Response of Five Deciduous Forest Herbs to Partial Canopy Removal and Patch Size

Abstract

-Forest canopy was partly removed [33% or 66% removal of canopy tree basal area (BA)] from patches of three sizes (0.015, 0.053, 0.196 ha) to determine whether the frequency of five deciduous forest herbs was affected by patch size. Herb frequency, irradiance and woody stem density were recorded after canopy removal and 2 yr later. Irradiance and woody stem density both increased more in large (0.196 ha) patches than in smaller patches (0.015 and 0.053 ha) with 33% and 66% of tree BA removed. In contrast, where 66% of tree BA was removed, the frequency of four herbs increased more in smaller patches than in large patches and the frequency of the fifth herb was unaffected by patch size. Where 33% of tree BA was removed, herb frequency also increased more in smaller patches than in large patches for one herb and by about the same amount in all patches for another herb. The remaining three herbs each increased more in medium-sized patches (0.053 ha) than in small or large patches. These results indicate that the frequency of perennial forest herbs does not increase more in large canopy openings than in smaller openings. Although irradiance was higher in large patches than in smaller patches, woody stem density was greater in large patches as well and competition from more woody plants in large patches may explain why herbs did not increase more in large patches than in smaller patches.