Skip To Content

Narrow Lake


View Larger Map

Location

Athabasca County No. 12 AB
Canada

Narrow Lake


View Larger Map

Location

Fraser-Fort George F BC
Canada

Ovenbirds (Seiurus aurocapillus) in riparian buffer strips: Short-term response to upland timber harvest in Alberta's boreal mixed-wood forest


Author(s): Lambert, J. D.

Year: 1998

Abstract:
In managed forests, riparian buffer strips are maintained primarily to protect water quality. They are also thought to safeguard diverse plant and animal communities. The value of buffer strips to area-dependent and edge-sensitive forest songbirds, however, is largely unknown. Numbers of one such species, the Ovenbird (Seiurus aurocapillus), have declined in narrow buffers following upland timber harvest I assessed the conservation potential of riparian buffer strips for Ovenbirds in Alberta's boreal mixed-wood forest. I measured abundance, territory characteristics, and pairing success in 20m, 100m, and 200m buffers, one year before and one year after upland clearcutting. Following timber harvest, Ovenbirds were absent from 20m buffer strips. Harvesting did not influence abundance, territory size, or pairing success in 100m or 200m buffers. Territories narrowed in both 100m and 200m buffers, though the response was significant only in the latter. Post-harvest territory position did not change in 200m buffers, but territories in 100m strips shifted lakeward, including more habitat adjacent to the riparian edge than before harvest. This positional adjustment may have resulted in changes to the structure of Ovenbird habitat. Further research is necessary to determine whether short-term results reflect long-term effects.

Size distribution of the macroinvertebrate community in a freshwater lake


Year: 1989

Abstract:
Macroinvertebrates were collected every 2 wk for 18 wk from three depth zones in a deep lake in Alberta. Unionid clams comprised 80% of the total macroinvertebrate biomass and were excluded from initial analyses. The seasonal average size-spectrum for the littoral zone community was bimodal with peaks in the 8–16 and 256–512 mg weight-classes; size-spectra for the sublittoral and profundal communities were unimodal with peaks in the 8–16 and 16–32 mg weight-classes, respectively. Slopes of the normalized size-spectra for the littoral, sublittoral, profundal and whole-lake communities were not significantly different from −1.0, −1.0, 0.0, and −1.0, respectively. These results suggest that biomass is evenly distributed across logarithmically even size-classes for the average macroinvertebrate community in the littoral zone, sublittoral zone, and on a whole-lake basis. The biomass peak for unionids (16.4–32.8 g weight-class) was 10–30 times greater than biomass peaks for the remaining macroinvertebrates. The slopes of normalized size-spectra for the littoral zone and whole-lake were changed significantly when unionids were included; however, unionids presumably play a minor role in the macroinvertebrate community because they are an energy sink in the present context. Despite wide seasonal variation, average normalized size-spectra based on samples collected at 4- and 6-wk intervals were very similar to those based on nine biweekly collections.