title: A cross-continental comparison of plant and beetle responses to retention of forest patches during timber harvest.
abstract: Timber harvest can adversely affect forest biota. Recent research and application suggest that retention of mature forest elements (retention forestry), including unharvested patches (or aggregates) within larger harvested units, can benefit biodiversity compared to clearcutting. However, it is unclear whether these benefits can be generalized among the diverse taxa and biomes in which retention forestry is practiced. Lack of comparability in methods for sampling and analyzing responses to timber harvest and edge creation presents a challenge to synthesis. We used a consistent methodology (similarly spaced plots or traps along transects) to investigate responses of vascular plants and ground-active beetles to aggregated retention at replicate sites in each of four temperate and boreal forest types on three continents: Douglas-fir forests in Washington, USA; aspen forests in Minnesota, USA; spruce forests in Sweden; and wet eucalypt forests in Tasmania, Australia. We assessed (1) differences in local (plot-scale) species richness and composition between mature (intact) and regenerating (previously harvested) forest; (2) the lifeboating function of aggregates (capacity to retain species of unharvested forest); and whether intact forests and aggregates (3) are susceptible to edge effects and (4) influence the adjacent regenerating forest. Intact and harvested forests differed in composition but not richness of plants and beetles. The magnitude of this difference was generally similar among regions, but there was considerable heterogeneity of composition within and among replicate sites. Aggregates within harvest units were effective at lifeboating for both plant and beetle communities. Edge effects were uncommon even within the aggregates. In contrast, effects of forest influence on adjacent harvested areas were common and as strong for aggregates as for larger blocks of intact forest. Our results provide strong support for the widespread application of aggregated retention in boreal and temperate forests. The consistency of pattern in four very different regions of the world suggests that, for forest plants and beetles, responses to aggregated retention are likely to apply more widely. Our results suggest that through strategic placement of aggregates, it is possible to maintain the natural heterogeneity and biodiversity of mature forests managed for multiple objectives.
authors: School of Biological Sciences, University of Tasmania, Private Bag 55, Hobart, Tasmania, 7001, Australia.|ARC Centre for Forest Value, University of Tasmania, Private Bag 55, Hobart, Tasmania, 7001, Australia.|School of Environmental and Forest Sciences, University of Washington, Box 352100, Seattle, Washington, 98195, USA.
authors: Susan C
authors: SC
authors: Baker
authors: School of Environmental and Forest Sciences, University of Washington, Box 352100, Seattle, Washington, 98195, USA.
authors: Charles B
authors: CB
authors: Halpern
authors: School of Biological Sciences, University of Tasmania, Private Bag 55, Hobart, Tasmania, 7001, Australia.|ARC Centre for Forest Value, University of Tasmania, Private Bag 55, Hobart, Tasmania, 7001, Australia.
authors: Timothy J
authors: TJ
authors: Wardlaw
authors: USDA Forest Service, Northern Research Station, 5985 Highway K, Rhinelander, Wisconsin, 54501, USA.
authors: Christel
authors: C
authors: Kern
authors: Institute for Marine and Antarctic Studies, University of Tasmania, GPO Box 252-49, Hobart, Tasmania, 7001, Australia.
authors: Graham J
authors: GJ
authors: Edgar
authors: Institute for Marine and Antarctic Studies, University of Tasmania, GPO Box 252-49, Hobart, Tasmania, 7001, Australia.
authors: Russell J
authors: RJ
authors: Thomson
authors: Washington State Department of Natural Resources, Forest Resources, Olympia, Washington, 98504, USA.
authors: Richard E
authors: RE
authors: Bigley
authors: School of Environmental and Forest Sciences, University of Washington, Box 352100, Seattle, Washington, 98195, USA.
authors: Jerry F
authors: JF
authors: Franklin
authors: Daniel B. Warnell School of Forestry and Natural Resources, University of Georgia, 180 E Green St, Athens, Georgia, 30602, USA.
authors: Kamal J K
authors: KJ
authors: Gandhi
authors: Department of Ecology, Swedish University of Agricultural Sciences (SLU), P.O. Box 7044, SE-750 07, Uppsala, Sweden.
authors: Lena
authors: L
authors: Gustafsson
authors: Department of Ecology, Swedish University of Agricultural Sciences (SLU), P.O. Box 7044, SE-750 07, Uppsala, Sweden.
authors: Samuel
authors: S
authors: Johnson
authors: USDA Forest Service, Northern Research Station, 1831 Hwy 169 E, Grand Rapids, Minnesota, 55744, USA.
authors: Brian J
authors: BJ
authors: Palik
authors: USDA Forest Service, PNW Research Station, 3200 SW Jefferson Way, Corvallis, Oregon, 97331, USA.
authors: Thomas A
authors: TA
authors: Spies
authors: USDA Forest Service, PNW Research Station, 400 N 34th Street, Suite 201, Seattle, Washington, 98103, USA.
authors: E Ashley
authors: EA
authors: Steel
authors: The Forestry Research Institute of Sweden (Skogforsk), SE751 43, Uppsala, Sweden.
authors: Jan
authors: J
authors: Weslien
authors: USDA Forest Service, Northern Research Station, 5985 Highway K, Rhinelander, Wisconsin, 54501, USA.
authors: Joachim
authors: J
authors: Strengbom
mesh_terms: D000818:Animals; D001315:Australia; D044822:Biodiversity; D001517:Coleoptera; D003247:Conservation of Natural Resources; D016468:Forestry; D065928:Forests; D008910:Minnesota; D013548:Sweden; D013648:Tasmania; D014197:Trees; D014861:Washington
keywords: aggregated retention; forest influence; ground-active beetles; lifeboating; retention forestry