8.1 ,8.9 , . 39 38 354 118 . C ■ 4.2 ' 4.2 .05 V. 57 ' . 1012. . 0 . . D ■' 8.5. 8.3 .21 35 46 .0 • E. 9.4 '9.6 . .45 . . 17 0 o •. F 6.8 7.1 .16 .. 30 . . 59 0 G 5.4 5.1 .12 15 649 649 H '7.4. 8.3 .37 • 21 : • •. 55 109 ■ ' I ■ 11.8 ■ 12.6 .65 ' 19 o 0 J ■ 7.9 . 8.9 . . .50 ■ 19' V ■ 45 ' 0 • K. 13.1 12.9 . .54 34 " 0 . 0 L 8.9 9.2 .36 22 0 ■■ . 135 'M' 3.3 4.3 . .1,0 . 16. - 0 0 N2 • 16.4 12.7 .54 40 . 14 . 0 . O 23.7 ' ■ 23.9 3.30 . 19: . .. 0 . 0 ..-P 13.7 12.9 . . 77 19 . 0 0 q: 10.2 . 12,6 .68 20 ■ ■ : . 0 ■ - 23 - R 8.o 9.5 .43 ■ : 3i 58 0 - . S 5.6 7.5 .32 23 0 0 T .. 5.1 . , 6.8 ' .22 22 , o 81 U- 9.5 : 9.7 .59 15 . o ■ 0 . . ■ . V 8.1 . 9.4 .61 18 'o ,. .80
Total . " 9.2 , 9.6 .52 '■ • Total ,7.8 , 8.6 . .37 25 : ; - (East of ; " -■ . Divide) Total 16.7 16.5 1.54 26 (West of , -Divide) 1CCAI z r n A - corrected______‘ J crown area (live crown area) 2Transects N , '0, P were West of the Continental Divide - 45- animals (unpublished data, Montana Department of FisH and Game) and had . an older average age. Mackie (1973) found that plants protected fiom browsing by total exclosures tended to be larger than those exposed to animal browsing. That plant height and the CCA generally increase with age was indicated by linear correlation coefficients of r = 0.54 and r = 0.63 .for relationships between CCA and age, and height and age, respectively. -Lonner (1972) found that crown volume generally increased with age in.mountain mahogany (r = 0.80).
Overall, about one-fourth of the crown area of mountain mahogany plants was comprised of dead branches or stems (Table 4). Mean percent ages .of dead crown were similar for stands east and west of the Divide,
25 and 26 percent, respectively, but variation among individual stands was great, ranging from 15 to 57 percent. In general, stands with higher, mean percentages of dead crown also contained more dead plants. Stand C at Scudder Creek (Fig. 5) had the highest mean percentage dead crown <
(57%) and also the greatest number of dead plants (1,012 plants/hectare). ■
Scudder'Creek, is an important mule deer winter range where heavy utili zation.and damage to mountain mahogany plants has been recorded since the early 1950's (South 1957; Allen 1967). Lonner (1972) reported a " ■ weak though significant (r = 0.43) linear correlation ,coefficient between age and decadency in mountain mahogany and concluded that, . although age probably influences decadency, other factors played an equal or more important part. —4 6-
Annual Growth Chronology
Annual growth began with formation of flower buds during April in stands west of the Continental Divide and May east of the Divide. Earli est recorded dates, were approximately April 5 and May 5, respectively
(Fig. 26). Although budding was completed in the western stands before it commenced in the eastern area, flowers bloomed simultaneously during : ■■ . . • . . ; . , . .. v.,' May in both areas. Similarity, seeds were formed in June and matured from early July through early August in both areas, though the rate of formation.was slightly slower and maturation was later on some sites east of the Divide. -
• Growth of annual twigs occurred from late May until early July, though most occurred in late May and June (Fig. 27).. Average twig lengths for a few stands decreased during July and/or August, perhaps as a result of rodent or ungulate use and/of.dessication. Generally,
twig, growth on plants west, of the Divide began a few days earlier, progressed slightly faster, and was completed sooner, than for plants,
east, of the Divide, though considerable variation ,occurred. 1
The onset, rate,and duration of growth of mountain mahogany appear-
V y . ... . ' ' - ■ - ed to be influenced both by general weather conditions prior' to and ■ during the. growth, period. and by local microclimates influences such as
elevation, slope, and exposure. . Overall, plants in stands west of the
Divide both began and completed growth phases earlier than those east
of the Divide, and plants.in stands of southeast exposure were the first West of Divide
Twig Growth
Seed Maturation
Seed Production
Flower Bloom
X Flower Budding > S
I 15 30 15 30 15 30 15 30 15 30 APRIL MAY JUNE JULY AUGUST
Figure 26. Phasic development and growth of mountain mahogany on stands east and west of the Continental Divide as determined by spring and summer observations. -48-
•C(157)
•D (2 3 )
15 MAY JUNE JULY Figure 27. Growth curves as determined by the measure of twigs greater than one centimeter from 200 tagged potential buds per transect (number of twigs read in parentheses). • L(IOS)
•1(81)
•K<60)
MAY JUNE JULY Figure 27 (continued). Growth curves as determined by the measure of twigs greater than one centimeter from 200 tagged potential buds per transect (number of twigs read in parentheses). iue2 (otne) Growthcurvesasdeterminedthe by of measure (continued).27Figure
LLIMETiRS A JN JULY JUNE MAY twigs thangreater onecentimeter200from twigsinreadparentheses). (numbertagged transectpotentialbudsper of —50— •1(175) R( ) 7 (7 •R •P(149) 0( ) 6 8 (1 •0 -51-
to show growth;. Blalsdell (1958) found early phasic development of
grasses and forbs on the upper Snake River in Idaho to be associated
mainly with high temperature and low precipitation. This may also apply
to shrubs. Monthly mean temperatures west of the Divide were higher
than those east of the Divide; and, in 1974, lower than normal precipi
tation was recorded in both, areas.
. Browse Production and Utilization Characteristics
Browse Production
Browse production measuretnents obtained from total clipping of
'current annual growth twigs in late summer are presented in Tables 5 and
6. Average numbers of twigs per plant were counted and numbers of twigs
per one square meter of corrected crown area were calculated (Table 5)
for both 1973 and 1974. Number of current annual growth twigs per nlant
among the various stands ranged from zero to 529 in 1973 and two to 634
in 1974. The calculated total twig production per hectare was greater
in.1974 than 1973 for 17 (81%). of 21 stands (Table 6). Total numbers .
of twigs produced per hectare.in 1973 ranged from zero to 1,484,984 .. ,
among the different stands add from 43,254 to 1,930,609 in 1974. -
The total length of twig- material ...per .hectare in each stand varied
with the total number of twigs produced .and the average length of growth
each year. Mean twig length for all stands was approximately the same
for,19.73 and 1974, 29,.2 and 28.7 millimeters,. respectively (Table 5). ••TABLE 5. PERCENTAGE OE■ PLANTS PRODUCING TWIGS, ,THE'NUMBER OF TWIGS PER PLANT, THE NUMBER OF • -•• • : TWiGS PER ONE SQUARE METER OF CORRECTED CROWN AREA, AND THE AVERAGE LENGTH OF TWIGS . CALCULATED FROM PRODUCTION MEASUREMENTS DURING T973 AND 1974. 1973 .' 1974 Percent of Number of Number of- Average Number of Number of Average Plant 'Having " Twigs/ TxngsVlM2' Length (mm) Twigs/ Twigs/IM2 Length (mm) Site • Twig's.. > Icm " Plant CCA ' of Twigs1 Plant ’ CCA of Twigs1 A - - 99 ■218 838 34.8 ■ 306 ■ 1,020 • 32.8 '• B - : 68 89 247 24.6 , 100. 435 25.3 C 79 13 ' ■ 118 28.2 79 ' 1,580 29.1 D • 12 ■ 320 2,286 30.8 .40 200 17.8 . E ■ 19 . 81 . 289 25.5' 20 23 20.5 F 62 199 ■765 32.5 .116 ' 773 20.5 G 2 0 ' 0 - 0 2 . 33 14.4 . H - . 56 47 168 ■ ' 20.9 123 615 20.4 v, I 41 116 ■ 163 35.8 : 200 339 31.5 Y J - 64 ■. - 7 19 27.0 . 126 420 26.7 K - :. 30 - 127 • 289 . 29.8 138 197.. 26.1 L - 51 88 166 26.4 . 118 . 492 40.3 . M- 69 65 650 ‘ ■ 31.4 . - .73 730 37.4 N2 ... 76 160 219 . 30.3 . . 366 ■ . 963 46.3 .0 .. 93 - 198 . 83 28.3 344 234 30.4 P ■ 75 109 105 32.5 .' 155 : 674 36.3 Q ' 20 ,, ' 5 17 34.5 22 . 55 . 17.1 R -' • 39 . 10 35 - 29.0 . 16 , .107 19.1 . s / 64 H 7 - - 488 38.1 114 393 . 32.9 T • 88 - . 45 ; 265 ' . 24.5 ' . 133 . 887 32.0 ' u ■ . , 89 529 1,017 . 47.6 634 1,981 46.6 Total East of •• Divide - 53 ; • 29.0 27.3 Total West of Divide 81 30.3 37.7 Combined Total . 60 , " . 29.2 28.7 1Average ' length of a subsample of 100 twigs greater than I. cm. .2Sites N, 0, P were west of the Continental Divide. . TABLE"6.. MEAN' CORRECTED CROWN AREA', DENSITY, AND CURRENT ANNUAL. GROWTH TWIGS PRODUCED FOR 21 MOUNTAIN MAHOGANY. STANDS IN 1973 AND 1974. Mean Corrected 'Plants/ Number o f ■Twigs/ Length of Twigs/ .'Weight of Twigs Stand Hectare Hectare (M/Hectare) ■ . 1973 : .1974 • 1973 .1974 1973 1974 1973 .1974
A ’ ' ' " .26 ' ,30 ' 6,303 1,371,533 1,930,609 47,729 63,324 50.6 154.2 B .36 . .23 ■ 5,894 . 522,729 587,242 12,859. 14,857 . 19.8 35.0 C .11 .05 9,200 123,004 .726,800 3,469 21,150 ■' 4.6 56.9 D - • .14 . ,20 4,636 I i483,984 185,440 45,707 3,301 38.7 12.9 E .28 .89 4,252 346,113" 85,040 8,826 1,743 7.3 6.9 E ' •' . 26 ,15 ■ 5,863 1,169,082 756,972 3.7,995 .15,518 39.8 51.3 G .77 ' .06 21,627 0 43,254 0 623 C 2.6
H - .28 .20 5,452 255,473 670,719 5,339 13,683 . 3.6 35.9 53- I. .71 .59 - 3,387 391,537 677,739 ■ 14,017. 21,349 17.9 57.0 ' J .37 . .30 4,487 - 22,612 390,735 611 . 10,433 0.5 36.8 K •44 - .70 766 97,205 ■ 105,631 2,897 2,757 4.1 8.7 L . ' ' ' .53 .24 ' 4,490 396,467 . 527,575 10,467 21,261 10.6 42.7 ■ M . .10 . .10 : 7,924 516,645 .- 581,622 16,223 21,753 13.5 36.6 .'N1. ■ ' /. .7 :3 . .3.8 . 1,442 . 2.30,388 527,628 6,981 24,429 . 8.6 58.7 0 ' . 2.40 - ,1.47 4.72 93,550 162,415 . 2,648 4i937 : 5.1 27.5 P . ' 1.04 ' 1 .23 : - 1,923 209,222 297,680 6,800 10,806 12.4 38.4 'Q-.- . . 29 ' .40 2,333 11,665 51,046 ■ 402 873 ' 0.4 ■ 3.5 R / .29 . .15 ■ 5,800 ■ 59,624 . 93,438 1,729 . 1,785 1.7 ■ 7.2 S . .. -24 6,666 779,922 759,257 29,715. 24,980 24.1 59.9 T ; .17 ■ • .15 - 8,105 . 362,294 1,075,534 8,876 .34,417 ■ . 9.0 63.1 U ..' .52 .32 2,302 "1,217,067 1,459,693 57,932 68,022 '70.2 168.4
. iSites N, 0, P were west of the Continental Divide. -54-
Total lengths generally increased from 1973 to 1974 as. did the total
number of twigs (Table 6). The total length varied between stands from
0 to 57,932 meters (187,701 feet).per hectare in 1973 and from 623 meters
(2019 feet) per hectare to 63,022 meters (220,392 feet) per hectare in.
1974. ‘ '
The total twig production by weight could not be compared between years because the balance used resulted in a slight error in measure ments for 1974. However, comparisons of relative forage production by weight between stands for the same year (Table 6) may still be vdlid..
The total weight of twigs varied between stands from zero to 70.2 kilo
grams (154 pounds) per hectare in.1973 arid from 2.6 kilograms (5.7 pounds) per hectare to 168.4 kilograms (370.5 pounds) per hectare in
1974; Weight estimates included leaf material which averaged 40,percent .
(20% to 60%) of.the total forage weight among stands. :
Mean corrected live crown areas of plants were larger in 14 (67%)
of the 21 stands iri 1973 than in 1974 (Table 6). The values ranged
from 0.10 square meters to 2.4 square meters in 1.973 and from 0.05 square
meters to 1.47 square meters in 1974. . The plants collected from each • ' ' •. ■ , • - stand in both years generally were of the same corrected crown area as.
calculated for the entire stand (Table 4) from, density'measurements..
The percentages of tagged buds which produced twigs varied from ■
■ .; ' ; ; .:■ ■■ ■ .V- : ■. . ■ ■ ■ ■ ■ ■ " : ' /-V-... ;• : ' two to 99 percent among stands. (Table 5). Averages were 81 percent
for stands located west of the Continental: Divide and 53 percent for
,.-V • -55-
stands east of the Divide. These data were for 1974, only. Since the
number of CAGT produced varied considerably between years, percentages
of buds which develop.into current annual growth stems would also be
■ expected to change between years.
■ Production differences between the two years of the study may have
been related to the amount of precipitation received during the previ
ous fall (September, October, November) (Fig. 25). 'Lower.production
• for 1973 was associated with below normal rainfall during, the fall of
1972 and.high precipitation in the spring of 1973, especially during:
June when growth occurs; higher production in 1974 was associated with
above normal precipitation in the fall of 1973 and lower than normal
spring precipitation. Blaisdell (1958). found that precipitation prior
to the growing season was fairly well correlated with herbage weight
(annual production) of shrubs in the Snake River area of Idaho. He ■ -v '■ • "• ' ■ ' ■ also found a positive correlation between spring precipitation .and the. ,
crown area of shrubs. .. My data suggested a similar relationship for
.mountain mahogany.
Medin (1960) found soil depth to be the most significant .'factor
■influencing'production of true mountain mahogany (CerooaarpuS' montanus),-
primarily through its effect, on waterholding capacity. Aspect and
slope were.not found, to be,significantly important,td production and
there was a negative relationship between production and the stoniness
of.the site. I did not measure either stoniness,or soil depth, but -56- general observations indicated that soils associated with most stands were both.stony and shallow. Similarly, aspect and slope did not appear
to influence production during my study.
Utilization appears to enhance twig production for mountain mahogany as well as other browse species (Mackie 1973). Utilization of mountain mahogany was related to plant availability as influenced by elevation* slope, and aspect as these conditions relate to snow cover, the severity of the winter, and the availability of other palatable food items. East browsing pressure may also influence the number of dead branches that block the use of interior growth; Garrison (1953) showed that amounts of dead material in the crown of curl-leaf mountain mahogany plants increased with the degree of clipping.
"Age classes" are generally considered to reflect the effects of past browsing intensity upon survival, vigor, and productivity of rate plants (Cole .1958). The use of 25 percent dead crown material to rate mountain mahogany plants as decadent may be too low to be indicative of senility or reduced vigor and production. Production did not appear to be hindered until plants had much more than 25 percent dead crown.
Three of the four stands.producing over one million twigs per hectare
(Table 6) averaged 30 percent crown dead (Table 4). ' The stand with the highest.average percent crown dead, 57 percent at site C,'still produced over 500,000 twigs per hectare. . >
Experiments in pruning mountain mahogany to simulate various -57-
browsing pressures have been conducted by Garrison (1953), Neff (1960),
Thompson (1970), and Shepherd (1971). Their findings generally show
that clipping from 50 to 75 percent of current annual growth generally
increased twig production the following year to the detriment of flower
and fruit production while destructive clippings (100%) caused a
decrease in production and eventual death of the plant. Small, mature
shrubs responded best to clipping and volume of browse production was
greater from these plants than from older, larger, and tree-like plants.
Utilization
Data on past utilization of mountain mahogany on key browse survey
transects in the vicinity of my study areas (unpublished data, Montana
Department of Fish and Game) are summarized in Table 7. Ocular esti mates of utilization during the winter of 1973-74 for the 21 stands
studied (Table 8) corresponded generally to the average level of use
oh mountain mahogany in these areas during past years, ranging from
zero to 90 percent. Pellet group counts along line transects through
the stands indicated intensities of deer use (Table 9) which roughly
corresponded to the relative levels of utilization of mountain mahogany
from ocular estimates (Table 8). Numbers of pellets counted ranged
from zero to 157, with the extremes representing lowest and highest
levels of usage on mountain mahogany.
Estimates of utilization in 1974 as a percentage of 1973 annual
production were made using linear regressions developed relating CAGT -58-
TABLE 7. AVERAGE UTILIZATION OF MOUNTAIN MAHOGANY ON BROWSE TRANSECTS ESTABLISHED BY THE MONTANA DEPARTMENT OF FISH AND GAME.
Percent Number Utilization Years Read Lima area 30.01 East Fork, Little Sheep Creek 77(59-88) 8 30.02 Little Sheep 73(45-88) 4 30.03 Middle Forki Little Sheep Creek 64(43-87) 10. . 30.04. Gallagher Gulch 60(17-90) 13 30.05 Chute Canyon 83(59-90) 9 30.06 Big Sheep Creek 87(79-90) 11
Dillon area 31.04 Bannack 54(25-90) 7 31.05 Bannack 64(31-90) 8 31.14 Scudder Creek 83(47-90) 12 31.17 New Departure Mine 25(17-41) 4 325.02 Axes Canyon '19( 4-45) 8
Melrose area 31.12 Canyon Creek (Lower) 62(38-82) 8 31.13 Canyon Creek (Upper) 42(29-76) 10 34.05 Soap Gulch (Lower) 9( 2-28) - 5. 34.06 Soap Gulch (Upper) 31( 5-51) 6 34.07 Camp Creek 48(13-66) 7 . 34.08 Opposite Fleecer (Lime Gulch) 49(16-90) 6
Twin Bridges-Whitehall area 34.03 Hell's Canyon (Low) 13( 5-33) 9 34.04 Hell's Canyon (High) 47(31-70) 9 ' 35.02 Pipestone-Dry Creek 34(16-77) 8 . ■320.05 Bear Gulch (Low) 71(32-90). 3 320.06 Bear Gulch (High) 54( 9-90) . 7 320.09 Gold Hill (High) 28( 2-62) I 320.14 Gold Hill 27(18-33) 3
Townsend area . 38.02 Indian Creek. 53(14-82) 10 38.06 Limestone Hills 77(65-90) 6
Hamilton-Darby area 25.05 Haley Chute 84(74-90) ■ 5 27.07. Robbin? s Gulch 25( 5-62) 9 -59-
TABLE 8. AVERAGE PERCENTAGE UTILIZATION AS DETERMINED BY SITE OBSERVA TIONS FOR THE WINTER OF 1973-74 ON 21 MOUNTAIN MAHOGANY STANDS.
Nearest Montana Fish and Game Percent Site Transect (from Table 7) Utilization
A 325.02 • 86 B 31.17 26 C 31.14 90 D 30.06 88 E 30.04 18 F 30.03 ' 85 G 34.07 . 0 H 31.12 .87 I 34:03 0 J 27 K 35.02 9 L 320.14 33 ■ M 38.06 59 N 1 25.05 54 0 27.07 2 P 38 Q 34.07 0 R 34.05 ■ I S 34.08 . 89 T 320.05 . 82 u .; 79
1Sites N, 0, P were west of the Continental Divide.
diameter to length and weight (Tables'10 and 11). Correlation coeffi cients and regression relationships differed between years for the same stand, indicating that it might be desirable to develop new on site regression equations each year for accurate estimates of pro- ‘ duction and utilization by this method. Twig diameter was more -60-
TABLE ■9. NUMBERS OF DEER PELLETS COUNTED WITHIN ONE METER OF THREE 100 METER LINE TRANSECTS ON 21 MOUNTAIN MAHOGANY STANDS FOR USE AS A RELATIVE INDEX OF UTILIZATION DURING THE WINTER OF ' 1973-1974.
. Site . Number of Pellets
A - . 157 B 53 - C ' 63 " ' D 66 . E 18 ' F - . ■ ■ 96 G ' 0. H 48 - I " ' ' 2. ' J 53 " : K .23 . L- . . 71 M- ■ 21 N 1 ' ' 8 0 .2 P ' . 10 Q 0 R 12 . S ■ 113 . T 94 ' '' U 62
^Sltes N, 0, P were west of the Continental Divide.
closely correlated with twig weight than length for all but one of t h e .
stands in 1973 (Appendix Table 18).
Estimates of average twig .length utilized in each stand during
..the 1973-1974 winter were computed in the spring of 1974 using the — 61-
TABLE 10. MEAN DIAMETER AT BASE OF GROWTH (DBG) AND ESTIMATED TWIG LENGTH UTILIZED ON 21 MOUNTAIN MAHOGANY STANDS DURING THE . WINTER OF 1973-1974.
Length Length Used/ Site . ■ DBG T 1 R2 Used P 3 v Hectare(m)
• A ' 1.37 38 25 13 ■ 34 . .. 17,830 . B . 1.70 . 37 • 26 . 11 28 .. 5,750 . C 1.58 39 ■ 25 14 36 ' 1,722 D . Ii17 . 35 18 . .1.7 : 49 25,228 ■ E. 1.55 39 .34 5 13 . ' 1,731 F 1.34 38 18. 10 26. . 11,691 G • 0 0 . 0 0 .0 0 H 1.45 ■ 28 24 4 ' 14 1,022. . I . 0 0 0 0 0 0 J 0.97 24 20 ' 4 : 17 ' 91 K 1.13 . 32 20 ■ 12 38 1,167 L . 1.33 ■ 34 22 12 . . 35 . 4,758 . . M . 1-27 :. 37 21 ■ 16 . : 43 ' ' 8,266. ■ N4 ■ 1.34 37 24 13 . 35 2,995 0 ' 2.10 60 42 18 30 1,684 . P 1.59 45 40 .. 5 ■ 11 . . 1,064 Q . 0 0 '0 0 ■ 0 . 0 R 1.20 34 . 19 ' 15 44 894 S : 1.57 59 27 • 32 54. 24,958 . T 1.57 52 28 24 46 8,695 U 1.70 63 30 33 52 40,163
1Estimated length before browsing in millimeters. 2Length. of. unused portion in millimeters. ^Percentage of total twig length browsed f P = 10Of=— . /+Sites Ni O', .P were west of the Continental Divide.
method described by Basile and Hutchings '(1966) and Lyon (1970) (Table
10). Utilization ranged from zero meters.at three stands to .40:163 meters (130,491 feet) per hectare of twig material:with 76 percent -62-
TABLE 11. MEAN DIAMETER AT POINT OF BROWSING (DPB) AND ESTIMATED TWIG WEIGHT UTILIZED ON 21 MOUNTAIN MAHOGANY STANDS DURING THE WINTER OF 1973-1974.
Weight Used Weight Used/ Site DPB (ga) Hectare(Kg) A 1.04 .02 . 27.4 B . 1.10 . 03 15.7 C '■ 1.20 .03 3.7 D 0.87 .02 29.7 E 1.30 .02 6.9 . , F O j 94 . .02 23.4 ■ G 0 o 0 ; H 0.89 .01 2.6 . ■ I 0 0 0 J 0.92 .02 ' 0.5 : K 0.82 .01 . 1.0 . L 0.96 .02 . ' 7.9 • ■ M 0.98 .02 10.3 N 1 . 0.99 .02 . 4.6 O . • . 1.64 .07 6.6 P 1.07 .02 4.2 Q . 0 . . o . 0 R ■ 0.78 ■ .01 0.6 . ■ ' S 1.07 . 03 ■ 23,4 . T 1.05 .02 . ' 7.2 U 1.13 .02 24.3
1Sitfes. N, 0, P were west, of the Continental Divide.
of the stands having less than 9,000 meters (29,241 feet)per hectare of twig material utilized. Percentages of twig material utilized, calcu- lated from the equation: P = (where T = the estimated average, length before browsing, and R = the average length of the unused portion of the twig CjBasile and Hutchings 19663), varied from zero to
54 percent. Mean basal diameters of. the twigs utilized by deer were ■ —63— generally larger than those of twigs measured,during production studies suggesting either that deer browsed more than the current annual growth, or that they ate entire twigs of shorter length and only portions of the larger ones, which were collected, and/or they selectively utilized only larger twigs. The larger average twig diameter predicted longer unbrowsed twig lengths arid probably over estimated total utilization.
Estimates of utilization by weight (Table 11) were computed using the diameter at point of browsing (DPB) method described by Peek (1971).
This method assumes the mountain mahogany twigs taper evenly such that ■ utilized length or weight can be predicted directly using the regression equations for twig diameter and length or. weight. Results indicated that weights of.twig material utilized varied among stands.from zero to 27.4 kilograms' (60.4 pounds) per hectare with .71 percent of the stands havirig less, than 11 kilograms (24.3 pounds) per hectare of twig material used. There were much higher estimates of utilization obtain ed than expected when the method was applied to estimate twig lengths utilized; similarily, iriflated weight utilization estimates were obtained. • Bucsis (1974) also found that the diameter at point of browsing method overestimated utilization as compared with diameter at base of growth method, and concluded the latter was more accurate • for estimating the utilization of big sagebrush arid bitterbrush. — 64-
In Idaho, use of mountain mahogany does not begin until January and the length of use depends on the severity of the winter (Claar 1973).
During this study no utilization was noted until November when light- use was observed on two of eight stands examined; six stands showed no utilization. By the middle of February, the two stands showing use in
November and one other had received heavy.usage; the remaining five . stands showed only little or no utilization although a show cover severely reduced availability of low growing, vegetation throughout the. area. "
’That browse production may have been influenced by prior utiliza tion was suggested by general comparisons of over-winter utilization on individual stands with browse production the following summer.
Stands receiving higher utilization during the winter of 1973-1974
(Table 8) generally produced greater amounts of current annual growth ■
in 1974 (Table 6) than stands of low overwinter utilization. For
example, stand G received no utilization in the winter of 1973-1974 and produced 43,254 twigs per hectare the following spring while stand S , within ten miles of stand G, received 89 percent utilization and subse
quently produced 759,257 twigs per hectare; There were some exceptions.
In three stands- (I, J , L) high production followed low utilization, and.
one stand (D) receiving high utilization subsequently produced, little
current annual growth. -65—
A linear regression relating age of mountain mahogany plants to the numbers of. twigs produced by.those plants indicated little corre lation between the two (r = 0.10). Lonner (1972) previously reported no apparent influence of age on the intensity of browsing received by an individual plant.
Age Distribution
. The average age of .210 randomly chosen mountain mahogany plants was 22 years, with a range of five to 85 years (Table 12). Plants from stands located west of the Continental Divide averaged 31 years while those from stands east of the Divide averaged 20 years of age.
These data indicated considerably younger ages for mountain mahogany than reported by Lonner (1972) who found an average age of 37 years with a range of two to 130 years for 210 plants collected from browse • transects and exclosures throughout the range of 'mountain mahogany in
Montana.. -Ldnner's collections were based, on general size and/or age structure of the stand which probably over-sampled older and. larger plants'. In Idaho, Scheldt (1969) found mountain mahogany plants older than 158 years and Claar (1973) found plants up to 200 years old; those with low, tightly hedged growth form ranged from ten.to 60 years old. •
The frequency distribution of plants, by 10-year age classes
(Fig. 28) indicated a preponderance of relatively young.' to middle-raged -66-
Age in Years
90 M 80 I. 70 I 60 I—I , so , 40 4 30 4 20 >
O m = = = ? = m ------»'----- = P = = = = , 40 30 20 10 0 10 20 30 40
Frequency, in Percent
Figure 28. Age class frequency distribution for 210 randomly chosen' . mountain mahogany plants. - 67-
TABLE 12. AVERAGE AGE AND AGE RANGES FOR 21 MOUNTAIN MAHOGANY'STANDS.
Site Average Age Range A ■ . 2 3 15-35 B 23 . 5-35 • C 22 15-35 D 16 5-25 " ■■ . E 17 5-35 ■ . ' F 20 15-25 .G 18 5-35 . ■ H 18 15-25 ' • I ' 26 5-35 : j 22 15-55 ; K 22 5-45 L 18 . . 5-55 M . 12 5-25 N1 35 . 25-85 0 32 5-45 P' 26 5-55 ' - ■■■■. - Q 19 5-35 . . : • R 23 5-45 • -s. 21 5-35 ' T 18 15-35 ' U 26 5-35. ' Total 22 ■ 5-85 ■ Total West of Divide 31 5-85 Total East of Divide 20 5-55
1Sites N,. 0,; P were located west of the Continental Divide. ■
plants similar, to. that described by Lonner (1972). Aside from,differ
ence between stands located east and west of the Continental Divide, age structures of individual stands were generally similar and contain
ed many age. classes (Table, 12). —68—
"Age classes" (Cole 1958) were estimated for a total of 1,221 moun tain mahogany plants in 22 stands (Table 13). Eight percent of these plants were rated young, 62 percent mature, and 30 percent decadent
(25% or more.crown dead). The "age classes" often reflected vigor rather than chronological age. Lonner (1972) stated that mountain mahogany plants rated "young" averaged 10.8 years with a range of three to 28 years; those rated, "mature" averaged 39,5 years, with a range of four to
100 years; and those rated "decadent" averaged 49.9 years with a range of five to 130 years.
Reproductive Characteristics
Seed production by mountain mahogany differed greatly between the two years of study. Copious amounts of seed were produced in 1974 and persisted on. the plants into August, while few seeds were either, seen or sifted from the ground beheath the plants in 1973. Phelps (1968) stated that good mountain mahogany seed crops occur, eyery 2 to 10 years.
Seeds used in the 19.74 germination experiments began to germinate after approximately two months, at which time they were taken from the refrigerator, and allowed to. continue germination for one more month, when the percentage showing' cotyledon development was determined. The presence of many different fungi on. the moist filter paper and seeds, despite the use of fungicides, apparently did not severely inhibit the -69-
TABLE 13. AGE CLASS DISTRIBUTION FOR 1,221 MOUNTAIN MAHOGANY PLANTS.
Percent Age Classes Site Young Mature Decadent A 8 47 45. B 6 29 65 C 4. 4 92 D - 45 , 55 • E- 18 71. ■ 11 . F - 2 43 ■ 55 G 8 77 ■ 15 H . 4 80 16 I 2 88 - ' 1 0 . J .7 67 . 26 K . ■ • . 5 43 ■ 52 L : 77 . 23 M,' . 89 11 -N 32 . 68 . 0 80 20 P 6 66 28 . . . -Q - 2 . 79 19 . R ■ . 5 72 23 S.. .4. 75 21 ■T 14 76 10 . U 6 78 16 LO , LO , Total 8 62 O
germination rate. Germination percentage averaged ' 76.percent' (36% to
99%) and cotyledon development averaged 50 percent (10% to 84%)
(Table 14).
Seedlings, were recorded in only seven of 22 stands in 1974
(Table 4), possibly reflecting the poor seed production- in 1973 and
"young"'plants (less than % inch basal.stem diameter) comprised only
8 percent of all plants measured in the stands (Table 13). However, —7 0—
TABLE 14. PERCENTAGE OF SEEDS THAT GERMINATED AND PERCENTAGE THAT DEVELOPED COTYLEDONS.
Percent Percent Site Germination Cotyledons A 86 81 B ' 87 61 C 99 48. D 90 . ' 19 . E 88 30 F 71 58 ■ G 85 58 ' H 72 i o ; I . 92 73 J . 79 . 38 K 93 79 L 66 ' 34 M 45 36 N 1 38 22 0 59 35 P 92 77 Q 97 39 R 93 84 S 57 25 T 74 64 U 36 30 Average 76 50
-1Sites N, 0, P were west of the Continental Divide.
age distribution data■(Fig. 28) showed that the stands were comprised of many different age classes. This might indicate that while seed production and reproduction may occur only sporadicallysuccessful reproduction does occur periodically. Harsh environmental conditions unfavorable for germination of seedlings as well as annual variations in seed production, may influence reproduction in mountain mahogany -71-
stands . Burkhardt (1967) found soil surface temperatures reaching 160
degrees F in stands of.western juniper (Junipevus oocidentalis) which were in the vicinity of mountain mahogany stands in southeastern Idaho.
Also, nearly all seedlings observed during my study were found in
shaded locations directly beneath established plants where a. cooler and probably more moist microclimate prevailed.
■ No tests of seedling survival were made during this study, however,
Scheldt (1969) found survival rates of seedlings to be between 23.and
32 percent and that, rabbits and deer account for approximately 50 per-:
cent of the overwintering mortality. Small rodents did not seem.to .
affect the seedlings. :
Due to the extreme site specificity of the shrub and the general
adverse conditions for seedling survival, mountain mahogany, might not
be expected to readily pioneer new areas or re-establish itself on
areas where existing populations have been destroyed: At sites where
the species has become established, reproduction and survival of seed
lings apparently are sufficient to maintain the stand even under
rather intensive browsing pressures. Adjacent transect and exclosure
data (Mackie, 1973) for Scudder Creek (site C) showed-3,120 seedlings
per hectare ' (1,263 seedlings per acre) within the exclosure and 543
seedlings per hectare (220 seedlings per acre) on the transect. The
opposite was found in the Limestone Hills area where 939 seedlings per -72-
hectare (380.seedlings per acre) occurred within the exclosure and
2,272 seedlings per hectare (920 seedlings per acre) on the transect.
, Nutritional Characteristics and Relationships . . "
Percentages of crude protein of current annual growth twigs of
curl-leaf mountain mahogany averaged 10.5, 10.4, 9.5, and 9.8 percent
■during the. spring, summer, fall, and winter, respectively. Values for
individual stands were similar in all seasons despite variations of
13 to 83 percent in past utilization (Table 7), moderately low to very ..- .'
high production of CAGT (Table 5), slope variation of 23 to 79 percent,
and elevational differences of 4,510 to 6,840 feet.
Although the average protein value for the spring sampling period was slightly higher than the average value for.the summer, protein values for individual stands were generally higher in the summer after
twig growth had been completed. Protein content decreased slightly in .
the fall and increased in the late winter as buds began to form.
Bissell and Strong (1955) found monthly crude protein content of
curl-leaf mountain mahogany to be highest in the spring and summer
during growth and lowest during the fall and winter when plants were
dormant. They.categorized mountain mahogany.as a plant of steady, but
lower protein value than such species as big sagebrush,- buck brush
(Querous dougtasii,)3 wavy leaf ceanothus (Ceanothus foliosus)3 and western (birchleaf) mountain mahogany (Oercoearpus betnfot-ius). They —73— also stated' that spring forage, being more succulent, will have a lower protein per unit food consumed content than that of.drier vegetation found in the fall. The driest samples from this study were found in the winter and early spring (Table 15) at the time when deer were using the plant.
Although mountain mahogany stands on some deer winter ranges, such as Scudder Creek (site C) have been categorized, as; "deteriorated"
(Allen 1967), my findings indicate that this rating may' be strictly subjective. Protein values show that forage produced on these ranges is of high quality and comparable to that of lightly browsed areas;
Similarly,. Dietz (1957), citing results from a Colorado clipping study, states that, prolonged,, heavy, browsing probably would not affect the nutritive content of the plants although it might adversely affect other plant attributes such as production, growth form, and longevity. TABLE -IS. • .PERCENTAGE CRUDE PROTEIN, MOISTURE 'AFTER AIR DRIED, AND MOISTURE AFTER OVEN DRIED •. -V - - FOR EIGHT MOUNTAIN MAHOGANY STANDS DURING SPRING, SUMMER/ FATJ,, AND WTNTRB.______I 9 o Site-, .. ' ■ Protein_____ - . - Percent Moisture Air-Dried Percent Moisture-Oven Driedj Spring Summer' Fall Winter Spring • Summer Fall- Winter. Spring "Summer Fall Winter
C 1 ■ • 10.2 . 10,4 . 9.5 40,0 39.0 50.0 38-1 , . 4.7 7.3 5.8 3.3
F - 10.8 ' 11.8 10.8 10.9 42.9 41.3 53,2 38.8 ' 4.5 ,5.3 5.3 3.4
I ■ 11.6 10.6 9.5 10.2 41.7 . 32.9 38.5 39.6 ; 4.6 . 5.8 4.9 3.6
M ■ 10.4 ' OO oV 8.9 9.1 37.5. 36.0 35.0 ' 40.7 4,5 7.0 5.2 3.1
P 11.7 11.7 10.4 10.5 31.6 65.8 . 49.8 41.8 ' 2.5 . 7.3 5.9 3.1
S 10.1 10.4 ' . 9.3 10.0 29.4 43.9 45.2 37.1 2.4 6:8 5.5 3.1 I T 8.8 9,3 8.2 8.7 37.5 40.7 11.4 30.6 4.8 6.5 5.4 3 . 2 f u- 10.1 10.1. 9.5 9.1 38,9 41.6 39.5 42.9 4.8 6.7 5.6 3.4
Average 10.5 10.4 ' 9.5 '9.8 .
^ Percent Protein = Prptein/Oven Dry Wt. ^ Percent Moisture Air-Dried = (Fresh Wt. - Air Dry Wt,.)'/Fresh Wt. ■ ■ Percent- Moisture Oven—Dried = (Air Dry Wt. — Oyen Dry Wt.)/Air.Dry Wt. -75-.
LITERATURE CITED
■ Allen, E.. CL 1967. Big game surveys and investigations— deer range segment. Job Comp. Rept., Fed. Aid Proj . No,.' W-73-R-8-9-10-11-12. Mont., Fish and Game Dept. 39 pp.
Basile, J. V. and S . S . Hutchings. 1966. Twig diameter-length-weight relations of bitterbrush. . J. Range Mgmt. 19(1):34-38.
Bissell, H. D. and H. Strong. 1955. The crude protein variations in the browse diet of California deer. CA Fish and Game. .41:145-155.,
Blaisdell, J. P . 1958. Seasonal development and yield of native plants on the upper Snake River plains and their relation to certain ■ climatic factors. U.S.D.A. Tech. Bull. No. 1190. 68 pp.
Booth, W. E. 1950. Flora of Montana, Part I, Conifers and Mohocots. Research,Foundation, Montana State College, Bozeman. 232 pp.
____ and J.C. Wright- 1959. Flora of Montana j' Part II, Dicotyledons. Montana State College, Bozeman. 280 pp.
■ Buckman, H. 0. and N. C. Brady. 1969. The Nature and Properties of Soils. 7th edition. The Macmillan Co. 653 pp.
Bucsis, R. A. 1974. Ecological characteristics of the Armstrong, mule deer winter range, Bridger Mountains, Montana.’ Urpubl. Thesis (M.S.), Montana State University. 104 pp. 7'
Burkhardt, J. W. 1967. Ecology of western juniper in Idaho. Unpubl. Thesis (M.S.), Univ. of Idaho. 93 pp.
Caprio, JL M. 1965. Average length of frost free season. Cooperative Extension Service, Montana State College, Bozeman. Folder No. 83;
Claar, J. J. 1973. Correlations of ungulate food habits and winter range conditions in the Idaho Primitive. Area,, Unpubl. Thesis . (M.S.), Univ. of Idaho. 85 pp.,
Cole, G. F. 1958. Range Survey Guide. Mont. Fish and Gamd Dept. Booklet. 18 pp. multilith. "■
Cottarn, G. and J. T. Curtis. 1956. The use of distance measures, in ■ phytosociological sampling. ' Ecology. 37:451-460. . - 76-
Daubenmire, R. F . 1943. Vegetational zonation in the Rocky'Mountains. The Botanical Review. 9(6):325-395.
_____. 1959. A canopy-coverage method of vegetational•analysis. Northwest Science. 33(I):43-64.
Dietzj, D. R. 1957. Nutritive composition of key species of mule deer browse in Colorado. Colo. Coop.. Wildl. Res. Utiit, Quart. Rpt. 11(1):10-14.
Garrison, G. A. ■ 1953. Effects of clipping on some range shrubs.- . J,. Range Mgmt. 6(5):309-317. •
Kirkwood, J.. E. 1930. . Northern Rocky Mountain Trees and Shrubs.. Stanford Univ. Press. 340 pp.
Lonher, T. N. 1972. Age distributions and some relationships of key browse plants on big game ranges in Montana. . Unpubl• Thesis (M.S .), ■ Montana State Univ. 79 pp. -
Lyon, L. J. 1970. Length and weight-diameter relations of serviceberry twigs. J. Wildl. Mgmt. 34(2):428-437.
Mackie, R. J. 1973. Statewide big game research. Job Compl.. Rept. , Fed. Aid Proj. N o . W-120-R-3. Mont. Fish and Game Dept. 30 pp. multilith. ... .
Medin, D. E. 1960. Physical site factors influencing.annual production of true mountain mahogany, 1 Cercoaavpus, montanus. Ecol. 41 (3.) : 454-460. '
Montana Agricultural Experiment Station. . 1973. Vegetative Rangeland Types in Montana. Bull. No. 671. 16 pp-
Mueggler, Ww F. and W. P. HandI. .1974. Mountain grassland and shrub- land habitat types of western Montana, an interim report. U.S.D.A. Forest Service Intermountain Forest and Range Experiment Station. ■ 89 pp. .
Neff , D. J. 1963. The effects ' of clipping on the vigor of big game browse plants and related studies in the Arizona chaparral. ■ " Unpublf Thesis (Ph.D. ) , Oregon State Univ. • 128:,pp.
Peek, J. Mf1; et al. 19.71. Variation in twig diameter-weight relation ships in northern Minnesota. J. Range Mgmt. 19(1):34-38. ' -77-
Phelps, J. E. 1968. Restoring big game range in Utah. Utah Division of Fish and Game Publ. No. 68-3. 183 pp.
Scheldt, R. S . 1969. Ecology and utilization of curl-leaf mountain mahogany in Idaho. Unpubl. Thesis (M.S.), Univ. of Idaho. 57 pp,
Shepherd, H, R. 1971. Effects of clipping on. key browse species in', southwestern Colorado. Colo. Div. of Game, Fish, and Parks. Tech. Publ. No. 28. 104 pp. '
South, P . R. 1957. Food habits and range use of the mule deer in the .Scudder Creek area, Beaverhead.County. Urtpubl. Thesis (M.S,), Montana.State College, Bozeman. - 34 pp.
Thompson, R. M. ' 1970. Experimental top pruning, of curl-leaf mahogany . trees on the South Horn Mountain Ferron Ranger District, Manti- LaSal National Forest. U.S.D.A. Forest Service Range Improvement Notes. Vol. 15, No. 3. 12 pp.
Torrey, J. and A. ..Gray. 1940. A Flora of North America. Wiley and Putnam'. 698 pp.
U.S. D.A. Forest Service. 1937. Range Plant Handbook. U. S . Govt. Printing Office. 841 pp. ’
1948. The Woody Plant Seed Manual. U.'SY Govt.-Printing ■ ■ Office-. 416 pp. " . ■
Soil Conservation Service. 1974. Average annual precipitation— . .Montana. U.S.D.A. SCS Publ. 14 pp. 1
Ui S . Dept." of Commerce. 1973.. Climatological data for Montana. Natl. Oceanic and Atm. Adm.. ■ Vol. 24, No. 1-12.
. 1974. Climatological data for Montana. Natl. Oceanic and Atm; . . Adm. VoI. 25, No. 1-12. ' " ■ APPENDIX APPENDIX TABLE -16. CLIMATOLOGICAL'DATA FOR 1973 AND 1974 FOR THE 10 WEATHER STATIONS NEAREST ' ■ '■ ' THE MOUNTAIN MAHOGANY STANDS STUDIED.______;______Frost Free • Total Precipitation ■ Yearly Average Max Temp ' Min Temp Period finches') . Temnerature f°F) f°F) (°F') __ (Days’) ID7'2 -■ 1973 1974 Norm - 1973 1974 Norm 1973 1974 1973 1974 1973 1974
Darby. ' _1 12.06 — . 15.69 46.5 44.1 44.9 103 . 93. -16 -26 135 85 Hamilton 14.18 12.09 13.64 12.22 ■ 45.9 46.1 !!46.3 102 93 -20 -23 113 105 Dillon WMCE 9.27 10.78 6.94 11.34 43.7 45.0 43.5 99 94 -26 -21 87 94 Divide 2NW 10.96 8.92 7.51 11.37 40.3 41.7 39.9 92 90 -30 -22 87 86 Ennis 14,64 15.44 8.14 10.57 43.2 44.2 43.0 94 94 -29 -21 87 .85 Lima 11.27 9.22 11.49 10.50 39.4 40.4 39.3 91 . 94 . -32 -24 74 85 Twin Bridges. 6.45 9,54 5.33 9.97 42.8 43.9 42.8 97 95 -27 -22 76 84 Whitehall 7E 8.82. 10.43 8.65 10.61 43.4 ■ 45.2 43.7 . 100 97 -35 -35 90 84 Toston 3SW 7.82 9-20 — - 10.25 44.7 44.9 44.3 105 99 , -28 -27 108 93 Townsend • . 8.67 8.60 7.80 11.44 44.8 45,9 43.0 98 97. -28 -23 114 '101
Average East .i of the Divide 9.74 10.27 7.98 10.74 .42,8 43.9 43.2
Average West • of the Divide 14.18 12.8 13,64 13.96 46.2 45.1 45.6
Overall Average 10.23 10.63 8.69 11.47 43.5 44.1 43.2 ■- " v
1Hata missing for I or more months'. APPENDIX TABLE.17. SPECIES OCCURRENCE'ON EACH OF. 22'MOUNTAIN'MAHOGANY STANDS EXAMINED.
A B C D E F G H I J K L M N O P Q R S T U V SHRUBS . ' " ' ~ ~ """" ! ! _ ' ~ : Amelanohiev alnifolia ' X Artemisia dvbusoula 'X, X X X . A X Artemisia tridentata X X X' X-X X X- ■ CTwysbthamnus nauseosus. X A X X X X X X . X X X . Gutierrezia sarothrae X X X X A X A- A Z A A X X. '- A. A A A A A Juniperus communis ‘ - X . A Juniperus soopulorum X X ..AA A A X X ; -XXXX Physooarpus malvaoeus A. Purshid tridentata ... A ' A - ■ Rhus trilobata A AAA A , M&gg cefewm A A A A A A A A . § Ribes montigenim A ." 1 .Rosa woodsii A Spirea betulifolia - . A. . 'Symphorioarpus albus . ; ' A A A Tetradymia oanesoens A A A A A A ' A A
TREES
• Pinus flexilis A A A A A' A Pinus ponderosa A- A A.
' ' Pseudotsuga menziesii ; A A\ A. A
GRASSES ' 'Agropyron dasystaohyum : A A
" Agropyron spioatm . A A ' A A A A A : A. "A A. A A A A' A A A A A A
. ■:'Aristida longiseta ■' A ' A A "■ ■■ Bouteloua graoilis A . ■A- ; . 'A
Bromus tebtorum A A :x ■a '’ A .A
Elymus oinereus ' ^ A.
- Pestuoa' idahoensi's A A • A A - A A A A A A
- Koeleria oristata ■ .. A ; A A- A 'A ... .A A A A A . A APPENDIX TABLE 17. (continued) ■ . ______A B CDEFGH I J KLM N OPQRS TU V GRASSES (continued) Ovysopsis hymeniodes Z Z Z Z Z Z Z Z Z Z Z Z Z
Poq pvat&nsis ■ . z- . • . . . ' ■ Z . Pod-seounda ; z Z Z '■XXX . Z Z Z Z Z . . Z ,Z .Z Z Poa -spp. Z Z Z Z Z Stipa oomaia ■ Z " Z Z Z Z ■ X-Z z- Z . Z ■
SEDGES . .■ Carex f-tl'Lfol'ia X . - X Cavex voss-ti .. .. - X Cavex spp. X X
FORBS ' ' AcGtZZea mtZZefbZtwM f Z ' Z Z ALLium cevnuim . . Z Z ALlium geyevi . - Z Z X X ALlium sp. : Z ' . Z Antennavia voseq : ■ . . ■ ■ ' ■■ X ’ 'Z' Apooynum andvosaemi- • X ■ folium ■ ■ . Avabis Iiolboellii - Z ' Z Z X X X . Z Avabis micvophylla ' Z Avabis sp. Z Z Avabis' sp. ' Z Avotdstaphylds uva-uvsi X- X- X Avenavia oongesta . Z
" Avtemisia oampestvis Z
; Avtemisia"dvaounoulus ' X .. Z Z
■' Avtemisid fvigida . X Z Z Z Z Z x - X X X- X x. ■X ' Z' Z Z Z ■ . Artemisia ■ ludovioiang
Aster canescens . . % % x - - . . .
•' Astragalus gilviflovus ■ Z APPENDIX TABLE 17. (Continued) _ ' . . / ■______■
. - A B C D E' F GHIJ K L M N 0 P Q R S T U V
FORBS (continued) • ' Astvagatus puvshii' ' ' X Astragalus stviatus . ■ ' X - BaZsamorrhiza Sagittatg XX, . .. • ' -. Bgrberis repens- ■ ' X \ Brodiaea grandiflora ‘ ' x Camelina mierocgrpa - - x Campanula rdiundifolia . . X Castillega angustifolia X Castillega flava X Castillega linariaefolia " X X . X • oo . Castillega sp. X X y .Castillega sp. x Centaurea repens -. XX Chaenaetis douglasii X X Chamaerhodos erecta . X Cheilanthes feei ■ " .' . : ■ X Chenopodium fremontii . X - Cryptantha celosioides X X X . X ''XX--. XX . ''X X. XX Chrysanthemum ' • •' .X leueanthemum- - - • Chrysopsis villos'a . - - X - X- X ...XX'. Cirsiurn undulatum ■ •/ X , - X - X X Collinsig pdrvifl'ora ' -.'.XX- XXX Comandra umbellata X . • X X '.X-. ' X X ' X X X XX Crepis acuminata. . ■, ■ X . ■ • , X X Cymopterus. bipinhatus X X X ' X X X X .XXX ■ Delphinium bicolor- . ' ■ X X X ■ Deseurainig pinnata . X .X- ; X X - ■ '■ X X X '. . \ X-XXX .DodeCatheon congugans .. ■ - X X ' Douglasid montana' - -■ ■ . X-' ■ . ' . x ■ - Drgba nemorosa . X ■ ■" X - . -X. ■ - X APPENDIX TABLE 17. .(Continued) . A B C B E F G H I J K L M N O. P 0 R S T U V FORBS (continued) • Draba oligosperma -',XXX.' X Z " ' % Draba stenoloba . ' X , Draba verna ■■ Z Z EryIgeron caespiiosus' \ ' X- ' X J ■ • Erigeron compositus X XX .X ' % ' -Erigeron divergens - X - X Erigeron orehroleueus ■ X Erigeron speaiosus . -X ■ ■ Erigeron taeedyi ; XX X- Eriogonvm f lavvm X ' - ,Eriogonvmmiorothecvm . X ' - X ' Eriogonvm ovaUfotiwm X X Eriogonvm strictvm .'X Ni N: Eriogonvm-VmbeUatvm - • X ... Erysimum aspervm - X . X - % r - . % .Euphorbia robusta " X Frasera albicaulis X Frititlaria pudiea 'X ' Gdlivm ■ aparine - Gevrn trif lorvm ' - X.. X ' Gilia sp. . . / :' ■ : ■ ' X- Grindelia squarros'a ' - . . . . . : ^ . • ■ Haploppapus doaulis X X X , - X. ■ X' X ■ X X. : ■ X X X X Eieraeivm albertivm. x Eueeherg eylindriea . X . X Eymenopappus filifoiius X ^ Hymenoxys aeaulis . - -Eymenoxys riehardsonii '■ ■_,[ .X- Eymenoxys torreyana X - Lappula redowskii,, X APPENDIX TABLE 17. (Continued) A B C D E F G E I J K L M N O P Q R S T U V FORBS (continued) Leptdiim densiflorum. ■ X Lesquerelld alpina ■ . XXX' X X . X X X Liatr-Is punctata Limm perenne ■ z ’ :■ z ■ : Lithophragma parviflora ■ Lithospermum arvense X . ■ X- X-
Lithospermum incisum ■, X ■ Z • . . - Z Lithospermum ruderale ' ' XXXX ■■X X X Z Lomatium tritenatum ' ' - . % ' Z Lupinus wyethii •. . Z ' Lygodesmia junced X - - Z Z Mertensia lanceolata Z Mertensia viridis Z Microsteris gracilis ... . Z z Montia perfoliata . Xf X Musineon divarication" X Z . Z . ■ Opuntia polyacahtha • X X X X X ■z- Z- Z .Penstemon albertinus : . . : ; - r Penstemdn cyarieus X X 'Penstemon diphyllus Z. Z Z ' Penstemon nitidus . Z .. .Z ' - Penstemon sp. XX Z Z - Z Petrophytum caespitosum . Phacelia hdstatq "; . . X X ' ' Z ■ - , '.Phacelia linearis . ' ZZ Phlox aibdmarginata •. X-' . Z. Z Z Z ■ .Phlox hoodii ■ X X ... Z Z ' Z.Z- Z Phlox longifolia ZZ.- ■Phlox muscoides X Physdria didymoearpa' . - Z Plantago patagonica. -Z.. ■ . ■- APPENDIX TABLE. 17. (Continued) A B C D E F G H I J K L M N 0 P O R S T U V FORBS (continued) Potentilla, gtandutosa. X -Ranunculus glaberrimus -X- X X - ' : Rumex venosus ■" X X- ' Sedum ZancecZaium • X- Sedum stenapetalum . X ' X SenecZo canus X X X- ■i x- x x SZsymbrium altZssZmum .X- - Sisymbrium Zinifolium 'X SoZidago missouriensis. ’ X . % Z ' Sphaeraleea eoecinea X X - X ■ Tqnacetum eapitatum : ■ ■ x' & ThZaspi fendleri X' Townsendia mensana - . X - . X Tragopogon dyibius . - X ' ■ Verbascum thapsus X, Viola nuttallii . . . - x Woodsia'seopulind. • X - " X :-: ■ / , Yueea glauea ■ ' ■ , ■ X' Zygadenus venenosus " X. ' - ■ . X . -86-
APPENDIX TABLE 18. REGRESSION EQUATION1 VARIABLES FOR TWIG DIAMETER AND LENGTH, DIAMETER AND WEIGHT.
Length Weight Correlation Correlation Site Coefficient Slope Y-intercept. Coefficient . Slope I'-intercept. t t .
A • .52 32.21 - 5.99, .69 .06 ' S B ’ .59 . 28.37 -11.46 .74 .06 -.04 ' C .38 - . 26.82 -. 3.87 .55 ' .06 . -.04 D .48. 31.56 - 1.50 ' .59 .05 ■..-•02. ./ E .52 26.37 - 1.80 . 67 .04 ■ -.02 F- .52 34.01 - 7.40 . -61 . .05 -.03
G 0 . o 0 0 ' 0 . - o \ ■ H .20 • 10.95 12.29 .. .. . 48 .02 -.01 I .54 57.42 31.35 .66 .10 -.08 J .32 32.23 - 7.17 .70 :. 06 -.04 K .49 . 39.01 . -11.85 .63 .06 -.04 ' L .54 34.06 -11.52 .67 v 05 -.03 I .
M .59 33.34 . - 5.41 . .72 .05 O LO
N .45 27.24 - .02 OO .05 . -.03 .0 .55 40.92 -26.43 .66 .09 . -.08 P .38 27.67 1.16 .55 . .05 -.03;
Q -.33 -35.47 ■ 77.53 — * 16 -.01 . .05 R .51 43.68 -18.81 .70 .06 - .04 • S .47. . 41.93 - 7.29 •59 .. . .06 -.03 T . .62 51.17 -28.17 . 73 .08 -.06 U . .60 . 50.00 -21.92 .82 .14 -.14 S23,T8S,R8W S27.T7S,PxllW S36,T13S,RlOW S25T1S.,R9W S35T3S,R5W SO5TSS5RZW S275T8S,R28E • Location S21,T6S,R12W 533, T14S,R9W 534, T14S.,R9W S16,T2S,R8W S6,T2S,R9W S8,T2S,R6W S2I,TSN5RlW S18,T2N5R2W SS5TlS5RAW S345T6N,RlE S235T2N,R21W S175T2N5R20W S23,T5N5R19W S165T2S5R8W S12,T2S5R9W -87- MAHOGANY STANDS STUDIED. Soap Gulch Indian Creek Skalkaho Creek . . Camp Creek - - Scudder Creek Lime Gulch Bear Gulch Canyon Creek Trapper Creek Big Sheep Creek Hough Creek Hell’s Canyon Creek Johnny Gulch Pipestone-Dry Creek Jefferson River Robbins Gulch Camp Creek ' Moore Creek Axes Creek Middle fork-Little Sheep Creek West fork-Little Sheep Creek .Cold Spring.Cold Creek S I O Q B C E P J . J K L N D F R H M G A H P >. Site Drainage APPENDIX 19. TABLE DRAINAGEAND EXACT LOCATION FOR THE MOUNTAIN22 mm
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