Effects of end of dry season shoot removal on the growth of three savanna grasses with different phenologies

This paper presents the results of a field experiment investigating the eff ects of shoot removal at the end of the dry season on tillering and aerial biomass in three perennial savanna grasses. The experiment was intended to simulate the effects of savanna fires at the end of the dry season. The exp eriment included three initial size classes of plants that were allowed to grow free from competitors. The results showed an immediate negative effect of shoot removal on tiller number in all three species; however, at the en d of the experiment, defoliated planes had recovered and their final sizes did not differ significantly from those of control plants. We registered an overcompensating response to shoot removal on aerial biomass of Trachypogo n plumosus, while the other two species (Andropogon semiberbis and Leptocor yphium lanatum) compensated completely for the removed aerial biomass. Diff erences in initial plane size were only significant in L. lanatum. Shoot re moval resulted in a significant decrease in the fraction of flowering tille rs in T. plumosus, hut had no significant effects on flowering in A. semibe rbis. Experimental plants of L. lanatum did nor flower during the experimen t. Although inmediate shoot removal effects were strongly negative, the thr ee species were able to recover nor only in the number of tillers but also in aerial biomass. Based on the differences between actual burning and expe rimental removal of shoots, we expect that the compensating responses to ac tual fire would be greater than the ones resulting from this study.