DANOS PROVOCADOS PELO FOGO SOBRE A VEGETA\u106\uc3O NATURAL EM UMA FLORESTA PRIM\uc1RIA NO ESTADO DO ACRE, AMAZ 4NIA BRASILEIRA

A emiss\ue3o do CO2 \ue9 uma das principais causas do efeito estufa e as queimadas amaz\uf4nicas contribuem para isso. Devido \ue0 alta umidade retida, a floresta prim\ue1ria amaz\uf4nica \ue9 considerada imune a queimadas, todavia, sob condi\ue7\uf5es clim\ue1ticas anormais \ue9 vulner\ue1vel. Este estudo objetiva avaliar os efeitos do fogo, decorrentes de inc\ueandios florestais ocorridos em 2005, sobre uma floresta natural prim\ue1ria no Estado do Acre. Foram monitorados os efeitos do fogo em \ue1rvores lenhosas, palmeiras e cip\uf3s em tr\ueas n\uedveis de tamanho: I-DAP=5 cm; II-5 cm>DAP=2 cm; e III-DAP<2 cm e altura =1,0 m. Os indiv\uedduos foram avaliados quanto \ue0 Condi\ue7\ue3o Geral (n\uedveis I e II), Casca e Copa (N\uedvel I) e brota\ue7\ue3o. Foram efetuadas cinco avalia\ue7\uf5es, a primeira em novembro de 2005 e a \ufaltima em janeiro de 2009. Os resultados mostraram que os indiv\uedduos de menor porte foram os mais impactados e apresentaram as maiores taxas de mortalidade, chegando a 80,1 % no N\uedvel II e decrescendo quanto maior a classe diam\ue9trica, sendo nula (0 %) nas superiores. Foi observado aumento do n\ufamero de indiv\uedduos sem dano aparente em todas as classes diam\ue9tricas e aumento de 43 % no n\ufamero de esp\ue9cies na regenera\ue7\ue3o, indicando um processo de recupera\ue7\ue3o da floresta. Foi verificada redu\ue7\ue3o expressiva na diversidade de esp\ue9cies (15 % no N\uedvel I e 33 % no N\uedvel II), indicando que a floresta foi modificada quanto \ue0 composi\ue7\ue3o flor\uedstica. Com base nos padr\uf5es de danos causados por apenas um inc\ueandio, o caso da \ue1rea estudada, \ue9 esperado que a incid\ueancia de novos inc\ueandios, em curtos intervalos insuficientes \ue0 recupera\ue7\ue3o, resulte na irremedi\ue1vel degenera\ue7\ue3o da floresta.The emission of CO2 is an important cause of the greenhouse effect and the Amazonian burns contribute to it. Because of the high moisture retained, the primary Amazon forest is considered immune to fire, however, under abnormal climate conditions it is vulnerable. The objective of this study is to evaluate the effects of fire, originated from forest-fires occurred in 2005, in a natural primary forest in the state of Acre, Brazilian Amazon region. The effects of fire on trees, palm trees and lianas were evaluated in three levels of size: I-DBH=5 cm; II-5 cm>DBH=2 cm; and III-DBH<2 cm and height =1,0 m. The individuals were evaluated for General Condition (levels I and II), Bark and Cup (Level I) and budding. Five evaluations were made, the first in November 2005 and last in January 2009. The results showed that the smallest subjects were the most impacted ones and showed the highest mortality rates, reaching 80.1 % for Level II and decreasing according to the increasing size of the tree and it is null (0 %) in higher classes. It was observed a growing number of individuals with no apparent damage in all diameter classes and a 43 % increase in the number of species in regeneration, indicating a recovery process of the forest. It was observed a significant reduction of species diversity (15 % in Level I and 33 % in Level II), showing that the forest was modified in its floristic composition. Based on the significant damage caused by only one fire, the case of study, it is expected the incidence of new fires, at short intervals insufficient for the recovery and it will promote the irremediable degeneration of forest