A heterogeneidade de habitat e sua influência nas diversidades taxonômica, funcional e filogenética em área de floresta ombrófila em Pernambuco

Abstract

Communities can vary in richness and diversity depending on the availability of resources which can be modified according to habitat heterogeneity. It was investigated whether habitat heterogeneity (represented by the toposequence) interferes in the assembly of tree communities in three areas of Ombrophilous Forest (two located in Igarassu and one in Goiana). In the first chapter, the hypothesis was tested that the variation of soil chemical variables along a toposequence (flat with water, slope and top) allows the existence of different patterns of richness and diversity of tree species and, in this case, the adopted forecast was that in more restrictive environments (areas with low levels of phosphorus and potassium, with high aluminum saturation and low pH) lower species richness and diversity were found. In the second chapter, the response of functional traits of arboreal plants along a toposequence (top, slope and plane with water) was evaluated, therefore, the expectation was that less functional diversity and less phylogenetic dispersion would be found in areas with more restrictive environments (flat areas with water) such as those found in the plots of flat areas with water. For the taxonomic study, arboreal individuals with a stem circumference ≥ 15 cm were included in the 45 plots (15 in each forest studied, subdivided into five plots in each area of the toposequence), with the plots being launched at a distance of 50 m in relation to the edge of the forest areas, with a distance of 10 m between them. In the plots, soil samples were collected at a depth of 0-20 cm for chemical analyzes of fertility (pH, Al, P and K). Alpha diversity was analyzed using the Hill Series and beta diversity was analyzed from its partitioning, using the βsor, βjac and βnes indices. The floristic list was prepared by the APG-IV system. For the study of functional diversity, six functional characteristics were analyzed (leaf area, specific leaf area, leaf dry matter, leaf chlorophyll content, wood density and height). The structure of functional diversity was analyzed by the Rao quadratic entropy index and the structure of phylogenetic diversity was verified by the Rao phylogenetic index and the Net Relatedness Index (NRI). The study of taxonomic diversity and its relationship with habitat heterogeneity did not prove the initial prediction that there would be less species richness and diversity in areas with more restrictive environments, but it did prove the relationship of beta diversity with topographic variation, as the process turnover is predominant in the communities studied, therefore signaling that other abiotic/biotic factors not identified in this research may be acting in the assembly process of communities together with biotic factors. It was observed that functional diversity is not associated with different topographic situations and that, possibly, stochastic processes may be more important in the structuring of communities. In relation to the phylogenetic Rao, there were no significant differences between the flat communities with water, slope and top, being the communities phylogenetically similar. The phylogenetic structure of tree communities evaluated by the NRI indicated that the slope NRI value was completely different from the flat areas with water and top. The research results showed that phylogenetic approaches should not be considered as a substitute for functional diversity, as they deal with distinct processes.