PARENT SESSION
Oral Session #44: Disturbance ecology of forests: Animals, wind, gaps, edges. Presiding: S. Archer.
Wednesday, August 8, 2001. 8:00 AM to 11:45 AM. Hall of Ideas G.
Influence of deer, cattle grazing and timber harvest on plant species diversity in a longleaf pine bluestem ecosystem.
Brockway, Dale1, Lewis, Clifford1, 1
ABSTRACT- Decline of the species-rich longleaf pine (Pinus palustris) ecosystem has led to increased interest in management impacts on ecological resources in remaining fragments. Our study objectives were to evaluate the effects of deer (Odocoileus virginianus) grazing, cattle grazing and grazing exclusion on the understory plant community in forests harvested by clearcutting or thinning (to 17 m2/ha) and discern the rates of ecosystem change and recovery following these disturbances. Plant cover and diversity were measured for 5 years following installation of grazing exclosures on the low dry sandy ridges of a southern Alabama flatwoods. Neither plant cover nor diversity were significantly affected by grazing. Woody understory vegetation steadily increased through time, with woody cover in clearcuts, dominated by tree seedlings (Pinus elliottii and Quercus spp.), being greater than that in thinned forests, dominated by shrubs (Ilex glabra and Rubus spp.). While grass cover (Schizachrium scoparium and Andropogon spp.) remained stable, foliar cover of all forbs declined through time as woody cover increased. Although species richness and diversity declined and evenness increased through time, understory species richness and diversity were consistently higher in thinned forests than in artificially-regenerated clearcuts. Whether grazing includes domestic cattle or is limited to native ungulates, we recommend that natural longleaf pine forests not be clearcut and replaced by plantations of other pines, if ecological diversity is to be conserved and high quality habitat maintained.
KEY WORDS: <|>Pinus palustris</|>, <|>Pinus elliottii</|>, <|>Schizachrium scoparium</|>, <|>Andropogon</|> spp.