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Publication Title: Shrub and herb community responses to experimental canopy gaps in Douglas-fir forests [Abstract]
Year: 1999 Publication Type: Abstract
H. J. Andrews Publication Number: 2691
Citation: Spies, T. A.; Pabst, R. J.; Gray, A. N. 1999. Shrub and herb community responses to experimental canopy gaps in Douglas-fir forests [Abstract]. In: The Ecological Society of America 84th annual meeting: legacies, landscapes and limits: bridging borders; 1999 August 8-12; Spokane, WA. Washington, DC: Ecological Society of America: 309.
Online PDF: http://andrewsforest.oregonstate.edu/pubs/pdf/pub2691.pdf
Abstract: The response of shrubs and herbs to canopy gap formation is not well understood in coniferous forests of western North America. For example, it is not clear to what extent the response to gap formation is controlled by gap size, within-gap position, and pre-gap species composition. Cover of shrub and herb species was measured at 1-2 yr intervals for seven years in 36 experimental gaps of different sizes created in mid-aged and old-growth Douglas-fir forests in western Oregon and Washington. Species richness on a meter square basis was higher in gaps than in canopy controls and increased with gap size. Dissimilarity (Sorensen's coefficient) between pre- and post-gap communities at seven years ranged from 9% to 17% in the controls to 21% to 74% in the gaps. Species accounting for increases in diversity included invaders such as Epilobium spp. and Cirsium spp., and spreading, residual species such as Rubus spp. and Achlys triphylla. Species differed in rates of response to gap formation and in spatial pattern of cover within gaps. Initial conditions also appear to influence response to gap formation. For example, the greatest changes in dissimilarity between pre- and post-gap communities occurred where initial species richness was lowest. Results indicate that gap size influences shrub and herb communities, but responses to gaps are highly variable and are also controlled by initial species composition.
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