Ecofisiologia de Aldina heterophylla Spruce Ex Benth em um gradiente vegetacional na Amazônia Central

Abstract

The Amazon biome is characterized by a great variety of landscapes and forest types, among them the Campina (CP) and Campinarana (CR). The CP is a landscape of low vegetation on size (3-4 m), open and scleromorphy on oligotrophic sandy soils, CR by a less open landscape, with medium size (10-15 m) in sandy soils with the presence of many of litter. Many questions about the dynamics of the plant gradient CP, CR and Rain Forest (FO) still persist. Thus, in view of these uncertainties can be proposed that the possible global climate change, which provides increased temperature and changes in rainfall regimes already in the coming decades, could change the dynamic of this vegetation gradient. In this context this study aimed to examine general aspects of ecophysiological of Aldina heterophylla, present throughout the gradient CP-CR-FO, investigating the effect of abiotic factors such as light, water and nutrients in mature leaves of adult plants. For this, anatomical analysis, physiological and biochemical were performed. The fieldwork was conducted in the Reserva Biológica de Campina do INPA, located at km 60 of BR-174 highway, Manaus - Boa Vista (2 ° 34'S, 60 o 02'W). The results showed that individuals of A. heterephylla in the CR are more vulnerable to microclimatic fluctuations, a fact observed mainly by the index of performance of photosystem II. Furthermore, it was observed that individuals in the CP have high capacity of acclimation to high irradiance and temperature. Additionally, we found that the morphological differences observed between the trees of A. heterophylla in different formations, especially the height, can be due of respiratory rates, higher for CP, which results in a lower accumulation of biomass, and lower for FO, which results in higher accumulation. Along the gradient A. heterophylla showed different strategies in the use of water. In FO individuals are more acclimated to lower water availability, using this resource more efficiently, and CP use of this feature possibly to avoid situations of photodamage. In the CR showed a lower performance for using this feature. The variation in soil nutrient was great between the depths analyzed, showing important aspect of the litter in the availability of soil nutrients. Despite the large differences observed for the levels of leaf nitrogen, this didn't influence the photosynthetic responses, which shows high physiological plasticity for the species, may be proved by the high efficiency in the use of nitrogen mainly in the CP. Morphological characteristics were modulated possibly by microclimatic and soil changes, as observed in the leaf area, specific leaf area and possibly in the ontogeny of the palisade parenchyma and spongy. Thus it is concluded that the lower capacity of adaptation of individuals of CR may reduce its occurrence in these areas ahead of possible climate change, converging in vegetation that has characteristics similar to that currently observed for CP, probably, increasing these areas in Amazonian vegetation.