EFFECT OF DIFFERENT FIRE SEVERITIES ON COPPICING OF CAATINGA VEGETATION IN SERRA TALHADA, PE, BRAZIL

The sprouting response of the vegetation in three areas that were slas hed and burned under different fire severities was determined in a 12 year second growth tropical dry forest (''caatinga'') near Serra Talha da, PE, Brazil. Plots were slashed at the onset of the dry season (Jul y) and burned on 19 September (B), 26 September (C) or 4 October (D). Sprouting responses were also examined in unburned areas. Longer dryin g periods resulted in increasing fire severity and increasing consumpt ion of the original biomass (almost-equal-to 74 Mg/ha): 72, 87, and 93 percent biomass consumption, respectively. Prior to burning, plant de nsity with a stem diameter greater-than-or-equal-to 1 cm at the soil s urface was 5815 plants/ha. Greater than 94 percent coppiced after slas hing, usually with epicormic sprouts, indicating their adaptation to p eriodical disturbance. Burning dramatically decreased the number of pl ants that coppiced. Two months following each burning 43, 21, and 10 p ercent of the plants had coppiced in the three burns, respectively. Th e majority of sprouts following fire arose from underground tissues. C oppicing crown area decreased from 1451 m2/ha in the slashed/unburn tr eatment to 350, 248, and 165 m2/ha in the three fires. The six species with highest plant densities, Croton sonderianus Muell. Arg. (2631/ha ); Cordia leucocephala Moric. (1264/ha); Bauhinia cheilanta Stand. (81 9/ha); Mimosa sp. (474/ha); Caesalpinia pyramidalis Tul. (308/ha) and Astroneum urundeuva Engl (140/ha) displayed a variable response to inc reasing fire severity. Mimosa sp. coppicing was Little affected (49-43 % survival) and its relative abundance increased with increasing fire severity, from 8 percent to dominance with 36 percent. C. sonderianus density decreased with increasing fire severity (946 to 174/ha) but it maintained a high relative abundance in all treatments (31-45%). B. c heilanta had the highest survival rate at low fire severity (78%) but it decreased sharply with increasing severity (down to 9%). Survival o f the other species decreased from 30-50 percent to approximately 10 p ercent. Coppicing of Mimosa sp. was much more vigorous than that of an y other species, with the highest number of sprouts per stump, crown a rea, and sprout height. The level of fire severity of the slash burnin g will influence future species composition of caatinga vegetation.