to competition may be dictated by the levels of resources available. The
objective of this study was to examine whether the amount of water influences
the intensity of competition among plants. Competition and watering were
manipulated in a crossed-design garden experiment in Texas. The experimental
species, Schizachyrium scoparium (Poaceae), was planted in three rows
that were not watered, but received only natural precipitation, and three rows
that were supplemented with additional water. Six target plants in each row were
randomly assigned to competition treatments and received either four conspecific
neighbours or no neighbours.
Competition was shown to be strong, and was demonstrated by a strong negative effect of neighbours on target plants. There was an indication of enhanced plant growth in the watered treatments and a trend for competition to be stronger in the watered treatments. We conclude that the intensity of competition is greater at the higher resource levels of water.