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songbird conservation, EMEND, forest harvest, variable retention management, boreal, songbird, emulation of natural disturbance, forest ecology

Odsen, Sonya G.

Supervisor and department: Spence, John Renewable Resources Acorn, John Renewable Resources

Examining committee member and department: Nielsen, Scott Renewable Resources Pinzon, Jaime Renewable Resources Schmiegelow, Fiona Renewable Resources

Department: Department of Renewable Resources

Specialization: Conservation Biology

Date accepted: 2015-09-21T10:59:48Z

Graduation date: 2015-11

Degree: Master of Science

Degree level: Master's

Abstract: The Canadian boreal forest is vital breeding habitat for North American songbirds. Extensive anthropogenic disturbances within this biome are therefore of conservation concern. Using unharvested stands as controls, I examined the effects of variable retention management VRM relative to clear-cuts on songbird assemblages and individual species in a boreal mixedwood forest. Breeding season point count surveys were performed in 10-ha cutblocks applied across four dominant forest types deciduous dominated, deciduous with spruce understory, mixedwood, and coniferous dominated, and harvested in winter 1998-99 to five retention levels clear-cut 2%, 10%, 20%, 50%, and 75%, plus unharvested controls. Surveys were conducted prior to harvest in 1998, and subsequent to harvest in 1999, 2000, 2005, 2006, 2012, and 2013 at the Ecosystem Management by Emulating Natural Disturbance EMEND experiment in northwestern Alberta. In the first two post-harvest years, songbird assemblages in stands with less than 75% retention differed significantly from those in unharvested stands. After 14-15 years, assemblages in stands with 20% retention or higher no longer differed significantly from the controls, suggesting accelerated recovery within high retention stands. In the controls, however, species richness increased after 7-8 years, and species composition changed after 14-15 years, suggesting that c. 10-ha unharvested stands were too small to maintain unchanged songbird assemblages of undisturbed forest. Closer examination of six old forest-associated species – brown creeper Certhia americana, winter wren Troglodytes hiemalis, ovenbird Seiurus aurocapilla, black-throated green warbler Setophaga virens, Canada warbler Cardellina canadensis, and western tanager Piranga ludoviciana - revealed that 20-75% retention prevented significant declines of all six species, and five of the six species increased significantly after 14-15 years. This suggests that variable retention management can be useful for conservation of songbird assemblages and species typical of unharvested forest. However, spatial trade-offs, lagged recovery in harvested stands, and assemblage changes in unharvested stands reinforce the importance of larger > 10 ha forest reserves in harvest planning.

Language: English

DOI: doi:10.7939-R3HX15W79

Rights: Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.





Autor: Odsen, Sonya G.

Fuente: https://era.library.ualberta.ca/


Introducción



Conserving Boreal Songbirds Using Variable Retention Forest Management by Sonya Gail Odsen A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Conservation Biology Department of Renewable Resources University of Alberta  Sonya Gail Odsen, 2015 Abstract The Canadian boreal forest is vital breeding habitat for North American songbirds.
Extensive anthropogenic disturbances within this biome are therefore of conservation concern.
Using unharvested stands as controls, I examined the effects of variable retention management (VRM) relative to clear-cuts on songbird assemblages and individual species in a boreal mixedwood forest.
Breeding season point count surveys were performed in 10-ha cutblocks applied across four dominant forest types (deciduous dominated, deciduous with spruce understory, mixedwood, and coniferous dominated), and harvested in winter 1998-99 to five retention levels (clear-cut (2%), 10%, 20%, 50%, and 75%), plus unharvested controls.
Surveys were conducted prior to harvest in 1998, and subsequent to harvest in 1999, 2000, 2005, 2006, 2012, and 2013 at the Ecosystem Management by Emulating Natural Disturbance (EMEND) experiment in northwestern Alberta.
In the first two post-harvest years, songbird assemblages in stands with less than 75% retention differed significantly from those in unharvested stands.
After 14-15 years, assemblages in stands with 20% retention or higher no longer differed significantly from the controls, suggesting accelerated recovery within high retention stands.
In the controls, however, species richness increased after 7-8 years, and species composition changed after 14-15 years, suggesting that c.
10-ha unharvested stands were too small to maintain unchanged songbird assemblages of undisturbed forest. Closer examination of six old forest-associated species – brown creeper (Certhia americana), winter wren (Troglodytes hiemalis), ovenbird (Seiurus aurocapilla), black-throat...





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