Fatores climáticos e edáficos direcionam a variação fenotípica em populações vegetais em ambiente semiárido

Abstract

Vegetable populations in semiarid environments are subject to unpredictability, environmental heterogeneity and anthropogenic disturbance that require morphological, physiological and anatomical adaptations that guarantee survival and avoid local extinctions. Understanding how plants modify their functional attributes in response to environmental conditions is essential, as it makes it possible to understand the niche of that species and its behavior under environmental changes. The main objective of the dissertation is to evaluate the effects of climatic and edaphic variables on the intraspecific variation in morphoanatomical attributes of Croton blanchetianus Baill, an endemic plant species widely distributed in the Caatinga. Six populations of C. blanchetianus were selected, distributed along a precipitation gradient (400-850mm) and different vegetation levels in the caatinga (lower coverage (SAVI 0.2-0.5); greater coverage (SAVI 0.6-0.8)), ten individuals were marked in each population and leaf samples were collected for morphological and anatomical analyzes. The climatic variables were obtained from the updated global repository of bioclimatic variables at WorldClim and for edaphic data, deformed and undeformed samples were collected at each point in the population. The data showed substantial variation in the functional traits between the populations of C. blanchetianus. This modification is shaped mainly by the joint interaction of environmental conditions, vegetation cover (SAVI), average annual precipitation, fertility and available water in the soil. Under less availability of water and nutrients, there is a reduction in leaf size and specific leaf area, while there is investment in the coating of leaf surfaces by a dense trichome inductor, and also stomata on both sides of the leaf, in order to guarantee high photosynthetic activity in the period of water availability. It is noted by the intraspecific variation in leaf traits, a high niche range of the species, with adaptability to the abiotic conditions prevailing in the environment. These levels of phenotypic variation may contribute to the persistence of C. blanchetianus in scenarios of present and imminent environmental changes.