Patterns of distribution, relative abundance, and microhabitat use of anurans in a boreal landscape influenced by fire and timber harvest

Abstract

Ecosystem management is a theoretical framework in which land managers attempt to approximate natural disturbance with harvesting practices. In the mixedwood boreal forest of northeastern Alberta, Alberta-Pacific Forest Industries Inc. alters cutblock size, structure, and distribution over the landscape to simulate fires, the dominant disturbance type. In 1997 and 1998, we sampled for Rana sylvatica (Le Conte) and Pseudacris triseriata maculata (Wied-Neuwied) near Owl River and Mariana Lake, Alberta, in undisturbed, harvested, and naturally burned landscapes. We compared patterns of distribution and relative abundance using transects, time-constrained lake margin searches, and opportunistic detections. In 1998, we characterized the understory, shrub layer, and canopy layer on each transect. We used stepwise logistic regression to describe microhabitat use by each species. We did not detect consistent differences between burned and logged areas. This may reflect pre-treatment variation in regional habitat. Our data suggest that the presence of R. sylvatica is related to deciduous leaf litter, and that both species may require extensive ground cover and moist soil conditions. Although the microhabitat descriptions we present can be used to plan future harvests, further work is required to determine the effectiveness of ecosystem management in the boreal forest.