Estrutura funcional de uma comunidade de herbáceas em um gradiente de regeneração natural na caatinga

Abstract

The ability of plants to alter phenotypic characters as a result of interaction with the environment can contribute to functional stability, especially when the phenotypic plasticity acts on traits related to survival, making it an important tool for adaptation. The Grime's C-SR theory is used to categorize plants according to the functional traits that determine the strategies, competitors, stress tolerant and ruderal. The objective of the study was to characterize herbaceous communities according to morphophysiological and phytochemical aspects in different areas of regeneration. The collection sites were in the pasture and in 6 areas with 8 to 100 years in regeneration. A relationship between the time of regeneration and expression of the CWM values - community weight mean (weighted average of each trait in a community) was analyzed using principal components analysis (PCA) and canonical correspondence analysis, and an intraspecific variation of the traits through the ANOVA test a factor and the Tukey a posteriori test for comparisons between as means. The results showed that the pasture and area communities with 8 years of regeneration have species with functional characteristics related to the strategies of ruderal species, with low plants, small leaves, leaf economics with more succulent leaves and with greater investment in dry matter. While the species located in the communities of the areas with 45, 60 and 100 years of regeneration presented functional characteristics related to the competitors, because they present a larger leaf area and specific leaf area, besides a higher nitrogen content in the leaves. In the analyzes of variance performed between the functional traits and the regeneration stage it was possible to observe that the species occupying the sites in different stages of regeneration have phenotypic plasticity. In general, as the regeneration progresses, there is an increase in the C:N ratio, the content of phenolic compounds and carbon assimilation, and a reduction in leaf area, plant height, succulence of leaves, biomass of individuals and nitrogen content. The study shows how changes in environmental conditions in natural regeneration influence functional traits and that the C-S-R theory can be used to quantify, compare and predict the structure of communities based on adaptive plant strategies.