A study was carried out to evaluate the effects of different burning dates on the population dynamics of a
Urochloa decumbens
sward. The experimental area was divided in three sites of 100 m
-2, and randomly assigned three treatments: Q
1: burning at the end of the rainy season (December), Q
2: burning at the middle of the dry season (February), and T: no burning. Measurements of sward cover, aboveground biomass, and numbers of tillers and crowns were done every 15 days in all treatments. The results showed that tillers of Q
1 kept a fair constant number during the dry season when compared with Q
2, but these differences disappeared when the rainy season started. A similar behavior was observed for crown number, decreasing with the precipitations. The highest biomass was recorded for Q2 treatment in June (355 g m
-2), while no significant differences were observed between the control and Q1 treatment (225 and 285 g m
-2, respectively). This result was the consequence of the fast recovery of the sward burned in Q
2 when precipitation started. The better response of the sward burned at the middle of the dry season could be attributed to some factors, such as, the utilization of the soluble carbohydrates in the roots, a more efficient use of the soil water because of less biomass, and possible damage to the photosynthetic apparatus in young tillers of plants under Q1 treatment.