Ecology / Ecologie (CBA/ABC)
Robinson, Lisa M.K. , Dech, J.P. , Nosko, Peter .
Changes in microenvironment and plant community characteristics following partial harvest: implications for regenerating red oak in Great Lakes - St. Lawrence (GLSL) forests.
Throughout its range, stands of northern red oak (Quercus rubra L.) are undergoing successional replacement by shade-tolerant competitors (e.g. Acer spp.) As oak seedlings require moderate light levels, partial harvest systems are recommended to promote red oak regeneration. The reduction of overstorey shade; however, could alter the diversity and abundance of understorey plants thereby maintaining a light limitation on red oak seedlings. The objective of this study was to investigate changes in plant community structure and red oak regeneration following partial harvest. An ordination based-approach was used to explore patterns in microenvironment and understorey plant community following different partial harvest treatments applied in a GLSL hardwood stand. Two years after harvest, we established 2 x 2 m plots in a stratified random design under two uniform shelterwood intensities (50 and 70 % crown closure), group selection cuts and uncut areas. A suite of microenvironment variables and percent cover of understorey plant species were measured for each plot. Partial harvesting altered the microenvironment and led to shifts in the structure of the understorey plant community. Correspondence analysis (CA) ordination extracted two major axes explaining 21.6 % of the variance in the species cover by plot matrix. Axis one (13.2 %) separated plots along a gradient of canopy cover and reflected a shift in dominance of understorey plants from shade-tolerant (e.g. Acer spp.) to shade-intolerant (e.g. Rubus idaeus , Carex spp.) colonizers. Axis two (8.4 %) separated plots along a fertility gradient showing a shift in dominance from competitive (e.g. A. saccharum) to stress-tolerant (e.g. A. rubrum) species. Our results suggest that partial harvest treatments changed the light limitation from the overstorey to the understorey environment, thereby changing the major competitors of red oak seedlings. This emphasizes the importance of considering the understorey environment in management efforts to enhance red oak regeneration.
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1 - Nipissing University, Biology, 100 College Dr., North Bay, ON, P1B 8L7, Canada
2 - Nipissing University, Biology, 100 College Drive, North Bay, Ontario, P1B 8L7, Canada
Great Lakes - St. Lawrence forest.
Presentation Type: Poster:Posters for Sections
Location: Ball Room & Party Room/SUB
Date: Monday, July 28th, 2008
Time: 12:30 PM