This study evaluated the impact of the presence of the exotic grass (Brachiaria decumbens) on the herbivory and development of seedlings of native species (Hymenaea stigonocarpa and Dipteryx alata) of the Cerrado. Thus, 10 pasture plots (former Cerrado) at the Embrapa Gado de Corte (Campo Grande-MS) were demarcated in January 2009. The grasses were kept intact in half of the plots and were removed in the other half. In each treatment, the herbivory, as well as height and diameter at ground level (DGL) of 25seedlings of each species were evaluated during one year. Carbon, nitrogen and water content of the leaves in each treatment were also quantified. Seedlings of Hymenaea stigonocarpa in plots without grasses had higher diameter growth rates than seedlings in plots with grasses. Dipteryx alata seedlings grown in plots without grasses had a higher height growth rate than seedlings grown in plots with grasses. There was a difference in the herbivory rate of D. alata between treatments. Seedlings of plots with grasses for the two species showed a higher concentration of carbon and lower amount of water. The leaf nitrogen content was higher in plots with grasses than without grasses in D. alata, while nitrogen in H. stigonocarpa did not vary between treatments. These results showed that each native species had distinct physiological responses and susceptibility to herbivory in environments under resource competition with the exotic grass B. decumbens.
competition; growth; Dipteryx alata; grasses; Hymenaea stigonocarpa
