An ecologist studying plants in the desert performed the following experiment. She staked out two identical plots, each of which included numerous small wildflowers. She found the same five wildflower species in roughly equal numbers in both plots. She then enclosed one of the plots with a fence to keep out major herbivores. After two years, four of the wildflower species were no long present in the fenced plot, but one species had increased drastically. The control plot had no change in species diversity.