1 June 2014, Pages 5–18
Mechanisms
and predictors of ecological change in managed forests: A selection of
papers from the second international conference on biodiversity in
forest ecosystems and landscapes
Avian response to timber harvesting applied experimentally to manage Cerulean Warbler breeding populations
Highlights
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- We studied effects of Cerulean Warbler management on other breeding forest birds.
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- We replicated our experiment at seven study areas in the central Appalachians.
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- 10–20 m2 ha−1 Residual basal area harvests had largest Cerulean Warblers increases.
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- They increased forest gap species and retained, but reduced closed-canopy species.
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- Ecologically-based forest management may benefit multiple breeding bird assemblages.
Abstract
Timber harvesting has been proposed as a management tool to enhance breeding habitat for the Cerulean Warbler (Setophaga cerulea),
a declining Neotropical–Nearctic migratory songbird that nests in the
canopy of mature eastern deciduous forests. To evaluate how this
single-species management focus might fit within an ecologically based
management approach for multiple forest birds, we performed a
manipulative experiment using four treatments (three intensities of
timber harvests and an unharvested control) at each of seven study areas
within the core Cerulean Warbler breeding range. We collected
pre-harvest (one year) and post-harvest (four years) data on the
territory density of Cerulean Warblers and six additional focal species,
avian community relative abundance, and several key habitat variables.
We evaluated the avian and habitat responses across the 3–32 m2 ha−1 residual basal area (RBA) range of the treatments. Cerulean Warbler territory density peaked with medium RBA (∼16 m2 ha−1). In contrast, territory densities of the other focal species were negatively related to RBA (e.g., Hooded Warbler [Setophaga citrina]), were positively related to RBA (e.g., Ovenbird [Seiurus aurocapilla]), or were not sensitive to this measure (Scarlet Tanager [Piranga olivacea]).
Some species (e.g., Hooded Warbler) increased with time post-treatment
and were likely tied to a developing understory, whereas declines (e.g.,
Ovenbird) were immediate. Relative abundance responses of additional
species were consistent with the territory density responses of the
focal species. Across the RBA gradient, greatest separation in the avian
community was between early successional forest species (e.g.,
Yellow-breasted Chat [Icteria virens]) and closed-canopy mature
forest species (e.g., Ovenbird), with the Cerulean Warbler and other
species located intermediate to these two extremes. Overall, our results
suggest that harvests within 10–20 m2 ha−1 RBA
yield the largest increases in Cerulean Warblers, benefit additional
disturbance-dependent species, and may retain closed-canopy species but
at reduced levels. Harvests outside the optimum RBA range for Cerulean
Warblers can support bird assemblages specifically associated with early
or late (closed-canopy) successional stages.
Keywords
- Upland hardwood forest;
- Silviculture;
- Residual basal area;
- Forest bird management;
- Cerulean Warbler;
- Bird assemblages
Copyright © 2013 Elsevier B.V. Published by Elsevier B.V. All rights reserved.
