부산대학교 도서관

To better understand the distribution and abundance of headwater-stream salamanders in managed conifer forests, we examined relationships between Cascade torrent salamanders (Rhyacotriton cascadae) and biotic and abiotic habitat attributes at landscape and within-stream levels in western Oregon, USA. In 2001 we found 145 torrent salamanders in 25% of 59 headwater (first-order) streams from randomly selected 2.58-km² sections of the study area. Landscape-level variation in torrent salamander distribution and relative abundance were related to the age of adjacent riparian forests and to the landform features parent geology and stream aspect. In 2002 we conducted a more detailed study of salamander occurrence and abundance within 49 10-m stream reaches, stratified by gradient, that were randomly selected from 15 streams known to contain salamanders. We recorded 475 salamanders from 33 (67%) of the stream reaches. Akaike's Information Criterion (AIC) model selection indicated that a streambed substrate model best explained salamander occupancy in stream reaches, but a model containing only the parameter distance to stream origin and another model containing abiotic landform features also received strong empirical support. In contrast, the distance to stream origin model was the best candidate model explaining reach-level salamander abundance. However, 2 additional models explaining abundance, including one that discriminated between the northern and southern portions of our study area and another that reflected stream reach habitat parameters, also received strong empirical support. Physical features of stream habitats appear to have an important influence on the distribution and abundance of torrent salamanders at multiple spatial scales, and these parameters should be addressed when designing management strategies (e.g., riparian buffers) to conserve these species. [ABSTRACT FROM AUTHOR]