U]Itbrs'v-- 7.9 Research Paper PNW-264 Cascade Range of I September 1979

4. 7 .. - .. T. , : - U S Department of Agriculture Regeneration ciniMixed Conifer:r..,I.- Forest Serv~ce - , - ;-1:- >. 3 Pacif~cNorthwest Forest'" Shelterwood Cuttings in the ' -I - ah& hnge Exper~rnentStat~on U]ITbRS'v-- 7.9 Research Paper PNW-264 Cascade Range of I September 1979 ,. - - Eastern Oregon - . RLE' GOEX, ...... -. , -.. - . , _;b 1 Hb. W. Sejld< 3 - METRIC EQUIVALENTS

1 acre = 0.405 hectare .: 3 I, -1 i 1 foot = 0.3048 meter .. 1 inche2.54centimeters 1 mile = 1.61 kilometers 1 square foot = 0.0929 square meter -1 square foot/acre = 0.2296 square meterlhectare Regeneration in mixed conifer sheltenrvood cuttings in the Cascade Range of eastern Oregon

Reference Abstract regeneration (artificial), mixed stands, Oregon (Cascade ~ange), Seidel, K. W. shelterwood cutting 1979. Regeneration in mixed method conifer shelterwood cuttings in . the Cascade Range of eastern Oregon. USDA For. Serv. Res. Pap. PNW-264, 29 p., illus. RESEARCH SUMMARY Pacific Northwest Forest and Research Paper PNW-264 Range Experiment Station, Portland, Oregon. 1979

A survey of shelterwood cut- Regeneration of shelterwood tings in mixed conifer forests in cuttings in upper slope, mixed the eastern Oregon Cascade Range conifer forests in the eastern showed that, on the average, Oregon Cascade Range was surveyed shelterwood units were well for an overview of the status of stocked with a mixture of advance, reforestation and to identify key natural subsequent, and planted environmental factors influencing reproduction of a number of establishment of seedlings. Plots species. Because of slow invasion were randomly located in shelter- by understory vegetation, frequent wood units harvested during the heavy seed crops, and adequate 1970-73 period in the mountain density of the overstory, natural hemlock/grouse huckleberry and regeneration was prolific on most mixed conifer/snowbrush-chinkapin units. Planting is recommended plant communities in the Cascade only as a supplemental reforesta- Range. tion method. Greater stocking was associated with increasing On the average, she1terwood overstory density and more exposed units were well stocked with a mineral soil; such factors as mixture of advance, natural sub- aspect, slope, and elevation had a sequent, and planted reproduction positive or negative relationship of anumber of species. An aver- to stocking depending on the age of 63 percent of milacre species and plant community. quadrats were stocked in both plant communities, and density of KEYWORDS: Regeneration (stand), seedlings of all origins averaged regeneration (natural), 4,483 per acre in the hemlock type and 2,968 in the mixed conifer. adequate natural regeneration in Over 90 percent of the seedlings most shelterwood units in hemlock in both types were of natural and mixed conifer communities. postharvest origin. A1 though Logging and slash disposal opera- planted seedlings were only a tions in these shelterwood units small fraction of the total number broke up heavy, compact layers of of seedlings, the percentage of litter and duff and exposed suf- milacres stocked with planted ficient mineral soil for estab- trees was relatively high because lishment of seedlings. of their good distribution over the plots. Planted seedlings were Only small amounts of understory also dominant on more of the quad- vegetation were present in these rats than their small numbers shelterwood units. The slow in- might suggest because of their vasion of understory vegetation, greater height. plus heavy seed crops every 3 or 4 years, and the uniform distri- Greater stocking was generally bution of seed trees in shelter- associated with increasing density wood units resulted in an abun- of the overstory and more exposed dance of natural regeneration in mineral soil. Other factors, such most units. It appears that as aspect, slope, elevation, and planting shelterwood units im- understory vegetation, had a posi- mediately after the seed cut is tive or negative effect on stock- necessary only in the following ing, depending on the species and cases: (1) in mixed conifer com- community. Equations for pre- munities if residual basal area is dicting stocking were derived for reduced below 60 square feet per several species in both communi- acre and (2) in pure mountain ties, but, because of the large hemlock communities containing no amount of unexplained variation, other species in the overstory. they serve only as crude estimates of possible stocking. Blowdown of the residual overstory was greater in the mountain Density of the residual over- hemlock plots. The risk of blow- story after the seed cut in a down can be reduced by marking shelterwood method should be no leave trees which are fully greater than needed to obtain crowned dominants or codominants natural regeneration, so that es- (the most windfirm and also the tablished reproduction is not best producers of seed) and by damaged or destroyed to an un- discriminating against mountain acceptable degree when the over- hemlock. story is removed. A range from 60 to 80 square feet of basal area Removal of the residual over- per acre is recommended as the story after the regeneration is minimum level for establishing established without unacceptable loss or damage to the reproduction is essential if the shelterwood method is to be successful. The key to achieving this goal is good coordination between timber and fuels management staffs and skillful application of logging techniques designed to preserve established regeneration, CONTENTS Page

INTRODUCTION ...... 1 OBJECTIVES ...... 1

STUDYAREAS ...... 1 METHODS ...... 4 Survey Design and Plot Selection ...... 4 Data Collection ...... 5 DataAnalysis ...... 6 RESULTS AND DISCUSSION ...... 6 Regeneration Stocking and Density ...... 6 Species Composition of Regeneration ...... -10 Dominant Species ...... -11 Relation of Present Stocking and Density to Environmental Factors . . -12 Prediction Equations ...... -17 Residual Stand Density and Regeneration ...... -20 Natural Regeneration Versus Planting ...... -22 Overstory Mortality ...... -23 CONCLUSIONS AND RECOMMENDATIONS ...... -24 LITERATURE CITED ...... -27 APPENDIX ...... 28 OBJECTIVES

The purpose of this study was to: (1) quantitatively evaluate the regeneration found on the shelterwood units, (2) evaluate condition of the residual overstories during the regeneration period, and (3) attempt to identify environmental factors associated with the presence or ab- INTRODUCTION sence of regeneration.

Specific objectives were to: During the late 1960's and 19701s, the shelterwood method has 1. Estimate success of regen- been used increasingly to harvest eration in terms of stocking timber from upper slope mixed percentage and density (number conifer forests of the east side per acre) Oregon Cascade Range. In some ; 2. Estimate species composition areas, this method has been tried of the regeneration; as a means of modifying the harsh 3. Estimate stocking of regen- microclimatic conditions found on eration of preharvest many high elevation clearcuts that (advance) and postharvest cause difficulties in regenera- (natural and planted) tion. And, as esthetic con- origin; siderations became increasingly 4. Estimate the relationship important, the shelterwood method between regeneration and was used in many areas open to some measurable environ- public view to maintain the visual mental variables, such as quality of the landscape. elevation, aspect, slope, and overstory density; and Some of these shelterwood units 5. Estimate survival and con- are now old enough for regenera- dition of the residual over- tion to be established. There- stories. fore, in 1978, I began a study to survey regeneration, the factors affecting its establishment, and the condition of the residual STUDY AREAS overstory. This paper reports the results of that field survey in Study areas (plots) were located 1978 on the Deschutes and Winema in the mixed conifer forest type National Forests. of the eastern Cascade Range in the Deschutes and Winema National Forests (fig. 1). A number of plant communities have been identified within this type by Volland (1976). Identification of these plant communities is based on the dominant overstory tree and the dominant understory shrub, forb, or grass. Plots were located in two of these communities: (1) a high elevation mountain hemlock/grouse huckleberry community and (2) a lower elevation mixed conifer/ snowbrush-chinkapin community. Figure 1.--Location of study areas in The major tree species found in Oregon; eight to ten 10-acre plots these communities are ponderosa were sampled in the vicinity of each dot. pine (Pinus ponderosa ~aws.1, lodgepole pine (Pinus contorta chrysophylZa), pine-mat m,anzanita, ~ougl.), Douglas-fir (Pseudotsuga and dogbane (Apocynwn pwni'hm). menziesii (~irb.) ~ranco), grand fir (Abies grandis (~ougl.1 Some characteristics of the ~indl.1 white fir (A. concozor shelterwoods sampled are given in (~ord.& Glend.) ~indl.), Shasta table 1. In the mountain hemlock red fir (A. magnifica var . community, the number of trees per shastensis Lemm.), western white acre in the residual overstory pine (Pinus monticoZa ~ougl.), and ranged from 11 to 34, of which 51 mountain hemlock (Tsuga percent were mountain hemlock, 35 mertensiana (~ong.) ~arr.). percent red fir, 6 percent grand Understory vegetation in the fir, 5 percent white pine, plus mountain hemlock/grouse huckle- small numbers of Engelmann spruce berry community is generally (Picea engelmannii Parry ex sparse, consisting primarily of Engelm.), lodgepole pine, and grouse huckleberry (~acciniwn Douglas-fir. In the mixed conifer scopariwn) , prince ' s pine type, from 6 to 46 trees per acre (Chimaphila wnbetlata), and remained in the overstory; the pine-mat manzanita (Arctostaphytos three dominant species were grand nevadensis). Major understory fir (52 percent), Douglas-fir (23 vegetation in the mixed- percent), and red fir (17 per- conifer/snowbrush-chinkapin cent). Ponderosa pine made up community consists of snowbrush about 5 percent of the overstory; (Ceanothus ve Zutinus ) , golden a few lodgepole pine, white pine, chinkapin (Castanopsis and Engelmann spruce were also Table 1--Mean and range of some characteristics of shelterwood units sampled in 2 plant communities in the Cascade Range of eastern Oregon

Mountain hemlock/ Mi xed coni ferl grouse huckleberry snowbrush-chinkapin Characteristic Mean Range Mean Range

Number of plots Elevation (feet) Slope (percent) Age (years)

Residual overstory Number of trees per acre Average diameter (inches) Basal area (ft2) Crown closure (percent)

Seed bed (percent coverage)-11 Mineral soil Litter Slash Litter and slash

Understory vegetation (percent coverage) Forbs Shrubs Grasses and sedges

1/ Total of all seed bed categories do not add to 100 percent because areas of some mil acre subplots are occupied by rocks and stumps. present (fig. 2). Slash in 69 METHODS shelterwood units was piled by machine and burned after the seed Survey Design and Plot Selection cut, and in 6 units it was not treated. The mountain hemlock and mixed conifer plant communities were considered separate populations. A record of shelterwood units harvested in 1973 or earlier in the two communities was obtained from the USDA Forest Service Regional Office in Portland, Oregon. Only units at least 5 years old were considered suitable for sampling so that reproduction would have had time to become established. The sampling unit was a square plot 10 acres in size. Therefore, all shelterwood areas 10 acres or larger and at least 5 years old were considered candidates for sampling. The total number of 10-acre plots in each plant community was then determined; fractional portions of Figure 2.--This sheZterwood unit in 10-acre areas were ignored. In the mixed conifer community contains an average of 16 trees and 50 square the mixed conifer community, 216 feet of basal area per acre. plots were available for sampling and 145 in the mountain hemlock community. Plots were within the pumice plateau region of south-central Oregon. Soils in this region are I estimated that a total of immature Regosols (~itrandepts), about 75 plots could be sampled developed from aerially deposited during the available time. There- dacite and rhyolitic pumice fore, 45 plots were selectd at ejected from Mount Mazama (crater random from the total number in Lake) about 6,500 years ago. These the mixed conifer community and 30 well-drained, coarse-textured from the total in the mountain soils have thin A horizons, low in hemlock community. This resulted fertility, which grade into un- in a sampling intensity of about weathered sand and gravel. A 20 percent. finer textured buried soil is found at a depth of 2 to 6 feet Within each shelterwood unit, (Larsen 1976). the sample plots were located the same as sections are numbered in a from field observations. Infor- township, beginning at the north- mation obtained was the plant east part of the unit. Candidate community in which the plot was sample plots were rejected if the located, average elevation of the shelterwood unit was seeded to plot, timber type, date of har- trees or if it had been converted vest, slash treatment method and to nonforest uses. When a plot year of treatment, species planted was rejected, it was replaced by and year of planting, subsequent another from a random list of cultural treatments, and general alternate plots. notes on size, growth, and distribution of regeneration, or damage. The plant community was Data Collection verified by observation of adjacent uncut stands. A grid of 25 sample points (subplots) was centrally located On each 1-milacre subplot, the on each 10-acre plot. Circular total number of seedlings of each subplots (quadrats) were system- species was counted and recorded atically spaced at 66-foot inter- by origin. Regeneration was vals on five parallel lines 66 classified as being of preharvest feet apart containing five sub- (advance) origin or of postharvest plots each. At each of the 25 (subsequent) origin. Trees of sample point locations in the subsequent origin were divided plot, three concentric subplots into 1- and 2-year-old seedlings (1-milacre, 4-milacre, and from natural seed fall, seedlings 0.0785-acre) were examined for 3 years and older from natural presence of regeneration, asso- seed fall, and planted trees. On ciated environmental variables, each 4-milacre subplot, the and condition of residual over- species and origin (advance, story. A sample point was re- natural subsequent, or planted) of jected if conditions making it the seedling most likely to domi- unsuitable for regeneration-- nate the subplot because of its streambeds, marsh or swamp, active size and vigor were recorded. roads, or gravel or cinder pits, Four-milacre subplots were used solid rock, or erosion--occurred for data on dominant seedlings to on more than one-half of a milacre reduce the probability of un- subplot. Only 0.2 percent of the stocked subplots. On each subplots were rejected for these 0.0785-acre subplot, the species reasons. and diameter at breast height (d.b.h.) of all standing overstory Information about the shelter- trees, including trees that died wood unit and the timber stand in during the regeneration period, which it was located was obtained were recorded plus the species, from Ranger District records and number, and d.b.h. of windthrown trees. Planted trees were identfied milacre subplots and number of from information on species seedlings per acre of the various planted, date of planting, and species and origins, and the spacing. In shelterwoods where independent (X) variables were the survival was high, regular rows of environmental factors given in the planted trees were clearly visi- appendis/. ble. Identification of planted trees was less certain when RESULTS AND DISCUSSION survival was low, but counting whorls to check the age of a tree Regeneration Stocking helped in determining planted and Density trees. Regeneration on shelterwood The following environmental units in both the mountain factors associated with each hemlock/grouse huckleberry and the 1-milacre sub lot were observed mixed conifer/snowbrush-chinkapin and recorded:!/ Aspect, slope, communities was excellent for all condition of the seed bed (mineral species established before and soil, litter, slash), degree of after logging (fig. 3). An aver- burn, understory vegetation age of 63 percent of the milacre (forbs, shrubs, grasses), residual overstory density (basal area and percent crown closure), and presence or absence of animal damage.

Data Analysis To illustrate the present status of reforestation, I summarized data in tables showing seedling numbers and stocking percentage of milacre subplots by species and origin for the plant communities. To determine the relationship between regeneration and environmental variables, I used stepwise Figure 3.--Natural regeneration in multiple regression procedures to a mixed conifer shelterwood unit. fit linear equations of the form Seedlings here are primarily grand Y=bo+blXl+b2X2+- -bnXn to the fir and Shasta red fir and are 4 . to 5 years old. Note absence of data. Dependent (Y) variables understory vegetation. used were stocking percentages of

-1 See appendix for details of pro- -/2 Subplots were considered stocked cedures for measuring and coding the if they contained at least one seed- environmental factors. ling. subplots were stocked (all acre in the hemlock type and 2,968 classes) in both plant com- per acre in the mixed conifer type munities, and seedling density (table 2). Of the 4-milacre sub- (all classes) averaged 4,483 per plots, 88 percent were stocked in Table 2--Average stocking percent and number of seed1 ings per acre of a1 1 species on shelterwood units in 2 plant communities in the Cascade Range of eastern Oregon, by class of reproductionl/

Mountain hemlock/ Mi xed coni fer/ grouse huckleberry snowbrush-chinkapin Class of reproduction Number Mean Number of Range of Mean Range + S.E.~ + s.E.~! plots - plots -

Stocking percent

Advance Subsequent : 1- and 2-year-old seed1 ings 3-year-old seed- 1 ings and older Pl anted seed1 ings

All classes except 1- and 2-year-old seed1 i ngs All classes

Number per acre

Advance 30 186 f_ 35 0-800 45 162 5 39 0-1,240 Subsequent: 1- and 2-year-old seed1 ings 30 979 5 182 0-3,000 45 894 5 273 0-10,760 3-year-01 d seed- 1 ings and older 3 0 3,192 + 583 0-12,400 45 1,781 + 321 40-10,600 Pl anted seed1 ings 15 205 5 36 0-880 43 134 19 0-440

A1 1 classes except 1- and 2-vear-old seed1 inqs 30 3,504 + 579 200-12,440 45 2,071 + 327 200-11,200 All classes 30 4,483 + 735 280-15,360 45 2,968 + 569 120-21,960

1' Based on 1-milacre subplots. 21 S. E. = standard error. the hemlock shelterwoods and 86 shelterwoods, stocking was raised percent in the mixed conifer, on 60 percent of the plots; but on only 7 of the 45 was the gain more Postharvest natural regeneration than 12 percent. made up the bulk of the seedlings in shelterwood units in both com- Postharvest natural regeneration munities. In the mountain hemlock was found on all plots except in plots, 93 percent of the repro- the mountain hemlock community, duction was of natural subsequent but there was a considerable origin compared with 90 percent in difference in number of seedlings the mixed conifer plots. Advance between five plots with an over- reproduction was a relatively story of pure hemlock and plots minor component of the regen- with a mixture of hemlock, true eration in both communities. This fir, white pine, and lodgepole was expected because slash in pine. In the pure hemlock plots, nearly all shelterwood units was an average of only 104 seedlings piled and burned, and much of the per acre of natural subsequent advance reproduction was de- origin were found, compared with stroyed. Planted seedlings were 3,650 in the plots with a mixed also only a small portion (5 to 10 overstory. The poor natural percent) of the total number of regeneration of mountain hemlock seedlings on the planted plots. in contrast to the other species Because of their uniform distri- is probably due to the low resid- bution, however, the percentage of ual overstory density (less than milacres stocked with planted 50 ft2 per acre). seedlings was higher than the small number of seedlings might Natural regeneration was suggest (table 2). established soon after the seed cut in the shelterwoods in both Although 22 to 30 percent of the plant communities. Although the reproduction in these shelterwood average age of these units is only plots consisted of 1- and Z-year- 6 or 7 years, the largest single old seedlings, the effect of these component of the reproduction is seedlings was to increase the den- natural postharvest seedlings 3 sity of the regeneration rather years and older (table 2). For than to greatly raise stocking seedlings of this age to be pres- levels, In the mountain hemlock ent, sufficient seed fall must shelterwoods, for example, stock- have occurred w5thin 1 to 3 years ing was increased on 73 percent of after the seed cut. the plots; but on only 4 of the 30 plots was the gain more than 12 During the 8-year period in percent. In the mixed conifer which these shelterwood units were cut, 2 heavy seed years occurred the number and percentage which (1971 and 1974). Apparently most attained specific levels of of the natural regeneration on the stocking or density (table 3). plots originated from these heavy Depending on the definition of seed crops. Obviously, a heavy adequate stocking, the proportion seed fall occurring soon after the of shelterwood units successfully seed cut offers the best chance regenerated can be determined. for successful establishment o$ For example, if 40-percent stock- seedlings because seed falls into ing of milacre quadrats is con- loose minerall soil. Large amounts sidered satisfactory (at least 400 of seed also allow for losses to trees per acre), then 77 percent rodents and birds and for sub- of mountain hemlock shelterwoods sequent mortality. Although meet this standard compared with the bulk of the natural repro- 84 percent of mixed conifer duction was from the 2 heavy seed shelterwoods. Similarly, on a years, seedlings of all possible seedling density basis, 80 percent ages were found in most plots. of the mountain hemlock shelter- Thus, although heavy seed crops woods and 76 percent of the mixed are ideal, it is possible to conifer plots had at least 700 obtain satisfactory stocking from seedlings per acre. several light seed years as long as the seed bed remains recep- Because of the generally tive. Williamson (1973) also abundant natural regeneration, reported that adequate natural some plots were overstocked. In regeneration of Douglas-fir in the the mountain hemlock type, six Cascades of western Oregon was shelterwood plots had more than obtained from establishment of 7,000 seedlings per acre and a seedlings during years of low seed density of 15,000 per acre was fall. These observations suggest found on one plot; in the mixed that it is desirable but not conifer community, about 22,000 absolutely necessary to schedule seedlings per acre were recorded seed cuts to coincide with heavy on one plot. Overstocking of seed years. reproduction after the seed cut is not a serious problem, however, In addition to overall average because some regeneration will be stocking of density of repro- lost when the residual overstory duction, a clearer picture of the is removed. If units are still status of regeneration on the overstocked after the final shelterwood units can be obtained removal cut, stocking level when plots are grouped into control should be begun promptly several stocking classes. There- to avoid loss of growth. fore, plots in both plant communities were grouped according to Table 3--Proportion of shelterwood plots stocked at various levels with 3-year-old and older advance and subsequent regeneration in 2 plant communities in the Cascade Range ,f eastern oregod/

- - Stocking percent Number of trees per acre

Stocking Proporti on Stocking Proporti on PI ots Plots at least of total at least of total

Number Number Percent Number -- per acre MOUNTAIN HEMLOCK/GROUSE HUCKLEBERRY--30 PLOTS

MIXED CONIFER/SNOWBRUSH-CHINKAPIN--45 PLOTS

1' Based on 1-mi lacre subplots.

Species Composition of follows: Shasta red fir 43.5 Regeneration percent, grand fir 14.1 percent, western white pine 10.0 percent, mountain hemlock 8.9 percent. The regeneration in both plant communities was composed of a In the mixed conifer community, mixture of species. In the moun- grand fir and red fir were the two tain hemlock type, Shasta red fir major species--both occurred on was found on more milacre subplots the average on about 38 percent of than any other species (table 4). the milacre subplots (table 4). Grand fir and western white pine Stocking of Douglas-f ir (32 per- were also major species in the cent) was almost equal to that of reproduction. For all origins the true firs, and ponderosa pine combined, average stocking of the was the fourth most common species four major species is ranked as in the reproduction. Table 4--Average stocking of advance and subsequent regeneration on shelterwood plots in 2 plant communities in the Cascade Range of eastern Oregon, by speci esl/

Mountain hernlock/grouse huckleberry Mixed conifer/snowbrush-chinkapin

Species Subsequent seed1 inqs Subsequent seed1 ings Advance 21 A1 1 Advance A1 1 seedlings 3-year-old 1- and 2- classes seedlings 3-year-old 1- and 2- classes and older year-old and 01 der year-01 d

Stocking percent 5 s.E.?/ Stocking percent 5 s.E.~ Grand fir 0.820.3 13.753.2 4.1 51.2 14.1 53.7 5.651.0 29.253.0 10.551.6 38.053.5

Shasta red fir 5.951.2 35.925.0 23.953.7 43.5~5.9 1.1 5 .4 27.5 ~9.1 10.854.6 38.5517.6

Pacific silver fir .1 2 .1 .2 5 .2 .2 5 .2 .35 .3 0 -+-- 0 -t-- 0 -+-- 0 -+ -- 0 0 0 .6 .3 21.4 6.2 9.7 t 2.5 31.9 513.3 Doug1 as-f ir 0 -+ -- -+-- -+-- -+ -- 5 2

Mountainhemlock 3.55.9 4.451.3 2.95.8 8.951.9 0 -+-- 0 5-- 0 -+ -- 0 -+ -- Engelmann spruce 0 -+ -- 1.5 5 1.0 .8 5 .7 1.7 5 1.2 0 + -- .4 2 .4 .1 2 .I .4 + .4 Western white pine .5 2 .3 6.9 5 1.4 2.1 5 .7 10.0 5 1.8 .5 2 .2 2.2 5 .6 1.9 2 .8 4.4 5 1.3

Ponderosa pine 0 A+-- 1.351.3 0 -+-- 1.3 5 1.3 .2 + .1 9.6 + 1.8 2.6 5 1.0 14.7 24.6

Lodgepole pine 0 A+ -- 6.1 5 1.7 1.5 5 .6 6.8 2 1.8 .2 5 .1 3.7 5 1.3 3.8 5 1.8 6.7 52.2

1/ Based on 1-milacre subplots. 2' Includes natural and planted regeneration. S.E. = standard error.

Dominant Species Although planted lodgepole pine was only a small component of the Although measurements of stock- regeneration in number per acre, ing and density give an indication it was classified as dominant on of abundance and distribution of 13.2 percent of the stocked the regeneration, a classification 4-milacre subplots--the second that includes an estimate of vigor largest species-origin combina- or size helps to give an insight tion. Planted red fir was domi- into the species most likely to nant on about 10 percent of the predominate in the immediate stocked subplots, although it was future. In mountain hemlock planted only in minor amounts. she1terwoods , the reproduction is composed of several dominant Reproduction of natural subse- species; Shasta red fir, lodgepole quent origin was also dominant on pine, grand fir, and mountain the largest number of stocked sub- hemlock occur most frequently plots (63 percent) in the mixed (table 5). Regeneration of conifer shelterwoods (table 51, natural subsequent origin was and again planted trees dominated dominant on about 56 percent of on 29 percent of the subplots. the stocked 4milacre subplots; Grand fir seedlings of subsequent planted seedlings on 29 percent. Table 5--Percent of stocked subplots by species and origin of dominant seedlings in 2 plant communities in the Cascade Range of eastern oregod/

Origin Grand Shasta Douglas- Mt. Iestern Engel Ponderosa Lodge- of white mann - pole Total seed1 ings fir red fir fir hemlock pine spruce pine p~ne

MOUNTAIN HEMLOCK/GROUSE HUCKLEBERRY

Advance 0.9 5.0 - - 7.7 0.6 0.4 - - - - 14.6

Natural

Subsequent

Pl anted

Total

MIXED CONIFER/SNOWBRUSH-CHINKAPIN

Advance 6.1 1 .O 0.4 - - .9 ------8.4

Natural

Subsequent

Planted

Total

1/ Based on 4-mi 1acre subpl ots ; 1 - and 2-year-01 d seed1 ings included.

origin were dominant on about 28 measured in this study, but ob- percent of the stocked subplots-- servations of annual height growth the single largest species-origin of 2 to 3 inches were common on combination; planted ponderosa the 3-year-old and older seedlings pine was the second largest cate- (fig. 4). gory. Because of their greater height, planted seedlings are dominant on more of the stocked subplots than their small numbers Relation of Present Stocking and would suggest. Density to Environmental Factors

Height growth of the regen- The influence of observed en- eration was not systematically vironmental factors on regeneration and their relative amounts of grass were especially detrimental to establishment of seedlings, and grasses entered as the first variable for all natural regeneration and 1- and 2-year-old reproduct ion. Aspect appeared as a negative term in hemlock shelterwoods, indicating that regeneration was generally less on more northerly aspects (table 7). This was con- trary to the expectation that northerly aspects are more favorable for natural regeneration as Seidel (1979b) found in mountain hemlock clearcuts. The reason is not clear, but one might speculate that perhaps a residual overstory does not allow sufficient insola- Figure 4. --Vigorous 5-year-o Zd grand tion for optimum germination of fir natural reproduction. seed on the cool, high elevation, importance in descriptions of northerly aspects in the mountain present stocking and seedling hemlock type. These results sug- density were determined by step- gest that, in terms of natural wise regression analyses. The regeneration, clearcutting is most results of these analyses are pre- useful on north to east aspects, sented in tables 6 and 7--the whereas the shelterwood system has positive or negative relationship the advantage on south to west to stocking and density and the slopes. In the mixed conifer order in which variables appear in type, a more northerly aspect was the equations. associated with more regeneration.

In mountain hemlock shelter- An increase in elevation re- woods, there was no correlation sulted in less regeneration in the between understory vegetation and hemlock type, and this variable stocking or abundance of regen- was one of the first factors to eration. This was expected, enter the equations describing since, on the average only about 7 stocking (table 6); in the mixed percent of the forest floor was conifer plots, elevation was posi- occupied by forbs, shrubs, and tively related to reproduction. grasses (table 1). In mixed coni- These are logical results since fer shelterwoods, however, the the environment for establishment amount of understory vegetation of seedlings improves as the hot was greater and was negatively and dry conditions found at the correlated with density of re- lower elevations of the mixed generation (table 7). Heavy conifer type give way to more Table 6--Positive and negative correlations of variables and the order in which they appeared in regression equations describing stocking of regeneration in 2 plant comnunities in shelterwood units in the Cascade Range of eastern oregodl

Species or Standard origin Eleva- Litter Quadratic error of tion Aspect Slope '::;f;"Litter Slash and (::' Forbs Shrubs Grasses :::tl $2!ty iiEs :;;;gr R~ stocking 'lash burn) percent

MOUNTAIN HEMLOCK/GROUSE HUCKLEBERRY A1 1 regeneration -3 +5 +1 +4 +6 0.67 All natural regeneration 3-year-old and older seed1 ings 1- and 2-year-old seed1 i ngs Subsequent red fir All red fir Subsequent white pine All white pine All mountain hemlock

MIXED CONIFER/SNOWBRUSH-CHINKAPIN Ph 1 regeneration +5 A1 1 natural regenera- +5 tion 3-year-old and older seed1 ings 1- and 2-year-old seedlings Subsequent red fir +1 +3 Subsequent grand fir +3 Subsequent Douglas-fir -1 All grand fir + 1 All Douglas-fir - 1 All red fir +1 +5

11 Numbers indicate the order in which variables entered the regression equation. Only the variables that accounted for the major portion of the variation in stocking percent are given. Variables were excluded if they failed to raise ~2 values by at least 3 percent. mesic conditions at the upper of correlation between basal area limits of the community. Con- and crown density (fig. 5), how- versely, seedling establishment ever, when one of these variables decreases at higher elevations in entered an equation, the other the mountain hemlock type because variable no longer contributed of more severe microclimates (pri- greatly to the explained varia- marily low temperatures). tion. In the mixed conifer shelterwoods, both basal area and Basal area had a consistent crown density were positively re- positive relationship to density lated to regeneration, but again of regeneration and entered as the not in the same equation. first variable for nearly all equations in the mountain hemlock It is apparent that the effect type (table 71, but crown density of these variables on stocking and did not appear as one of the first density of regeneration depends on factors. Crown density was re- both the species and origin of lated to the dependent variables reproduction and the plant com- about as strongly as was basal munity. In general, the effect of area. Because of the high degree these variables on stocking and Table 7--Positive and negative correlations of variables and the order in which they appeared in regression equations describing density of regenerati-on in 2 plant comnities in shelterwood units in the Cascade Range of eastern Oregod/

Specie? or orlgln Litter Residual Standard Aspect Slope Litter slash and (pile Forbr Shrubs Grasses crOWn trees %~~~$icR~ Of y:;y1 area density diameter seedling slash b:::l density

ROUNTAIN HEMLOCKIGROUSE HUCKLEBERRY A1 1 regeneration -5 -4 -2 +1 +3 0.65 2.607 A1 1 natural regeneration -4 -5 +6 -2 3-year-old and older seedlings -3 -5 -4 1- and 2-year-old seed1ings -6 -3 +4 -2 Subsequent red fir -3 +1 -2 .66 2,547 All red fir Subsequent white pine -2 -5 All white pine -3 Subsequent mountain hemlock -7 -6 All mountain hemlock -1 -2 +3 -4 .77 85

MIXED CONIFER/SNOWBRUSH-CHINKAPIN

A1 1 regeneration -1 -4 -2 +3 A1 1 natural regeneration 3-year-old and older seed1ings 1- and 2-year-old seedlings Subsequent grand fir All grand fir Subsequent Douglas-fir All Douglas-fir Subsequent red fir All red fir

l1Numbers indicate the order in which variables entered the regression equation. Only the variables that accounted for the major portion of the variation in density of seedlings are given. Variables were excluded ifthey failed to raise ~2 values by at least 3 percent.

80 I I I I I 1111 Figure 5.--Relationship between basal area and crown density of residual 70 - y ,67.5 ( l-e-O.~l~) - overstory for all shelterwood plots -.- r2 = 0.75 in both mountain hemlock and mixed $ 60- - conifer plant communities in the L al eastern Cascade Range.

- - abundance of regeneration in the - mountain hemlock and mixed conifer

- communities can be summarized by listing the variables associated with increased stocking, decreased 0 20 40 60 80 100 120 140 160 180 200 BOSOI area (square feet per acre) stocking, or having no strong relationship to stocking as follows: MOUNTAIN HEMLOCK COMMUNITY Increased stocking Decreased stocking Little relationship More mineral soil Higher elevation Slash More litter and slash Greater slope Burn More basal area More litter Forbs Greater average More northerly aspect Shrubs diameter of the Grasses overs tory Crown density Overstory trees per acre

MIXED CONIFER COMMUNITY Increased stocking Decreased stocking Little relationship Higher elevation More litter Slash More northerly aspect Greater severity Litter and slash Greater slope of burn Overstory trees per acre More mineral soil More forbs Average diameter of More basal area More shrubs overs tory Greater crown density More grasses

The indication that more litter servations in this study and other and slash lead to increased stock- studies. Mineral soil is clearly ing in the mountain hemlock com- the most favorable seed bed for munity, whereas more litter de- establishment of seedlings in creases stocking appears to be a both plant communities, but I contradiction. The increased observed many seedlings growing in stocking associated with litter light to medium litter layers and slash probably is due to the (114 to 1/2-linch-deep). Heavy, effect of slash more than litter continuous litter mats (more than and may reflect some difficulty in 112-inch- thick) severely reduce classification of seed beds into the number of seedlings. the litter, slash, and litter and Similarly, many seedlings were slash categories. In any case, found growing in the shade of the relationships between con- light amounts of slash throughout dition of the seed bed and estab- the shelterwood plots, but very lishment of natural regeneration few in deep concentrations of are evident from the data and ob- slash (fig. 6). Similar eration after shelterwood cutting would be useful. The regression equations summarized in the pre- ceding section include variables--such as grasses, forbs, and. shrubs--that change with time-- similar to the change in stocking--and therefore cannot be used for predicting stocking. To derive prediction equations, I used only the variables that remain independent and can be measured before or directly after harvest ..?I Variables used were Figure 6.--Seedlings growing in shade elevation, aspect, slope, slash, of stash. degree of burn, basal area, crown density, number of overstory trees per acre, and average diameter. conditions were observed in another shelterwood study in a Strictly speaking, amount of slash mixed conifer plant community in and degree of burn do not remain central Oregon (Seidel 1979a). completely unchanged over time; Therefore, it is not necessary or but within the timespan this study covers they changed 1it t le desirable to completely remove all , . litter and slash from the seed Basal area, trees per acre, and average diameter were adjusted to bed. Enough disturbance is caused values immediately after the seed by logging and slash disposal to cut by adding data from dead and provide a receptive seed bed. down trees.

Some light damage to the regen- Because of the large amount of eration by animals was observed on unexplained variation present, it these shelterwood plots. In the is not possible to accurately pre- mountain hemlock type, damage dict regeneration stocking after caused by gophers was found on about shelterwood cutting in either the 1 percent of the subplots compared mountain hemlock or mixed conifer with 7 percent in the mixed coni- communities (tables 8 and 9). In fer community. Damage by other animals (primarily deer) was observed on 4 percent of the sub- 3 plots in the hemlock plots and 7 -' Variables that remain independent are those that are unchanged or nearly percent in the mixed conifer. so over time or can be adjusted to preharvest values. For example, understory vegetation was not used because Prediction Equations it can vary during the time after the seed cut, similar to tree regeneration. Reliable equations to predict stocking or density of regen- Table 8--Prediction equations for milacre stocking of regeneration on shelterwood units in a mountain hemlock/grouse huckleberry community in the Cascade Range of eastern Oregon, by species and class of reproduction

Dependent Variation Standarderror of variable explained estimate ~2 Sy-x --- Percent - - -

1- and 2-year- old seed1 ings =15.91+0.28(basal area)-1 1.48(slope) 3-year-old and older seed1 ings =231.22+0.02(crown densi ty)-0.04(elev.) .50 19.6 +2.36(average diameter)+l6.17(~1 ash)-1.68(aspect) -22.44(burn)

All natural regenerati on =258.12-0.05(el ev. )+2.28(average diameter) .45 20.2 +9.66(slash)-21.42(burn)

A1 1 regenerati on =182.29+0.08(basal area)-0.02(elev. ) -1.46(aspect)+0.98(average diameter) Subsequent red fi r =-16.25+2.33(average diameter)-31.87(burn) .47 21 .O All red fir =-4.81+0.29(basal area)-34.08(burn) .49 24.6 Subsequent white =103.83-0.01 (elev. )-0.37(crown densi ty) pine -0.66(aspect)

A1 1 whi te pine =108.39+9.29(burn)-0.02(el ev. ) .69 5.8 -0.39(crown density)

All hemlock 45.71 -0.01 (el ev. ) -0.58(average diameter) +12.09(burn)

Variables are arranged in the order in which they entered the regressions. Only the variables that accounted for major portions of the variation in stocking percent are given. Variables were excluded if they failed to raise R~ values by at least 3 percent. the mountain hemlock plots, the cent); the equation for all equation predicting milacre stock- regeneration accounted for the ing of all white pine accounted least (29 percent). The equations for the most variation (69 per- showed that the establishment of Table 9--Prediction equations for milacre stocking of regeneration on shelterwood units in a mixed conifer/snowbrush-chinkapin community in the Cascade Pange of eastern Oregon, by species and class of reproduction

Standard Dependent Variation error of variabl e ex~lained estimate ~2 sy-x - - - Percent - - - Subsequent =-214.96+0.03(el ev. )+1.40(average diameter) red fir +0.84(aspect)+O. 15(basal area)+7.00(slash) Subsequent grand fir =-57.36+0.51 (crown densi ty)+O.Ol (el ev. ) Subsequent =99.29-0.02(elev)+8.12(slope) Doug1 as-fi r +O. 26(crown density) Allgrandfir =-48.28+0.02(elev.)+0.55(crowndensity) -6.68(sl ash) A1 1 Dougl as-fir =134.98-0.03(elev.)+0.20(basal area) +13.06(sl ope) All red fir =-231.71+0.04(elev. )+Z.OO(average diameter) +O. 61 (trees/acre)+7.50(~1 ash) 1- and 2-year- old seed1 ings =-3.44+0.30(basal area)+0.77(aspect) +7.86(slope) 3-year-01 d and 01 der seed1 ings =19.17+0.68(crown densi ty)+9.32(slope) All natural =17.26+0.74(crown closure)+l5.53(slope) +0.98(aspect)

A1 1 regeneration =-33.06+0.27(basal area)+O.Ol (el ev. ) +10.33(sl ope)+O. 79(aspect)

l' l' Variables are arranged in the order in which they entered the regressions. Only the variables that accounted f ,r major portions of the variation in stocking percent are given. Variables were excluded if they failed to raise ~2 values by at least 3 percent. white pine (a shade-intolerant the more shade-tolerant species species) was reduced by heavier which were favored by increasing residual overstories compared with stand densities. The amount of variation explained by the equa- managers . A1 though the equations tions was similar for mixed coni- in this study do not permit an fers and mountain hemlock and accurate estimate of expected ranged from 17 percent for 3-year regeneration, some idea of the and older regeneration to 42 per- general trend of reproduction as cent for all Douglas-fir (table 9). stand density varies and the range of stand densities most suitable Although these equations are not for regeneration can be obtained accurate enough for predictions, from these data and similar they are probably as good as can studies. be expected when the variables involved and complex distribution In both plant communities, there pattern of natural regeneration is a general trend of increasing are considered. Unexplained vari- stocking as stand density (basal ation exists for several reasons. area) increases and a large amount In a survey study, no estimate of of unexplained variation in the amount of seed fall on the stocking (fig. 7). It appears shelterwood units is obtainable. that there is no problem in ob- In addition, factors measured taining an abundance of natural (aspect, slope, etc.) are second- regeneration at relatively high ary variables. These variables influence the five primary variables (light, temperature, mois- ture, and chemical and physical factors) in which seedlings re- spond directly. Finally, it should be mentioned that, ideally, equations such as these should be verified on an independent set of data not used in their deriva- tion. Therefore, I want to empha- size that these equations should not be considered precise pre- dictors of expected regeneration after shelterwood cutting but only crude estimates of possible stocking. I A I I I1 I I I I 0 20 40 60 80 100 120 140 160 180 200 Basal area ( square feet per acre)

Residual Stand Density and Figure 7.--Relationship between basal Regeneration area and milacre stocking of natural regeneration in the mountain hemlcok and mixed conifer plant communities The question of the appropriate in the Cascade Range of eastern stand density to leave after the Oregon. seed cut is important to land stand densities of over 100 square IIIIIIIII Flevolia I feet per acre. When the shelter- I (feet) wood system is used in the general forest zone, however, residual stand density should be reduced to the minimum level at which an acceptable amount of regeneration will be obtained. Also, the established reproduction must not be excessively damaged or destroyed

during removal of the overstory Basal area (square feet per acre) and disposal of slash. My ob- Figure 8.--Relationship between basal servations suggest that if at area, e Zevation, and milacre stocking least 40-percent stocking of of aZl regeneration in the mountain milacre plots is desired, then a hemlock and mixed conifer plant communities in the Cascade Range of basal area of about 60 square eastern Oregon. feet per acre should result in adequate stocking on most units. A few shelterwood plots were 50 elevation in the mixed conifer to 70 percent stocked with resid- type, and the decrease in stocking ual basal areas as low as 30 to 40 at higher elevations in the moun- square feet per acre, but the tain hemlock type. Even though probability of failure of regen- milacre stocking of 40 to 60 per- eration increases at this low cent is indicated by these curves density . at basal areas of 20 to 30 square feet per acre, the wide scatter of Basal area and elevation were these data suggests that a resid- two variables that appeared in ual stand density that low will many of the prediction equations. probably result in some under- Their relationship to milacre stocked units. stocking is illustrated in figure 8!!/ A1though not accurate The range of stand densities enough for predictions, these where adequate natural regen- curves show the wide range of eration occurred in this study was basal area where stocking occurs, similar to that found in several the increase in stocking with other shelterwood studies in central Oregon. In a single moun- 4 tain hemlock stand, Seidel and -' Mountain hemlock equation is Cooley (1974) estimated that about Y = 163.38 + 0.22 (basal area) -0.02 (elevation) ~2 = 0.23*, standard error 80 square feet of basal area per of estimate = 19.2 percent. Mixed acre was needed in the residual conifer equation is Y = -20.62 + 0.26 overstory for adequate repro- (basal area) + 0.013 (elevation) duction of grand fir. And Seidel R2 = 0.25**, standard error of estimate = 18.6 percent. (1979a) found in a mixed conifer cormnuni ty that good regenerat ion of true fir was established under regeneration is light; planting a residual overstory of 50 square can then be the difference between feet per acre. It is apparent an understocked and an adequately from these studies that natural stocked stand. For example, using regeneration in the mixed conifer a 40-percent stocking of milacre and mountain hemlock plant com- quadrats as representing adequate munities is established under a regeneration, planting increased wide range of residual stand den- stocking on 10 mixed conifer plots sities and that, because of the from less than 40 percent to above many variables affecting repro- the 40-percent level. The only duction, no single level is suit- apparent common factor related to able in all areas. A range of 60 lack of natural regeneration on to 80 square feet of basal area these plots was a light residual per acre is suggested as the mini- overstory. After the seed cut, 7 mum level for natural regeneration of the 10 plots had less than 60 to occur on nearly all shelterwood square feet of basal area. 'units. On the 15 shelterwood units Natural Regeneration Versus Planting planted in the mountain hemlock community, on only 1 was stocking Because of the good to excellent increased above 40 percent by the natural regeneration that occurred planted seedlings. Although on most of the shelterwoods plots, planting was generally not needed planting does not seem necessary to insure an adequately stocked when considered only in terms of stand in this plant community, the contribution of the planted there appears to be a relationship seedlings to total numbers of between species composition of the seedlings. Only 5 to 10 percent overstory and a need for plant- of the total number of seedlings ing. On the plots where the over- in planted plots was planted story consisted of a mixture of stock. As discussed previously, species, natural regeneration was however, the advantages of plant- good to excellent, even at resid- ing lie not with seedling numbers ual densities of less than 60 but with the good distribution and square feet per acre, and planting greater height of the planted was not needed. On the other seedlings. hand, natural regeneration was poor on plots where the overstory In the mixed conifer community, was 100 percent mountain hemlock planting increased stocking on 29 and planted seedlings made up 70 of the 43 planted plots; on 9 of percent of the reproduction. these plots, stocking was raised by more than 12 percent, Ob- The amounts of understory vege- viously, the effect of planting is tation that became established on greatest on units where natural these shelterwood plots a£ter the seed cut were small, especially in Overstory Mortality the mountain hemlock community where only about 7 percent, on the Mortality of the residual over- average, of the seed bed was oc- story after the seed cut was cupied (table 1). The absence of greater in the mountain hemlock heavily competing vegetation for a plots than in the mixed conifer number of years, together with the community. An average of 2.4 high probability of a heavy seed trees per acre were blown down and crop every 3 to 4 years as re- 1.7 trees per acre were standing ported by Franklin et al. (1974) dead in the mountain hemlock in mixed conifer stands and the type. This amounted to about 16 good distribution of seed trees percent of the total number of over the area, results in a high trees left after logging. In the probability of success of natural mixed conifer community, about 6 regeneration. percent of the overstory was lost--an average of 0.5 tree per Because of the abundant natural acre blown down and 0.6 tree per regeneration that can be expected acre standing dead. within a few years after the seed cut, planting appears better Blowdown can be a problem when suited as a supplemental means of the shelterwood system is used in reforestation to raise stocking unmanaged old-growth stands be- above minimum standards. The most cause trees growing at high den- efficient use of planting in the sities have not developed the shelterwood system is probably to windfirmness needed to resist increase stocking where removal of greater stresses from wind after the residual overstory has reduced heavy partial cuts. Mountain hem- stocking below minimum standards. lock is especially susceptible be- Planted seedlings are then not cause of its relatively shallow subject to loss or damage by log- root system (fig. 9). The risk of ging operations as they are when blowdown can be reduced by leaving planted before the overstory is dominant or codominant, full- removed. crowned trees which are the most windfirm and also the best seed In summary, results of this producers (Gordon 1973). Mountain study suggest that planting hemlock should be discriminated shelterwood units immediately against in favor of the other after the seed cut is necessary species in the overstory when the only in the following cases: (1) seed cut is marked. This not only in mixed conifer communities if reduces the chance of blowdown but residual basal area is reduced also increases the chance of re- below 60 square feet per acre and generation success by providing (2) in pure mountain hemlock com- more seed of species, such as the munities containing no other true firs, that apparently regen- species in the overstory. erate better than mountain hemlock at stand densities from 60 to 80 CONCLUSIONS AND RECOMMENDATIONS square feet per acre. The results of this survey indicate that use of the shelterwood system can provide satisfactory natural regeneration of a number of species in terms of stocking and seedling density in both mixed conifer/snowbrush-chinkapin and mountain hemlock/grouse huckleberry plant communities. Obtain- ing adequate natural regeneration depends on many factors. Two of the most important are a sufficient and uniform overstory density and a seed bed receptive to establishment of seedlings. A Figure 9.--Blowdown of mountain hem- uniform residual overstory in the lock. range of 60 to 80 square feet of basal area per acre is recommended for natural regeneration in both plant communities. Adjustments in the basal area level can be made for various aspects, slopes, or elevations by use of the prediction equations; that they provide only very rough estimates of expected stocking because of the considerable amount of unexplained variation must be considered. A suitable seed bed is provided by logging and slash disposal operations, which serve to break up heavy litter layers and expose mineral soil. A heavy seed year soon after the seed cut pro- vides the best chance of securing regeneration immediately; but, because competing understory vegetation is not a serious problem, seed beds remain receptive and adequate stocking can be obtained over a period of years from a number of light seed crops. Planting on these shelterwood reduces the tendency to leave too units served mainly as a supple- heavy an overstory, which some- mental rather than a primary means times occurs when the cut trees of reforestation. Seedlings are marked. should be planted in mixed conifer shelterwood units immediately It is clear from the results of after the seed cut if overstory this and other studies that ade- density is less than 60 square quate natural regeneration is feet per acre and in mountain obtained when the shelterwood hemlock shelterwoods where the system is used in mixed conifer overstory consists only of moun- and mountain hemlock plant com- tain hemlock. Otherwise, natural munities in the Cascade Range of regeneration should be relied on. eastern Oregon. Establishment of If natural regeneration has not a satisfactory stand of repro- resulted in adequate stocking duction after the seed cut, how- after 3 or 4 years in unplanted ever, is only part of the refor- units, the land manager can then estation job when the shelterwood (1) underplant to raise stocking system is used. Unless the resid- to satisfactory levels or (2) ual overstory can be removed remove the residual overstory and without causing unacceptable loss then plant. Alternative 2 is and damage to the regeneration, recommended because planted seed- all the time and effort involved lings are then not subject to loss in securing regeneration have been or damage from logging and slash wasted. Although there are many disposal operations. Ponderosa mixed conifer shelterwood units in pine and Douglas-fir are the pre- the Cascades where the seed cut ferred species to plant in mixed has been made, the residual over- conifer communities; lodgepole story has been removed on very pine and the true firs survive and few; so experience is lacking grow well in the mountain hemlock regarding the best procedures. type. Planting stock grown from Limited experience, however, has seed collected in the same geo- shown that it is possible to graphical and elevational zone as remove an overstory of 24,000 the shelterwood unit should be board feet per acre and still used. preserve ponderosa pine saplings (~arrettet ale 1976). And The residual overstory in McDonald (1976) reported that up shelterwood units should consist to 10 overstory trees per acre of only the most vigorous domi- were removed from shelterwood nant or codominant trees. This units in California without ex- objective is accomplished better cessive loss of reproduction. if the leave trees rather than cut trees are marked. This focuses The key to saving the regen- the marker's attention on the most eration is good coordination desirable trees to leave and also between timber and fuels manage- should be bucked into ment staffs and the skillful ap- 16-foot logs rather than plication of logging techniques 32-foot logs. Tractors designed to preserve the estab- should stay on trails and lished reproduction. After study- back toward direction of ing logging methods in mixed coni- fall. fer stands in Arizona, Gottfried and Jones (1975) suggested several 3. Careful winching.--Restricting changes to reduce loss and damage tractors to marked and to regeneration. They include: precleared skid trails would require more winching. Logs 1, Marking and clearing skid being winched to a tractor trails.--Skid trails should sometimes catch on down be marked on the ground and material and drag it sideways, the same trails used for all destroying and damaging cuts. Windfalls are regeneration. A swamper or commonly found lying across the choker setter could saw skid trails when the out sections that lay in the overstory is removed. way, making winching easier Pushing these tree length and reducing damage to the windfalls out of trails does reproduction. considerable damage to the reproduction. Damage can be 4. Yarding unmerchantable avoided by having a swamper material.--Moving preclear skid trails by unmerchantable logs to sawing out sections of the landings will reduce the blowndown trees and then amount of material that must pushing them into areas be handled in the slash where damage would be least. disposal operations.

Directional falling and 5. Season of logging,--Logging on variable log lengths.--Trees snow offers possibilities for should be felled in a reducing root damage and herringbone pattern so that destruction of fewer trees. logs can be pulled onto skid Logging operations should be trails with the least avoided, if possible, during disturbance. Trees should the spring when terminal be felled into openings in shoots are tender and easily preference to maintaining a strict herringbone pattern. broken and at times when Trees lying at a poor angle freezing conditions make stems for wihching to skid trails brittle. mixed conifer watershed. USDA For. Serv. Res. Pap. RM-147, 20 Barrett, James W., Stanley S. p., illus. Rocky Mt. For. and Tornbom, and Robert E. Range Exp. Stn., Fort Collins, Sassaman. Colo. 1976. Logging to save ponderosa pine regeneration: A case Larsen, Daniel M. study. USDA For. Serv. Res. 1976. Soil resource inventory-- Note PNW-273, 13 p. Pac. Deschutes National Forest, Northwest For. and Range Exp. Pacific Northwest Region. 381 Stn., Portland, Oreg. p., illus. USDA For. Serv., Pac. Northwest Reg. [Portland, Day, Frank P., and Carl D. Monk. rego on. ] 1974. Vegetation patterns on a southern Appalachian McDonald, Philip M. watershed. Ecology 55: 1976. Shelterwood cutting in a 1064-1074, illus. young-growth, mixed-conifer stand in north central Franklin, Jerry F., Richard California. USDA For. Serv. Carkin, and Jack Booth. Res. Pap. PSW-117, 16 p., 1974. Seeding habits of upper- illus. Pac. Southwest For. and slope tree species. I. A Range Exp. Stn., Berkeley, 12-year record of cone Calif. product ion. USDA For. Serv. Res. Note PNW-213, 12 p., Seidel, K. W. illus. Pac. Northwest For. and 1979a. Natural regeneration Range Exp. Stn., Portland, Oreg. after shelterwood cutting in a grand fir-Shasta red fir stand Gordon, Donald T. in central Oregon. USDA For. 1973. Damage from wind and Serv. Res. Pap. PNW-259. Pac. other causes in mixed white Northwest For. and Range Exp. fir-red fir stands adjacent to Stn., Portland, Oreg. clearcuttings. USDA For. Serv. Res. Pap. PSW-90, 22 p., Seidel, K. W. illus. Pac. Southwest For. and 19 79b. Regeneration in mixed Range Exp. Stn., Berkeley, conifer clearcuts in the Calif. Cascade Range and Blue Mountains of eastern Oregon. Gottfried, Gerald J., and John R. USDA For. Serv. Res. Pap. Jones . PNW-248, 24 p., illus. Pac. 1975. Logging damage to advance Northwest For. and Range Exp. regeneration on an Arizona Stn., Portland, Oreg. Seidel, K. W., and R. Cooley. 2. Aspect. One of eight 1974. Natural reproduction of compass points measured on grand fir and mountain hemlock each subplot. The method after shelterwood cutting in proposed by Day and Monk central Oregon. USDA For. (1974) was used to code the Serv. Res. Note PNW-229, 10 p., aspect, and the following illus. Pac. Northwest For. and values were assigned to Range Exp. Stn., Portland, Oreg. compass directions: N - 14; NE - 15; E - 11; Strickler, Gerald S. SE - 7; S - 3; SW - 2; 1959. Use of the densiometer to W - 6; NW - 10. Average estimate density of forest coded value off the 25 canopy on permanent sample subplots was used in plots. USDA For. Serv. Pac. analyses. Northwest For. and Range Exp. Stn. Res. Note 180, 5 p., 3. Slope. Percentage slope of illus. Portland, Oreg. each subplot was measured with a clinometer and Volland, Leonard A. coded as follows: 0-9 1976. Plant communities of the percent, 0; 10-19 percent, central Oregon pumice zone. 1; 20-29 percent, 2; 30-39 USDA For. Serv. Pac. Northwest percent, 3; etc. Average Region R6 Area Guide 4-2, 110 coded value of subplots was p., illus. used.

Williamson, Richard L. 4. Mineral soil. The per- 1973. Results of shelterwood centage of each subplot harvesting of Douglas-fir in containing mineral soil was the Cascades of western estimated, coded in the same Oregon. USDA For. Serv. Res. way as slope values, and Pap. PNW-161, 13 p., illus. averaged. Pac. Northwest For. and Range Exp. Stn., Portland, Oreg. 5. Litter. The percentage of each subplot covered with litter was estimated, coded in the same way as slope values, and averaged.

Independent (x) variables used in 6. Slash. The percentage of regression analyses. each subplot covered with slash was estimated, coded 1. Elevation. The average in the same way as slope elevation of the plot to values, and averaged. the nearest 10 feet as measured with an altimeter. 7. Litter and slash. The 12. Basal area. The overstory percentage of each subplot basal area at each subplot covered with litter and was measured with a slash was estimated, coded 10-factor angle gage and in the same way as slope averaged for use in values, and averaged. analyses.

8. Degree of burn. Estimated 13. Crown density. The on each subplot and coded overs tory crown as: None, 0; light, 1; density or closure was medium, 2; heavy, 3. measured with a spherical Averaged coded value was densiometer at each subplot used in analyses. Degree by Strickler's (1959) of burn is defined as: method. Average value of None--no visible effect of the 25 subplots was used in fire; light--£ ire charred analyses. the surface of the forest floor but did not remove 14. Overstory trees per acre. all the litter layer; The numbers of standing medium--fire removed all overstory trees (living and dead) and blown down trees the litter layer and some were recorded on of the duff; heavy--fire 0.0785-acre subplots at removed all the litter and each of the 25 sample duff and imparted a color points, averaged, and to the mineral soil. converted to a per-acre basis. 9. Forbs. The percentage of each subplot covered with Overstory average diameter. forbs was estimated, coded The diameters at breast in the same way as slope height of living and dead values, and averaged. standing trees and blown down trees on each 10. Shrubs. The percentage 0.0785-acre subplot were of each subplot covered measured to the nearest with shrubs was estimated, inch and averaged. coded in the same way as slope values, and averaged.

11. Grasses and sedges. The percentage of each subplot covered with grasses and sedges was estimated, coded in the same way as slope values, and averaged. - Seidel, K. W. 1979. Regeneration in mixed conifer shelterwood cuttings in the Cascade Range of eastern Oregon. USDA For. Serv. Res. Pap. PNW-264, 29 p., illus. Pacific Northwest Forest and Range Experiment Station, Portland, Oregon.

A survey of shelterwood cuttings in mixed conifer forests in the eastern Oregon Cascade Range showed that, on the average, shelterwoodLlunitswere trell-stocked with a mixture of advance, natural subsequent, and planted reproduction of a number of species. Because of slow invasion by understory vegetation,-frequent heavy seed crops, and adequate density of the overstory, natural regeneration was prolific on most units. Planting is recommended only as a supplemental reforestation method. Greater stocking was associa~ted with increasing overstory density and more exposed mineral soil; such factors as aspect, slope, and elevation had a positive or negative relationship to stocking depending on the species and plant connuunity.

KEYWORDS: Regeneration (stand), regenerat ion (natural), regeneration (artificial), mixed stands, Oregon (Cascade ~ange), shelterwood cutting method.