Groundlayer vegetation gradients across oak woodland canopy gaps

Journal of the Torrey Botanical Society
By: , and 



Frequency of groundlayer plants was measured across oak woodland canopy gaps at three sites in northwest Indiana to examine how vegetation varied with gap size, direction along the gap edge, and microhabitat. Microhabitats were defined as under the canopy adjacent to the gap, along the gap edge, and within the gap. Gap-sites consisted of gaps plus adjacent tree canopy. Gaps were classified as small (16 ± 1 m2), medium (97 ± 8), and large (310 ± 32). Neither richness nor diversity differed among microhabitats, gap sizes, or edges. Similarity between microhabitats wthin a gap-site increased as the distance between plots decreased and as the difference in PAR decreased, the latter explaining twice the variation in percent dissimilarity compared to Mg concentration, A horizon depth, and litter cover. Diervilla loniceraFrageria virginianaHelianthus divaricatusPolygonatum pubescensQuercus velutinaSmilacena stellata, and Tradescantia ohiensis decreased, whileTephrosia virginiana and legumes increased in frequency, from canopy to gap, and C4 grasses peaked at the gap edge, independent of gap size. Additional species frequency varied across the microhabitat gradient within specific sites. Sorghastrum nutans was three times more frequent in gaps at large sites than elsewhere. The vegetation in medium-sized gap-sites was more variable than within small and large gap-sites, suggesting greater environmental heterogeneity at that scale. Within gap-sites, vegetation was more heterogeneous within edges and canopies than in gaps. Edges were more similar in composition to gaps than to canopy groundlayer within gap-sites. Few species varied significantly in frequency around the gap edge. The oak woodland groundlayer on sandy substrates can be characterized as a mosaic of forb dominated vegetation that varies across light gradients associated with canopy gaps, transitioning to islands of grassland vegetation when gaps exceed 160 m2.

Publication type Article
Publication Subtype Journal Article
Title Groundlayer vegetation gradients across oak woodland canopy gaps
Series title Journal of the Torrey Botanical Society
DOI 10.3159/1095-5674(2006)133[225:GVGAOW]2.0.CO;2
Volume 133
Issue 2
Year Published 2006
Language English
Publisher Torrey Botanical Society
Contributing office(s) Great Lakes Science Center
Description 5 p.
First page 225
Last page 239
Online Only (Y/N) N
Additional Online Files (Y/N) N
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