PARENT SESSION
Oral Session #8: Restoration Ecology: Grasslands, wetlands, aquatic. Presiding: G. Noe.
Monday, August 6, 2001. 8:00 AM to 12:15 PM. Hall of Ideas H.
Plant community diversity and heterogeneity in response to resource manipulations in a tallgrass prairie restoration.
Baer, Sara1, Collins, Scott1, Blair, John1, Knapp, Alan1, 1
ABSTRACT- Species richness and diversity are often correlated with environmental heterogeneity, yet ecological restorations often occur in homogeneous environmental conditions. To assess the role of resource heterogeneity on plant community richness and diversity during restoration, we manipulated soil depth (buried limestone) and nutrient availability (N and C additions) in replicated 6x8 m grids using a strip-plot design on former agricultural land seeded to native dominant grasses and >30 forb species. Previously, we reported that C amendments reduced soil nitrogen availability, aboveground biomass, species richness and diversity. Variability in species richness and diversity increased over time in all treatments, but there was no relationship between richness and diversity and soil resource heterogeneity. Coefficient of variation (CV) of total aboveground net primary production (NPP) and CV of percent cover were greatest in the maximum heterogeneity grids. Total diversity (H') was correlated with heterogeneity of NPP (r=0.43, p=0.002), heterogeneity of total cover (r=0.53, P=0.0001) and heterogeneity of cover of the C4 grass, Panicum virgatum (r=-0.40, P=0.004). Thus, although richness and diversity were not directly related to resource heterogeneity as initially hypothesized, resource heterogeneity affected the abundance of the dominant perennial grasses which indirectly impacted species diversity and richness in this grassland restoration.
KEY WORDS: prairie restoration, species diversity, community heterogeneity