The importance of beaver lodges in structuring littoral communities in boreal headwater lakes

The littoral zones of many boreal headwater lakes in northwestern Ontario are composed of rocks, boulders, and sand, with sparse macrophyte growth. This study investigated the possibility that abandoned beaver lodges might structure littoral communities in these systems through providing accumulations of coarse woody debris and entrapped sediment. The richness and abundance of 10 benthic macroinvertebrate taxa, 6 species of small fishes, and 2 species of amphibians were found to be significantly elevated near beaver lodges compared with areas of sand and rocks otherwise characteristic of the littoral zones in these lakes. Beaver in Ontario are generally regarded as a nuisance or a resource; wildlife managers therefore encourage extensive trapping before large populations can become established. The results of this study suggest that beaver provide an important habitat resource for littoral communities in boreal headwater lakes. As a result, endorsement of limiting beaver populations through increased trapping should be reexamined for regions containing macrophyte-impoverished lakes with a rocky shore.

Download Full-text

Influence of habitat and microhabitat on carabid (Coleoptera: Carabidae) assemblages in four stand types

The Canadian Entomologist ◽

10.4039/n02-031 ◽

2003 ◽

Vol 135 (3) ◽

pp. 337-357 ◽

Cited By ~ 40

Author(s):

J.L. Pearce ◽

L.A. Venier ◽

J. McKee ◽

J. Pedlar ◽

D. McKenney

Keyword(s):

Coarse Woody Debris ◽

Woody Debris ◽

Habitat Associations ◽

Litter Layer ◽

Forest Types ◽

Disturbed Habitat ◽

Northwestern Ontario ◽

Spruce Stands ◽

Insight Into ◽

Important Habitat

AbstractStudies based on presence/absence of a species may provide insight into habitat associations, allowing the distribution of species to be predicted across the landscape. Our objective was to characterize the carabid fauna in three mature boreal forest types (conifer, mixedwood, and deciduous) and a disturbed habitat (clearcut) to provide baseline data on the carabid species inhabiting the major forest types of boreal northwestern Ontario. Only spring-active carabids were considered for logistical reasons. We further identified the coarse woody debris structure and microhabitat characteristics within these stand types to try to refine our ability to predict the within-stand occurrence of carabids. We found the carabid composition of deciduous stands (mixedwood and aspen) similar and typical of the carabid fauna found in mixedwood forest in other nearby studies. The important feature of these forest types may be the presence of a deciduous leaf litter layer. In contrast, spruce stands contained fewer species and individuals and a distinct carabid fauna. As predicted, the clearcut habitats were dominated by open habitat species, although the fauna was dissimilar to what was recorded in clearcut habitats in other studies within northwestern Ontario. Coarse woody debris appeared to be an important habitat attribute for several carabid species in clearcut habitats.

Download Full-text