Larson 1985, Stebbins 1951) or large chunks of down wood 

(Aubty and others 1988, Bury and Corn 198%x, Whitaker and 

others 1986). 

Plethodontid salamanders--One goal of our surveys of 

down wood was to provide estimates of the density of salamanders strongly associated with down wood. Estimated 

numbers of clouded salamanders and western redback salamanders per hectare were strongly correlated to stand age 

(fig. 6) because of the snong correlation between volume of 

down wood and stand age (Spies and others 1988). Because 

numbers of these two species (per cubic meter of down 

wood) did not vary among forest age-classes, changes in 

numbers per hectare apparently were solely due to changes 

in the volume of down wood. Predicted abundance of 

ensatinas did not increase with the age of the forest (fig. 6) 

because the number (per cubic meter of down wood) was 

significantly lower in old-growth stands. The increased 

volume in down wood in old-growth stands compensated 

for this, so the estimated numbers of ensatinas did not vary 

significantly among age-classes 

The estimated abundance of plethodontid salamanders 

(combined) was also positively correlated with stand age 

(fig. 6). The mean density (D) was 364 salamanders per ha 

in young stands, 387 per ha in mature stands, and 744 per 

ha in old-growth stands. These figures are considerably less 

than the 2367 redback salamanders per ha that Burton and 

Likens (1975) estimated for the Hubbard Brook Experimental Forest in New Hampshire, or the 7000 PIerhodon per ha 

that Hairston (1987) estimated for forests in the southern 

Appalachian Mountains. The abundance we estimated, 

however, includes only salamanders closely associated with 

down wood. We may be somewhat close to estimating the 

actual abundance of clouded salamanders, but ensatinas and 

western redback salamanders use a broader range of habitats. 

These species were 49 and 56 times more abundant in pitfall 

traps than clouded salamanders, suggesting that neither species is closely associated with down wood. A recent 3-year 

study of western redback salamanders on two small plots on 

Vancouver Island found only about 15 percent of captures 

associated with down wood (Ovaska and Gregory 1989). 

Stebbins (1954) estimated 1708 ensatinas per ha at a site in 

the San Francisco Bay area, and Gnaediiger and Reed (1948) 

estimated 2833 ensatinas per ha in a ravine on the campus of 

Reed College in Portland. Ovaska and Gregory (1989) recorded surface activity of up to 1.16 western redback salamanders per square meter. Relative abundances of ensatinas 

and western redback salamanders were equivalent in oar 

pitfall traps, so the true density of plethodontid salamanders 

in Douglas-fu forests in western Oregon may be several 

thousand per ha, similar to salamander densities in eastern 

forests. 

Stand age (years) 

Microhabitat Features 

We found few stmng associations between amphibians and 

habitat features unique to old-growth forests. Upland habitats 

used by tailed frogs tended to be dense, moist forests, which 

is not unexpected for a species with low tolerance to high 

temperature and desiccation (Claussen 1973a. 1973b). These 

conditions may be supplied by young forests as well as old 

growth, however. 

Three general microhabitats are available to terrestrial salamanders: rocky substrates, down wood, and leaf litter. The 

four plethodontid salamanders in the Coast Range segregate 

among these habitat types with various degrees of overlap. 

Dunn’s salamander is most abundant in rock rubble in seeps 

and along small streams (Buy 1988, Bury and Corn 1988b, 

Corn and Bury 1989, Dumas 19.56, Nussbaum and others 

1983). Western redback salamanders are most abundant on 

rocky slopes (Dumas 1956, Nussbaum and others 1983, 

Ovaska and Gregory 1989). as are most western Plerbodon 

(Herrington 1988, Herrington and Larson 1985, Nussbaum 

and others 1983, Ramotnik and Scott 1988, Stebbins 1951). 

Western redback salamanders apparently select drier habitats 

than Dunn’s salamanders and are more tolerant of desiccation 

(Dumas 1956). Clouded salamanders are the dominant species 

associated with down wood, and prefer large, intact logs with 

hose bark (Bury and Corn 1988a; Bury and Martin 1973: 

315 
Welsh and Lind 1988, this volume: Whitaker and others

1986). Ensatina is the most primitive western plethodontid

(Wake 1966) and has the most general habitat use

(Gnaedinger and Reed 1948, Stebbins 1954). Ensatinas

were common on rocky slopes and in older decay-classes

of down wood; their abundance was positively correlated

with litter depth.

Considerable evidence has been found that differences in

habitat use by terrestrial amphibians are driven by competition (see Hairston 1987), and western plethodontids with

similar adult body size have large overlap in diets (Altig

and Brodie 1971, Lynch 1985). Our study was unable to

determine whether competition is occurring in terrestrial

salamanders in the Coast Range or whether current habitat

preferences reflect past selective pressures.

The abundance of ensatinas in pitfalls was negatively correlated with percentage cover by decay-class 4 and 5 down

wood, which initially seems paradoxical in view of the data

from the log surveys, where ensatina preferred well-decayed

wood. Salamanders that are closely tied to down wood,

however, such as clouded salamanders or Oregon slender

salamanders in the Cascades (Bury and Corn 1988a; Gilbert

and Allwine, this volume c), are rarely captured in pitfalls.

Surface activity of ensatinas should decline in stands with

large amounts of well-decayed wood.

Managed Forests

Clearcutting may significantly affect terrestrial herpetofauna.

Several studies have documented declining abundance,

changes in the species composition of amphibians, or both

(Buhlman and others 1988, Bury 1983, Bury and Corn

1988a, Pough and others 1987, Raphael 1988c). Meanwhile,

populations of reptiles, particularly lizards, increase and

exploit new openings in the forest canopy (Bury and Corn

1988a, Raphael 1988c). The three clearcuts we studied in the

Coast Range did not display significant changes in amphibian

populations. Abundance was slightly lower, and two species

found in adjacent old-growth stands were absent, but the

pattern of amphibian abundance was similar in old growth

and clearcuts.

Three stands are inadequate to assess the effects of clearcutting in the Coast Range, but even in an intensively managed forest, a minority of the landscape will be in the open

canopy stage (Bury and Corn 1988b, Harris 1984). The

problem for most amphibian species will be how to exist

in short-rotation second-growth forest that is structurally

dissimilar from naturally regenerated forest. Harris and

others (1982) predict a loss of about 25 percent of vertebrate

species in managed forests, primarily because snags and

down wood are eliminated. Raphael (1988c) predicted that

the abundance of three plethodontid salamanders in northern

California could decrease by 29 to 75 percent if logging of

old-growth forest continues. Few actual studies have been

made of the long-term effects of logging on amphibian

populations, however. Terrestrial amphibians were reduced

in some second-growth forests in the Eastern United States

(Bennett and others 1980, Pough and others 1987), and

density and biomass of stream amphibians in the Coast

Range were greatly reduced in streams flowing through

stands logged 14 to 40 years before (Corn and Bury 1989).

Stream amphibians are particularly vulnerable in a managed

landscape, because headwater streams are not protected and

they are less than 0.4 percent of the landscape in Coast

Range forests (Bury 1988).

Logging may have negative impacts on amphibians associated with talus (Herrington 1988, Herrington and Larson

1985), which is an important consideration for species with

limited distributions (Bury and others, this volume a). Assuming that the talus slope is not destroyed by such activities as

rock removal for road building (Herrington 1988, Scharpf

and Dobler 1985), however, the habitat should persist. The

main talus-dwelling salamander in the Coast Range is the

western redback salamander, which is widely distributed,

abundant, and unlikely to be seriously threatened by logging.

Managed forests have reduced amounts of coarse woody

debris (Bartels and others 1985, Harmon and others 1986),

which is exacerbated in each rotation as residual down wood

decays and little new down wood enters the system (Spies

and Franklin 1988, Spies and others 1988). Species associated with down wood, such as clouded salamanders and

Oregon slender salamanders (Bury and Corn 1988a; Gilbert

and Allwine, this volume c), are likely to decline in managed

landscapes. Previous studies have found clouded salamanders

to be common in clearcuts but always in association with

large woody debris (Bury 1983, Bury and Corn 1988a,

Whitaker and others 1986). Although we have said that this

species does not appear to be associated with old-growth

conditions (Bury and Corn 1988b), we believe that survival

of clouded salamanders in managed forests over a few

rotations is open to question.

Generalist species such as ensatinas are likely to persist in

managed forests, although populations may be reduced.

Female ensatinas use large, well-decayed down wood for

nest sites (Aubry and others 1988), but considering the high

abundance of this species in nearly all stands sampled in

Washington, Oregon, and California (Bury and others, this

volume a), down wood seems unlikely to be an absolute

requirement.

Recommendations

Forests in the Coast Range of Oregon are among the most

heavily impacted by logging in the Pacific Northwest (Harris

1984, Monthey 1984). Much of the second growth, however,

316
results from past logging practices that left considerably

more woody debris than current practices, and harvesting

of second growth on Federal lands is just beginning. For this

reason, we believe that none of the terrestrial amphibians in

the Coast Range of Oregon are in immediate danger of extinction or severe reduction from logging, but we make the

following suggestions for further research:

l Investigate amphibian populations in managed forests.

Research to date has focused on naturally regenerated

forests, and only a few clearcuts have been sampled:

l Determine ways to increase amounts of down wood in

managed forests. Logging plans could be modified to

increase the amount of cull timber left after cutting, but

a more difficult problem is how to increase recruitment

of new down wood before the next rotation;

l Determine the effects of forest fragmentation on

amphibians. Amphibians may not be particularly

sensitive to fragmentation (Rosenburg and Raphael

1986), but this needs more attention in the Coast Range;

l Increase our knowledge of the basic natural history of

amphibian species. Much basic information, including

population sizes and reproductive characteristics, is

lacking; and

l Initiate long-term monitoring of amphibian populations

in natural and managed forests immediately. Long-term

studies of communities are critical for understanding the

processes that are shaping them, but are rarely done

(Scott and Campbell 1982).

Acknowledgments

Funding was supplied by the U.S. Department of the Interior,

Bureau of Land Management, and the U.S. Department of

Agriculture, Forest Service, through cooperative agreements

between the Forest Service and Fish and Wildlife Service.

We thank L. Benson, J. Corn, B. Fiero, A. Gillesberg,

L. Jones, R. Kuntz, P. Morrison, R. Newton, L. Rottman,

D. Smith, W. Stolzenburg, P. Sullivan, and K. Wetzel for

assistance in the field. G. Mires allowed us to turn his kitchen

into a laboratory. We acknowledge the valuable contributions

of BLM Roseburg and Salem Districts, Siuslaw National

Forest, and the Pacifc Northwest Research Station for logistical support. K. Aubry, A. Carey, R. Storm, and two anonymous reviewers commented on the manuscript.

This paper is contribution 110 of the Wildlife Habitat

Relationships in Western Washington and Oregon Research

Project, Pacific Northwest Research Station, USDA Forest

Service. 0

317

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

Ensatina was the most common terrestrial amphibian in the

Oregon Cascade Range, representing over 50 percent of all

captures. The tailed frog was the second most abundant species but was the dominant species of the northernmost study

location (Mount Hood). The roughskin newt was the only

other species captured in the pitfall traps with 25 percent of

the total captures. Species richness did not differ between

locations or between years.

No species was significantly associated with old-growth

stands, although time-constrained searches indicated the

clouded salamander and the Oregon slender salamander were

found primarily in logs of the older decay classes. The northwestern salamander was associated with old growth at Mount

Hood. Most amphibians seemed to select the mesic to wet

portion of the moisture gradient, but the Pacific giant salamander was the only species with captures significantly

associated with wet sites. Ensatina was overrepresented in

dry stands and was captured at sites with a high percentage

of exposed rock and bare soil. Relation to ground cover was

Terrestrial Amphibian Communities in the

Oregon Cascade Range

Frederick F. Gilbert and Rochelle Allwine

generally consistent between years, but the vegetative

associations had little predictive value between years. The

Oregon Cascades amphibians apparently can be retained as

viable populations wherever crown closure has occurred and

breeding streams remain cool and unsilted. Forest management practices for these species should include protecting

riparian zones, maintaining topography favoring ephemeral

ponds as breeding sites, and considering cutting practices

that would provide stand structure and coarse woody debris

like those in naturally regenerated stands.

Introduction

Amphibians are an often-neglected component of the vertebrate fauna, despite their relative abundance and contribution to the faunal biomass in most locations. Studies at the

Hubbard Brook Experimental Forest, New Hampshire, indicate that amphibians contribute about twice the biomass of

breeding birds and about the same biomass as small mammals

(Burton and Likens 1975). Many forest amphibian species

are aquatic in part or all of their life cycle, and much of the

amphibian literature is devoted to them (for example, Bury

and Corn 1988b, Hawkins and others 1983, Murphy and Hall

1981, Murphy and others 1981).

Aubry and Hall (this volume), Corn and Bury (this volume b)

and Raphael (1988c) have used pitfall traps (with and without drift fences) and time-constrained sampling to identify

319
amphibian communities in Douglas-fir forests from California

to Washington. Our study was intended to provide information on these vertebrates in the Oregon Cascade Range and,

where possible, to relate their presence and abundance to the

age, moisture conditions, and vegetative structure of the

Douglas-fin- stands where they were found.

Materials and Methods

Amphibian populations were sampled at three sites on the

west side of the Oregon Cascades during 1984 (Mount

Hood, Hood; H.J. Andrews, the Andrews; and Rogue

River-Umpqua, Rogue-Umpqua). Only the Andrews was

studied in 1985. Pitfall trapping was done in September and

October both years. Grids (6 x 6) with stations 15 m apart

were used in each of 56 stands in 1984 and 15 stands in

1985. An additional eight pitfall grids were placed in the

Andrews stands in 1985 to determine effects on amphibian

populations of the previous year’s trapping (Gilbert and

Allwine, this volume b: see appendix table 15). Timeconstrained searches were conducted in the spring of 1984.

Each stand was searched intensively for 4 person-hours.

Ephemeral (melt-water) ponds, located in all the study

stands when time-constrained searches were conducted,

were examined at least twice during the spring of 1984

for amphibians and egg masses. Egg masses found were

collected and allowed to hatch so species could be identifed.

Water temperature, surface area, and water depth were

measured at each visit.

The abundance and diversity of species related to the chronosequence (young, 30-80 years; mature, 80-200 years; and

old-growth, >200 years), the moisture gradient (wet, mesic,

and dry old-growth stands), and vegetational structure were

analyzed. Vegetation was described by measurements within

a 5.6-m radius (100 m2

) and a 15-m radius (707 m2) centered

on nine pitfall traps (Gilbert and Allwine, this volume a: see

appendix table 12). Individual amphibian species were compared between the 1985 old and new grids in eight stands to

determine if differences in abundance were significant.

Animals were weighed, measured (snout-vent length, total

length), and either released at the capture location or preserved for food habits studies or as specimens for the Conner

Museum at Washington State University.

Data analysis was based on two major statistical goals: testing the hypotheses that animal abundance and the number of

species (species richness) did not differ among age-classes,

moisture-classes, or locations; and using exploratory statistics

to associate individual species with individual habitat components and with either age-classes or moisture-classes.

We used nonparametric analysis of variance (ANOVA) to

test the hypotheses that neither abundance of animals nor

species richness differed among the age- or moisture-classes

in each location. We used detrended correspondence analysis

(DCA) (Hill 1979a) to explore the relation between animal

abundance and habitat-classes as 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. The axes that explain (by

the ranking of their eigenvalues) the largest variability with

the original matrix are determined as being important in

exploring distribution with the data set. To determine whether

stands were grouped according to a physiographic gradient, a

plot of the DCA axes scores was examined to detect

clustering.

To classify sites into community phases, two-way indicator

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

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

correspondence analysis scores, was used to classify species

into categories related to location and age- or moistureclasses.

Species found to be associated with old-growth forests from

TWINSPAN analysis or from Spearman rank correlations of

animal. abundance with stand age were then correlated with

individual environmental and vegetative variables to examine

the relation between animal species and individual habitat

features.

The log-likelihood ratio was used to test for significance

in the use of logs by salamanders collected during timeconstrained searches. Three decay-class categories (see Fogel

and others 1973) were used: category 1 includes decayclasses 1 and 2; category 2 includes decay-class 3; and

category 3 includes decay-classes 4 and 5. A G test (likelihood ratio chi-square) was performed after comparison of

use to availability.

Statistical significance was at the P < 0.05 level (Zar 1974).

Means are presented with standard errors.

Results

1984

A total of 951 amphibians were collected in pitfall traps in

1984. With the exception of ensatina, the amphibian species

were most abundant at the Hood location (table 1). Hood

produced significantly more specimens than either of the

320
Table l-Amphibians captured in pitfall traps by subprovince 

in the Oreeon Cascades. 1984 

6 

II 

4 

0 

0 

4 

1SS* 

1 

0 

8 

12 

12* 

0 

*2* 

- 

7.44 

38 

6 

238 

6 

* 

43 

338 

2 

75 

153 

23 

12 

3 

12 

- 

951 

DCA 1 

others (31.3 + 6.8 vs. 12.4 k 1.4 at Rogue-Umpqua and 11.2 

f 2.0 at Andrews). Ensatina was the most common amphibian 

at Andrews (45 percent of captures) and at Rogue-Umpqua 

(78 percent of captures). At Hood, the tailed frog (40 percent 

of captures) was the most common amphibian. The average 

number of amphibians caught compared to the age of the 

stand was not significantly different (old-growth 14.0 * 2.7, 

mature 15.8 f 2.1, young 29.7 + 10.7 (ANOVA F value 

2.87,P < 0.07). 

DECORANA analysis showed no influence of stand age on 

the amphibians captured (fig. 1). Some separation appeared 

between wet and dry stands, indicating some selection was 

occurring (fig. 2), and a definite location effect was found as 

Rogue-Umpqua separated from Hood with the Andrews 

interfacing with both (fig. 3). 

No species were significantly associated with old-growth 

stands, although the frogs were found only in mature and 

old-growth stands and the Olympic salamander was found 

only in old-growth stands. The tailed frog (ANOVA F value 

2.71, P c 0.08) and the roughskin newt (ANOVA F value 

4.99, P < 0.01) captures were associated with young stands. 

Although the most amphibians were collected in mesic stands 

(average 19.6 f 5.8; wet 12.0 k 3.3; dry 11.1 + 3.5). no significant differences were found along the moisture gradient. 

Ensatina was the only species significantly associated with 

321 
Mesic Wet 

Moisture category 

dry sites (ANOVA F value 4.81, P = 0.02) and the Pacific 

giant salamander, the only species significantly associated 

with wet stands (ANOVA F value 3.88, P = 0.03) (figs. 4-5). 

F&e” different species were captllred. and species richness 

was identical (10) at all three sites. The northwestern salamander was significantly associated with old-growth at Hood. 

Although Dunn’s salamander generally was found in younger 

stands in the Oregon Cascades, it was found primarily in 

mattw. stands at the Andrew. The tailed frog was associated 

with young stands at Hood, mature stands at the Andrew, 

and found only in old-growth stands at Rogue-Umpqua. 

The presence of water “ear the pitfall site was not related to 

capture for any species, with the possible exception of the 

“nidentificd frogs (ANOVA P = 0.06). 

Ensatina was found where forest-floor conditions had a high 

percentage of bare soil (Spearnun rank correlation R = 0.32, 

P = 0.02). and this species was negatively associated with 

moss ground cover (Spearman rank correlation R = -0.44, 

P = O.ooOl). The tailed frog and the Pacific giant salanunderby contrast, were captured at locations with moss cover 

(R = 0.40, 0.30; P = 0.002.0.02.respective1y). The tailed 

frog was negatively associated with areas of bare soil and 

fine litter, another characteristic selected by ensatina. Areas 

with high coverage by grass were negatively correlated with 

the roughskin newt (R = -0.39, P < 0.003). Dunn’s salanxuder (R = -0.31, P < 0.02), and the Oregon slender sakunander (I7 = -0.31, P < 0.02). The Pacific giant salamander was 

captured at sites with fern cover (O-O.5 m high R = 0.42, 

P = 0.001; 0.5-2.0 m high R = 0.37,P = O.Wi),as were 

Moisture category 

0 

Dry Mesic Wet 

the clouded salamander (O-O.5 m R = 0.36, P = 0.006, 0.5- 

2.0 m R = 0.37, P < 0.005) and Dunn’s salamander (O-O.5 m 

R = 0.30,P = 0.02; 0.5-2.0 mR = 0.40,P = 0.W.E). 

Time-constrained searches produced 375 amphibians representing nine species (table 2). Eight species were captured 

at Hood and six each at the Andrew and Hood (P > 0.05). 

Ensatina was the most abundant amphibian (50.7 percent of 

captures), followed by the Oregon slender salamander (25.3 

percent of captures) and clouded salamander (13.3 percent of 

captures). The tailed frog, the Pacific treefrog, the Olympic 

salamander, Dunn’s salamander, the western redback salamander, and the roughskin newt were the only other species 

represented. 

The Oregon slender salamander and the western redback 

salamander were associated with the wet portion of the. moisture gradient and ensatina with the dry. No spies was significantly associated with the chmnosequence, although the 

only specimens of the tailed frog (2) and the Olympic salamander (1) were taken in old-growth stands. Use of logs by 

decay-classes (1+2,3,4+5) by ensatina, the clouded salamander, and the Oregon slender salamander was tested to see 

if it varied by species. The G test was highly significant (P = 

0.001). Of these common species, the Oregon slender salamander (G = 2.25, P < 0.001) and ensatina (G = 6.32, P = 

0.04) deviated from availability for decay-class 4 and 5 logs, 

but the clouded salamander showed no significant differences 

from expectedvalues(P= 0.88). 

Surveys showed that at least four species-the red-legged 

frog. the Pacific txefrog, the noahwestern salamander, and 

the roughskin newt-used meltwater ponds as breeding sites. 
Table 2-Amphibians collected during time-constrained searches

in the Oregon Cascades, spring 1984, related to stand age (values

in brackets are mean captures/stand)

Species

Ensatina

Oregon slender

salamander

Clouded salamander

Western redback

salamander

Dunn’s salamander

Roughskin newt

Pacific treefrog

Tailed frog

Olympic salamander

Oldgrowth Mature

92 (3.41) 69 (3.45)

34 (1.26) 42 (2.10)

26 (0.96) 20 (1.00)

8 (0.30) 5 (0.25)

9 (0.33) 3 (0.15)

4 (0.15) 1 (0.05)

0 (0.00) 1 (0.05)

1 (0.04)

0 (0.00)

0 (0.00)

- -

176 (6.52) 141 (7.05)

Young Total

29 (3.22) 190 (3.39)

19 (2.11) 95 (1.70)

4 (0.44) 50 (0.89)

l (0.11) 14 (0.25)

0 (0.00) 12 (0.21)

3 (0.33) 8 (0.14)

2 (0.22) 3 (0.05)

0 (0.00) 2 (0.04)

0 (0.00) 1 (0.02)

- -

58 (6.44) 375 (6.69)

Red-legged frog adults and egg masses were found in all but

one of the 35 ponds surveyed. Pond depth, temperature, and

surface area were all unrelated to presence or absence of amphibians. Ponds were only studied in old-growth or mature

stands because none of the young stands studied had meltwater ponds.

Studies in 1985

Of the 462 amphibians captured in pitfall traps in 1985,

ensatina contributed 267 and the roughskin newt 98 specimens (79.1 percent of all captures). The tailed frog was the

only one of the other seven species to have more than 3 percent of the captures (table 3). The roughskin newt was significantly associated with young stands (ANOVA F value

4.86, P c 0.03). Young stands had more amphibians caught

(average 52.7 + 15.8) than either mature (34.0 + 10.1) or

old-growth stands (22.7 + 3.8) (F value 3.92, P < 0.05). Wet

stands produced more amphibians (average 27.5 + 6.3) than

did mesic (25.5 + 10.5) or dry stands (14.3 + 2.4), but the

differences were not significant.

Although some forest-floor characteristics differed significantly between 1984 and 1985, general patterns were similar.

For example, Dunn’s salamander continued to be captured

at sites with high percentages of bare rock and bare soil

(1984 values R = 0.44, P = 0.10; R = 0.43, P < 0.11 and

1985 values R = 0.62, P = 0.01; R = 0.75, P = O.OOl), and

the Pacific giant salamander was caught at sites with a high

percentage of moss (1984 R = 0.55, P = 0.03; 1985 R = 0.43,

P < 0.11) based on Spearman rank correlations. Ensatina

was found associated with logs of decay-class 1+2 (1984

R = 0.52,P < 0.05; 1985 R = 0.47,P < 0.08).

Table 3-Herpetofauna captured in pitfall traps at the H.J.

Andrews, fall 1985 (values in brackets represent percentages)

original New

Species grids (15) grids (8) Total

Ensatina 174 (66.4) 93 (46.5) 267 (57.9)

Roughskin newt 38 (14.5) 60 (30.0) 98 (21.2)

Tailed frog 29 (11.1) 25 (12.5) 54 (11.7)

Dunn’s salamander 8 (3.1) 4 (2.0) 12 (2.6)

Pacific treefrog 2 (0.8) 7 (3.5) 9 (1.9)

Pacific giant salamander 6 (2.3) 2 (1.0) 8 (1.7)

Oregon slender salamander 2 (0.8) 4 (2.0) 6 (1.3)

Red-legged frog 3 (1.1) 2 (1.0) 5 (1.1)

Northwestern salamander 0 (0.0) 3 (1.5) 3 (0.6)

- - -

Total 262 200 462

Comparison between years showed that only the tailed frog

had a difference in its relation to the chronosequence, moisture gradient, or both. More captures were made in the dry

portion of the moisture gradient in 1985 (chi-square = 5.669,

2 df,P = 0.06).

Although no significant difference was found in the amphibian species captured in the old and new grids of the

same stands, the number of amphibians captured was different (chi-square = 20.164, 8 df, P < 0.01). The roughskin

newt, the Pacific treefrog and the tailed frog were more

abundant in the new grids.

Discussion

Porter (1972) suggested that amphibians tend to be restricted

by dry conditions. Our findings support this generalization

because Rogue-Umpqua, the subprovince with the least average annual precipitation, had the lowest number of amphibians, and many species selected mesic-wet stands over dry

stands. Some species though, such as ensatina, may prefer

drier sites. In general, we found similar relations between the

amphibians and habitat conditions to those described in

Nussbaum and others (1983) and Stebbins (1985).

Clouded salamanders and Oregon slender salamanders were

seldom taken in pitfall traps. Both species live under the bark

on logs, or within the logs, so time-constrained searches

were the only effective way of sampling their presence and

abundance (Bury and Corn 1988a). They were the second

and third most abundant amphibians taken in me searches,

and the Oregon slender salamander used more-decayed logs

than did the clouded salamander. The decay-class use by

these two species was similar to Bury and Corn’s (1988a)

observation that the clouded salamander used logs of decayclass 2 and 3 and the Oregon slender salamander used the

older decay classes. Raphael (1988c) considered the clouded

salamander to be associated with old growth because of its

dependence on logs.

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Tailed frogs seemed dependent on ambient temperature. They

used stands of different ages at the three sites. At the warmest

location (Rogue-Umpqua), old growth seemed to be selected;

at the intermediate location (Andrews), mature stands had the

most captures; and at the coolest location (Hood), the species

was most abundant in young stands. This species breeds and

the larvae develop in cool flowing streams, so the temperature in the streams may be what restricts distribution (Bury

and Corn 1988b, Gilbert 1985). At Rogue-Umpqua, most of

the streams were in old-growth stands; streams in the younger

stands may be mostly intermittent and thus incapable of

supporting tailed frogs. The Olympic salamander is more

restricted to the vicinity of cool streams and seeps. It, too, is

likely to be temperature dependent, but the major threat to

these aquatic forms may be stream siltation, which destroys

their prey base (Corn and Bury 1989).

The roughskin newt and northwestern salamander, like the

red-legged frog, used meltwater ponds as breeding sites.

Unlike the frog, the other two species were more ubiquitously distributed along the chronosequence and perhaps not as

restricted in their movements. In partial contradiction, however, the roughskin newt may have been partially trapped

out in 1984 because the old pitfall grids produced fewer of

this species than the new grids in the same stands.

None of the amphibians we found was restricted to old

growth, although some, such as the Olympic salamander,

selected habitat conditions that may be most abundant in old

growth, which may also be true for the Oregon slender salamander. This species used logs of the older decay-classes, a

feature usually associated with old-growth forests (Franklin

and others 1981). Logs in all age-classes were abundant in

the natural stands we studied, however.

Because all the common (>6 observations) species were

found in young as well as older stands, closed canopy conditions are apparently sufficient to sustain these species in

the Oregon Cascades. Nonetheless, Bury (1983) and Bury

and Corn (1988b) may well be correct that logging, especially

clearcutting, can be disruptive to amphibian populations.

Clearcuts are unlikely to have the coarse woody debris or

stand structure characteristic of the natural conditions in our

study stands. If these characteristics could be maintained in

managed forests, all the amphibian species we found in the

Oregon Cascades should also be present in such forests.

Vegetative structure was not predictably related to species

captures between years, probably because of the time of year

of the pitfall trapping and the high percentage of juveniles in

the populations. “Pulses” of high capture rates corresponded

with periods of precipitation, a finding similar to other

studies (Bury and Corn 1987, Bury and Corn 1988b). These

pulses consisted of dispersing juveniles, so the capture sites

may not represent actual habitat requirements.

When amphibian communities are studied, recognizing that

shifts occur in resource use is important, as exemplified by

differences between breeding and nonbreeding communities.

Such factors as spatial or temporal partitioning of available

breeding sites like meltwater ponds or of male calling sites

generally organize the community (Bogert 1960, Collins

1975, Dixon and Heyer 1968, Wiest 1982). In essence, the

community structure shifts; our studies in the Oregon

Cascades have not fully analyzed any single structural entity.

As Crump (1982) stated, “There has been little integration of

reproductive ecology and community dynamics.” We have

some tantalizing hints of these relations but often little

beyond life histories. Scott and Campbell (1982) stress the

need for long-term studies of herpetological communities if

we are to understand the roles of competition and intrapopulation social behavior. Our understanding is sketchy and

our findings, particularly from this study, hardly predictiveexcept for the obvious need for adequate breeding conditions, whether that means clear, cool streams or sufficient

ephemeral ponds, and for adequate substrate, such as logs for

certain salamanders. None ,of these factors requires oldgrowth forests if forest planning and management succeed in

ensuring uneven-aged structure, maintaining coarse woody

debris, and protecting riparian zones.

Acknowledgments

The Oregon Cascades study was made possible by the

contributions of many people, including U.S. Forest Service

personnel. 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 113 of the Wildlife Habitat Relationships in Western Washington and Oregon Research

Project, Pacific Northwest Research Station, USDA Forest

Service. 0
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Terrestrial Amphibian Communities in the

Southern Washington Cascade Range

Keith B. Aubry and Patricia A. Hall

Authors

KEITH B. AUBRY is a research wildlife biologist and

PATRICIA A. HALL’ is a wildlife biologist, USDA Forest

Service, Pacific Northwest Research Station, Olympia,

Washington 98502.

Abstract

We surveyed terrestrial amphibian communities with pitfall

traps in 46 forest stands of various ages and moisture conditions in the southern Washington Cascade Range in 1984

and 1985. We captured a total of 1516 individuals of 13

species. Data were sufficient to examine community- and

species-habitat relationships for seven species: ensatina,

western redback salamander, northwestern salamander,

roughskin newt, tailed frog, red-legged frog, and Cascades

frog. We found no significant differences among stand ageclasses for either species richness or diversity. Species richness, however, decreased significantly with both increasing

elevation and increasing stand moisture. Detrended correspondence analysis (DCA) of amphibian communities

revealed non-overlapping clusters of stands with distinct

community composition; DCA axes were associated with

gradients of slope, stand age, temperature, elevation, and

1

 Now wildlife biologist, School of Forestry, Northern Arizona University,

Flagstaff, Arizona 86011.

moisture. In general, older stands with cooler temperatures

and relatively flat slopes had the highest amphibian species

richness.

The tailed frog was significantly more abundant in mature

stands than in young stands. Although differences across the

age gradient for other species were not significant, patterns

of abundance for these species were evident. The ensatina

and western redback salamander were most abundant in

young stands, the red-legged frog in mature stands, and the

north-western salamander, roughskin newt, and Cascades

frog in old growth. Only abundances for the roughskin newt

varied significantly among old-growth moisture-classes;

abundance of this species was low in wet old-growth stands

compared to either moderate or dry stands. The ensatina and

north-western salamander also were least abundant in wet

stands. The northwestern salamander and roughskin newt are

associated with old-growth Douglas-fir forests in the southern

Washington Cascades during the fall, whereas the ensatina,

western redback salamander, and possibly the red-legged

frog are associated with coarse woody debris that is characteristic of old-growth forests and unmanaged young forests.

Introduction

In recent years, harvest of old-growth Douglas-fir forests in

the Pacific Northwest and its potentially detrimental effects

on biological diversity have become a political and economic

issue of national significance (see Lumen and Neitro 1980,

327
Meslow and others 1981, Norse 1990, Norse and others 1986,

Wilcove 1988). Most research on the habitat relationships of

species associated with old-growth forests has been directed

primarily at larger birds and mammals (for example, Meehan

and others 1984), especially the spotted owl (GmZrrez and

Carey 1985), which has become the social and political focus

of concern over the loss of old-growth Douglas-fir forests.

Little work had been done on the habitat relationships of

other birds, small mammals, amphibians, or reptiles in oldgrowth Douglas-fir forests, with the exception of vertebrate

community studies conducted in the early 1980s in northern

California (Raphael 1984, Raphael and Barrett 1984). In

1983, a comprehensive program of research was initiated

throughout the Pacific Northwest to identify wildlife species

that are associated with old-growth Douglas-fir forests and

to investigate the ecological basis of observed patterns of

association (this volume; Ruggiero and Carey 1984).

As part of this program of research, amphibian communities

in different-aged Douglas-fir forests in the southern Washington Cascade Range were sampled with time-constrained

searches, stream surveys, and pitfall trapping. Results of

time-constrained searches were reported previously (Aubry

and others 1988), and results of stream surveys are reported

here by Bury and others (this volume b). In this paper, we

report the results of pitfall trapping conducted in the fall of

1984 and 1985. Our objectives are to:

l Characterize the structure and composition of terrestrial

amphibian communities in Douglas-fir forests of

southern Washington and relate community patterns to

features of the environment;

l Describe the habitat relationships of terrestrial amphibians

in these forests;

l Identify terrestrial amphibian species that are associated

with old-growth Douglas-fir forests; and,

l Make recommendations for further research.

Methods

Study Areas

We studied terrestrial amphibian communities in 46 closedcanopy forest stands on the western slope of the Cascade

Range in southern Washington from Mount Rainier south to

the Columbia River Gorge (see frontispiece). Stands were 55

to 730 years old, at least 20 ha in extent, and at elevations

ranging from 404 to 1218 m. All had resulted from natural

regeneration after catastrophic wildfires; none had undergone

silvicultural manipulations.

All stands were in the Western Hemlock Zone and lower

elevations of the Pacific Silver Fir Zone (Franklin and

Dyrness 1973), which are characterized by a wet and mild

maritime climate. Old-growth stands typically contained high

proportions of both Douglas-fir and western hemlock. Old

growth stands in wet sites also contained a high proportion

of western redcedar. Mature and young stands consisted

predominantly of Douglas-fir. In all age-classes, other species

such as red alder, vine maple, bigleaf maple, Pacific silver

fir, and western hemlock occurred in lesser amounts . See

Spies and Franklin (this volume) and Spies (this volume) for

more detailed descriptions of the vegetative and structural

characteristics of the study stands.

Stands were selected for study in accordance with a

“T-matrix” design consisting of an age gradient of stands

of comparable moisture condition ranging from young to old

growth, and an old-growth moisture gradient that consisted

of old-growth stands ranging from wet to dry. See Carey and

Spies (this volume) for a detailed description of the experimental design.

At least nine stands were selected in each of five age- and

moisture-classes: wet old growth (210-730 years old), moderate old growth, and dry old growth; moderate mature

(80-190 years old); and moderate young (55-75 years old).

The average age of each stand was determined by growthring counts from increment coring or examination of cut

stumps in nearby stands (Spies and others 1988). Stands

were selected and tentatively classified into moisture-classes

during initial field reconnaissance based on vegetation,

physiography, and soils. Subsequent analyses of vegetation

data collected in each stand resulted in refinements to the

original classifications (Spies and Franklin, this volume).

These analyses indicate that the young and mature stands we

sampled encompass a broader range of environmental

conditions than originally intended. Some of the wet and dry

old-growth stands, for example, were comparable in moisture

condition to the ‘moderate’ mature and young stands. Several

old-growth stands were therefore reclassified as moderate for

inclusion in age-gradient analyses. As a result, the age

gradient of stands of comparable moisture condition for the

southern Washington Cascade Range consisted of 37 stands:

19 old growth, 9 mature, and 9 young.

To compare moisture-classes of old-growth stands, Spies

and Franklin (this volume) used ordination analyses of the

species composition of old-growth stands to reevaluate the

relative moisture condition of each stand. The resulting

classification consisted of 9 wet, 12 moderate, and 7 dry

old-growth stands. Because this classification is independent

of the age-gradient classification, data from these two gradients were analyzed separately. Variation related to age was

328