CDR LTER

This experiment is designed to examine the mechanisms of competition among grasshoppers, effects of grasshoppers on plant competition, and the effects of plant species and biomass on the ability of grasshoppers to coexist. The plots were set up within the E026 fenced exclosure. The plots are 60cm x 60cm. They are enclosed by a cage which is 1.2m high. The 240 plots were seeded with monocultures and pairwise combinations of two grasses, Schizachyrium scoparium, Poa pratensis, and a legume Lespedeza capitata. To each plant monoculture and species combination, two grasshopper species were added at high density according to four treatments: each grasshopper species by itself (2 treatments), both species together, and no grasshoppers (empty cage). Introduced grasshoppers were allowed to decline to an "equilibrium" density, as determined by counting all grasshoppers in cages every 5 days. After grasshoppers reached "equilibrium", vegetation was sampled by clipping a 50cm x 5cm strip. Soil samples were taken 5 times during the summer to determine the effect of grasshoppers on available soil nitrogen. For a list of treatments, see the treatment layouts in file trmte71.