SURVIVAL BY SPROUTING FOLLOWING FIRE IN TROPICAL FORESTS OF THE EASTERN AMAZON

Current anthropogenic activities in Amazonia are resulting in the widespread occurrence of fire; an ecosystem that is believed to have evolved in a fire-free environment. Even in areas away from intensified human land use, warmer and drier climatic conditions could increase the probability of fire in tropical forests. In this study the capacity of tree species to sprout following fire in disturbed moist tropical evergreen forests was quantified. Additionally, mortality and the modes of survival of standing forest trees at four sites were measured. Crown mortality ranged from 64-97 percent. Eight months after fire, 36-69 percent of all trees present on the sites at the time of burning were dead (i.e., no sprouting occurred). Out of 124 species measured (500 total individuals), 46 percent had the capacity to sprout from subterranean tissues and 27 percent sprouted from epicormic tissues. Forty-one percent of the sampled species were found to lack any capacity to sprout vegetatively. The percentage of individuals that survived by sprouting varied among tree species. Survival of the 14 most common species encountered ranged from 15-83 percent. Survival also varied among sites and this was primarily attributed to differences in fire severity. Fire severity and plant mortality were greatest in selectively logged forests that were intentionally burned for pasture conversion (> 65% mortality). One ecological advantage of sprouting over establishment from seeds is rapid regrowth and a greater capacity for exploitation of limited resources in tropical forests. Mean sprout height was 0.8-1.6 m for 8-month old sprouts and 4.2 m for 20-month old sprouts.