Document: JIN-3-40-26

Woody canopy influences on understory plants during old field succession.

YAO, J.* ¹ and P.M.RICH ^1,2

University of Kansas, Lawrence, KS 66045 USA ¹
Kansas Biological Survey, Kansas USA ²

Abstract:
Few studies of old field succession have focused on the transition from herbaceous to woody dominated stages. We examined influences of colonizing woody plants on understory herbaceous plants and early-succession tree seedlings during this transition. As part of a long-term experiment on old field succession and habitat fragmentation in the prairie-forest ecotone of eastern Kansas, the vegetation composition has been sampled using quadrats since the fall of 1984. Overall, woody plant colonization has proceeded linearly since 1984; stem density, canopy height, and leaf area index (LAI) have increased; ground-level light indices have decreased; and variance in these canopy measures has increased. As the woody canopy has developed, both the abundance (cover) and species richness of grassland and old field herbaceous species has begun to decline and forest herbaceous species have begun to appear at microsites under overstory canopy, while intercanopy microsites typically maintain a full complement of grassland and old field herbaceous species. The abundance of early-succession tree seedlings is highest at intermediate overstory development, and locations with high overstory LAI values are associated with seedling mortality and low growth rates. This stage of succession, with high canopy heterogeneity, is associated with strong local gradients in the physical environment (e.g., light, soil moisture, temperature), a shift in productivity from the herbaceous to the overstory stratum, and a period of high species richness.

Keywords: canopy, community composition, diversity, old-field succession, succession, woody colonization

This abstract is being presented at: 3:30 PM in session:
Poster Session #17: Vegetative Analysis.