CS37 Watershed Ecology and Ecosystems
Date: Wednesday, June 12, 2002
Location: Poster Session - VCC
JohnsonRK, Allegheny College, Meadville, USA, johnsor@allegheny.edu
Ostrofsky, M, L, Allegheny College, Meadville, USA, mostrofs@allegheny.edu
Factors affecting aquatic plant community structure in Lake Pleasant, PA
The identification of factors affecting the distribution and abundance of organisms and the structure of communities is central to ecology. Most studies on submerged aquatic vascular (SAV) plant communities have sought to identify these factors using a cross-lake analysis, and in these studies, water chemistry has emerged as an important factor. It is less clear, however, what factors affect community structure within a lake. We have analyzed 103 stands of SAVs in a small mesotrophic lake of simple morphometry. At each stand plant biomass, water depth and concentrations of total- and extractable- N, P and K in the sediments were determined. Overall 16 species of SAV, plus Chara, were identified. Stand richness ranged from 1 to 12 species. The most frequent species included Ceratophyllum demersum, Megalodonta beckii, Potamogeton amplifolius, and P. pusillus, although 9 of the species encountered occurred in half or more of the stands. Total plant biomass ranged from 0.3 to 415 g dry wt/m2, with P. amplifolius and Megalodonta beckii contributing the most to biomass. Depth explained much of the variation in total community biomass. There was little evidence of any allelopathic interactions among species. Canonical correspondence analysis identified depth and extractable-K as important determinants of community composition.