Principles of community ecology

Question

: An ecologist studying plants in the desert performed the following experiment. She stalked out two identical plots, including a few sagebrush plants and numerous small, annual wildflowers. She found that 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 the kangaroo rats, the most common grain eaters in the area. After two years, four of the wildflower species were no longer present in the fenced plot, but one species had increased drastically. The control plot had not changes in species diversity. Using the principles of community ecology, propose a hypothesis to explain her results. What additional evidence would support your hypothesis?

Answer 1

The plant that became more abundant in the experimental plot was able to do so because it was not being consumed by the kangaroo rat.  Without a predator, the plant was able to increase its abundance and competitively exclude the other species.  In this scenario, the kangaroo rat may be considered a keystone species because removal of it drastically alters the floral species composition.

Additional evidence:

Remove the exclosure and see if the four species return.

Construct new plots where you remove the plant species that takes over.  Perhaps the species that disappeared need the kangaroo rat for something (fertilizer?).