Grasshopper cage data: Vegetation Phenology and Grasshopper Competition

Vegetation was sampled at the termination of the experiment on June 25, 1989. Grasshopper densities outside the cages were sampled on May 23 and 24, 1989. After the first experiment, cages were set up on new plots 3m from the edge of the macroplot to avoid using vegetation disturbed by counting. On July 25, adult grasshoppers of two different species (Melanoplus femur-rubrum (FR) and Melanoplus bivattatus (BV)) were stocked according to the above treatments (randomly reassigned) in the following densities: FR by itself, 6/cage; BV by itself, 4/cage; FR and BV together, 4 FR and 3 BV /cage. Vegetation was sampled at the termination of the experiment on August 31, 1989.

In late May of 1990, grasshoppers were stocked in the following numbers in both fertilized and unfertilized plots: no grasshoppers (empty cages), AC by itself (5/cage), PA by itself (4/cage), and both species together (3 of each). With 8 replicates of each fertilizer x grasshopper combination, a total of 64 cages were used. Vegetation was sampled at the end of the experiment as in 1989.

In late July of 1990, two new grasshopper species were used in addition to Melanoplus femur-rubrum (MF): Phoetaliotes nebrascensis (PN) and Spharagemon collare (SC). Grasshoppers were stocked in the following numbers: no grasshoppers (empty cages), MF by itself (6/cage), PN by itself (10/cage), SC by itself (6/cage), MF + PN (3 MF and 5 PN per cage), MF + SC (3 of each per cage), SC + PN (3 SC + 5 PN per cage), and all three species together (2 MF, 2 SC, and 3 PN per cage). Vegetation was sampled at the end of the experiment as in 1989. At the end of the early and late 1990 experiments, a single soil sample was taken from each cage plot and analyzed for soil solution ammonium and nitrate with 0.02M KCl. For a list of treatments, see the treatment layouts in file trmte60.

本实验于1989年6月25日结束时开展植被取样。于1989年5月23日至24日对养虫笼外的蝗虫密度进行取样。首轮实验结束后，为避免使用因计数操作而受干扰的植被，研究人员在距离大样地边缘3米的新样地搭建养虫笼。1989年7月25日，根据上述处理方案（已随机重新分配），投放两种不同物种的成虫蝗虫：分别为红腿黑蝗（Melanoplus femur-rubrum, FR）与二斑黑蝗（Melanoplus bivattatus, BV），投放密度如下：仅投放FR，每笼6头；仅投放BV，每笼4头；同时投放FR与BV，每笼4头FR及3头BV。本实验于1989年8月31日结束时再次开展植被取样。

1990年5月下旬，研究人员在施肥与未施肥样地中按以下数量投放蝗虫：无蝗虫（空白笼）、仅投放AC（每笼5头）、仅投放PA（每笼4头），以及同时投放两种物种（每笼各3头）。每种施肥×蝗虫组合设置8个重复样，共计使用64个养虫笼。本实验结束时的植被取样方法与1989年一致。

1990年7月下旬，除红腿黑蝗（Melanoplus femur-rubrum, MF）外，额外引入两种新的蝗虫物种：内布拉斯加剑蝗（Phoetaliotes nebrascensis, PN）与斑翅蝗（Spharagemon collare, SC）。本次实验按以下方案投放蝗虫：无蝗虫（空白笼）、仅投放MF（每笼6头）、仅投放PN（每笼10头）、仅投放SC（每笼6头）、MF+PN（每笼3头MF及5头PN）、MF+SC（每笼各3头）、SC+PN（每笼3头SC及5头PN），以及同时投放三种物种（每笼2头MF、2头SC及3头PN）。本实验结束时的植被取样方法与1989年一致。在1990年上、下两次实验结束后，研究人员从每个笼养样地采集1份土壤样品，采用0.02M KCl浸提法分析土壤溶液中的铵态氮与硝态氮。如需查看处理方案列表，请参阅文件trmte60中的处理布局。