Terrestrial Amphibian Communities in the

Oregon Coast Range

Paul Stephen Corn and R. Bruce Bury

Authors

PAUL STEPHEN CORN and R. BRUCE BURY are zoologists, U.S. Department of the Interior, Fish and Wildlife

Service, National Ecology Research Center, Fort Collins,

Colorado 80525-3400.

Abstract

We used pitfall trapping and surveys of down wood to sample

amphibian populations on clearcuts, young, mature, and oldgrowth forests on Forest Service or Bureau of Land Management land in the Coast Range of Oregon in 1984 and 1985.

We attempted to identify species or unique groups of species

associated with old-growth forests and structural components

of the habitat associated with abundance of amphibians. Pitfall traps captured 10 species and 1878 individual amphibians

in 45 forested stands and three clearcuts in 80 nights in 1984

and 1985. Western redback salamanders, ensatinas, and

roughskin newts were the species most commonly captured

by pitfall traps in both forested stands and clearcuts. Significantly more Olympic salamanders were captured in oldgrowth compared to mature and young forest stands. On a

moisture gradient in old growth, tailed frogs were more abundant in wet stands. Western redback salamanders were most

abundant on steep, rocky slopes, but few strong correlations

were found between amphibian abundance and habitat features characteristic of old-growth forests. We also sampled

536 logs in 18 stands and captured 328 amphibians (seven

species). Clouded salamanders (166 individuals, compared to

only 13 caught in pitfalls), and ensatinas (111 captures) were

the most common salamanders found associated with down

wood. Habitat preferences differed markedly. Clouded salamanders preferred large Douglas-fir logs with bark still attached, but ensatinas were found more often in well-decayed

logs. Based on amounts of down wood available in Douglasfir forests, we predict densities of clouded salamanders to be

highly correlated with stand age, and we expect this species

to be rare in intensively managed forests where down wood

is reduced.

Introduction

Amphibians and reptiles are the subjects of less than 10

percent of recent studies in ecology and wildlife ecology

(Gibbons 1988), yet they are numerically dominant in many

habitats and supply an important component of the energy

present in terrestrial and aquatic ecosystems. Hairston (1987)

estimated that energy present in salamanders in southern

Appalachian forests exceeds that of all other vertebrate

predators combined. Terrestrial salamanders typically have

stable populations that are suitable for assessing impacts of

disturbance (Hairston 1987).

Although the number of species of amphibians and reptiles

in Douglas-fir forests of the Pacific Northwest is low relative

to mammals and birds (Harris and Maser 1984), the herpetofauna are a distinctive and important component of the

vertebrate fauna (Bury 1988). Several species of amphibians

305
that occur in the Coast Range in Oregon, including the tailed

frog, Olympic salamander, Pacific giant salamander, clouded

salamander, DUnn’S salamander, western redback salamander,

and roughskin newt, are endemic to the Pacific Northwest

(Nussbaum and others 1983). Species adapted to a specific

habitat (Douglas-fir forests) might be expected to be sensitive to major disturbance of that habitat (logging). Studies in

northern California found differences among seral stages of

Douglas-fir and redwood forests in composition and abundance of the herpetofauna (Bury 1983; Raphael 1984, 1988c;

Raphael and Barrett 1984).

The Old-Growth Program was designed, in part, to gather

information on abundance of forest. amphibians and their

habitat preferences in Oregon, Washington, and California

(Ruggiero and Carey 1984). Pilot studies were conducted in

the Cascade Range in 1983 (Bury and Corn 1988a), and in

1984, vertebrate community studies were extended to the

Coast Range in Oregon. We used pitfall traps and hand

collecting (Bury and Corn 1987, Bury and Raphael 1983,

Campbell and Christman 1982) to sample the terrestrial

herpetofauna.

Pitfall trapping provides good estimates of relative abundance of many amphibian species, but it severely undersamples salamanders that are closely associated with down

wood (Bury and Corn 1988a). Time-constrained collecting is

effective for capturing individuals of these species, but the

technique produces potentially biased estimates of relative

abundance (Bury and Corn 1988a; Corn and Bury 1990). To

estimate the relative abundance of salamanders associated

with down wood, we searched uniform numbers of down

logs.

In this paper, we report the results of sampling amphibians

over a large area of the Coast Range in 1984 and 1985. Our

objectives were to:

l Identify amphibians associated with old growth by

determining the relative abundance of amphibians in

young, mature, and old-growth forests and across a

moisture gradient in old growth;

l Compare the abundance of amphibians to major physiographic and vegetation gradients, and to identify important habitat features that could be incorporated into

managed forests to maintain the diversity of amphibians;

l Contrast changes in abundance of amphibians between

old-growth forests and clearcuts as a first step in comparing managed and natural forests; and

l Estimate abundance of salamanders associated with down

wood, and describe differences among species in the use

of this microhabitat.

Methods

Study Areas

We studied 45 closed-canopy forest stands and 5 recently

clearcut stands in the Coast Range of Oregon (see frontispiece). Most stands were in the interior or on the eastern

flank (valley margin) of the Coast Range. Most of the stands

south of Eugene were on land managed by the Bureau of

Land Management (BLM) Eugene, Roseburg, and Coos Bay

Districts. Stands north of Eugene were on BLM (Salem

District) land, the Siuslaw National Forest (including Cape

Perpetua and Drift Creek Wilderness Areas), or land managed by the city of Corvallis (Marys Peak).

Stand Selection and Classification

Stands initially were selected to conform to a chronosequence

of four categories beginning with five clearcuts (<10 years

old), eight closed-canopy young stands (40 to 75 years), 10

mature stands (80 to 120 years), and 27 old-growth stands

(150 to 525 years). Most forest stands were composed of

naturally regenerated forests. Ages of stands were estimated

a posteriori by increment coring or by examining stumps in

adjacent clearcuts and roadsides (Spies and others 1988).

A moisture gradient (wet, moderate, and dry) was examined

for old-growth stands. The moisture classification was based

on a multivariate ordination of understory vegetation (Spies

and Franklin, this volume).

Pitfall Trapping

We installed 36 pitfall traps (6.41 volume, 15 m apart in a

6 x 6 grid) in each forest stand and three clearcuts in summer

1984. Details of trap construction and installation are in Bury

and Corn (1987) and Corn and Bury (1990, this volume a).

Before and after each trapping season, traps were closed with

a tight-fitting plastic lid. Each grid was placed at least 100 m

from the edge of the stand. This distance was a compromise

between the need to avoid edge effects and the need for a

field crew to be able to check the grids in five to seven

stands in one day.

We opened traps during the first week in October and trapped continuously for 50 days in 1984 and for 30 days in

1985. The same grids were used in both years. No water was

put in the traps because amphibians that drowned did not

preserve well. In practice, most traps accumulated some

water and some amphibians drowned. Traps were checked

about once a week; nine times in 1984 and five times in

1985. Any water that had accumulated was bailed out.

Amphibians taken from traps were killed in dilute chloretone

(a saturated solution of hydrous chlorobutanol in 95-percent

ethanol, diluted to about a 5-percent solution in water). After

identifications were verified, we determined the sex and

306
measured snout-vent length (SVL), total length, and mass.

Amphibians were fixed at least 24 hours in 10 percent formalin and then rinsed in water and preserved permanently

in 50 percent isopropyl alcohol. Amphibians that had

drowned were identified. sexed, and measured, and stomachs

and eggs (if any) were dissected and preserved. Specimens

were deposited in the National Museum of Natural History,

Washington, DC.

Vegetation Sampling

We sampled vegetation at nine points within the pitfall grid,

with the center of each sampling plot equidistant from four

pitfall traps (Corn and Bury, this volume a). We estimated

physiographic, coarse woody debris, live tree, and ground

cover variables (see appendix in Corn and Bury this volume

a) in two nested circles of 5.6-m radius (100 m ) and 15-m

radius (707 m2

 ). Percentage cover was estimated by eye.

Count variables were converted to density (number per

hectare).

Surveys of Down Wood

We conducted surveys of down wood in 18 stands (nine

old-growth, three mature, three young, and three clearcuts)

between 19 March and 10 April 1985. We searched 30 logs

in each stand (26 in one stand) with minimum diameter of 10

cm and minimum length of 1 m. Down wood was classified

on a five-point scale (Franklin and others 1981, Maser and

others 1979): (1) intact, recently downed trees; (2) intact

wood with loose bark; (3) bark beginning to slough off and

decayed sapwood; (4) loss of most bark and decayed heartwood; and (5) hummocks of wood chunks and organic

material. In each stand, we sampled equal numbers of logs

in three broader categories: 10 class 1 and 2 logs, 10 class 3

logs, and 10 class 4 and 5 logs. We recorded the slope,

aspect (to the nearest 459, tree species, length, diameter,

and decay-class of each log sampled. We then searched for

amphibians under the bark, in the wood, under the log, and

under bark on the ground adjacent to the log for a maximum

of 20 staff minutes (a staff minute is one person searching

for 1 minute). We recorded the length and diameter of the

portion of the log that was searched. For every amphibian

encountered, we determined the sex, measured SVL, and

recorded where found (such as under bark or in log) and the

depth inside the log. A series of voucher specimens was

preserved from each stand, but most amphibians were

released at the site of capture.

Logs were sampled as the crew traced an irregular path

through a portion of the stand away from the pitfall grid.

Logs were generally sampled as encountered, except that we

attempted to maintain about equal numbers in each decay

category as the survey progressed. Therefore, logs in abundant decay categories were occasionally passed in the search

for the next log in a less abundant category.

Statistical Analyses

Captures in pitfall traps-All statistical analyses were done

on a microcomputer using SYSTAT (Wilkinson 1988). Analysis of the chronosequence was originally intended to compare young, mature, and old-growth stands with similar

moisture conditions, and so was to exclude wet and dry

old-growth stands (Carey and Spies, this volume). Because

mature and young stands had much greater variation on the

moisture gradient than expected (Spies and Franklin, this

volume), however, only those old-growth stands that were

outliers on the moisture gradient were excluded. In the Coast

Range, all but two old-growth stands were retained in the

chronosequence analyses. Analysis of the moisture gradient

was restricted to old-growth stands.

We measured abundance as the number captured per 100

trap-nights. Pitfall traps may capture large numbers of youngof-the-year amphibians that are dispersing from breeding

ponds or streams (Bury and Corn 1987). To reduce the bias

introduced by the proximity of breeding habitats to grids, the

analyses of abundance used only adult tailed frogs (> 35 mm

SVL), red-legged frogs (235 mm SVL), northwestern salamanders (270 mm SVL), and roughskin newts (> 40 mm

SVL). Analysis of the abundance of individual species

depended on numbers captured. “Common” species were

species with more than 50 total captures, and differences on

the age and moisture gradients were analyzed by analysis of

variance (ANOVA) of (loge abundance + 1). “Rare” species

had fewer than 50 and greater than 10 total captures. Because

of the low sample sizes, we used all captures of these species

in both years. We put “common” and “rare” in quotes, because captures in pitfalls may not reflect the actual abundance of these species. For example, clouded salamanders

are rarely captured by pitfalls but commonly are taken in

time-constrained surveys (Bury and Corn 1988a). Differences

in numbers captured among age- and moisture-classes were

tested using the G-test (log likelihood ratio) for goodness of

fit (Sokal and Rohlf 1981).

Physiographic and vegetation variables-variables measuring percentage cover were arcsin-transformed (Sokal and

Rohlf 1981) before analysis. Count variables had large variances which were log-transformed. We computed Pearson

product-moment correlation coefficients between continuous

physiographic and vegetation variables and abundance of

common species. Associations between abundance and categorical physiographic variables were tested with ANOVA.

For rare species, we compared mean values of physiographic

and vegetation variables between stands where each species

was present or absent, or we computed log likelihood ratios

based on the presence or absence of amphibians and categorical physiographic variables.

307
We performed a principal components analysis using a subset

of eight vegetation variables (Corn and Bury, this volume a)

representing habitat features that have been used in ecological

definitions of old-growth Douglas-fir forests (Franklin and

Spies 1984, Morrison 1988, Spies and Franklin 1988). Three

factors accounted for 67.6 percent of the variance. Factor 1

(33.1 percent of variance) describes an age gradient, factor 2

(19.3 percent) was associated with down wood, and factor 3

(15.2 percent) was associated with shrub cover (Corn and

Bury, this volume a). We tested the abundance of common

species against these three factors using multiple regression,

and we tested the three factors against the presence or absence of rare species using multivariate analysis of variance.

Salamanders in down wood-The density in down wood

of each species of salamander (number per cubic meter) was

calculated as the number caught in each log divided by the

volume of wood sampled in each log. Mean densities in

down wood in each stand were calculated for each of the

three decay-categories (decay-classes 1 and 2, class 3, classes

4 and 5). We used a nested ANOVA (stands within forest

age-classes) to test whether density (log transformed) in

down wood of any species varied among decay-categories

or age-classes (old-growth, mature, and young).

We compared slope and log dimensions for sites where each

species was captured versus sites where each species was

absent with one-way ANOVA. For the categorical variables

aspect (four categories; N and NE, E and SE, S and SW, W

and NW), tree species (Douglas-fir versus other), decaycategory, and position (under bark, in log, or on ground;

either under log or under bark), we compared total captures

of each species among categories using log likelihood ratios.

We calculated predicted densities of plethodontid salamanders in 45 forest stands from the following formula:

3

D = E (di

 * Vi)

i=l

where D = number of salamanders per hectare, di = density

in down wood in decay-category i, and Vi

 = m

3

 of down

wood per hectare in category i (data provided by T. Spies).

If d varied among age-classes, then D was calculated using

the mean density in down wood for each age-class. Predicted

densities are minimum estimates, because we did not investigate salamander populations in other microhabitats.

Results

Pitfall Trapping

Abundance of amphibians--In 1984 and 1985 combined,

we captured 1797 individuals and 10 species of amphibians

in 45 forest stands (table l), and an additional 81 individuals

in three clearcuts. Only a few young-of-the-year northwestern

salamanders, roughskin newts, and red-legged frogs were

captured, but 28 juvenile tailed frogs (30 percent of captures)

were excluded from further analyses. Combined abundance

of amphibians was higher in 1985 (1.767 per 100 trap-nights)

than in 1984 (1.158 per 100 trap-nights; Wilcoxon signedranks test, P < 0.00l), but among individual species, only

ensatina was captured significantly more often in 1985

(0.728 per 100 trap-nights) than in 1984 (0.348 per 100

trap-nights; P < 0.001). The patterns of combined abundance

and abundance of ensatina across the age and moisture gradients were similar in both years, and because abundance

did not differ between years for any other species, all further

analyses used the combined abundance (captures in 1984 +

1985 with 80 nights of trapping [2880 trap-nights] per grid).

Five species (Pacific giant salamanders, ensatinas, western

redback salamanders, roughskin newts, and tailed frogs) were

considered common, with 61 to 737 captures. Four other species, including northwestern salamanders, Olympic salamanders, clouded salamanders, and Dunn’s salamanders had 13

to 45 captures and were considered rare. Fewer than 10 adult

red-legged frogs were captured, and the abundance of this

species was not analyzed.

Table l-Total numbers of amphibians captured by pitfall grids

in 45 forest stands in the Oregon Coast Range in 1984 and 1985

(grids were open for 50 days in 1984 and 30 days in 1985)

Species 1984 1985 Total

Salamanders”

Northwestern salamander

Pacific giant salamander

Olympic salamander

Clouded salamander

Ensatina

Dunn’s salamander

Western redback salamander

Unidentified

Roughskin newt

12 (15)

42

22

6

282

21

412

93 (97)

6 (7)

19

8

7

354

24

325

52 (61)

18 (22)

30

13

636

45

737

14: (158)

Frogs

Tailed frog 25 (44) 40 (49) 65 (93)

Red-legged frog 3 (4) 5 (6) 8 (10)

Total 911 (938) 839 (859) 1750 (1797)

a

 Only adults of northwestern salamanders (snout-vent length 270 mm),

roughskin newts (snout-vent length 540 mm), tailed frogs (snout-vent length

> 35 mm), and red-legged frogs (snout-vent length 235 mm) were used in

analyses of abundance. Total captures of these species am in parentheses.

308
Table 2-Mean abundance, mean relative abundance,” and percentage occurrence of eommcm amphibians MO total captures) in 

different forest types in the Oregon Coast Range 

Species 

Pacific giant salamander 

EIlSatina 

Western redback salamander 

Rough&in newt 

Relative abundance 

Percentage of stands 

Number/l00 TN 

Relative abundance 

Pwxntage of stands 

Number/l00 TN 

Relative abundance 

Percentage of stands 

Number/100 TN 

Relative abundance 

Tailed fxog 

Percentage of stands 

Number/100 TN 

Relative abundance 

One northern alligator lizard not listed in table 1 was captured in a clearcut in 1984. This contrasts with 120 reptiles 

captured by pitfall arrays (pitfall traps with drift fences) at 

30 sites in the Cascade Mountains of Oregon and Washington 

in 1983 (Bury and Corn 1988a). The lack of reptiles in 1984 

and 1985 reflects both the absence of drift fences (Corn and 

Bury 1990) and the trapping season (reptiles are less active 

in the fall after the rains begin). 

Variation on the chronosequence-Neither combined abundance nor abundance of any of the five common amphibian 

species were significantly different among age-classes of 

forest stands (table Z), but the patterns of relative abundance 

appeared to differ somewhat. The ensatina was the most common species captured in young and mahne stands, while the 

western redback salamander was the most common species 

in old growth. Roughskin newts were a higher proportion 

of captures in old-growth stands than in mature and young 

stands. Abundance of western redback salamanders was 

highly variable and not well correlated to frequency of occurrence. Mean abundance of this species was 0.812 per 100 

trap-nights in young stands and 0.532 per 100 trap-nights in 

old-growth stands, but western redback salamanders occurred 

in only 50 percent (4 of 8) of young stands compared to 88 

percent (22 of 25) of old-growth stands. The high mean abundance. in young stands was due to two stands with exnaordintily high abundance (3.056 and 2.014 per 100 trap-nights). 

Captures of two rare species varied among age-classes. ^. . . ,^. _. r ulymp~c sammnders (*lg. 1) were capture0 more often m 

old-growth stands than in mature or young stands (G = 9.30, 

2 df, P = 0.01). Pitfall traps captured 11 clouded salamanders 

in old-growth stands versus two clouded salamanders in 

young and mature stands combined (C = 4.25, 1 df, P = 

0.039). Numbers of northwestern salamanders (P = 0.97) and 

Dunn’s salamanders (P = 0.43) did not differ among 

old-growth, mature, and young stands (fig. 1). 

Variation on the moisture gradient-Tailed frogs (table 3) 

were absent from dry stands in old growth and much more 

abundant in wet stands than moderate stands (F = 10.5; 2,24 

df; P = 0.001). Ensatinas composed a higher proportion of 

captures in dry stands compared to wet stands, but this was 

probably a result of the lower number of species captured in 

dry stands because abundance did not vary significantly 

across the moisture gradient. Too few clouded salamanders 

were. captured by pitfall traps for analysis, but none were 

captured in dry stands. Captures of the other rare species did 

not vary significantly across moisture-classes (fig. 2). 

309 
Table 3--M&m abundance, mean relative abundance: and percentage occurrence of common amphibians (~50 total captures) on 

the moisture eradknt in old-umvth stands in the Oreeon Coast Ranee 

AU amphibians 

Pacific giant salamander 

EIlS&U3 

Western redback salamander 

Rough&in newt 

Tailed frog 

Numb-d100 Ti? 

Numbez/loO TN 

Relative &wmJmce 

Percemage of stands 

Number/100 TN 

Relative abundance 

Percentage of stands 

Number/100 TN 

Relative abundance 

Percentage of stands 

Number/100 TN 

Relative abundance 

Percentage of stands 

Number/100 TN 

Relative abundance 

Percentage of stands 

0 

Young Mature Old-growth Dry Moderate Wet 

Moisture-class 
Mean relative abundance (log scale) 

Old growth versus clearcuts-We captured seven species 

in three clearcuts (I?= 4.3 per stand) and nine species in 

three adjacent old-growth stands (Z= 4.7 per stand). Two 

species, northwestern salamanders and tailed frogs, were 

captured in old growth and not in clearcuts. No species 

captured in the clearcuts were absent from old-growth stands. 

Total abundance in old growth (1.25 per 100 trap-nights) was 

not significantly greater than total abundance in clearcuts 

(0.76 per 100 trap-nights, P = 0.40). Aside fmm the two 

missing species, the pattern of relative abundance was not 

very different in clearcuts compared to old growth (fig. 3). 

The ensatina, western redback salamander, and roughskin 

newt were the most abundant species in both old-growth 

stands and clearcuts. Newts had the highest mean relative 

abundance in clearcuts because they were the only amphibians captured in one clearcut (relative abundance = 100 

percent). 

Microhabitat associations-We compared abundance or 

occurrence of amphibians with physiographic variables 

measured at the pitfall grids plus stand age, latitude, and 

longitude. The strongest associations were with plethodontid 

salamanders. Dunn’s salamander occurred more often on 

steep slopes (F = 16.7; 1,43 df: P < 0.001). where exposed 

talus was present (G = 10.5, 1 df; P = 0.001). and in stands 

at higher latitudes (F = 8.23; 1.43 df; P = 0.006). Western 

redback salamanders were more abundant on steep slopes 

(r = 0.603, P < 0.01) and in stands with talus present 

(F = 18.D; 1, 43 df; P < 0.001). Stands where Olympic 

salamanders were present were older than stands where 

they were absent (F = 4.23: 1,43 df: P = 0.046). Roughskin 

newts were more abundant in stands at higher latitudes 

(T = 0.463, P < 0.01). but they were less abundant in stands 

with surface water present in the pitfall grid (F = 4.69; 1.43 

df; P = 0.036). Tailed frogs were more abundant in western 

stands (r = 0.505, P < 0.01). and northwestern salamanders 

occurred more often in eastern stands (F= 4.56; 1.43 df; 

P = 0.038). Ensatinas were less abundant on wanner (soutlfacing) slopes (r = -0.376, P < 0.05). 

Twenty of 32 vegetation variables were significantly associated with abundance or occurrence of one or more amphibian species (table 4). Few of the significant correlations were 

very large; most were between 0.3 and 0.5. One exception 

was the positive correlation between abundance of western 

redback salamanders and amount of ground cover by rocks 

(r = 0.566, P < 0.01). but this reflected the presence of talus. 

Mean rock cover was 1.12 percent where talus was present 

and 0.11 percent where talus was absent (F= 14.2; 1.43 df; 

P < O.Kll). Abundance of tailed frogs was correlated to nine 

vegetation variables, most of which were negative correlations to understory hardwood trees and shrub cover (table 4). 

This pattern probably reflects the absence of tailed frogs 

fmm dry old-growth stands, where the understory was more 

dense than in moderate or wet stands (Spies and Franklin, 

this volume). 

The tailed frog was the only species significantly associated 

with the three habitat variables generated from the principal 

components analysis (multiple r = 0.323; F = 6.53; 3,41 df; 

P = 0.001). Abundance was negatively associated with factor 

3 (shrub cover, P = 0.001) and positively associated with 

factor 2 (down wood, P = 0.016). but abundance was unrelated to factor 1 (age, P = 0.365). 

Salamanders in Down Wood 

We searched 536 logs (!i = 18 staff minutes per log), and the 

amphibians comprised seven species dominated by clouded 

salamanders (166 captures), ensatinas (111). and western redback salamanders (40). We also captured six Dunn’s s&manders, three rough&ii newts, one Pacific giant salamander, 

and one Olympic salamander. Reptiles were encountered in 

the three clearcuts. We captured six northern alligator lizards, 

two western fence lizards, one western skink, and one nortbwestern garter snake. All analyses involve the three commonly captured salamanders. 

Clouded salamanders were found in 110 logs, and the density 

was 1.48 per cubic meter of down wood (table 5). Significant 

differences in density were found among decay-categories 

(table 6); density was highest in class 1 and 2 logs and lowest 

in class 4 and 5 logs. Density of clouded salamanders in 

down wood did not vary significantly among age-classes. We 

found ensatinas in 82 logs, and the mean density was 1.30 

per cubic meter of down wood. Density varied significantly 

311 
Table 4-Significant assoclat~ ion 

variables measured at pitfall gri 

s between abundan& of cmnmon amphibians or occurrence of rare amphibians and vegetation 

ds (table 1) in the Orecon Coast Range 

Variable 

DLOGSC (Percentage cover) 

STUMP (Number,ha) 

MSNAG (Number/ha) 

CTREEM (Number/ha) 

BTREES (Number/ha) 

BTREEM (Numberfia) 

MDTREE (Percentage cover) 

MCTREE (Percentage cover) 

CDTREE (Percentage cover) 

CBTREE lPercentaee cover) 

CCI’REE ~Percent& mverj 

LITDEPTH (cm) 

SOIL (P,,,, cow) 

ROCK (Percentage cover) 

FORB (Percentage cover) 

GRASS (Percentage cover) 

FERN (Percentage cover) 

ESHRUB (Percentage cover) 

DSHRUB (Percentage cover) 

MSHRUB (Percentage cover) 

n acific gia 

alamande 

II) 

Xympic 

,lamand< 

Tr 

(- -1 

+ 

ailed 

iog 

Table S-Density (number/m3 of down wood) of clouded salamanders, ensatinas, and western redhack salamanders by age- and 

decay-class 

Species 

Old-growtha 

(266) 

M.%tuE Young Clearcut All 

(90) (90) (90) (536) 

l&2 0.61 1.98 1.43 0 0.87 

3 0.77 2.40 2.17 0.09 1.16 

4&S 1.26 3.19 2.40 1.60 1.84 

AU 0.88 2.55 2.00 0.56 1.30 

Western redback salamander 

’ The number of logs searched in each age-&w are in parenlheses. 

312 
Table 6-Nested analysis of variance (stands within age-classes)

of mean density (number/m3 of down wood, log-trans ormed) of s f

clouded salamanders, ensatinas, and western redback salamanders acre old-growth, mature, and young forest age-classes

and 3 decay-classes of down wood (1 & 2; 3; 4 & 5)

Species Factor df MSS F P

Clouded

salamander

Ensatina

Western

redback

salamander

Stands

Age-class

Decay-class

Error

Stands

Age-class

Decay-class

Error

Stands

Age-class

Decay-class

Error

12 1.110 1.85 0.039

2 0.059 0.10 0.908

2 3.081 5.13 0.006

429 0.600

12 1.530 2.64 0.002

2 2.318 4.11 0.017

2 1.844 3.19 0.042

429 0.579

12 0.6% 3.43 <0.001

2 0.434 2.14 0.119

2 0.475 2.35 0.097

429 0.203

both across age-classes and decay-categories (table 6). Density was highest in mature and young stands and class 4 and

5 logs, and it was lowest in clearcuts and old growth and

class 1 and 2 logs (table 5). Western redback salamanders

were found in 34 logs, and density did not vary significantly

among either age-classes or decay-categories (table 6). Mean

density of this species was 0.42 per cubic meter of down

Wood.

Habitat characteristics-logs where we found clouded

salamanders were larger (both diameter and length) than logs

where we did not find this species (table 7). Clouded salamanders were found in Douglas-fir logs more often than in

logs of other tree species (table 8). Logs with ensatinas

present were on flatter slopes than logs without ensatinas,

but the size of logs with and without this species did not

differ (table 7). Logs with western redback salamanders were

on steeper slopes than logs without redback salamanders

(table 7), but redback salamanders were also captured more

often where the aspect was to the west or northwest (table 8)

and logs were on flatter slopes (19 percent) compared to the

other three aspect categories (21-23 percent).

The strongest variation among species in use of microhabitats

involved the decay-class of down wood and the locations

occupied by salamanders in logs. Clouded salamanders were

captured most often in class 1 and 2 logs and least often in

class 4 and 5 logs (fig. 4, G = 33.6,2 df, P < 0.01). Captures

of ensatinas were opposite; they were most common in class

4 and 5 logs and least often in class 1 and 2 logs (fig. 4, G =

13.8,2 df, P < 0.01). Western redback salamanders appeared

to occur less frequently in class 1 and 2 logs (fig. 4), but the

differences among decay-categories were not statistically

significant (G = 5.16, 2 df, P = 0.08). Sites at each log where

Table 7--Characteristics of logs where salamanders were captured (differences between capture sites with and without each

species were tested with one-way ANOVAa

Log Log

Slope diameter length

Category (percentage) (cm) (m)

All logs (n = 536) x 20.6 45.1 9.8

SE 0.50 0.86 0.42

Logs with clouded

salamanders (n = 110) x 21.3 52.4** 11.2**

Logs with ensatinas

(n = 82)

Logs with redback

salamanders (n = 34)

SE

_

x

SE

x

SE

1.10 2.12 1.07

17.7* 44.7 9.1

1.17 0.94 0.45

26.1** 51.2 10.2

1.70 4.00 1.74

a

 * P < 0.05, *+ P < 0.01.

Table Number of captures of clouded salamanders, ensatinas,

and western redback salamanders by aspect and tree species

Western

All cloded redback

Variable Category logs salamander Ensatina salamander

Aspect N and NE 120 29 19 9

W and NW 131 53 22 18

E and SE 132 36 34 4

S and SW 144 45 32 9

G 6.02 4.16 10.31

P 0.11 0.24 0.02

Trees Douglas-fir 454 148 95 35

Othera

78 15 16 5

G 4.38 0.01 0.16

P 0.04 0.92 0.69

a

 Western hemlock (30). western redcedar (21), grand fir (10). hardwoods

(17).

salamanders were captured were characterized as inside the

log, under bark on the surface of the log, or in contact with

the ground. All three species showed distinct preferences

for specific sites in down wood (fig. 5, G = 71.2,4 df,

P < 0.001). Clouded salamanders were found inside the log

or under bark, but rarely in contact with the ground. Ensatinas

were captured most often inside the log, and they were

captured in contact with the ground more often than were

clouded salamanders. Western redback salamanders were

captured most often in contact with the ground. The mean

depth inside the wood of 88 clouded salamanders found

inside logs was 6.5 cm, and the mean depth of 64 ensatinas

was 7.9 cm, but the difference was not significant (Student’s

t = 1.30, P = 0.19).

313
Clouded salamander Discussion 

G 

Western redback salamander 

l&2 3 4&5 

Decay-class 

Species Associated With Old-Growth Forests 

Olympic salamanders were captured by pitfall traps more. 

often in old-growth stands, and stands where this species was 

present were older than in stands where it was absent. Welsh 

and Lind (1988, this volume) obtained similar results in 

Douglas-fir forests in northern California. Olympic s&manders arc closely tied to headwater streams and seeps (Bury 

1988, Nassbaum and Tait 1977). however, and they are not 

often captured by pitfall traps in upland settings (A&y and 

Hall, this volume; Bury and Corn 1987, 1988a; Gilbert and 

Allwine, this volume. c; Raphael 1988c). The best evidence 

that Olympic salamanders are associated with old-growth 

forests comes from the stream surveys of aquatic amphibians 

(Bury and others, this volume b). Density was four times 

greater in streams in old-growth forests than in streams in 

young stands. Abundance of Olympic salamanders was 

greatly reduced in streams in the Coast Range that flowed 

through logged stands (Corn and Bury 1989). possibly resalting from increased siltation. Olympic salamanders may 

be very slow to recolonize areas from which they have been 

extirpated (Bury and Corn 1988b). 

Other Coast Range amphibians that were sampled more 

effectively by pitfall traps showed little preference for old 

growth. This is in general agreement with data from the 

Cascades in Oregon and Washington (Aubry and Hall, this 

volume; Bury and Corn 198%; Gilbert and Allwine, this 

volume c), although Aubry and Hall (this volume) found a 

greater abundance of northwestern salamanders in oldgrowth stands in the Southern Washington Cascades. 

Ensatinas (Raphael and Barrett 1984, Welsh and Lind 1988), 

Del Nor@ salamanders (Raphael 1988c. Welsh and Lind 

1988) and black salamanders (Raphael 1988c) were more 

abundant in older Douglas-fir forests in northern California. 

One maior factor may be interferine with our abilitv to 

0” ground 

I” wood 

dctcrm~e the habitaipreferences o~amphibians: t&es!riaJ 

pitfall trapping largely ignores breeding habitats. A majority 

of the amphibian species we captured breed in water, either 

in cascading headwater s!xanu (tailed frogs, Pacific giant 

salamanders, Olympic salamanders), or in ponds or backwaters of streams (red-legged frogs, northwestern salamanders, Pacific giant &mit;ders, r&hskin newts). Most 

amphibians have poor dispersal ab%ties (relati& to bids and 

.Redback mammals), so upland habitat use by aquatic-breeding species 

II cncrtinm may be influenced heavily bv uroximitv to water. Most oitfaligrids were within a f&v i&xired m&s of a pew&l 

stream, but we have little information about the distribution 

of ponds relative to our grids. Plethodontid salamanders lay 

Percentage of captures their eggs on land where the embryos hatch into small 

replicas of the adults. These species do not require surface 

Figure-Lmstims ofdmdedralamanders,8lsatinas,andwestemrrdbaek water but may be tied to other habitat features such as talus 

salamanders captured during surveys of down wmd. slopes (Dumas 1956, Herrington 1988, Herrington and 

314