Carbon assimilation of oak seedlings in response to canopy thinning treatments at The Morton Arboretum in Lisle, Illinois, USA
Moses, Mary Rebecca
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White and bur oak savanna was once the dominant vegetation type in the Midwestern United States prior to European settlement. Within the oak savanna biome were pockets of oak-hickory closed forested sites, usually occurring in mesic areas and on the east side of rivers. Restoration efforts to restore the land back to savanna and closed canopy oak dominated forests are met with varying success. There is a need for understanding canopy openness requirements, and ideal forest floor light levels for successful oak regeneration. The purpose of this study is to determine success of oak seedlings growing under varying canopy treatments. Two sites at The Morton Arboretum (DuPage County, Illinois) with varying topography received either a 20% basal area removal, a 10% basal area removal, or no treatment. From May to October 2014 light levels (photosynthetically active radiation) were monitored every 15 minutes immediately adjacent to 24 seedlings. Leaf-level and carbon assimilation was modeled for each seedling throughout the growing season. Key findings suggest that canopy thinning does impact understory light environments, but the management strategy at the levels used in this study are not enough to have a biological impact on seedlings. Long term analysis is be needed to determine if the canopy openness manipulations create successful oak restoration of seedlings to the canopy.