Trocas gasosas de espécies arbóreas em resposta à variação de temperatura foliar: efeito do ambiente topográfico na Amazônia Central

Abstract

Climate change implies changes in temperature and precipitation and may affect the physio-logical processes of plants. The objective of this study was to determine the gas exchange res-ponses as a function of leaf temperature variation (Tfoliar) and vapor pressure deficit (DPV) in ten species five in the plateau and five in the valley in the Experimental Station of Tropical Forestry in the Central Amazonia. In order to do this, data were collected on variables such as photosynthesis (Anet), conductance (gs), transpiration (E), internal and external carbon (Ci/Ca) concentrations and water use efficiency using the portable infrared gas analyzer, being related to the variation of Tfoliar and DPV. Analyzes were performed between the species of each environment, using linear regression and Pearson correlation. As a result, the species had different behaviors with temperature and DPV variation, both in the plateau and in the valley, being able to maintain high Anet rates for some species, with negative correlation with Tfoliar and DPV. As well as gs and Ci / Ca that also had a negative correlation with both parameters, however, the transpiration obtained a positive correlation with the two parameters analyzed. Among the gas exchanges, the values were significant (p <0.05) for some trees and others not in the same environment and one variable does not always influence the other, as in the case of gs that in some trees did not have the ability to limit Anet and E. Already the efficiency of water use had a negative correlation with the Tfoliar. The trees, in general, had different behaviors among the species, but not significant among environments, demonstrating that caution is needed when modeling a given environment.