Field_Guide_TP-028-91-1992.pdf

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United States Department of Agriculture

Forest Service

Pacific Northwest Region

R6-ECOL-TP-028-91

Field Guide to the

Forested Plant Associations of the Mt. Báker-Snoqualm ie National Forest

THE AUTHORS

JAN A. HENDERSON, AREA ECOLOGIST

Leader of the ecological classification projct for the Olympic and Mt.

Baker-Snoqualmie National Forests since 1979. Prior to that he was Assistant Professor of Forest Ecology and Silviculture at Utah State University. He holds a BS in Forest Management from Washington State University (1968), an MS in Forest Ecology (1970) and a PhD in Botany (1974) from Oregon State University.

ROBIN D. LESHER, ECOLOGIST

Assistant to the Area Ecologist, she has worked on this project since 1984. She has been involved in all aspects of the project, and had primary responsibility for moss and lichen taxonomy and ecology.

Prior to this project, she worked several years doing botanical and ecological surveys in the North Cascades. She holds a BS (1979) and an MS (1983) in Biology from Western Washington University.

DAVID H. PETER, ECOLOGIST

Assistant to the Area Ecologist, he has worked on the project since 1980. He has been involved with all aspects of the project, with primary responsibility for collection and analysis of soil data. He earned a BS in Biology from The College of Idaho (1973) and an MS in Botany from Washington State University (1977).

DAVID C. SHAW

Currently a PhD candidate at the University of Washington, College of Forest Resources. He has worked on this project as a Biological Technician since 1984. He had responsibility for field identification of diseases and insects and wrote sections dealing with these subjects.

He holds a BS in Biology from Northern Arizona University (1977) and an MS in Biology from Western Washington University (1982).

Field Guide to the

Forested Plant Associations of the

Mt. BakerSnoquaImie National Forest

By

Jan A. Henderson

Robin 0. Lesher David H. Peter

David C. Shaw

USDA

Forest Service

Pacific Northwest Region

Technical Paper

R6 ECOL TP 028-9 1

June 1992

ABSTRACT

A classification of forest vegetation is presented for the Mt. Baker-snoqualmie NationalForest. It is based on the potential vegetation and uses the plant association as the basic unit.The classification is based on 2464 sample plots distributed across the Forest from 1979 to1990. Of these 1963 were in late successional stands over 150 years old. An additional 633plots were taken in non-forest communities or undescribed plant associations. The hierar-chical classification includes 4 forest series, 19 plant association groups, and 60 plantassociations. Diagnostic keys are presented to aid in the identification of vegetation seriesand plant associations. Descriptions are presented for each series and association. Plantassociation descriptions include information about plant species occurrences, distribution,environment and soils, potential timber productivity, management considerations, and com-parisons with similar plant associations.

Key words: vegetation classification, climax plant communities, potential vegetation, plantassociation, vegetation series, forest ecology, forest environment, Cascade Mountains.

ACKNOWLEDGEMENTS

Many people have contributed to this publication. These include but are not limited to RegionalEcologists Fred Hall and Len Volland. Fred Hall initiated this project and has made significanttechnical contributions overthe years. Many people assisted during field sampling in additionto the authors. These include B. Brown, C. ChappeJi, A. Davenport, L. Ecklund, J. Evans, R.Evans, A. Freed, M. Freiberg, J. Koontz, C. Maddox, P. McKenney, L. O'Callahan, A.Pemberton, L. Potash, D. Rial, B. Schrader, A. Tokach, S. Wagstaff. S. Edwards-Aithauserassisted in data entry. 0. Atkinson and J. Coffey assisted with the maps. E. Ketchesonassisted with editing of the final manuscript. Primary responsibility for the study design andInterpretation of results belongs to the senior author. D. Peter did most of the soil profiledescriptions and soil analysis. R. Lasher had major responsibility for moss and lichenidentification, as well as for much of the data analysis. Bird and mammal identification wasgreatly assisted by C. Chappell, B. Schrader, 0. Shaw and A. Lasher. 0. Shaw was primarilyresponsible for identification and interpretation of insects and fungi. Many of the computerprograms used in the project were developed or modified by M. Connelly, L. Volland, D.Wheeler or B. Smith. D. Hood helped in many computer applications. Finally, the seniorauthorwishesto acknowledge the contributions of four people-- W. Chilcote, A. Daubenmjre,J. Franklin and A. Pfister, whose ideas and philosophies greatly influenced the ecologicalapproaches used here.

This document was assembled using Aldus Pagemaker. Figures were prepared using DG MOSS, Microsoft Chart, Jandel Sigmaplot, and Coreidrawl Photographs are by the authors.

TABLE OF CONTENTS

Introduction How to Use This Guide Ecological Concepts Topographic Moistire Ecozones Table of Plant Associations, Plant Association Groups and Ecoclass Codes Environmental Ordination of Plant Associations by Ecozones and Elevation Key to the Series

p. 1

p. 2

p. 6

p. 8

p. 9

p. 16

p. 17

p. 18

WESTERN HEMLOCK SERIES

p. 19

Key to Plant Associations In the Western Hemlock Series

p. 23

Ordination of Plant Associations in the Western Hemlock Series

p. 24

Table of mean environmental values for Western Hemlock Plant Associations p. 25 Table of mean site Index values for Western Hemlock Plant Associations p. 26 Table of timber productivity values for Western Hemlock Plant Associations p. 27 Table of relative cover and constancy for Western Hemlock Plant Associations p. 28TSHE/ACCI-BENE

P. 34

TSHEIBENE

p.TSHEIBENE-CHME p.TSHE/GASH

p. 40

ISHE/GASH-BENE

p. 42

TSHE/GASH-VAME

TSHE/GASH-XETE

p.

TSHE/LYAM

p. is TSHE/OPHO-ATFI p. 50

TSHE/POMU-BENE

p. 52

TSHE/POMU-GASH

p. 54

TSHE/POMU-T1TR

p. s

TSHE/TITR.GYDR

p. 58 TSHEIVAAL p. 60

TSHENAAL-BENE

p. 62

TSHENAAL-POMU

p. 64 TSHENAAL.xETE

p. 66

SILVER FIR SERIES

p. 69

Key to Plant Associations of the Silver Fir Series

p. 73

Ordination of Plant Associations In the Silver Fir Series p. 74 Table of mean environmental values for Silver Fir Plant Associations P. 75 Table of mean site index values for the Silver Fir Plant Associations p. 76 Table of timber productivity values for the Silver Fir Plant Associations p. 77 Table of mean relative cover values for the Silver Fir Plant Associations p. 78

ABAM/ACTR

p. 84 ABAM/BENE p. 86

ABAM/GASH-BENE

p. 88

ABAM,'LYAM

p. 90 ABAMIOPHO-VAAL p. 92

ABAM/RHAL-VAAL

p. 94

ABAM/RHAL-VAME

p. 96

ABAMIRUPE-BLSP

p.

ABAMfTIUN-STRO p. lao

Table of Contents (continued)

ABAM/VAAL p 102 ABAMNAAL-BENE p. 104 ABAM/VAAL-CWN p. 106 ABAM/VAAL-GASH p. 108 ABAMNAAL-MADI2 I p. 110 ABAMNAAL-POMU p. 112 ABAMNAAL-PYSE p. 114 ABAMNML-TIUN p. 116 ABAM/VAAL-XETE p. 118 ABAMNAME p. 120 ABAM/VAME-PYSE p. 122 ABAM/VAME-STRO p. 124 ABAM/VAME-VAAL p. 126 ABAMNAME-VASI p. 126 ABAM/VAME-XETE p. 130 ABAM/XETE p. 132

MOUNTAIN HEMLOCK SERIES p. 135 Key to Plant Associations In the Mountain Hemlock Series p. 139 Ordination of Plant Associations In the Mountain Hemlock Series p. 140 Table of mean environmental values for Mountain Hemlock Plant Associations p. 141 Table of mean site Index values for Mountain Hemlock Plant Associations p. 142 Table of timber productivity values for Mountain Hemlock Plant Associations p. 143 Table of relative cover and constancy for Mountain Hemlock Plant Associations p. 144 TSME/CABI p. 150 TSME/CLPYRUPE p. 152 TSME/OPHO-VAAL p. 154 TSME/PHEM-VADE p. 156 TSME/RHAL-VAAL p. 158 TSME/RHAL-VAME p. 160 TSMEF11UN-STRO p. 162 TSMENAAL p. 164 TSMENAAL-CLUN p. 166 TSMENAAL-MADI2 p. 168 TSME/VML-STRO p. 170 TSME/VAME p. 172 TSMENAME-RULA p. 174 TSMENAME-STRO p. 176 TSMENAME-VML p. 178

TSME/VAME-VASI

p. 180

TSMENAME-XETE

p. 182

SUBALPINE FIR SERIES p. 185 Table of mean environmental values p. 187 Table of mean relative cover values p. 188 ABLA2/VASI p. 190

References cited p. 192 Ust of Indicator Species p. 193 Key to Plant Associations p. 104

This is a field guide to the classification of forest vegetation of the Mt. Baker-Snoqualmie National Forest. it Is based on the potential forest vegetation and uses the plant associa-tion as the basic unit. The complete version of the classification along with supporting docu-mentation and background information is pub-lished separately. Potential vegetation Is the projected climax plant community which will occupy a site, given current climate and site conditions.

This classification is part of the Region 6 Ecology Program, initiated by Fred Hall about 1960. Efforts are completed or in progress to ecologically classify and characterize the veg-etation of Region 6 using this approach. A classification of the plant associations of the Western Hemlock, Silver Fir, Mountain Hem-lock and Subalpine Fir Series Is presented here. Classification of subalpine parkiand and non-forest plant associations is underway and will be published later. Even though the keys are built to apply to the late successional stages, and the name of the association is based on the potential vegetation, the asso-ciation concept applies to the entire sere, i.e.

to the entire time-span of ecological succes-sion from very young to old-growth to climax.

Analytical methods used to delineate the plant associations are outlined in the following sec-tion and described in more detail in the full version of the classification. Analysis was based on plots taken from 1980 to 1990. Two types of plots were used. Reconnaissance vegetation plots were used from 1980 to 1984 and intensive plots from 1985 to 1990. Recon-naissance plots were temporary and recorded basic vegetative and site data while intensive plots were permanently marked and included information on mammals, birds, insects, dis-eases, mosses, lichens and soil. Potential plot locations were located on a systematic grid using the center of each section of land as a target point. If the section was accessible by

INTRODUCTION

road or trail, the point on the road or trail that was closest to the target point was identified.

A compass line was run from the road toward the target sample point. A distance was traveled from this point toward the section-center until the potential plot location was outside the influence of the road. The plot center was then randomly located within the stand; however the plot itself was not allowed to cross significant ecotones. in roadless areas a transect of plots was used to approxi-mate the 1 plot per section sample. This assured that sample plots would be distributed evenly across the Forest and be located with-out bias by the field crews. Plot locations were potentially biased however, by the non-ran-dom locations of roads and trails. Additional plots were randomly located in stands of se-lected age classes to ensure that the sample included a range of ages forsuccessional and productivity analysis. Plots totalling 3097were distributed across the Forest using this scheme.

Of these, 2464 were in forested stands, and 1963 were In late-successional stands, i.e.

over 150 years old.

Plant Associations can be identified using the following keys and plant association descrip-tions, orthey can be predicted or inferred using indirect means. The keys presented follow the classical dichotomous key format except the second lead of the dichotomy is omitted (and is assumed to be "not as above"). The keys are presented as aids to Identification of the plant association, but often some interpretation is necessary In addition to the keys. Refer to the following section "How to Use This Guide", which provides Information on use of the keys, the indirect means of identifying a plant asso-ciation and interpretation of the plant associa-tion descriptions.

This book Is a guide to the identification and interpretation of Plant Associations (PA) in the field. Identification of a plant association in late seral condition is relatively straight-forward and isthe mainfocus ofthis guide. Species are Identified and cover estimates made. Then the keys presented are used to Identify the PA.

Stands in early successional stages which are densely stocked or with under-developed un-derstory may not key out easily. Still other sites may represent unique stand conditions not included in this classification.

Three different methods are outlined below which may be used to identify a PA, depending on the age and condition of the community.

Method 1 applies to normally developed, late-seral stand conditions. Species and cover values are identified and the keys to plant associations are used In the classical ap-proach. Method 2 applies to early seral or depauperate stand conditions. Stand compo-sition and structure are interpreted and the conditions projected forward in time to late-seral stages. Method 3 is an indirect method which applies simple environ mental models to predict the PA from location, topography and elevation. To use any of these methods, start with the following steps.

STEP 1. In the field, LOCATE AN AREA (plot) to be Identified. The plot should be no smaller than 1/20 acre or larger than 1/2 acre. Mark the plot center and plot boundaries.

STEP2. DETERMINE STAND AGE - This can be approximated by using the age of the oldest tree in the stand. Determine if the community is mature enough to fit the keys to the plant associations or whether the community com-position must be projected to an later stage of succession.

STEP 3. ANALYZE STAND STRUCTURE -

Determine whether the stand is even-aged, all-aged or irregularly-sized. Both the relative

HOW TO USE THIS GUIDE

amounts of trees of different ages and sizes are Important.

STEP 4. DETERMINE RELATIVE TREE

STOCKING - relative to the amount of light penetrating the canopy. Judge whether the regeneration of shade-tolerant tree species Is Inhibited or whether the abundance of poten-tial shrub and herb species is affected by the tree stocking.

STEP 5. EVALUATE DOWN LOG AND LIT-

TER DEPTh - judge whether the amount of down logs (maybe from a previous fire) or litter Is thick enough to Inhibit establishment or reproduction of Indicatortrees, shrubs or herbs.

STEP 6. LOOK FOR RECENT DISTUR-

BANCES - determine If there are any recent disturbances from soil movement, wind, fire, flood, animals or management activities that may have significantly affected the species compositIon of the community.

Atterevaluating the above community charac-teiistics, determine if the community repre-sents a normal undisturbed forest community over 150 years old. if so, see method I below.

If not, see method 2.

METhOD 1identify a Plant Association In the field using the keys

Step 1. Identify the series by evaluating the relative amounts of tree species, especially In the reproduction size classes. Use the Key to Series on page 18. The 10% canopy cover criterion used in the key applies to a stand age of 300 years. Interpretation may be needed in some stands less than about 150 years. The order of the forest series in this key Is impor-tant, and one needs to workstep-wise through the key. The Mountain Hemlock Series is identified if mountain hemlock Is present and reproducing successfully, and has the capabil-ity of supporting at least 10% canopy cover at a stand age of 300 years. Silver fir is usually present and may be dominant or codominant with mountain hemlock.

The Silver Fir Series is identified If silver fir is present and shows signs of being able to reproduce successfully, and if Its canopy cov-erage Is at least 10% at a stand age of 300 years, and the potential for mountain hemlock cover Is less than 10%. Silver fir, or western hemlock and silverfir are the projected climax (potential) tree species.

The Western Hemlock Series is identified if western hemlock and/orwestem redcedar are the projected climax (potential) tree species.

Silver fir may occur as a very minor species only, reproducing sporadically or irregularly and showing no signs of being able to develop to the point where It could occupy at least 10% of the stand.

The Subalpine Fir Series is identified if subal-pine fir is the projected climax tree species. ft occurs primarily in the high elevation, rainshadow areas of the Forest.

In the arkland Series, mountain hemlock is the dominant trees species along with some slive rfir, Alaska yellowcedar and/or subalpine fir. The structure of the tree-dominated com-munities changes from a closed forest to islands and stringers of forest in a mosaIc of meadows and rock.

Step 2. Identify the plant association by using the key for the appropriate series. To do this, first determine the cover of each indicator species present (i.e. those species used in the plant association keys). Use the methods on

p. 510 estimatethe canopy coverof species on the plot. See p.4 for instructions on how to use the key. Each key is structured to help place a community of known species composition into the proper plant association. in some cases, especially where the cover of an indica-tor species is near the critical cover in the key, the best placement may be found after follow-ing both leads in the key and using the PA descriptions to decide the final placement. If this is the case, turn to the association descrip.

tion and compare the community composition to the table of common plants and check the.

map of known locations for the plant associa-tion. Then use the series ordinations (e.g. Fig.

12p. 24forthe Western Hemlock Series), and tables of environmental values (e.g. Table 2p.

25 forthe Western Hemlock Series) andcom-pare to the community being Identified.

METhOD 2 IdentIfy an early semi, dis-turbed or depauperate community

If the community to be identified has been disturbed, or is too young ortoo dense to have fully developed (usually less than 100 years), then some interpretation of the potential com-position of the community is necessary. The plant association keys can be used to facilitate identification here, but since interpreted or projected estimates of abundance are used, the key must be applied with some flexibility and caution.

The composition of the community projected to late-seral condition must be estimated. Two approaches may be used: 1) project the communityforward in time using knowledge of plant succession for the area, or 2) Interpret the relative community composition from ar-eas nearby, which may give clues to what the normal successional development might be.

Use either openings or an adjacent stand to estimate the normal composition and stock-ing. Then use projected cover values and the appropriate key.

METhOD 3Predict the plant association using environmental variables

This approach uses measured environmental variables inthefield orestimated from maps or models to predict the plant association for a site. It can be used to verify acommunity in the field, orto predict the most probable associa-tion. This approach can also be used In modeling or analysis of spatial - environmental patterns.

The first step using this Indirect approach Is to identify the ecozone (p. 9). Locate the site using the map (Fig. 4, pp. 10 -11). Identify which ecozone the site occurs in. Sites In lower numbered ecozones occur In areas with greater precipitation.

The next step is to predict the series. Use Figures 5-8 (pp. 12-15) to predict the series (zone). Locate the elevation and aspect of the site on the graph and choose the curve forthe appropriate ecozone. If the site falls above the ecozone curve in Figure 5, the site is probably In the Silver Fir or Mountain Hemlock Series.

If it occurs above the ecozone curve In Figure 6 or 7 it probably belongs to the Mountain Hemlock Series. These curves represent the modal mountain slope positions. Dry ridgetops or warm steep slopes will cause the curves to shift up 100-400 feet. Wet pockets or cold air drainages will cause the curves to shift down in elevation 100- 500 feet. As a rule-of-thumb, a topographic moisture of 3 (Fig 2, p. 8) will shiftthecurves uptheequivalentof 1 ecozone, and a topographic moisture of 7 will shift the curves down 1 ecozone. Once the probable series (zone) is predicted from these curves, use Figure 9(p. 17) to get a first approximation of the plant association by plotting elevation and ecozone on the graph. Find the associa-lions closest to this point. They are the most likely plant associations to occur at this site.

Next go to the environmental ordination for each series (e. g. Figure 12 p. 24 for the Western Hemlock Series). The X axis In this case is an integration of topographic moisture (p.8) and ecozone (p. 9). Use the equation In the figure caption to calculate a Moisture Index Value (MW) for the site. Plot MIV against elevation on Figure 12 and locate the associa-tion closest to this point.

Next use the mean envi ronnie ntal values table for the appropriate series (e.g. p. 25 for the

Western Hemlock Series). Compare the mean elevation, aspect, slope, topographic moisture and ecozoneforeach association with the site being identified. Identify about 501 the most likely plant assocIations. Go to each type description and look at the map of plot loca-tions and compare the site characteristics with the plot frequency diagrams for each associa-tion. Some candidatetypes can be discounted if they fall outside the range of sampled data.

By now a list of 2-5 most likely associations should have emerged. Lastly, compare the number of plots for each of these candidate associations to help rank these by which ones are most abundant In the landscape. This approach cannot establish the identity of the site but can identify which plant associations are most likely to occur there.

HOWTO USE THE KEY

To use the keys, evaluate the age, stocking and disturbance history of the community in question. If the community is older than 150 years and Is normally developed, go directly into the key. If not followthe instructions atthe top of the key or see Method 2 (p. 3). Once in the main part of the key, read each lead as a question. The statement "Salal 1 0%" should read "is salal1 0%?". If so, read onto the right in the key, If not, read down to the next lead Immediately below. The first entry in the main part of the Western Hemlock Key is "Skunkcabbage 5%". if this statement is true, then read on to the right Le. to "TSHE/ LYAM". If it is false read down to the next lead i.e. "Swordfem 35%". In this format, the second entry in the dichotomy is omitted. If the second entry were present, it would say "not as above" and the key would direct the reader to an entry down the page.

METHODS FOR ESflMATING COVER

Cover Is the percent of an area which is occupied by the crowns of an individual spe.

cies. To determine the area occupied by an individual plant, mentally connect the outer portions of the crown wtth a line, thus making a polygon. Do not subtract for small areas between leaves or gaps between branches.

Project this polygon to the ground as If It were a solid shadow. Determine the area of this shadow' and then determine the cumulative area of all the shadows of the plants of each species. Convert this area to a percentage of the plot. This is percent cover.

There are numerous ways to estimate cover of a species on a plot. First determine the size of the plot. A 1/10th acre plot (4356 sq. ft. or

37.24 ft radius) works well for most young stands. Mark the plot boundary in at leastone place. Begin by choosing one of the dominant species on the plot and using one or more of the following methods, starting with 1.

Estimate whether the species covers less than 1/4 or more than 3/4 of the plot. If the species Is greater than 75%, use methods 5 and 6. if the species is between 25%-75%use methods 3, 4, 5 and 6. If the species is less than 25% then use methods 2, 3, 4 and 7.

Measure or estimate areas which are 1% (3.724 ft radius) and 10% (11.78 ft radius) of the 1/10 acre plot. Many types key out based on a species cover of 10%, so this is a critical area. Mentally try to fill the 10% area with plants so that their crowns don't overlap.

Determine how much of the 1 0% area is unfilled or estimate how many 10% areas could be filled. For species with low cover In the plot, it is often useful totryto mentallyfill the 1% area with plants. If there are still plants left over, fill another 1% area, and so on.

Measure the actual area covered by indi-vidual plants or clumps. This works well for large or clumpy plants such as vine maple or trees. Forexample, given a large clump of vine maple, measure a typical radius, convert to area, and then to percent of the plot. (If the radius = 9.5 ft, then (3.1417 x 9.5 x 9.5=284 sq ft), then convert to percent of the plot (284 sq ff/4356 sq ft) = 6.5 percent cover].

Measure the size of a typical individual of a species and then count the Individuals of that species. This works well for small to medium-sized plants such as ewordfeni or beargrass.

If a typical swordfem on a plot has a radius of.

2.6 ft, and there were 24 plants. ((2.6 x 2.6 x

3.1417 x 24 plants)=(509.71 sq ft/4356 sq It)

11.7 percent cover].

Estimate the area notcovered by a specIes.

Use this method when a species has more than 75% cover. Use methods 2, 3 or 4, but apply them to areas not covered by a species.

This often works well for dense salal.

Divide the plot Into quarters or halves If the species is very unevenly distributed or if the plot is large. If you divide a plot into quarters, estimate each quarter separately, then aver-age the four quarters together. If most of the plants of one species occurs In one of the quarters, mentally try to fill in the holes with plants from the other quarters.

Use a point Intercept method. This Is a time consuming but reliable method for precise estimates of cover. It Is most usefulforspecies which are small or irregularly distributed in the plot, but can be used for any species. Ideally, a grid would be used to evenly distribute about 500 points across the plot. AS X 3 foot grid on a 10th acre plot would give 484 poInts. in practice It is more convenient to use measur-ing tapes stretched at 10 foot Intervals with sampling intervals of 1 footalongthetape. The procedure is to stretch one tape across the center of the plot along the contour. This gives a length of 74 feet, or 74 potential sample points. Identify each species encountered at each 1 foot mark along the tape. Tally the occurrences by species. Lay additional tapes parallel to the first at 10 foot intervals up and down the slope. Count the number of occur-rences by species and divide by the total number of points. Multiply by 100. This gives a precise estimate of the cover of each species on the plot. This method is often used to check or verify other methods.

Classification and vegetation modeling.

The purpose of a vegetation classification such as the one presented in this book, Is to describe the kinds of vegetation that occur over a landscape in both time and space.

Variations overspace are mostly related to the environment, and variations over time are related to successional and climatic changes.

The potential or climax successional stage is used as a benchmark for naming and compar-ing the basic units of the vegetation. Since vegetation is the major component of the ecosystem, and this kind of model also relates soil, climate and animals to the vegetation, this approach can be interpreted as a vegetation-based ecosystem model.

Classical anaiysis procedures were used to develop this classification of potential vegef a-tion. Initially, cluster analysis was used to search for mathematical similarities among groups offloristicailysimilarcomjnunft. Then association tables were constructed which arranged sampled stands based on similari-ties of dominant and associatedspecies. This was relatively simple and the analysis would have ended at this point If all communities were In the same stage of ecological succes-sion, the climate had been staticduring the life of these communities and the area sampled was uniform in climate and history. However communities change significantly over their developmental life, and the environment var-ies over the landscape and has changed over time. Because of this complexity, the proce-dures used to finish the classification are more like modem modeling than they are classical vegetation classification. The outcome of this approach is a model (rather than simply a classification) of vegetation, which describes the different kinds of vegetation, the various stand conditions and stages of succession, and their relationships to the environment

Since this classification is a model and there-fore an invention of the ecologist, the scale and

ECOLOGICAL CONCEPTS

resolution used by the model builder Is Impor-tant to understanding the classification. How finely does one dMde the mosaic of vegetation and what criteria are used to place the bound-aries between one type and another? The basis for these standards is that one must be able to relate the classification to perceived elements of the environment and the scaie must be relevant to the management of the ecosystem. To help resolve these questions, two standards were applied: 1) the variation of fioristic and environmental parameters should be significantly less within type than between types, and 2) that splits in the classi-fication not go beyond what Is perceived to be noise" or unexplained variation in the type statistics.

The classification and keys presented here apply to forest vegetation in mature and old-growth stages of succession, and reflect the potential vegetation for a site. The potential vegetation, therefore, Is the referencepoint for describing successlonai relationships and cor-relations between vegetation and environment.

This classification Is consistent with and part of the widespread potential vegetation hierarchy represented in Hall (1988) and Drlscoll et aL (1984).

The classIfIcation hierarchy. The classifi-cation hierarchy used here is represented by 5 levels of organization. They are, In Increas-ing order of resolution: Class, Formation, Se-ries, Plant Association Group (PAG) and Plant Association (PA). There are 5 Classes of vegetation represented on this Forest. They are Forest, Shrubland, Dwarf-shrubland, Herb and Cryptogam. In each case the name Identifies thetailest ordominant element of the particular class. WithIn the Forest Class we recognize three Formations, two of which are described in this book. They are: 1) Temper-ate Evergreen Forest, and 2) Subalpine Ever-green Forest. A third, the mosaic of forest Islands and subalpine meadows (Parkiand) will be covered with the non-forest ciassiftca-tion in a later volume. The Temperate Ever-green Forest Includes the Western Hemlock and Silver Fir Series. The Subalpine Ever-green Forest includes the Mountain Hemlock and the Subalpine Fir Series. Within each of these forest series are 1-8 plant association groups and 1-25 plant associations (see p.

16). The plant association is the finest level of resolution of the vegetation classification that we recognize here. In this guide, the series are arranged ecologically, approximating an envi-ronmental gradient from low elevation and warm, to high elevation and cold, beginning with the Western Hemlock Series, followed by Silver Fir, Mountain Hemlock and lastly the Subalpine Fir Series. Plant associations are presented alphabetically by scientific name acronym within each series.

Ecological successIon. Ecological succes-sion Is the term used to describe the natural processes of change overtime. Changes are often described in terms of species composi-tion, size or structure of plant communities.

Changes may be due to growth of individual plants, replacement of one species or cohort by anoher, competition between organisms, or the effects of weather or climate, and may be influenced by composition or conditions inheritedfromapreviousstage. Succession is often characterized by stages of development.

For forests, these are often described as herb, shrub/seedling, young tree, mature tree, old-growth and climax. More appropriately, how-ever, succession is viewed as a continuum over time, as changes are gradual, and no distinct stages are readily defined. Early stages of succession are often simplerin structure but not necessarily less complex in species diver-sity than older stages.

Climax stage of succession. The hypotheti-cal end point of succession is called the climax.

The climax stage is stable in regard to species composition and structure, and shows no evi-dence of changing. It is sometimes simpler in species composition and structure than earlier stages and shows a great deal of vertical and horizontal structural variability. Some com-munities in ourareatake on the characteristics of a climax community, expressing a full range of age classes and a large degree of structural diversity. However, climax should be viewed as a concept ratherthan something necessar-ily concrete or finite.

Potential vegetatIon. The potential for a site is the projected climax vegetation. Species that can or do exist on a site are projected to a future stablestate condition based on repro-ductive capability and competitive interactions of the species. This projection assumes that any changes In competition or structure an due to internal interactions and not due to climatic or other external conditions. The potential vegetation, therefore, Is an Indicator of the current climate and site conditions, and the potential for vegetative development.

Vegetation SerIes. Series are taxonomic units which are aggregates of Plant Associa-tions with the same climax indicator tree spe-cies. The vegetation zone isa similar concept except that It refers to the land area where a particular series occurs.

Plant Association Groups. Plant Associa-tion Groups are aggregates of Plant Associa-tions based on similarities in floristics, environ-ment and productivity.

Plant Associations. Plant Associations are the basic units of vegetation. The term refers to all successional stages of development and growth of one type of vegetation. The name is based on the potential or late-successional stage and includes the name of a ciimax tree species and one or two diagnostic ground vegetation species. The name of the Plant Association includes the name of the series to which it belongs followed by a slash ("1') and the diagnostic ground vegetation species each separated by a dash "-" e.g. Silver Fir/Salal- Oregongrape.

Topographic moisture is a concept used to describe and analyze the movement or redis-tribution of water by gravity through the soil and bedrock. For any mountain slope, precipi-tation falls more or less evenly as snow or rain.

Any unevenness of precipitation Is due mostly to wind and the orographic effect of moun-tains. However this effect is small relative to the redistribution of wateronce it is Intercepted by the ecosystem. As precipitation Is ab-sorbed by litter or soil, it is immediately af-fected by the downward pull of gravity. The water In the soil that is free to move is therefore redistributed downward from ndgetops, steep slopes and convex surfaces to lower slopes, toeslopes and valley bottoms (Figure 1). The resuft of the redistribution of soil water by gravity is called "topographic moisture". We use a scale from 1-9 to quantify the relative effects of this redistibution of soil water, where a "1" represents a very dry site where water immediately begins moving downhill. At the other extreme is code "9" which represents a body of open water. Code 5 represents a modal site where the effect of topography

TOPOGRAPHIC MOISTURE

Figure 1. Water moves downslope under the effect of gravity.

results in neither an accumulation or deficit of soil water. Codes 3 and 4 are dry forest sites and codes 6 and 7 are moist forest sites. This coding system is Illustrated in Figure 2.

Figure 2. The topographic moisture scale relative to a schematic landscape.

Ecozones are areas of land with similar envi-ronments, and are defined by the elevation of the lower limit of the Silver FirZone. The Silver Fir Zone is the collective area where silver fir, or silver fir and western hemlock are the potential or climax tree species. It Is a band about 1000 feet high and occurs throughout the Forest. Figure 3 shows the relationship of the Silver Fir Zone (ABAM ZONE) to the Western Hemlock Zone (TSHE ZONE) below and the Mountain Hemlock Zone (TSME ZONE) above, in the area defined as Ecozone 10 (Fig.

4), the Silver Fir Zone is first encountered (on modal sites) at about 2700 feet on northeast aspects and at about 3200 feet on southwest aspects. The aspect-elevation curves forthe lower boundary of the Silver FirZone are given in Figure 5. This set of curves defines the range of ecozones found on the Forest.

ECOZONE 10

2OOO

1000.

TSME ZONE

TSHE ZONE

O 60120180240 300360

ASPECT

Figure 3. Aspect-elevation curves for the Western Hemlock, Silver Fir and Mountain Hemlock Zones, in ecozone 10.

ECOZONES

The ecozone curves are based on the modal site conditions for a mountain slope. This corresponds to mesic topographic moisture values of 4, 5 and 6 and to iandform features other than moist valley bottoms or cold air drainage. The Sliver Fir Zone can extend to lower elevations in cold air drainages and higherelevatlons on ndgetops orsteep slopes.

The lower boundary of the Silver Fir Zone can deviate from these aspect-elevation curves by 200-300 feet in such areas, and byas much as 500 feet In extreme topographic positions.

Maps of ecozones are given in Figure 4. Lines on these maps mark the boundary between each ecozone. The map of ecozones can be used to Interpret a broad moisture-related environmental pattern across the Forest. Af-ter mapping the ecozones, a correlation was discovered with precipitation. Ecozone 5 may have 180 inches of precipitation or more, depending on elevation. Ecozone 13 usually has less than 80 inches. The vegetationzones shift progressively higher In elevation in the drier ecozones. The upper boundary of the Silver Fir Zone for each ecozone is shown in Figure 6. The lower boundary of the Mountain Hemlock Zone is given in Figure 7. The upper boundary of the closed forest Is represented by the lower boundary of the Parkland Zone in Figure 8.

The pattern represented by ecozones can be used to interpret otherenvironmental relation-ships across the Forest. The distribution of many of the plant associations are correlated to this pattern. Some are more abundant in wetter ecozones, while others occur much more frequently in the drier ecozones. This relationship is depicted in the ecozone histo-grams given for each plant association. Fire history, wind disturbance history, and timber productivity as well as many other ecologically related values are well correlated with these ecozones.

z ABAM ZONE

5000- PorkInd Zone

FIgure 4. Ecozones of the Mt. Baker-Snoqualmie National Forest. Page 10 Is the north half of the Forest, page 11 Is the south half of the Forest. Ecozone 5 represents the wettest part of the Forest and Ecozon 13 represents the driest area.

Figure 4 (continued).

- LOWER BOUNDARY SILVER FIR ZONE

-r T

0 60

Figure 5. Aspect-elevation curves for the low9r boundary of the Silver Fir Zone. This also corresponds to the upper boundary of the Western Hemlock Zone. The curves are nurrered by ecozone (see map of ecozones on pp. 10 and 11). These curves apply to modal sites. On dry ridges the WHZ may extend higher, while In cold air drainages the SFZ may extend lower.

120 180 240 300

ASPECT

-0 5000-

LU --j

LU

UPPER BOUNDARY: SILVER FIR ZONE:

2000- I 0 60 120 180 240 300

ASPECT

Figure 6. Aspect-elevation curves for the upper boundary of the Silver Fir Zone. This also represents the lower boundary of the Mountain Hemlock Zone In Ecozones 5-11 and part of 12, and the lower boundary of the Subalpine Fir Zone in Ecozone 13 and part of Ecozone 12. The curves are numbered by ecozone (see map of ecozones on pp. 10 and 11). These curves apply to modal sites. On dry ridges the SFZ may extend higher, while In cold air drainages the MHZ may extend lower.

6000-

5000-z0 - I-w _J -lJ

4000-

LOWER BOUNDARY MOUNTAIN EfEMLOCK ZONE

2000 I

0 60

1O ' 10 ' 240 300

ASPECT

Figure 7. Aspect-elevation curves for the lower boundary of the Mountain Hemlock Zone. This also represents the upper boundary of the Silver Fir Zone in Ecozones 5-12. The curves are numbered by ecozone (see map of ecozones on pp. 10 and 11). These curves apply to modal sites. On dry ridges the SFZ may extend higher, in cold air drainages the MHZ may extend lower.

7000-

6000z0 I-w -J w

4000-

LOWER aOUNDARY PARKLAND ZONE:

I I j 1 J I -i I 60 120 180

ASPECT

240 300 360

Figure 8. Aspect-elevation curves for the lower boundary of the Parkland Zone. This also represents the upper boundary of the Mountain Hemlock Zone In Ecozones 5-11 and part of 12, and the upper boundary of the Subalpine Fir Zone In Ecozone 13 and part of Ecozone 12. The curves are numbered by ecozone (see map of ecozones on pp. 10 and 11).

Table 1. Plant Associations (PA) by Plant Association Group (PAG). Numbers In first column are the same as in Figure 9 on page 17.

Code Ecoclass Plant Assoclation PA Group No. of plots l5Oyears

Total plots

1 2271 CHSI32 TSHE/GASH-XETE I DvyGASH-XETE 12 17

2 2557 CHS622 1HE/VML-XETE 1 3 6

3 2381 CHSI4O TSHEIGASH-VAME 1 8 14

4 2384 Ci4SI41 TSHEIBENE-cHUE 1 13 18 5 2639 CHS626 TSHENAAL-BENE 2 MseGASH-BEI 14 17

6 2556 CHSI35 TSHE/GASI-4-SENE 2 41 104

7 2383 CHS1 31 MBS TSHE/GASH 2 19 48

8 2387 CHS138MBS TSHE/SENE 2 24 31

9 2388 CHS251 TSHEJAGCI-8ENE 2 13 33

10 2881 CHS6 25 TSHE/V$AL-POtJU 3 M..icPOUU 7 21 11 2838 CHSB21 TSHENAAt. 3 19 34

12 2635 CHFI33 TSHEIPOM U-GASH 3 9 27

13 2632 CHFI 34 TSHEPOMU-8ENE 3 22 74

14 2698 C11F250 TSHE/TTTR.GYDR 4 MostPOUU 8 10 15 2696 CI4FI 32 TSHE/POMU-TflR 4 53 231 16 2918 CH$513 TSHE/OPHO.A1FI 6 Wit 8hrub 21 61

17 2951 CI4MI11MBS T$HE/LYAM 6 1 7

18 3448 CFS5 54 A8AJ'JRI.AL-VAME 6 Co0IVAME 4 10

19 3431 CFS2 21 ABAMNAME.VASI 6 6 18

20 3700 CF5229 ARAMNAME-PVSE 7 DyVA1lE 22 22

21 3224 CFS2 11 ABAMNAME-XETE 7 9 27

22 3222 CFF3II ABkM/XETE 7 15 21 23 3445 CFS224 ABAMNAME 8 MIcVAME 7 32

24 3432 CFS2 22 ABAM/VAME-STRO 8 9 10

26 3752 CFF25O ABAM/ACTR 8 14 18

26 3449 CFS5 55 ABAM/RHAL-VAAL 9 DTyVAAL 3 9

27 3718 CFS2 I2MBS ABAMNUL 9 48 84

28 3719 CFS228 ABAMNAAL-PYSE 9 20 23

29 3447 CF$2 23 ABAMNANE-VAAL 9 23 43

30 3522 CFS2I4 ABAMNAAL-XETE 9 5 10

31 3363 CFS1 10 MBS ABAM/BENE 10 Ms&cGASI4-8ENE 27 33

32 3365 CFS1 54 ABAMASH-8ENE 10 0 14

33 3524 CF$2 16 ABAMNAAL-BENE 10 25 37

34 3525 CFS23OM8S ABAMNAAL.GASH 10 20 26

35 3753 CF5231 ABAMNAAL-POMU 11 WarmMoI.tPOMU 16 33 36 3715 CFS2 18 ABAMNAAL-CLUN 12 MoIst VML 191 294

37 3755 CFF1 54 ABAM/TIUN-STRO 12 29 35

38 3800 CFF45O ABAM/RUPE-BLSP 12 17 19

39 3853 40 3854 41 3857 42 3961

CFS226

CFS225

CFS3 52

CFM1 11

ABAMNAAL-TIUN

ABAMNAAL-MADt2

ABAM/OPHO-VAAL

ABAMA.YAM

13 W.tShrub

43 4408 44 4419 45 4411 46 4417 47 4416 48 4415 49 4414 50 4772 51 4171 52 4939 53 4776 54 4761 55 4732 56 4736 57 4778 58 4035 59 4930

CN$245 MBS

CMS254

CN$246 MBS

CMS352

CN$250

CN$251

CN$244

CN$351

CMS3 50

CMS353

CMS241

CN$253

CMF25O

CMS252

CMS255

C251

CMS45O

TSMENAME-XETE

TSMEIVAME-RUL.A

TSME/VAME

TSMERHAL-VAME

TSME,VAME-STRO

T$MEIVAME-VASI

TSMENAME-VAAL

TSME/RHAL-VAAI.

T$ME/PHEN-VADE

TSME/CLPY-RUPE

TSMENAAI

TSMENML-CLUN

TSMEIT1UN-STRO

TSME/VML.STRO

T$MENAAI.-MADI2

TSMEICABI

TSMEOPHO-VAAL

14 DryVAME 15 MssIcVA&IE

18 PHEM.VADE

17 MoIstVAAL 18 Wst8lirub

60 5331 CEF341 ABL.A2NASI 19 MusIc Hsrb 5 11

9 TSHE41

.42 14

. II

13'

I7

ECOZONES

.7

8 .. 3

-I ' I ' 1 1

Figure 9. Environmental ordination of plant asssoclations on the Mt. Baker-Snoqualmle National Forest. Associations are plotted by mean elevation and mean ecozone value and Identified by number. See List of Plant Associations (Table 1) and reference numbers on page 16.

6 7 8 9 10 11 12 13

Key to the SERIES

Potential vegetation dominated by continuous cover of trees'

Forest with at least 10% cover of Mountain Hemlock TSME SERIES p. 135 Forest with at least 10% cover of Silver Fir ABAM SERIES p. 69 Forest with at least 10% cover of Western Hemlock TSHE SERIES p. 19 Forest with at least 10% cover of Subalpine Fir ABLA2 SERIES p. 185

Potential vegetation otherwise Parkiand, Knimmholz or Non-forest Series

'See "How to Use this Guide" p.2 and "How to Use the Key" p.4.

WE STERN

HEMLOCK

SERIES

The Western Hemlock Series (Zone) covers about 500,000 acres (30%) of the Mt. Baker- Snoqualmie National Forest. it was sampled by 772 plots distributed throughout the Forest (FIgure 10). It occupies the lowland areas, up to about 1200 feet elevation in the wetter ecozones (Mt. Pilchuck area), and upto about 4200 feet elevation in the drier ecozones (Suiattle River area) (Figs. 4, 11). At higher elevations It is replaced by the Silver Fir Zone, except In Ecozones 12 and 13 (White River District), where it is replaced by the Subalpine Fir Zone. The Western Hemlock Zone in-cludes some of the most productive lands on the Forest. It also includes some low site lands on shallowsoils oron steepwell-drained slopes.

The productivity within this zone variesgreatly, mostly as a function of water and nutrient availability.

The climate of the Western Hemlock Zone is characterized as warm temperate to maritime.

Winter temperatures are cool and summer mperatures are moderate. Precipitation var-ies from over 130 Inches annually In the wetter areas of the Forest (Mt. Pilchuck) to about 60 kches in the rainshadow area (Crystal Moun-bin). In addition, fog and clouds can contrib-wte a significant amount of uprecipitatlonw In the rm of tree drip during the year. Snow' accumulations are low. Winds can play a significant ecological role, especially along the western part of the Forest.

The relative environments of the different plant associations can be inferred from the ordina-on In Figure 12 (p. 24). It shows the mean elevation plotted against the Moisture Index Value (MIV) for each type. For example, the TSHE/GASH..XETE PA is a high elevation dry type, while the TSHE/LYAM PA is a wet type of low elevations. The relationships shown in Figure 12 can be used to predict or verify the entity of a plot or stand.

Western Hemlock Series

Figure 10. Map showing all plot locations for the Western Hemlock Series on the Mt. Baker- Snoqualmie.N.F., total number of plots is 772.

Soils are typically warm and moist with a fairly well developed 0 horizon. The A horizon is often relatively low in organic matter and nitrogen. The average pH is higher than any other zone. Textures of these soils are fine to coarse but most commonly have manycoarse fragments. Topographically the soilsoccur on a wide range of slope positions spanning low to mid-elevations across the Forest. They occupy nearly all types of regolith and bed-rock, and the entire range of slopes from flat to very steep and slope positions from bot-toms to ridgetops.

The soil moisture regime may be udic (the rooting zone is usually moist throughout the summer), xeric (with a prominent summer drought), or aquic (saturated for extended periods). The soil temperature regime is frigid which indicates the rooting zone is cool (aver-age annual temperature less than 8 °C, with a greater than 500 summer-winter fluctuation), or mesic (the average annual temperature is higher than 8 °C).

The organic layercanbe mull, duff mull ormor.

Duff mulls occur slightly more often than mulls or mors, which have nearly the same fre-quency. The thickness of the 02 horizon in any one stand is quite variable. Causes of variation are climate, topographic configura-tion and stand history. Stands onginating following windthrow may inherit the previous 0 layer and the windthrowr, trees. Stands originating from fire may or may not inherit a previous 0 layer depending on the intensity of

80 -

60 -

40 -

20 -

46810 24 the fire. The fire frequency is greatest in the Western Hemlock Zone, and the fires tend to be hotter. In general, the thickest 02 horizons occur In the wetter ecozones where the soils are more moist andthe stands are older. While some of the thickest 02 horizons occur in the Western Hemlock Zone, they tend to be less dense than those in the Silver Fir or Mountain Hemlock Zones. 0 layers in hardwood stands in the Western Hemlock Zone are mulls. In these stands there is a thin to moderate 01 horizon and little if any 02. This probably reflects the ease of decomposition of most hardwood litter.

Most soils classify as andisols, inceptisols, spodosois or entisols. Andisois represent a new soil order which is usually dominated by volcanic ash. Spodosols are often weakly developed and the inceptisols mayshow signs of becoming spodosols especially in thewetter ecozones. E ntisois are poorly developed soils, such as flood or landslide deposits, or eroded surfaces.

The dominant tree species are Douglas-fir and western hemlock. Douglas-fir, a long-lived seral species, Is common except In the wettest ecozones. Western hemlock and western redcedardomin ate the climax stage of succes-sion. In the wetter areas of the Forest, western hemlock is the most competitive tree species in young stands, where it establishes readily after a clearcut or burn. Red alder is a major early seral species in the wetter western hem-lock plant associations, It is short-lived and is

80- 80- 80 - 60- 60- 60- 40- 40- 40- 20 _ 20- 20-

°i,i'ir-'---i 0 1 2 3 4 5 0 90 180 270 360

ELEVATION ASPECT TOPO-MOISTLJRE ECOZONE

Figure 11. Frequency of plots by elevation (1000 It), aspect, topographic moisture and ecozone.

usually succeeded by western hemlock or western redcedar. Bigleaf maple, black cot-tonwood, grand fir, iodgepole pine, western white pine, Pacific yew and Sitka spruce may also occur.

Root diseases of concern in this zone are laminated root rot, Armitiarta root disease, annosus root disease, and black stain root disease. Armiilarta root disease Is present throughout the zone. Armillaria may be a problem in Douglas-fir plantations, but Im-pacts should be minimal after3O years. Anno-sus root disease is a root, butt and stem decay of western hemlock throughout this zone. ft is common in old-growth and is present In re-sidual root systems left from logging. In additIon, ft readily colonizes thinning stumps.

In stands managed for western hemlock, annosus root disease may be a problem…