Table 3-Mean captures (number per 100 trap-nights) of amphibians across the moisture gradient in old-growth stands (standard 

deviations are in wrentheses) 

ilw8 ‘, :: : :: :.316’.: ! :: I ,119’ 

(.oz*y : : ; : : (.9x): : : : : : f.Z47( 

:025 ‘::::,.040::::::~.0”2: 

@67j a j i / j (.ni): : I j j: <.oosj 

Table 4-Significant associations between amphibian abundances and major physiographic and vegetative gradients (negative 

assoclatlons in parentheses) 

Habitat Associations Responses of individual species varied widely with habitat 

More significant associations of amphibian abundance with wiablcs. Northwestern salamanders were more abundant in 

physiographic variables were found than with vegetation cool old-growth forest than in other combinations. Pacific 

variables (table 4). Analysis of covariance controls for dif- giant salamanders were more abundant in warmer, wetter 

ferences among provinces (for example, elevations were stands than in other conditions. The abundance of Olympic 

generally lower in the Coast Range), but gradients within salamanders was low in all provinces, and this spccics was 

provinces may complicate interpretation of these results. For not related to any of the gradients examined. 

example, elevation was highest in Washington in the north, 

but in the Cascade Range in Oregon the southern stands were 

highest. 

345 
& 

1) 1.0 

~1,, 

E 

: 0.5 

0.0 

0 20 40 60 SO lb0 

Slope (percent) 

Ensatina was more abundant in younger, drier stands, and 

steeper stands at lower elevations, than in other combinations 

of conditions. Western redback salamanders were more abundant on steep slopes (fig. 2). Roughskin newts were most 

abundant at lower elevations, and tailed frogs were more 

abundant at higher elevations with southern exposures than 

in other situations. Red-legged frogs were most abundant at 

lower elevations with flatter slopes. 

Regional Patterns 

Based on the multidimensional scaling of species richness, 

the Oregon Coast Range appears to be distinct from the 

Cascade Range, whereas the Cascade Range in Oregon and 

Washington shows a degree of overlap (fig, 3a). This observation is supported by a separate analysis: the nonheimrchical 

clustering of three pools of stands (table 5). Two of these 

pools identify stands in the Oregon Coast Range and Washington Cascade Range; the largest pool (pool 1) contains 

most of the stands in the Oregon Cascade Range and half 

of the Washington stands. The Coast Range pool had the 

highest species richness, with six species present in more 

than 50 percent of the stands, and the Washington pool had 

the lowest richness, with only three species present in more 

than 50 percent of the stands. 

E .- 

E! 

-2 

ii 

.- 

0 

Dimension 1 

Plotting the MDS by age-class shows no discernible 

differences among old-growth, mature. and young stands 

(fig. 3b). Ellipses that enclose about 75 percent of the stands 

in each age-class essentially overlap completely. 

346 
Table 5-Nonhierarchical clustering of 12 amphibian species 

(presence-absence) In 55 forest stands In Oregon and Washington 

11 

3 

10 

3 

12 

I 

1 

cascades frog 

Biogeography 

The occurrence of amphibians among and within provinces 

varied greatly. Six species of terresaial salamanders were 

widely distributed in the Pacific Northwest (fig. 4), and 

species richness was concentrated in western Oregon and 

north coastal California. Among these six species of widespread occurrence, the number present in any locality varied 

from zero to four and changed over relatively short distances. 

Five salamanders were endemic in Oregon and Washington 

(fig. 5). and most had non-overlapping ranges. Three other 

endemic species in Idaho and northern California are not 

examined here. 

Discussion 

Variation Across Provinces, Chronosequences, and Moisture Gradients 

The lack of response by terrestrial amphibians to the moisture 

gradient in the Coast Range might be due to several factors. 

The moisture gradient was not strong, and most stands 

tended to be relatively dry. Old-growth stands in the Coast 

Range tended to be similar to the drier old-growth forest in 

the Cascade Range (Spies and Franklin, this volume). 

Mean abundance of species differed more among provinces 

than across either the chmnosequence or moisture gradients 

(table 2). Mosr species were more common in one province 

than in the other two. Large numbers of both the roughskin 

newt and northwestern salamander were captured in only a 

few stands, resulting in high variance that clouds interpretation of trends. The observed geographic variation in 

341 
arch Mountain 

---e--. 

, Siskiyou Mountains 

l Limestone 

I 

I 

Red-bellied newt 

captures may reflect the location of special habitat features 

in certain stands more than any environmental differences 

among provinces. 

The resident amphibians apparently are somewhat similar in 

naturally regenerated Douglas-fii forests. All stands sampled 

had established canopies and generally contained large 

amounts of coarse woody debris, which are characteristics 

that may reduce differences among stand types (young to old 

growth, wet to dry). 

Habitat Associations 

Some of the observed patterns of abundance may be due to 

special habitat features required by certain species. These 

may include aquatic habitats, down wood, and rocky slopes. 

Proximity to water for aquatic breeders-The strong interaction between province and stand age for roughskin newts 

might be better explained by the proximity of breeding habitats than by dependence on unknown forest characteristics. 

Newts migrate to ponds, slow-moving streams, or other 

standing bodies of water to breed. Migration may extend over 

considerable distances. Twitty (1966), for example, reported 

that newts may move hundreds of meters to and from breeding sites, and that individuals displaced several kilometers 

away (some over 10 km) returned to home waters. Thus, a 

favorable site for breeding is a focal point for migration. 

Capture of newts in pitfall traps may represent no more than 

movement by the animal through the forest. The newt may 

only temporarily depend on that place of capture. Capture of 

migratory species in one type of habitat, however, may also 

suggest chat they prefer or require these upland conditions 

after the breeding season. 

Similarly, adult northwestern salamanders migrate to ponds 

for breeding, and then both adults and juveniles return to 

land. The proximity of ponds or slow-moving creeks may 

also determine the occurrence and abundance of this species 

in forested stands. Frogs and toads also breed and live most 

of their lives in or near water. In particular, ranid frogs are 

aquatic or mostly aquatic throughout their lives, and the 

tailed frog breeds in small streams. The location of these 

ponds or flowing waters will strongly influence the occurrence of these species in surrounding forest stands. During 

rains, however, frogs may move out onto the forest floor to 

forage, and they may occasionally disperse overland. Additional studies are needed to better address the importance of 

dual habitats (aquatic breeding and upland nonbreeding sites) 

in the life histories of forest amphibians. 

Searches were conducted in vernal ponds in the Oregon 

Cascades (Gilbert and Allwine, this volume c). Most of the 

ponds were in mahre and old-growth stands. These habitats 

proved to be important breeding areas for northwestern salamanders and ranid frogs. The relation between the stability 

(predictable occurrence) of vernal ponds and forest developmental stage needs further investigation. 

Coarse woody debris-Time-constrained collecting and 

surveys of down wood suggest that coarse woody debris is 

important habitat for several species of plethodontid salamanders, including ensatina, clouded salamanders and 

Oregon slender salamanders (Aubry and others 1988; Aubry 

and Hall, this volume; Bury and Corn 1988a: Corn and Bury, 

this volume b; Gilbert and Allwine, this volume c). Natural 

disturbances (for example, fire) add appreciable debris to 

young stands, but these features do not persist as the stand 

matures. Forest stands do not accumulate new, large pieces 

of down wood until the forest reaches old-growth conditions 

and debris inputs increase as a result of natural tree mortality 

(Franklin and others 1981, Harmon and others 1986, Spies 

and others 1988). 

348 
Although ensatina was the only one of eight species suspected of having a strong association with down wood, none

of the amphibians collected in pitfall traps were related to the

habitat variable (DF2A) for coarse woody debris (table 4).

Clouded salamanders and Oregon slender salamanders were

not well-sampled by pitfall trapping, but time-constrained

collection indicate that they are most abundant in stands with

high amounts of coarse woody debris.

Ensatina is a generalist and may be competitively displaced

by the clouded salamander where they are sympatric (Corn

and Bury, this volume b). In Oregon, clouded salamanders

were most abundant in less-decayed classes of down wood,

mostly in decay-classes 1 and 2 (Bury and Corn 1988a; Corn

and Bury, this volume b). Clouded salamanders and Oregon

slender salamanders, however, do not occur in the Cascade

Range in Washington, and in that region ensatina uses a

broader range of microhabitats (Aubry and others 1988) than

ensatina in the Cascade Range in Oregon, where all three

species occur (Bury and Corn 1988a), or in the Oregon Coast

Range where ensatina and clouded salamanders are

sympatric (Corn and Bury, this volume b). The density of

ensatina also may not be strongly related to the amounts of

coarse woody debris in stands because that species is a

generalist. Ensatina may, however, require coarse woody

debris as breeding habitat (Aubry and others 1988).

Raphael and Barrett (1984) found that the abundance of

ensatina in northern California was correlated to the density

of large Douglas-fir trees. They found few ensatina in the

youngest stands (less than 150 years old) they studied, however, and they included ensatina with species associated with

old-growth stands. We cannot explain why ensatinas were

ubiquitous in Oregon and Washington and had no apparent

correlation with old growth.

Rocky habitats-We think the most underestimated environmental factor affecting salamanders is underlying soils, and

particularly the occurrence of talus (rock rubble) in the Pacific Northwest. Western redback salamanders are associated

with steep slopes and talus (fig. 2). Steepness of slope and

the presence of talus are related factors because talus is more

often exposed on hillsides than on valley floors where rocky

soils are often covered with alluvium or deeper soils. Most

western plethodontid salamanders frequent talus slopes

(Dumas 1956, Herrington 1988, Nussbaum and others 1983,

Ramotnik and Scott 1988), including the Larch Mountain,

Siskiyou Mountain, and Del Norte salamanders. Also, Dunn’s

and Van Dyke’s salamanders occur in talus habitat or along

rocky streamsides (Dumas 1956, Corn and Bury 1989).

The strong association of the woodland salamanders with

talus or rocky soils may override other habitat relations. For

example, both Raphael (1988c) and Welsh and Lind (this

volume) indicate that the Del Norte salamander is most

numerous in the oldest seral stages of Douglas-fir/hardwood

forest in northern California. Soil types were not indicated,

however, so these relations may be incidental to an uneven

distribution of rocky habitats. We suggest that the occurrence

and abundance of most species of woodland salamanders are

more likely to be related to the presence of rocky outcrops or

underlying talus than to forest development (stand age) or

amounts of coarse woody debris. Determining this relation is

essential to future studies of western salamanders and their

habitats.

Herrington and Larsen (1985) and Herrington (1988) suggest

that forested talus slopes were required by the Larch Mountain salamander and some other salamanders. The response

of salamanders to the removal of forested stands on talus

slopes, however, has not been examined critically. Individuals may simply move underground (Ovaska and Gregory

1989; N. Scott, unpubl. manuscript). Insufficient evidence is

available to resolve this question, but it is a major issue

because many forested areas of the Cascade and Coast

Ranges in the Pacific Northwest have soils dominated by

talus or rock rubble. These areas may be open slopes, partly

forested, or totally overgrown with trees. Thus, considering

both the substrate (for example, soil versus talus) and forest

conditions (for example, clearcut versus closed canopy) is

increasingly important in evaluating the occurrence and

abundance of terrestrial salamanders.

Managed Stands

Bury and Corn (1988a) used pitfall traps in five clearcut sites

(all less than 10 years old) in the Cascade Range in Oregon

and Washington to describe the occurrence and abundance of

the herpetofauna in managed stands. The relative abundance

of the herpetofauna in these clearcuts differed markedly from

six comparable young stands that were naturally regenerated.

Reptiles predominated in clearcuts, which most likely was a

response to increased solar radiation and higher ambient temperatures. The Pacific treefrog also was most abundant in

clearcuts, which reflects its propensity for invading openings

(Bury 1983). Interestingly, clearcut stands that we sampled in

the Oregon Coast Range in 1984-85 did not show such

marked differences in terrestrial species (Corn and Bury, this

volume b).

Although tailed frogs were captured in pitfall traps in closedcanopy forests, they were absent or rare in clearcuts (only 1

percent of the total catch). Both the Olympic salamander and

the tailed frog seem to be sensitive to timber harvest, and the

survival of these species may depend on the availability of

cool streams for breeding and larval development as well as

the presence of adjacent forested habitats for shade and retention of stream substrate quality (Bury and Corn 1988a; Bury

and others, this volume b, Corn and Bury 1989). Assessing

the effects of logging in streamside and upland forests is

urgently needed.

349
Biogeography

Regional patterns-Both multidimensional scaling and nonhierarchical clustering generated clear patterns separating the

three provinces (fig. 3a, table 5) but not the forest age-classes

(fig. 3b). This result is underscored by the strong differences

among provinces in the abundance of species that occurred

in all provinces, and by the general lack of abundance differences among habitat types.

Analyses of the amphibian communities were somewhat surprising because distribution differences among the provinces

for several species had little apparent influence on the results.

Considerably more overlap was found between the Cascade

Range in Oregon and Washington than between either Cascade Range group and the Oregon Coast Range despite the

absence of clouded salamanders and Oregon slender salamanders in Washington. Biogeography, however, appears to

play a much more important role in the organization of amphibian communities than do forest habitat gradients. Thus, a

mandate exists to better document species’ occurrence, and

their centers of diversity, biogeographic relations, and distributional limits.

Importance of endemic amphibians-Eight species of terrestrial salamanders in the Pacific Northwest have restricted

distributions (fig. 5), five in Oregon and Washington. Even

widespread species, however, are not distributed over the entire region (fig. 4). The superimposing of the ranges of endemic and widespread species of salamanders would further

complicate which species might be expected to occur in a

given province or area. The specialized habitats and disjunct

distributions of many species also confounds generalizations

about herpetofaunas. Marked differences in the herpetofauna

depend on the geographic location sampled.

We suspect that the distribution patterns of individual species

may influence the organization of herpetological communities more than factors such as forest age, once canopy is reestablished. In most areas of the Pacific Northwest, however,

herpetological studies have been insufficient to compile reliable community profiles (accurate lists of resident species

and relative numbers of species).

Still, herpetological communities can be understood; relatively few species of amphibians and even fewer reptiles live in

the Pacific Northwest. An intensive study in a project area

usually can reveal almost all of the common species and

many of the rarer ones, if the searcher knows what to look

for and if sites are sampled during appropriate weather (Corn

and Bury 1990).

Management Suggestions

Localized distributions and special habitat requirements of

amphibians may make managing of selected species easier

than might be anticipated. The presence of small permanent

streams or headwaters is an indicator that Olympic salamanders or tailed frogs may occur in the area. Another key factor

is to recognize the importance of distinct microhabitats.

Presence of talus or rocky substrate, for example, is a clue

that one or more species of plethodontid salamanders likely

inhabit the site.

Management strategies need to be individually tailored. Most

of the “common” amphibians, such as ensatina and clouded

salamanders, are apparently not irreversibly affected by current timber harvest activities. Thus, we would recommend

that most attention be directed at endemic species with small

geographic ranges (fig. 5). All five of the endemic species in

Oregon and Washington are already proposed for Federal

listing as threatened or are protected by individual States.

A long-term perspective needs to be developed. Species that

require large, well-decayed down wood may be continually

reduced in numbers in managed forests because tree removal

reduces or eliminates the input of fallen woody debris.

Coarse woody debris, therefore, is not carried over from

sequential harvests, and terrestrial amphibian populations

may suffer as a result.

Acknowledgments

We thank our field crews for their efforts and assistance over

many regions and years of effort. We are grateful to R. E.

Herrington, K. B. Jones, and M. G. Raphael for reviews and

comments on the manuscript.

This paper is contribution 131 of the Wildlife Habitat

Relationships in Western Washington and Oregon Research

Project, Pacific Northwest Research Station, USDA Forest

Service. m

350
This page was intentionally left blank

Aquatic Amphibian Communities in Oregon and

Washington

R. Bruce Bury, Paul Stephen Corn, Keith B. Aubry, Frederick F. Gilbert, and

Lawrence L.C. Jones

Authors

R. BRUCE BURY and P. STEPHEN CORN are zoologists,

U.S. Department of the Interior, Fish and Wildlife Service,

National Ecology Research Center, Fort Collins, Colorado

80525-3400. KEITH B. AUBRY is a research wildlife biologist and LAWRENCE L.C. JONES is a wildlife biologist,

USDA Forest Service, Pacific Northwest Research Station,

Olympia, Washington 98502. FREDERICK F. GILBERT is

a professor and wildlife biologist, Department of Natural

Resource Sciences, Washington State University, Pullman,

Washington 99164-6410.

Abstract

We sampled first- and second-order streams in naturally regenerated forests (young, mature, and old-growth stands) in

three provinces: the Southern Cascade Range of Washington,

the Oregon Cascade Range, and the Oregon Coast Range. We

found no significant differences in physical habitat variables

(except stream gradient in one of the three provinces) nor in

densities of amphibians among the provinces. Giant salamanders were the most abundant amphibians, followed by tailed

frogs. Dunn’s salamander and Olympic salamander were less

common, partly because they did not occur in all the watersheds we examined. These four species differed markedly in

their microhabitat use: tailed frogs were most often found in

riffles; Olympic salamanders frequented riffles and banks or

shallow seeps; giant salamanders were about equally abundant in pools and riffles; and Dunn’s salamanders mostly

occurred on stream banks. Three species have aquatic larvae,

and they appeared to occupy different ecological niches.

Amphibian densities and biomass were 10 and 4 times

greater, respectively, than those reported for salmonid fishes

in small streams. Thus, amphibians can be the predominant

vertebrates in headwaters in Pacific Northwest forests. In the

Oregon Coast Range, we found that the number of species,

the densities, and the biomass of resident amphibians were

2 to 7 times greater in streams flowing through uncut forests

than in logged areas. Responses of amphibian populations to

timber harvest may differ regionally, and more comparative

studies are needed on amphibian communities in managed

stands.

Introduction

Concerns have been expressed about how timber harvest

affects salmonid fishes in Pacific Northwest streams (see

Brown 1985, Meehan and others 1984, Salo and Cundy

1987). Recent studies in western Oregon indicate that both

salmonids and the Pacific giant salamander are common in

streams in uncut and logged habitats (Hawkins and others

1983, Murphy and Hall 1981, Murphy and others 1981).

Other studies suggest, however, that logging has negative

impacts on aquatic amphibians, particularly those with narrow environmental tolerances (Bury 1968, Bury and Corn

353
1988b, Metter 1964, Nnssbaum and others 1983). Negative 

effects from logging also may be intensified in headwater 

streams (Corn and Bury 1989). 

Integrated management of forests requires an understanding 

of the complex ecosystems of headwater streams, and how 

they function. Headwaters and other small channels provide 

nursery habitat for salmonids (Hamnan and others 1987, 

Sedell and Swanson 1984) and are important in maintaining 

downstream fish habitat and water quality (Rice and others 

1979). Everest and others (1985). furthermore, reported that 

“pslope activities (for example, road development or timber 

harvest) and manipulation of canopy or streambank vegetation create. immediate changes in the equilibrium of small 

streams. 

Haiiton (1987) estimated that the biomass of both terrestrial 

and aquatic salamanders was greater than that of any other 

vertebrate predators in the southern Applachian mountains. 

To date, we lack comparable estimates of the biomass of 

different vertebrate groups in Pacific Northwest forests. 

Although amphibians are the dominant vertebrates in some 

Northwestern headwater streams (Buy 1988, Murphy and 

Hall 1981, Nussbaum and others 1983). large gaps exist in 

OUT understanding of how these species function in aquatic 

or riparian communities. We know little about the effects 

of habitat alteration on their survival. 

The s!mct”re of Douglas-fu forests varies considerably 

(Spies and Franklin, this volume) and, for that reason, we 

need to investigate how amphibian populations vary across 

successional gradients. In this paper, our objectives are to 

determine the occurrence and abundance of amphibians in 

streams flowing through three successional stages (young, 

mature, and old-growth) of naturally regenerated Douglas-fir 

forests in western Washington and western Oregon, compare 

amphibian communities in streanw in Uncut forests to streams 

in logged areas, discuss the major physical characteristics of 

streams and the microhabitat associations of aquatic amphibians, and identify regional patterns in the density and biomass 

of amphibians in headwater streams. 

Geographic Distributions and Life Histories 

Four species (or groups of sibling species) of aquatic amphibians (fig. 1) OCCUT in the temperate forests of the Pacific 

Northwest: Olympic salamanders, giant salamanders (genus 

Dicampdon), Dunn’s salamanders, and tailed frogs. Distribution maps are based mostly on locality records in 

Nnssbaum and others (1983), with additional information 

from Bury (1%8), Good and others (1987). Green and 

Campbell (1984), and our recent field work. Range “taps 

presented here are new interpretations; they were. designed to 

denote areas lacking records as well as areas with known 

faunas. 

Good and others (1987) indicate that the Olympic salamander comprises at least three genetically distinct groups in the 

following areas: the Olympic Peninsula to northwestern 

Oregon, the Coast Range from central Oregon to northern 

California, and the Cascade Range of Oregon and Washington (fig. 2). This species requires cool waters, and 

individuals are usually found only in the splash zone or 

shallows of seeps and streams (Nwsbaum and Tait 1977, 

Nussbaum and others 1983). 

Giant salamanders are widespread in the Pacific Northwest 

(fig. 2). Pacific giant salamanders are large (up to 350 mm 

long) and inhabit streams and standing water over a relatively wide range of temperatures. Their eggs and larvae 

OCCUI in water, but transformed juveniles and adults may live 

on land. Cope’s giant salamander is a smaller species that is 

mostly aquatic and neotenic (Nwsbaum 1970). The Rocky 

Mountain giant salamander, which OCCUTS in interior areas 

(Daugherty and others 1983). is not discussed here. 

The tailed frog is distributed similarly to the giant salanxmder (fig. 3). Eggs and tadpoles of this frog require cool, flowing waters (Buy 1968.1988; de Vlanting and Bury 1970; 

Metter 1964; Nwbaum and others 1983). Their larval stage 

reportedly lasts for 2 to 3 years (Metter 1967) and, in the 

Rocky Mountains, adults may not breed until 7 to 8 years of 

age (Daugherty and Sheldon 1982). Tailed frogs OCCUT in 

disjunct populations, especially in interior or drier areas 

(Daugherty and Sheldon 1982, Metter 1967). 

354