Influência do distúrbio antrópico crônico e fatores climáticos na variação fenotípica e fisiológica da Aspidosperma pyrifolium Mart & Zucc. (Apocynaceae) em ambientes de caatinga

Abstract

The Caatinga faces chronic anthropogenic disturbances that threaten its plant diversity. Aspidosperma pyrifolium Mart. & Zucc. (Apocynaceae) is a species adapted to water stress and high temperatures, and it is studied for its survival and regeneration capabilities. Understanding its phenotypic and physiological adaptations can assist in the recovery of degraded areas and in facing both climatic and anthropogenic impacts. This study investigated how A. pyrifolium, a shrub-tree species from the Caatinga, responds to chronic anthropogenic disturbance (CAD) through its morphology and phytochemistry. The hypothesis tested was that in areas with different levels of disturbance intensity, the species exhibits adaptations in its leaf functional traits, as well as increased production of phenolic compounds due to livestock pressure. These adaptations aim to optimize the use of water and nutrients, as well as enhance the production of phenolic compounds to defend against herbivory. The study was conducted in the cariri region, in the central part of the state of Paraíba, Brazil, where eight areas of Caatinga were selected. Leaf samples were collected for the measurement of morphological attributes (leaf area, specific leaf area, leaf thickness, leaf density, and leaf dry matter content) and phytochemicals (total phenolic compounds), using standard methodologies for quantifying phenolic compounds. The results indicated that the predictor variables play a crucial role in the intraspecific variations of the species, suggesting different adaptive responses to adverse environmental factors. The leaf traits responded distinctly depending on the ontogenetic stage of the plant, as resource allocation strategies vary according to the plant's life stage. Regarding phytochemical adaptation, contrary to what was proposed, A. pyrifolium does not increase its production of phenolic compounds in anthropized areas.