Caracterização do material combustível superficial e efeitos da queima controlada sobre sua redução em um povoamento de Eucalyptus viminalis

Abstract

The purposes of this study were to characterize the fuel under a Eucalyptus viminalis stand and to determine burning effects on forest fuel load and duff depth. It was used a randomized block experimental design, with five treatments and four replicates. The burning technique (strip headfire and backfire) were conducted on October 10, 1994 (spring) and March 23, 1995 (fall), respectively. The fuel was inventoried before and after burnings to determine the dry weight fuel load, fuel consumption, duff depth, and percentage of inorganic matter and mineral nutrients. Before burning, the total fuel load was 26.2 (spring) and 27.8 ton.ha-1 (fall). The average consumption of fuel load was 56 % (56; 61 and 90 % for C-1, C-2 and C-3 classes, respectively). The strip headfire consumed, in the average, 3.7 ton.ha-1 (in spring) and 2.9 ton.ha-1 (in fall) more than backfire. The duff depth presented average reduction of 30 % and 34.7 % for spring and fall seasons, respectively. The tissue analysis conducted before and after fuel burning detected a significative decrease after burning for K in the two-season burning treatments and a Ca increase after burning, except for fall backfire burning.