Ecology / Ecologie (CBA/ABC)
Diebolt, Tara , Nosko, Peter , Dech, J.P. .
Herbivory chlorophyll and phenol levels of northern red oak leaves under partial harvest treatments.
Recruitment of northern red oak (Quercus rubra L.) seedlings requires moderate light levels in the forest understorey. In the absence of occasional disturbances that create canopy gaps, the regeneration of this species is compromised by successional displacement by various shade tolerant species (e.g. sugar maple, red maple). Successful regeneration is further limited by high levels of herbivory as many herbivores preferentially consume red oak. Forest management programs attempting to enhance the natural regeneration of red oak commonly employ partial harvest methods; however, altered light conditions could directly or indirectly modify the palatability, digestibility or nutritional quality of red oak leaves. The objective of this study was to compare levels of herbivory, chlorophyll and phenols in leaves of red oak seedlings under different partial harvest treatments. For each of four sampling periods from late June to early October, 2006, leaves were collected from 15 oak seedlings per harvest treatment under 50% uniform shelterwood, 70% uniform shelterwood and group selection areas of an oak-dominated hardwood stand in Phelps Township near North Bay ON. Prior to, or following leaf collection, collar diameter, height, percent herbivory and leaf chlorophyll and phenol content were measured for each seedling. Canopy closure and total plant cover were also measured in relation to each sampled seedling. Herbivory, chlorophyll and phenol levels changed over the growing season. While canopy closure did not affect the degree of herbivory to which oak leaves were subjected, leaf chlorophyll and phenol levels varied among canopy treatments. Chlorophyll levels were positively related to phenols and negatively related to herbivory. Although red oak is well known to rely on phenols for chemical defense against herbivores, we observed no relationship between leaf phenol and herbivory levels. Our results suggest that partial harvest systems affect the ability of red oak seedlings to defend against herbivores.
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1 - Nipissing University, Biology, North Bay, ON, P1B 8L7, Canada
Presentation Type: Poster:Posters for Sections
Location: Ball Room & Party Room/SUB
Date: Monday, July 28th, 2008
Time: 12:30 PM