PARENT SESSION
Oral Session #96: Plant Competition II.
Presiding: K. Suding
Thursday, August 8. 1:00 PM to 3:45 PM. Mesquite Room, Radisson.
Community stability in the mesotrophic grasslands of Park Grass.
de MAZANCOURT, Claire*,1, CRAWLEY, Michael1, 1 Imperial College, SILWOOD PARK, Berkshire, UK
ABSTRACT- The Park Grass experiment was set-up in 1856, to investigate the effect of fertilisers on hay yield. The communities are now as close as we can get to equilibrium communities. The biomass of all species in each of the 89 plots was recorded over the last ten years. We investigate structure of the variance and covariance between species biomasses, to explore the effect of species abundance and species richness on population and community variance. We show that more abundant species are less variable, species in communities with high total biomass are more variable, and species in species rich communities are less variable. Species show on average more positive covariances than expected if species varied independently of each other. This effect decreases when fertilisers are added, suggesting that fertilisers result in increased negative interspecific dynamics (competition or complementarity). These findings have strong implications in the debate on whether plant species richness increases or decreases community stability.
KEY WORDS: community stability, grassland, Park Grass experiment, plant biomass