Soil nitrate and ammonium: Grasshopper removals

This experiment is designed to examine the effect of removing particular grasshopper species from a community with natural (uncaged) grasshopper densities. During the summer, beginning in 1991, grasshoppers are removed from forty, 2m x 4m plots in Field B, macroplot #6, according to the following 8 treatments: (1) No grasshoppers removed, (2) All grasshoppers removed, (3) All early season grasshopper species removed (Pardalophora apiculata and Arphia conspersa), (4) All late season grasshopper species removed (Melanoplus femur-rubrum, Phoetaliotes nebrascensis, conocephalus sp. + others present), (5) Melanoplus femur-rubrum removed, (6) Phoetaliotes nebrascensis removed, (7) Conocephalus sp. removed, (8) All late season grasshopper species with an average mass greater than 0.5g are removed. Grasshopper removals will occur once a week from June1- September 7. Grasshopper abundances will be sampled by capturing all individuals in a plot in late June and late August. Vegetation will be sampled in August by clipping 10cm x 1.5m strips from within each plot, drying and weighing green vegetation sorted to species. Soil solution concentrations of ammonium and nitrate will be determined in September from two soil samples from each plot. For a list of treatments, see the treatment layouts in file trmte90.