Table I4-Total bird-observation effort (number Table E-Total bird-observation effort (number 

of stations times number of visits) in the southern of stations times number of visits) in the southern 

Oregon Coast Range, 1985 Oregon Coast Range, 1986 

Stand Number of 

lUlIbe~ of stations 

Number 

of vi& 

Total 

effort 

Number of 

of stations 

Number 

of visits 

Total 

Lff”Iffort 

701 

702 

703 

704 

705 

706 

717 

718 

719 

721 

726 

728 

732 

733 

737 

740 

741 

742 

750 

75s 

760 

761 

764 

765 

806 

810 

812 

815 

817 

818 

819 

821 

835 

837 

838 

839 

840 

845 

847 

848 

860 

861 

062 

865 

870 

7 11 

12 7 

11 6 

12 7 

12 7 

12 7 

12 7 

12 7 

12 7 

12 7 

12 7 

12 6 

10 8 

12 7 

12 8 

12 6 

12 7 

12 7 

12 7 

12 7 

12 7 

12 7 

12 7 

12 7 

12 a 

12 8 

12 a 

12 8 

12 6 

12 9 

12 6 

11 6 

12 6 

12 6 

12 8 

12 6 

12 8 

12 8 

12 a 

12 8 

11 9 

12 6 

12 8 

12 6 

12 8 

77 

84 

66 

84 

84 

84 

84 

84 

84 

84 

84 

72 

80 

84 

96 

72 

84 

84 

84 

a4 

84 

84 

84 

84 

96 

96 

96 

96 

72 

108 

72 

66 

72 

72 

96 

72 

96 

;: 

96 

99 

72 

96 

72 

96 

702 

704 

705 

718 

719 

720 

722 

726 

733 

737 

742 

750 

755 

761 

764 

765 

a06 

810 

812 

815 

818 

819 

835 

838 

839 

840 

845 

847 

848 

860 

861 

862 

870 

12 

12 

12 

12 

12 

12 

12 

12 

12 

12 

12 

12 

12 

12 

12 

12 

12 

12 

12 

12 

12 

12 

12 

12 

12 

12 

12 

12 

12 

11 

12 

12 

12 

7 84 

7 84 

7 84 

6 72 

7 84 

7 84 

7 84 

7 84 

7 84 

7 84 

7 84 

7 84 

7 84 

7 84 

7 84 

6 72 

7 84 

7 84 

7 84 

7 84 

7 a4 

7 84 

7 84 

7 84 

7 84 

7 84 

7 84 

7 84 

7 84 

7 77 

7 a4 

7 84 

7 84 

141 
Table lbStandard detiatlons (and percent coeffkients of variation) for age-class means 

of densities of birds associated with old-growth forests In the southern Oregon Coast 

Range, 1985 

Species 

Brown creeper 

Chesmut-backed chickadee 

Hairy woodpecker 

Olive-sided flycatcher 

Pileated woodpecker 

Red-breasted nuthatch 

Red-breasted sapsucker 

varied thrush 

Western flycatcher 

Age-class 

Table 17-Standard deviations (and percent coefficients of variation) for age-class means 

of densities of birds associated with old-growth forests in the southern Oregon Coast 

Range, 1986 

Species 

Age-class 

Bmwn creeper 

Chestnut-backed chickadee 

Hairy woodpecker 

Olive-sided flycatcher 

Pileated woodpecker 

Red-breasted nuthatch 

Red-breasted sapsucker 

Varied dash 

Western flycatcher 

6.3 

9.3 

.5 

.3 

.O 

2.1 

.3 

L 

5.0 

15.4 

(39) 

(36) 

(125) 

(254) 

(75) 

WJ) 

(122) 

(38) 

142 
This page was intentionally left blank
Pacific 

Ocean j 

Roseburg 

:i 

0 1 20 

-- 

Miles 

c? Crater Lake 
Spring Bird Communities in the Oregon

Cascade Range

Frederick F. Gilbert and Rochelle Allwine

Authors

FREDERICK F. GILBERT is a professor and wildlife biologist, and ROCHELLE ALLWINE is an agriculture research

technician, Department of Natural Resource Sciences, Washington State University, Pullman, Washington 99164-6410.

Abstract

Spring bird communities in the western Oregon Cascade

Range were examined in 1984 and 1985 using point counts.

Three locations in the northern (Mt. Hood), central (H.J.

Andrews), and southern (Rogue River-Umpqua) portions of

this physiographic region were studied in 1984; in 1985, only

the central location was studied.

A total of 70 species was detected in 1984 in 56 Douglas-fir

stands ranging in age from 30 to 450 years. Species richness

values were similar for all locations in 1984 but increased

slightly between years at H.J. Andrews to 62 species (from

56) in 1985. Numbers of bird species did not differ across

the chronosequence (old, mature, young) or moisture gradient (dry, mesic, wet) in either year. The hermit warbler was

the most common species encountered in 1984, and the winter wren the most common species at H.J. Andrews in both

1984 and 1985.

Locational differences were found for particular species,

and the birds segregated out on the basis of elevation, latitude, and longitude and-where they shared the same

environments-on the basis of resource utilization, Species

associated with older stands, based on significant correlations

with stand age or old-growth stands in the chronosequence,

were the brown creeper, chestnut-backed chickadee, hairy

woodpecker, rufous hummingbird, varied thrush, and winter

wren. Two other species that were, with small sample sizes,

significantly associated with old growth in 1984 were Vaux’s

swift and the olive-sided flycatcher; the red-breasted sapsucker was found only in old growth. In 1985, the evening

grosbeak and western flycatcher were significantly associated

with stand age, and Cooper’s hawk, blue grouse, Hutton’s

vireo, red crossbill, and Vaux’s swift were found only in

old-growth stands.

In all, 17 species over the 2 years of study were significantly

associated with either the dry or wet portion of the moisture

gradient. Hutton’s vireo and Swainson’s thrush were found

only in wet stands in 1985. At Andrews, however, 14 species

changed their use of the moisture gradient from dry to mesic

or wet between 1984 and 1985.

The variability found among locations and between years in

bird detections suggested considerable flux in the way avian

species selected habitats and that environmental factors and

interspecific competition were important in modifying the

relations of avian species to habitat but not necessarily to

vegetative structure.

145
A few (5-6) species dominated the avifauna (>60 percent of

all detections), and most were common in all age-classes.

The only important old-growth associates may be some of

the rarer species, such as Vaux’s swift; spotted owl management prescriptions may accommodate the needs of these and

other species.

The vegetative structure in the young stands studied, which

were all fire-derived, had similar characteristics to that of the

old-growth stands. Thus, our findings are probably not representative of the avifauna that might be found in managed

stands of similar ages.

Introduction

The avifauna is the most visible component of the vertebrate

community. As such, it frequently is used to define and thus

indicate the total faunal support capacity of any given environment (see Graber and Graber 1976). Spring bird communities are the most stable and thus predictive because they

normally are composed primarily of breeders. Breeding

forest birds select and use habitat based on its structure (for

example, Anderson and Shugart 1974; Crawford and others

1981; De Graaf and Chadwick 1987; Karr and Roth 1971;

MacArthur and others 1962, 1966; Smith 1977). Although

this relation to structure is generally accepted, some researchers disagree (for example, Tomoff 1974, Willson 1974).

Old-growth Douglas-fir forests have structural characteristics

that distinguish them from younger and managed forests

(Franklin and others 1981; Franklin and Spies 1984; Spies

and others, unpubl. manuscript). Theoretically, determining

the structural components responsible for any given bird

species’ presence and abundance in old growth should be

possible. Management prescriptions to ensure its continued

existence could be developed or appropriate areas set aside,

as is being attempted for the spotted owl (U.S. Department

of Agriculture 1988a). Conceivably, these structural components, if known, could be provided in younger stands.

The objectives of this study were to document the spring bird

communities in the Oregon Cascade Range and to relate

particular species and associations of species to the age and

structural characteristics of unmanaged Douglas-fir forests.

Materials and Methods

The study was conducted at three locations on the west

side of the Oregon Cascade Range during 1984 (Mt. Hood,

H.J. Andrews (Andrews), and Rogue River-Umpqua (RogueUmpqua)) and Andrews in 1985. In 1984,56 stands extending along a chronosequence of 35 to 500 years (appendix

table 15) and dominated by a Douglas-fir overstory were

sampled (see frontispiece). Although mesic stands dominated

the young (30-80 years) and mature (80-200 years) categories, a moisture gradient (wet, mesic, and dry) was determined for the old-growth stands. Of the 56 stands, 46 were

used for chronosequence analysis and 28 for the old-growth

moisture-gradient analysis.

Birds were sampled using simple point counts (Vemer 1985).

Twelve stations separated by 150 m and at least 75 m from

the edge of the stand were established within each stand. Six

surveys were run for each stand in 1984 with the direction

being reversed for each survey (that is, 1 to 12, 12 to 1, 1 to

12 and so on) and observers were randomly assigned to minimize observer bias. Different crews were used at the three

locations, so despite common training procedures, observer

bias among locations was possible. Detections were summed

among stations and reported as counts of species per stand.

Only birds detected within 75 m of the station and species

detected on at least two sample days in a stand and in more

than one stand per location were included in the data

analyses. This strategy reduced the number of species from

70 to 38, suggesting that 46 percent of the species detected

were migrants, transients, or rare breeders at the three

locations. For the purpose of analysis, Empidonax flycatchers

denote dusky and Hammond’s flycatchers. Seven surveys

were done in 1985 in each of 15 stands at Andrews.

Vegetational data were collected for the forest floor, shrubs,

and trees, and physical characteristics of the 56 stands were

measured (appendix table 16). Each station was individually

described using a nested plot design with 500-m2

(13-m

radius) and 2000-m2 (25-m radius) sampling areas.

We used nonparametric analysis of variance (ANOVA) to

test the hypotheses that abundance of birds and species richness did not differ among age- or moisture-classes or locations. We used detrended correspondence analysis (DCA)

(Hill 1979a) to explore the relation between bird abundances

and habitat-classes or environmental variables. Detrended

correspondence analysis is an ordination technique that

arranges a matrix of species’ abundances (communities) by

samples (stands) in low-dimensional space so that the communities occurring in each stand are represented in space

along several axes. Thus, many components are reduced to a

few important ones and variability is reduced. Communities

with similar species composition and relative abundances

occupy positions near each other within the space described

by the first and second DCA axes. To determine whether

stands grouped themselves with respect to age, moisture, or location categories, a plot of the DCA axis scores

was examined to detect clustering of stands that might be

caused by these factors.

To classify sites into community phases, two-way indicator

species analysis (TWINSPAN) (Hill 1979b) was used. The

analysis, based on a multilevel, two-way partitioning of the

146
correspondence analysis axis scores, was used to classify

avian species into categories related to location and to the

stand age- and moisture-classes.

Bird species found to be associated with old-growth forests

from the TWINSPAN analysis were correlated with the vegetational and environmental variables to examine the relation

between individual bird species and individual environmental

features.

Old-growth-associated species based on significant, positive

Spearman rank correlations with stand age were examined in

relation to the vegetative structure of the old-growth stands

to identify which vegetational characteristics may have been

important elements in effecting the observed association.

Avian guilds were assembled (Manuwal and others 1987) to

examine intraguild habitat use.

In 1985, only the Andrews location was studied. The procedures followed were identical to the previous year, but as

noted earlier only 15 stands were sampled (appendix table

15). Data from 1984 were compared to those from 1985 in

the same 15 stands. Because of differences in species richI ness and relative abundances between the 2 years, these data

I could not be combined for analysis. Chi-square analyses (Zar

1974) were used to examine differences between years.

Statistical significance is reported at P < 0.05; means are

presented with standard errors.

Results

1984

A total of 38 different bird species were considered in 1984,

although the total data set consisted of over 18,000 detections

of 70 different species. Using the restructured data set, an

average of 15.8 species were detected per stand (range 10-

23). ANOVA indicated that neither abundance of birds detected (57.8 per stand in old-growth, 55.9 in mature, and

52.4 in young) nor the species richness values were related

to age or moisture (table 1). The mean numbers of species

in old-growth, mature, and young stands were 16.4 + 0.6,

16.5 + 0.7 and 15.2 + 0.6. Species numbers detected at the

three locations were not different (Rogue-Umpqua, 18.2 +

0.9; Andrews, 15.0 f+ 0.7; Mt. Hood, 14.3 + 0.7). The most

frequently detected species for all three sites combined was

the hermit warbler, although the winter wren was the most

frequently detected species at Andrews.

Nineteen species exhibited significant location effects by

being predominantly found at only one or two of the three

locations (table 2). More birds were detected at RogueUmpqua than at Andrews (average 62.5 + 2.7 vs 52.7 + 3.9

birds per stand per visit) (P < 0.05).

Table l-Analysis of variance for bird abundance and

species richness values compared to age and moisture

conditions, Oregon Cascades, 1984

Factors DF F- value Prob>F

Species richness x age 2 0.01 0.9876

Species richness x moisture 2 0.26 0.7728

Bird abundance x age 2 0.67 0.5163

Bird abundance x moisture 2 0.33 0.7191

Seven species were positively associated (P < 0.05) with

stand age and three negatively associated (table 3), based on

Spear-man rank correlations. ANOVA showed the chestnutbacked chickadee to be significantly associated with oldgrowth compared to young stands, and Steller’s jay and

the western flycatcher detections approached significance

(P < 0.06 and < 0.07, respectively). Two species with small

sample sizes significantly associated with old growth were

Vaux’s swift and the olive-sided flycatcher.

TWINSPAN analysis distinguished two groups of birds

(table 4), as indicator species. The first group was somewhat

associated with stands that were old and mature, and the second with stands that were young and mature. Correlations of

individual environmental components with DCA axis scores

showed 10 significant physical variables correlated with

DCAl (table 5). Foremost were elevation, latitude, and the

two fern-height categories. More (20) physical variables were

significantly correlated with DCA2, but only slope, largediameter, and medium-height snags of decay-class 4, berryproducing and deciduous shrubs, and needle-leaved evergreen

trees in the lower to midstory had r values > 0.50 (table 6).

Plots of DCAl versus DCA2 showed that age and moisture

stands did not cluster, although location did (figs. l-3).

The most commonly detected species were represented similarly in the different-aged stands (table 7).

Species with old-growth associations differed considerably in

relation to vegetative and physical factors of the environment.

Spearman rank correlations showed that the varied thrush

occurred significantly more than expected at locations with

little exposed soil or fine organic litter, few tree pits but

good ground cover by logs of decay-class 3 (R = 0.42;

P = 0.01). This species was found predominantly in western

hemlock (R = 0.52-0.67; P < 0.001) and, to a lesser extent, in

stands of very large western redcedars (R = 0.39; P < 0.03)

and Douglas-firs (R = 0.32; P c 0.02). The associations with

deciduous tree species were generally negative although small

alders (R = 0.28; P = 0.03) and maples (R = 0.34; P = 0.01)

were used preferentially.

147
Table 2cBIrd species showing significant (P c 0.05) association with location (based

on ANOVA), Oregon Cascades, 1984

Species F-value P Location influence0

Brown creeper 3.73 0.03 1 RRU>HJA

Black-headed grosbeak 5.42 0.007 RRU>MTH

Chestnut-backed chickadee 13.59 O.oool RRU>MTH HJA>MTH

Red-breasted nuthatch 41.62 0.0001 RRU>MTH RRU>HJA

Hermit thrush 11.80 0.0001 RRU>MTH RRU>HJA

Townsend’s solitaire 5.93 0.005 RRU>MTH RRU>HJA

Nashville warbler 8.53 0.0006 RRU>MTH RRU>HJA

Yellow-rumped warbler 5.41 0.007 RRU>MTH RRU>HJA

Western tanager 6.71 0.003 RRU>MTH RRU>HJA

Pine siakin 11.05 0.0001 RRU>MTH RRU>HJA

Dark-eyed junoo 9.17 0.0004 RRU>MTH RRU>HJA

Hermit warbler 3.46 0.039 HJA>MTH

Winter wren 14.26 0.0001 HJA>RRU MTH>RRU

Band-tailed pigeon 4.41 0.017 Only at MTH

Empidonaz flycatchers 18.35 0.0001 MTH>HJA RRU>HJA

Western flycatcher 20.48 0.0001 MTH>H JA MTH>RRU

Varied thrush 19.67 0.0001 MTH>H JA MTH>RRU

Golden-crowned kinglet 21.16 0.0001 MTH>H JA RRU>HJA

Wilson’s w arbIer 13.52 O.oool MTH>HJA MTH>RRU

Swainson’s thrnsh 4.06 0.023 MTH>RRU

a RRU = Rogue River-Umpqua National Forest; HJA = H.J. Andrews Experimental Forest;

MTH = Mount Hood National Forest.

Table 3Significant associations of bird species with stand

age, Spearman rank correlations, Oregon Cascades, 1984

Species Correlation coefficient Probability

Hairy woodpecker 0.439 0.0009

Varied thrush 0.410 0.0021

Western flycatcher 0.384 0.0041

Rufous hummingbird 0.356 0.0082

Stiller’s jay 0.304 0.0255

Brown creeper 0.297 0.0293

Winter wren 0.276 0.0430

American robin -0.449 0.0007

Evening grosbeak -0.323 0.0170

Hermit warbler -0.266 0.0520

The western flycatcher was detected primarily in areas with

down logs of decay-classes 3 and 4 (R = 0.34-0.41; P < O.Ol),

substantial fern cover (R = 0.43; P = O.OOl), deciduous shrubs

in the understory (R = 0.32-0.57), and with an overstory dominated by western hemlocks (R = 0.30-0.40; P c 0.02) and

very large western rcdcedar (R = 0.27; P c 0.05).

The hairy woodpecker was detected at sites with very large

Douglas-firs (R = 0.43; P = O.OOl), large and very large westem redcedars (R = 0.30-0.32; P c 0.02), large and very large

western hemlocks (R = 0.30-0.32; P = 0.02), and large Pacific madrones (R = 0.31; P = 0.02). The winter wren was

Table ABird species sorting out by stand

age, TWINSPAN analysis, Oregon Cascades,

l!x4

Species generally associated with older stands:

Northern flicker

Pileated woodpecker

Hairy woodpecker

Common raven

Brown creeper

Varied thrush

Pine siskin

Species generally associated with younger stands:

Blue grouse

American robin

Swainson’s thrush

Nashville warbler

Black-throated gray warbler

Townsend’s warbler

Wilson’s warbler

Western tanager

Black-headed grosbeak

associated with western hemlocks of all size-classes

(R = 0.44-0.54; P c 0.006) and very large western rcdcedars (R = 0.30; P = 0.02). The rufous hummingbird was

found at sites with large and very large western hemlocks

(R = 0.07-0.32; P < 0.04).

148
Table 5-Physical and vegetative variables slgnlficantly 

associated with DCAl (DECORANA) bird species, Oregon 

Cascades, 1984 (Spearman rank correlations) 

F.%?OI Rvalue P 

Elevation 

Latitude 

Short snags, decay-class 3 

Medium-tall snags. decay-class 5 

Fern (0-0.5-m tall) 

Evergreen shrub (0-0.5-m tall) 

Fern (0.5-2-m tall) 

Needle-leaved evergreen trees 

(super canopy) 

Logs. decayclass 2 

Logs, decay-class 3 

0.57 <o.CQOl 

-0.73 <o.ooOl 

0.30 0.024 

-0.39 0.003 

-0.51 <0.ooo1 

0.29 0.032 

-0.54 <O.OOl 

0.44 0.0008 

-0.32 0.018 

-0.37 0.005 

Table 6-Physical and vegetative variables significantly 

associated with DCAZ (DECORANA) bird species, Oregon 

Cascades. 1984 &wannan rank correlations) 

F&.ZOI Rvalue P 

Stand age 

latitude 

Slope 

Number of very large trees (04.5 m) 

Number of verv laree trees fO.5.2 ml 

Number of ver$ la& trees (2 m-n&tory) 

Medium-diameter, medium-tall’ snags, 

decay-class 5 

Medium-diameter, tall snags, decay-class 4 

Medium-diameter. tall snags. decay-class 5 

Large-diameter, medium-tall snags, decayclass 3 

Largediameter. medium-tall snags, decayclass 4 

Large-diameter. medium-tall snags, decayclass 5 

Berry-producing shrubs (O-o.5 m) 

Evergreen shrubs (O-O.5 m) 

Deciduous shrubs (O-O.5 m) 

Needle-leaved evergreen trees (2 mmidstory) 

Deciduous shrubs (all height-classes 

combined) 

Logs. decay-class 3 

Logs. decay-class 4 

Logs. decay-class 5 

0.33 0.015 

0.27 0.045 

-0.50 -ZO.OWl 

0.38 0.004 

0.29 0.038 

-0.39 0.003 

0.27 0.041 

0.34 0.009 

0.30 0.023 

0.45 0.0005 

0.50 CO.OcQl 

0.30 o.ozA 

0.62 rn.OQOl 

-0.37 0.005 

0.67 <o.COOl 

0.52 <o.OOOl 

0.58 <o.OOOl 

0.35 0.008 

0.42 O.oOl 

0.35 0.008 

Clear segregations of habitat associations occurred within 

two guilds, the aerial insectivores (western and Empidom 

flycatchers) and tree-seed eaters (evening grosbeak and pine 

siskin). Pine siskins were positively associated with sites 

with grand fir trees, and evening grosbeaks were negatively 

associated (table 8). Empidom flycatchers were detected at 

sites with deciduous trees and medium-large Douglas-fus, 

tree types either avoided or having no significant association 

with the western flycatcher based on Spearman rank correlations (table 9). 

149 
= H. J. Andrews 

q Mount Hood 

Table ‘I--The 6 most frequently detected bird species 

(combining Hammond’s and dusky flycatchers as Empidonar 

flycatchers) by stand age, Oregon Cascades, 1984 

Other guilds-for example, understory-ground insectivores 

and bark insectivores-were separately related to tree species 

and size-class. The only overlap in significant Speaman rank 

correlations for bark insectivores was for small sugar pine 

with the fed-breasted nuthatch and the red-breasted sapsucker 

(table 10). The large understory-ground insectivore guild 

showed more overlap, but clear separations of habitat association were evident between the hermit thrush and Swainson’s 

and varied thrushes, and between Wilson’s warbler and the 

winter wren and three other smaller members of the guild 

(tables 11-12). 

Table g-The tree-seed-eater guild and the signlfkant 

Spearmao rank correlations for tree specks and sizeclasses, Oregon Cascades, 1984 (correlation coefficient 

with probability in brackets) 

Tree species and size Evening grosbeak Pine siskin 

Medium Douglas-fir 

Small grand tir 

Medium grand fir 

Large grand fir 

Very large grand fr 

Small golden chinkapin 

Medium golden cbinkapin 

Small incensecedar 

Medium incense-cedar 

Large incense-cedar 

Very large incense-cedar 

Large wt?Smn white pine 

small sugar pine 

Medium sugar pine 

Large sugar pine 

vely large sugar pine 

Small California red fir 

Small hazel 

Small red alder 

co.37 (0.004) 

-0.36 (0.007) 

-0.37 (0.006) 

xl.31 (0.02) 

-0.10 (0.48) 

-0.08 (0.55) 

tO.05 (0.73) 

-0.29 fO.031 

-0.29 (0.03j 

-0.27 (0.04) 

-0.19 (0.16j 

-0.10 (0.48) 

4.18 (0.19) 

-0.24 (0.07) 

-0.28 (0.03) 

-0.23 (0.09) 

-0.05 (0.69) 

4.13 (0.35) 

+0.42 (0.001) 

AllO (0.48) 

+0.59 (0.oc41) 

+0.60 (0.0001) 

+0.53 (0.0001) 

+0.44 (0.0007) 

+0.26 (0.05) 

+0.34 (0.01) 

+o.so (O.owl) 

+0.47 (O.OOa2) 

+0.47 (0.0003) 

+0.44 (o.cm7j 

+0.36 (0.007) 

+0.29 (0.03)’ 

4.35 (0.008) 

+oso (O.ocm) 

4.47 (O.OOa2) 

+0.27 (0.05) 

a.46 (0.0004) 

-0.22 (0.10) 

Table 9Significant Spearman rank correlations of the aerial 

insectivore guild with tree species and size-classes, Oregon 

Cascades, 1984 (correlation coefficient with probability in 

brackets) 

Tree species and size 

Empidom 

flycatchers 

Medium Douglas-fx -0.28 (0.04) +0.27 (0.05) 

Large Douglas-fir -0.37 (0.005) +0.28 (0.04) 

Very large redcedar 4.27 (0.05) 4.07 (0.60) 

SmaU western hemlock +0.30 (0.02) -0.23 (0.09) 

Medium western hemlock t0.32 (0.02) a.33 (0.01) 

Large western hemlock Ml.40 (0.002) -0.28 (0.03) 

Very large western hemlock xl.40 (0.002) -0.46 (O.COO4) 

Small bigleaf maple -0.04 (0.75) 4.28 (0.04) 

Medium bigleaf maple +0.04 (0.79) a.30 (0.03) 

Small golden chinkapin -0.15 (0.26) +0.35 (0.01) 

Medium golden chinkapin a.21 (0.13) 4.31 (0.02) 

Medium red alder -0.05 (0.70) a.27 (0.05) 

Small Pac%c dogwood xK21 (0.13) t0.54 (0.0001) 

Medium Pacific dogwood 4.18 (0.19) a.46 (0.0004) 

150 
Table ltLS&nincant Spearman rank correlations with tree 

spies and sizes for members of the bark insectivore guUd, 

Oregon Cascades, 1984 

- 

-.41 

+.43 

- 

- 

+.3* 

- 

- 

- 

- 

+.32 

+.30 

- 

+.32 

+.30 

- 

- 

- 

-.34 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

+.32 

+.29 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

+.40 

- 

- 

+.33 

+.36 

- 

+.57 

+.I35 

+.&I 

-.30 

- 

22 

-58 

-.38 

-36 

- 

- 

-.33 

- 

+.35 

+.55 

+.63 

+A3 

+.51 

+A8 

+.69 

+&5 

+.fX 

+.54 

-27 

-.37 

+.39 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

+.36 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

1985 

More than 6500 detections of 62 species were made. Although the most species (40) were found in old growth, the 

differences (30 in mature and 35 in young) were not significant. Only 40 species were used in the other analyses, and, 

for this data set, 21.0 f 2.4 species were. found in old-growth, 

19.7 + 4.4 in mature, and 21.0 * 4.2 in young stands. Mean 

detections per stand did not differ between young, mature, 

and old-growth (24.0 * 7.0.27.0 + 15.1, 33.2 f 6.9). 

Species associated with old growth based on significant 

positive Speamun rank correlations with stand age were the 

evening grosbeak (R = 0.54, P < 0.04) and the western flycatcher (R = 0.55, P < 0.04). Five other species, Cooper’s 

hawk, blue grouse, Hutton’s v&o, red crossbill, and Vaux’s 

swift, were found only in old-growth stands. 

ANOVA indicated no significant associations with old 

growth. Similar analyses for these same stands in 1984 

showed only that the brown creeper was associated with oldgrowth stands though not significantly (ANOVA, P < 0.08). 

No significant differences were found based on the moisture 

gradient in either abundance or species richness values in 

1985. 

We found 21.5 + 4.7 species in wet stands, 20.5 * 4.5 in 

mesic stands, and 20.7 & 4.7 in dry stands: 37.3 + 11.8 

individuals were detected per stand in wet stands, 31.6 f 

21.3 in me&c. and 28.7 + 10.8 in dry. Blue grouse, ruffed 

grouse, and rufous hummingbirds were found only in the dry 

portion of the moisture gradient, and Hutton’s vireo and 

Swainson’s thrush were found only in the wet portion. None 

of these species was significantly (ANOVA) associated with 

the moisture gradient, however. Based on Spearman rank 

correlations, five species were significantly associated with 

older stands at Andrew in 1984: the brown creeper (R = 

0.77; P = O.oOOl), hairy woodpecker (R = 0.60; P = 0.006), 

pileated woodpecker (R = 0.52; P = 0.02). western flycatcher 

(R = 0.46: P = 0.04) and Steller’s jay (R = 0.49; P = 0.03). 

The hahy woodpecker selected both mesic and wet stands, 

the hermit thrush and pileated woodpecker selected mesic 

stands, and the winter wren selected dry stands (ANOVA). 

The five most abundant species in 1985 represented 65.9 percent of the detections. When the Empidonax flycatchers were 

added, 72.2 percent of the detections were accounted for, 

which compared with 76.1 percent for these same species 

in 1984 in the same stands (table 13). 

The hairy woodpecker and hermit thrush were the only species that showed any differences in their use of vegetative 

structure and physical environment between years--that is, 

changed from three or more positive or negative relationships 

to the opposite (Spearman rank correlations). 

Fourteen species had significant (chi-square) differences in 

relation to the moisture gradient in 1985 when compared to 

1984. The hairy woodpecker and winter wren shifted from 

the wet to dry portion of the gradient, and the numbers of the 

northern flicker, pileated woodpecker, and western tanager 

increased in either dry and wet stands when they had been 

most common in mesic stands in 1984. Nine other species 

shifted from dry to wetter stands in 1985 compared to 1984 

(table 14). The majority of the species showed consistent 

patterns of chronosequence and moisture-gradient use. The 

Empidom flycatchers were a good illustration of this 

consistency (figs. 4-7). 

151 
Table ll-SignUlcant eonlfer associations for larger members of the Loa under$toryground Insectivore @Id, based on Spearman rank carrelntlons, Oregon Cascades, 1984 

Tree species American H.ZXlllit Northem swainson’s Varied 

and size mbin thrush flicker thrush thrush 

Small Douglas-fir 

Medium Douglas-fir 

very large Douglas-fir 

Small grand fir 

Medium grand fu 

Large grand iir 

Small we~tem hemlock 

Medium western hemlock 

Large we~tem hemlock 

Very large western hemlock 

Small western redcedar 

Medium western redcedar 

Large we~tem redcedar 

Very large western redcedar 

Smdl sugar pine 

Medium sugar pine 

Large sugar pine 

very large sugar pine 

Small Pacific yew 

Medium Pacific yew 

Small incense-cedar 

Medium incease-cedar 

Large incense-cedar 

very large incensecedar 

- 

+.50 

-34 

- 

14 

-.42 

-29 

-27 

-28 

- 

- 

- 

19 

-.35 

- 

+.31 

- 

- 

+.46 

+.49 

+.47 

,29 - 

-33 

- 

- 

- 

- 

+.32 

+.42 

+.42 

- 

+.55 

+.48 

+A6 

+A4 

- 

- 

- 

- 

- 

+.27 

- 

- 

- 

- 

- 

- 

+.27 

- 

- 

+.26 

- 

,46 

-.40 

-32 

+.29 

+.38 

- 

+.31 

- 

-30 

-.34 

+.32 

-18 

-A6 

-54 

+.52 

+.57 

+.67 

+.66 

- 

- 

,27 

-32 

-.41 

-36 

- 

+.39 

-30 

-A6 

-A9 

-.43 

-a9 -.55 

-.49 -.54 

-.46 -.51 

-.35 -.35 

Table 12-Signlfhnt conifer associathns for smaller members of the low understory-ground 

lmectlvore @ld, based on Spearman rank correlslions, Oregon Cascades, 1984 

Tree species Dark-7E-d MacGillivray’s TOwnSad’S Wil.WlI’s Winter 

and sim junco warbler solitaire warbler wren 

small Douglas-fr 

Large Douglas-fir 

Small grand fn 

Medium grand fir 

Large g&d fir 

Very large grand fir 

Small western hemlock 

Medium we~tem hemlock 

Large wesrem hemlock 

Very large western hemlock 

Small western redcedar 

Medium western rdcedar 

Large western redcedar 

Very large western red& 

Small sugar pine 

Medium sugar pine 

Large sugar pine 

Very large sugar pine 

Small Pacific yew 

Medium Pacific yew 

small incense-cedar 

Medium incense-cedar 

Large incensecedar 

Very large incense-cedar 

+.53 

+.28 

+.43 

+.43 

+.39 

-.41 

-.49 

-.35 

-.28 

+.37 

+.27 

+.32 

+.31 

- 

+.42 

+.41 

+A4 

+.31 

- 

- 

+.32 

- 

+.37 

+.33 

+.35 

+.42 

- 

- 

+.41 

+.51 

+.35 

+A6 

-.36 

-.43 

-26 

,36 

-.27 

-.31 

- 

- 

- 

- 

-.30 -.49 

- - 

-.42 -.54 

-.35 -50 

+.45 

- 

+.51 

- +.54 

+.44 

+.37 +.51 

- 

- 

- 

- +.30 

12 -.5247 

-.38 -55 

-30 -51 

-.38 - 

-.30 

-.45 ,56 

-.44 -.56 

-.42 -.60 

-.36 -.44 

152 
Table 13-The 5 most common bird species plus the 

Empidonax flycatchers detected at Andrews in 1984 and 

1985 by point counts, Oregon Cascades (values are percentages of total detections) 

Table 14-Bird species that changed 

their use of the moisture gradient from 

dry to wet between 1984 and 1985, H.J. 

Andrew, Oregon Cascades 

Species Chi-square 

Western flycatcher (P < 0.002) 

Chesmut-backed chickadee (P = 0.06) 

American robin (P < 0.002) 

Hermit tish (P < 0.0001) 

Swainson’s thrush (P < 0.co01) 

Black-throated gray warbler (P < 0.001) 

Townsend’s warbler (P < 0.0001) 

Hermit warbler (P < 0.0001) 

Wilson’s warbler (P < 0.002) 

4 

oh ,,,,,, Xm,,” ,,,, ,,., ,,,,,,,,, ,,,, x ,,,, I 

Dry Mesic wet 

Moisture category 

Discussion 

The similarity in species richness values and bid abundances 

along the chronosequence parallels findings in the Oregon 

Coast Range (Carey and others, this volume), northern 

California (Ralph and others, this volume; Raphael and 

Barrett 1984). and southern Washington (Manual, this 

volume; Manuwal and Huff 1987). The very similar stand 

physiognomies probably accounted for this. The young and 

mature stands had considerable coarse woody debris both 

standing (snags) and on the ground (logs) (see Spies and 

others 1988). Most of the stands studied were fire-derived 

rather than a result of logging. Therefore, our findings do not 

answer the concerns of Harris and others (1982) that longterm declines in species richness might be expected if 

truncation of seral development occurs at 80 to 100 years. 

Even in naturally regenerated stands, large-diameter snags 

would be gone after the harvest unless specific provision was 

made for them in the stand prescription, or uneven-aged 

153 
management was used. Nyberg and others (1987) discuss 

the implications of such management activities to provide 

old-growth components in younger stands. 

Many authors, including De Graaf and Chadwick (1987), 

Johnson and Landers (1982), Kessler and Kogut (1985). 

Manuwal and Huff (1987), and Wetmore and others (1985). 

have shown the changes in bird species and populations that 

can be expected from logging or changing the sizes of trees 

in a stand. But few long-term studies provide information on 

whether old-growth-associated species such as those in oar 

study would persist 100 to 200 years from now in commercial forests without management intervention. The cavity 

nesters are the most vulnerable, but models are available that 

should ensure even their existence (Davis and others 1983, 

Thomas and others 1979). 

Breeding bird communities in the Oregon Cascade Range 

were dominated by a few, relatively abundant species. Odum 

(1971) suggests that a more stable environment tends to have 

dominance shared among more species. Stand age appeared 

to have little effect on the dominance values, possibly because Douglas-fir forests in the western Oregon Cascades are 

a seral stage on the way to a western hemlock climax. Spies 

and others (1988) postulate that such forests may not reach 

an equilibrium state until they are 1000 years old. The implication is that many of the avian species present are generalists rather than specialists in the still-evolving landscape, and 

the species have not had the opportunity to segregate into 

niches of more equal size (see Orians and Willson 1964, 

Slobodkin and Sanders 1969). Huff and others (1985), however, found only four dominant species in a 5%year-old 

hemlock stand on the Olympic Peninsula of Washington 

State; they noted that more species reached their highest 

populations in this forest compared to younger stands. 

Rufous hummingbird, brown creeper, chestnut-backed chickadee, hairy woodpecker, western flycatcher, varieil thrush, and 

winter wren were associated with older stands and showed a 

positive selection for sites with very large trees. Western 

hemlock, western redcedar, and sugar pine were as important 

as Douglas-fir, however. The rufous hummingbird is normally 

associated with forest edges, and the numerous small openings in the older stands probably created suitable edge conditions. The counting stations were at least 150 m from 

edges in the young and mature forests, so fewer rufous 

hummingbirds were counted in these younger age-classes. 

The brown creeper, chestnut-backed chickadee, and the hairy 

woodpecker are foliage or bark insectivores and thus 

exploited the surfaces of the large trees for foraging. The 

western flycatcher, as an aerial-sallying insectivore, has a 

feeding behavior that requires open space beneath, or in the 

canopy, which is best met in the older stands. The varied 

thrush is an understory-gleaning insectivore, and the complex 

understory characteristics of old-gmwrh stands probably 

favored this species. The particular patterns observed 

suggested that resource partitioning was occurring within 

guilds. More niche overlap was evident in the larger guilds, 

such as the low understory-ground insectivore guild, but 

species still separated oat, with bird size an obvious factor. 

Noon and others (1980) found considerable consistency in 

habitat preferences of Eastern forest birds despite acknowledging that local population-genetic differences, changes in 

habitat availability, or changes in the competitive environment could theoretically result in selection of different habitats. Those species that shifted between dry stands in 1984 

and wet stands in 1985 continued to use stands of similar 

structure. Thus, predictability of stand vegetative and physical 

characteristics was possible between years for these birds. 

The importance of weather cannot be overestimated. The wirter of 1983-84 was long, with deep snow cover, especially in 

the southern portion of the Oregon Cascades. Spring was late 

and wet in 1984 and insect populations may have been low, 

resulting in fewer nesting pairs. This wealher may have been 

responsible for the greater use of the dry portion of the moisture gradient in 1984 at Andrew. 

Two species (hairy woodpecker and hermit thrush) at 

Andrew used very different habitats between the two years. 

At the same time, population size of other species apparently 

changed (an order of magnitude in a few cases), with 10 more 

species meeting the abundance criteria for analysis in 1985 

than did so in 1984. Some changes in field personnel occurred between years, and although uaining techniques were 

equivalent, observer variability might have accounted for the 

major differences in detection rates (Verner and Milne 1989). 

154 
The cold, wet spring of 1984 may have depressed breeding

activity by some species. The hairy woodpecker may have

been influenced competitively in 1985 because other species

in its guild (pileated woodpeckers, red-breasted nuthatches,

red-breasted sapsuckers, and northern flickers), which compete either for foraging locations or nesting sites (Bull and

others 1986a), were much more abundant or participated

more in breeding in 1985.

What are the implications for Douglas-fir forest management

other than the obvious ones already mentioned? The variety

of vegetative structure in old-growth Douglas-fir stands favors a few rare species, such as the Vaux’s swift, that comprise a small component of the total community. These species may never be common even in stands aged 1000 years

or more. Instead of concentrating on old growth in unmanaged stands, perhaps we should examine much more closely

such factors as moisture, where obvious relations, if not

dependencies, exist. Old-growth trees are impressive to the

human observer but most bird species apparently make little

discrimination between trees 200 years old and trees 450

years old. The chronosequence can therefore end at the point

where sufficient vegetative diversity and structural elements

generate coarse woody debris and microhabitats for the rarer

species. Large tracts of old growth may not be necessary for

such mobile species as birds. Work is needed on minimum

viable population sizes for these rarer species and the extent

of habitat needed for their support. Intuitively, we suspect

the minimum area sizes for most species will be less than

those projected for the spotted owl (Anon. 1988), so that the

spotted owl habitat conservation areas may accommodate the

needs of these other birds. If that proves true, selection of the

spotted owl as an indicator species may have been fortuitous,

despite the current controversy.

Acknowledgments

The Oregon Cascades study was made possible by the contributions of many people, including U.S. Forest Service

peronnel. Effective field supervision was given by Wynn

Cudmore, and crew leaders Jim Reichel and Troy Cline at

Rogue River-Umpqua, Kathleen Fulmer at H.J. Andrews,

and Jeff Picton at Mount Hood in 1984. The 1985 crew

leader was Tony Fuchs. John Teburg, Dick Gilbert, Rich

Alldredge, and Betsy Piersone all assisted in data entry and

analysis. The hard-working field crews, primarily made up of

Washington State University wildlife students, were essential

to successful completion of the work.

This paper is contribution 120 of the Wildlife Habitat

Relationships in Western Washington and Oregon Research

Project, Pacific Northwest Research Station, USDA Forest

Service. 

155
Appendix

Table 15-Douglas-fir stands in the Oregon Cascade Range examined for vertebrate communities, Spring 1984 (age and moisture

condition of stand given where appropriate)

Typea Stand Forest-Ranger District Section Township Range Elev Lat Long Age Moisture

Mt. Hood

OG 5001

OG 5005

OG 5009

OG 5017

OG 5019

OG 5020

OG 5031

OG 5033

OG 5039

M 5041

M 5052

M 5048

Y 5050

M 5066

Y 5067

Y 5061

H.J. Andrewsb

OG lLw

OG

OG E

OG lQl3

OG

OG

OG

OG 2%

OG

M EC

M 1111

M 1037

M 1038

M 1066

M

Y

g$:

Y

Y E%

Rogue RiverUmpqua

OG 6006

OG 6001

OG 6003

OG 6021

OG 6028

OG 6017

OG 6031

OG 6032

OG 6039

OG 6046

Mt. Hood-Columbia Gorge 8 TlS

Mt. Hood-Columbia Gorge 2 TlS

Mt. Hood-Columbia Gorge 4&9 TlS

Mt. Hood-Columbia Gorge 22 TlN

Mt. Hood-Columbia Gorge 27 TlN

Mt. Hood-Columbia Gorge 29 & 32 TlS

Mt. Hood-Columbia Gorge 29 TlS

Mt. Hood-Columbia Gorge 26 TlN

Mt. Hood-Columbia Gorge 19 & 30 T1.S

Mt. Hood-Columbia Gorge 3 T2S

Mt. Hood-Columbia Gorge 29 TlS

Mt. Hood-Zig Zag 18 T3S

Mt. Hood-Zig Zag 33 T3S

Mt. Hood-Zig Zag 3 T4S

Mt. Hood-Columbia Gorge 34 TlN

Mt. Hood-Columbia Gorge 14 TIS

Willamette-Blue River

Willamette-Blue River

Willamette-Blue River

Willamette-Blue River

Willamette-Blue River

Willamette-Blue River

Willamette-McKenzie

Willamette-McKenzie

Willamette-McKenzie

Willamette-Blue River

Willamette-Blue River

Willamette-Blue River

Willamette-Blue River

Willamette-Blue River

Willamette-Blue River

Willamette-Blue River

Willamette-Blue River

Willamette-Blue River

Willamette-Blue River

Willamette-Blue River

32 T16S R5E 560 44.220 122.240

25 T15S R5E 815 44.220 122.150

30 T15S R5E 975 44.220 122.150

14 & 23 T15S R5E 793 44.250 122.170

25 T15S R5E 862 44.220 122.160

15 T15S R5E 902 44.250 122.180

25 & 26 T16S R5E 700 44.150 122.150

25 & 26 T16S R5E 950 44.130 122.150

26 T16S R6E 819 44.230 122.060

14& 11 T16S R5E 1000 44.260 122.170

3 T17S R5E 610 44.100 122.290

15 T16S R3E 490 44.160 122.430

24 T16S R3E 535 44.160 122.420

13 T15S R5E

15 T16S R3E 708

44.260 122.150

44.170 12.430

14 T16S R3E - 44.165 122.435

7 T17S R6E 600 44.100 122.150

2 T15S R5E 909 44.290 122.170

2 T15S R5E 1073 44.290 122.150

14 T16S R4E 520 44.160 122.300

Umpqua-Tiller

Rogue River-Prospect

Rogue River-Prospect

Umpqua-Tiller

Umpqua-Tiller

Rogue River-Prospect

Rogue River-Prospect

Rogue River-Prospect

Umpqua-Tiller

Umpqua-Tiller

23

24&z

13

31

25

31

36

12

27

T29S RlW 437 43.030 122.810 300

T32S R4E 1199 42.770 122.310 260

T3os R2E 1284 42.940 122.510 270

T28S RlW 566 43.050 122.780 250

T28S RlW 920 43.090 122.850 450

nos R2E 1189 42.930 122.550 270

T30S R3E 1123 42.900 122.510 430

T30S R2E 1110 42.910 122.510 270

T29S RlW 642 43.060 122.760 250

T28S R2E 737 43.100 122.560 250

R7E 610 45.490

R6E 641 45.510

R7E 907 45.490

R6E 940 45.550

R6E 937 45.560

R6E 557 45.420

R6E 580 45.430

R6E 980 45.560

R8E 1081 45.450

R5E 326 45.400

R6E

R6E 711

45.300

45.300

R8E 928 45.260

R7E 677 45.260

R6E 871 45.520

R6E 552 45.480

121.980

122.030

121.980

122.050

122.050

122.080

122.070

122.020

121.850

122.200

122.070

122.110

121.810

121.930

122.030

122.020

470

450

450

500

500

450

450

500

320

90

-

85

75

85

60

75

450

450

450

450

450

450

200

300

200

130

130

90

90

130

90

90

79

69

35

Wet

Wet

Wet

Mesic

wet

Mesic

Mesic

Wet

Wet

Mesic

Wet

Wet

Wet

Wet

Mesic

Dry

%

Wet

Wet

Mesic

Mesic

Mesic

z

%

Mesic

See footmtes on next page.

156
Table E-continued

Typea

Stand Forest-Ranger District Section Township Range Elev Lat Long Age Moisture

M 6052 Umpqua-Tiller 26 T28S RlW 943 43.080 122.850 120

M 6040 Rogue River-Prospect 26 T30S R3E 1092 42.930 122.430 90

M 6041 Umpqua-Tiller 32 T28S RlW 840 43.090 122.830 115

M 6044 Rogue River-Prospect 27 T31S R4E 1478 42.850 122.330 90

M 6047 Umpqua-Tiller 23 T28S R2E 698 43.100 122.590 180

M 6050 Umpqua-Tiller 25 T28S R2W 1052 43.090 122.860 120

M 6051 Umpqua-Tiller 5 T29S RlW 831 43.080 122.840 120

Y 6063 Umpqua-Tiller 1 & 12 T30S RlW 924 42.980 122.760 60

Y 6069 Umpqua-Tiller 5 T30S RlW 1072 42.980 122.780 60

Y 6099 Rogue River-Prospect T32S R4E 1428 42.820 122.350 75

a

 OG = old-growth, M = mature, Y = young.

b

 Andrews stands studied in 1985 are underlined.

c

 Andrews stands sampled for small mammals and amphibians with new pitfall grids in 1985.

Table M-Vegetation and site measurements for stations used in the point count bird surveys

Measurements on a 500-m2 area (13-m radius) centered at station).

Forest floor

1. Cover of logs by decay class (%) (>l0-cm diameter).

2. Cover of forest floor by various substrates: exposed bare rock, exposed bare mineral soil, fine organic litter (l0-cm diameter),

coarse organic litter (>l0-cm diameter), moss, lichen (Total = l00%.)

Vegetation characteristics

3. Cover of foliage by height interval and life form

a. Height intervals:

1. 0-0.5 m (500-m2 area)

2. 0.5-2.0 m (500-m2 area)

3.

4.

2.0 through midstory (trees and shrubs not entering main canopy) (measured on 2000-m2 area)

Canopy trees forming main canopy layer (2000-m2 area)

5. Super canopy trees (crowns extending well above main canopy layer) (2000-m2 area)

b. Life forms

1. Herbs

2. Graminoids

3. Ferns

4. Berry-producing ericaceous shrubs

5. Evergreen shrubs (including those in no. 4)

6. Deciduous shrubs (including those in no. 4)

7. Deciduous trees

8. Broad-leaved evergreen trees

9. Needle-leaved evergreen trees

Stand characteristics

4. Number and species of small-diameter live trees (l-10 cm d.b.h.).

5. Number and species of medium-diameter live trees (l0-50 cm d.b.h.).

6. Number by decay class of short snags (any d.b.h., 1.5-5 m tall).

7. Number by decay class of medium-diameter, medium tall snags (l0-50 cm d.b.h., 5-15 m tall).

8. Numbers by decay class of large-diameter, medium tall snags (50 cm d.b.h. and 5-15 m tall).

9. Number of recent tree-fall mounds or pits with exposed tree roots or mineral soil.

157
Table H-continued

Measurements on a 2000-m2 area (25-m radius centered at counting station)

A. Site characteristics

10. Surface water (presence/absence).

11. Type of water: I (intermittent stream); P (perennial stream); S (seep); 0 (pool/pond).

12. Rock outcrop (% of area) (presence/absence).

13. Exposed talus (% of area) (presence/absence).

14. Aspect

15. Slope (%)

B. Stand characteristics

16. Average height of dominant canopy trees.

17. Number and species of large, live trees (50-100 cm d.b.h.).

18. Number and species of very large, live trees (>lOO cm d.b.h.).

19. Number by decay-class of medium-diameter, tall snags (l0-50 cm d.b.h. and 15 m).

20. Number by decay-class of large-diameter, tall snags (>50 cm d.b.h. and 15 m tall).

158
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