Mb. Kolozsvary et Rk. Swihart, Habitat fragmentation and the distribution of amphibians: patch and landscape correlates in farmland, CAN J ZOOL, 77(8), 1999, pp. 1288-1299
Citations number
53
Categorie Soggetti
Animal Sciences
Journal title
CANADIAN JOURNAL OF ZOOLOGY-REVUE CANADIENNE DE ZOOLOGIE
We studied the effects of agriculturally induced fragmentation of forests a
nd wetlands on amphibian assemblages and their distribution in a landscape
of the midwestern United States. Potential breeding pools and upland areas
in 30 forest patches of various sizes and degrees of isolation were intensi
vely sampled for amphibians during April through August 1996 and March thro
ugh August 1997 in Indiana. Species presence was documented using pitfall t
raps, anuran vocalization surveys, and cover-board sampling for adults and
minnow traps and dip nets for larvae. Amphibian, anuran, and salamander ass
emblages were nonrandomly distributed across the landscape. American toads
(Bufo americanus) and gray treefrogs (Hyla versicolor) were ubiquitous, whe
reas the distributions of several other species were ordered in a predictab
le manner. Logistic regression was used to develop predictive models of pro
babilities of occurrence for species in response to forest and wetland patc
h and landscape variables. Occurrence of redback salamanders (Plethodon cin
ereus) was positively associated with the area of a forest patch. Occurrenc
e of ranid frogs was positively associated with proximity of wetlands for t
hree of four species, and occurrences of smallmouth salamanders (Ambystoma
texanum), spring peepers (Pseudacris crucifer), and western chorus frogs (P
seudacris triseriata) were related to the degree of wetland permanency. Mul
tiple linear regression revealed that species richness was greatest for wet
lands with intermediate degrees of permanency. The observed nonrandom distr
ibution exhibited by several amphibians suggests that they respond to lands
cape-level attributes. Moreover, species differed substantially in the natu
re of their responses to fragmentation, consistent with differences in thei
r life history and ecology.