|These projects were designed to examine: 1) the effect of the different treatments on the diversity, abundance and microhabitat selection of breeding birds and small mammals; 2) determine if maintaining mature forest habitat by partial cutting continues to support bird and mammal species typical of mid- to late-seral stands and, 3) to understand how birds and small mammals respond to changes in stand structure.|
|Red-backed vole (Clethrionomys gapperi)|
|Lincoln's sparrow (Melospiza lincolnii)|
Steventon, J.D., MacKenzie, K., and Mahon, T. 1998. Response of small mammals and birds to partial cutting vs clearcutting in northwest British Columbia. For. Chronicle, 74:703-713.
Abstract: A challenge facing forest managers is providing habitat for wildlife that are associated with mature or old-growth forests while minimizing reductions in timber supply. One approach is to use partial cutting which maintains forest cover while still allowing for timber harvest. We compared small mammal (mice, voles and shrews) and bird abundance after 2 intensities of partial cutting (30% and 60% volume removal) in previously unmanaged stands, to clearcuts and uncut natural stands in coast-interior transitional forests in north-western British Columbia. The 30% removal showed no significant difference in the bird community compared to the unmanaged stands, while the southern red-backed vole (Clethrionomys gapperi) increased in abundance. The 60% removal treatment was still closer to the unmanaged forest in bird and small mammal community structure then to the clearcuts, but began to include species typical of clearcuts such as the meadow vole (Microtus pennsylvanicus) and Lincoln’s Sparrow (Melospiza lincolnii). At least one bird species, the Yellow-rumped Warbler (Dendroica coronata) preferred the 60% removal treatment. Several species were most abundant in clearcuts, and scattered aspen and birch trees left in 2 clearcuts were used as nesting sites by cavity nesting birds such as the Red-breasted Sapsucker (Sphyrapicus ruber) and Tree Swallow (Tachycineta bicolor). We conclude that both partial cutting treatments maintained a significant component of the mature forest small mammal and bird communities, although the heavy removal was beginning to show a shift towards early seral species. Since no single treatment is optimal for all species, we recommend that partial cutting be considered as part of a landscape strategy to provide a range of forest habitats similar to those occurring under natural disturbance regimes.
Steventon, J.D., Ott, P.K. and MacKenzie, K. 1999. Effect of partial cutting on predation risk to artificial bird nests. Can. J. For. Res., Vol.29(12) 1911-1915.
Abstract: Based on relative abundance data,
partial cutting has been suggested as a technique to maintain habitat for
birds associated with late-seral forests, but there has been little study
of partial cutting effects on nesting success. One of the primary limitations
to nesting success is nest predation. We compared predation rates (proportion
of nests disturbed in a 14-day period) in partially cut (30 or 60% basal
area removal), clearcut, and uncut forests in northwestern British Columbia,
in two experiments using ground-placed (1993) and shrub-placed (1998) artificial
nests. In the ground-nest experiment there was a very low predation rate
(0.06) and no detectable difference among treatments (p = 0.403). In the
shrub-nest experiment, there was a 0.36 predation rate and little evidence
of treatment differences (p = 0.295). Based on 90% confidence intervals
for differences in observed predation rate, the 30% removal clearly did
not increase predation risk relative to uncut forest. With the 60% removal,
however, we cannot rule out a possible increase in predation risk compared
with either uncut forest or clearcuts.
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