Propose a hypothesis to explain the results

Q. An ecologist studying plants in the desert performed the follow experiment.
She staked out 2 identical plots, each of that included a few sagebrush plants and numerous small annual wildflowers. She found the same five wildflower species in roughly equal numbers on both plots. She then enclosed one of the plots with a fence to keep out kangaroo rats, the most ordinary grainivores of the area. After two years, four of the flower species were no longer present in the fenced plot, but one species had increased drastically.
Using principles of community ecology, propose a hypothesis to explain the results and outline her methods and science processes (as in dependent variable, independent variable, controls, constants) as used in the experiment. What extra evidence would support your hypothesis?