Herança biogeográfica e priorização de conservação em um hotspot de biodiversidade de floresta tropical

Abstract

The causes of current diversity patterns and how to effectively conserve them are big questions, classic and current, of concern to biogeographers and ecologists. A megadiverse system with hybrid biogeographic heritage and significant environmental variation, such as the Atlantic Forest provides us with valuable clues to fill the gap in the understanding of the relative importance between ecological and historical factors in the assembly of communities. Besides, the high degree of degradation suffered by this biodiversity hotspot since the arrival of Europeans impels the diagnosis and planning of how much of its biodiversity and ecosystem services can be protected for its persistence. In this study, we propose that (i) the North and South sectors, with different biogeographical histories, present dynamics of different diversities. About current environmental gradients, we suggest that (ii) environmental heterogeneity promotes greater taxonomic and phylogenetic diversity, as it allows the realization of a greater number of niches of different species. Regarding the historical gradients, we suggest that (iii) the refuge areas of the Atlantic Forest (climatic stability in the Late Quaternary) present greater phylogenetic diversity of the tree assembly. We use data from the occurrence of more than three thousand tree species from the entire forest to investigate how the relationship between the facets of taxonomic and phylogenetic biodiversity occurs with values of climatic stability and current climatic and topographic gradients through Geographically Weighted Regression (GWR) ( Cap I); the efficiency of the current reserve system in protecting the facets of biodiversity and the carbon stock was tested and improvements were proposed through spatial prioritization using Systematic Conservation Planning (SCP), with the Zonation program (Cap II). Our results show that the relationship between gradients and biodiversity in the Atlantic Forest is dependent on a phylogenetic and biogeographic scale. The North and South sectors of the Atlantic Forest have different patterns of diversity and different responses to current and historical gradients, with the taxonomic and phylogenetic diversity of trees in the North sector being more dependent on current climate stability and topographic heterogeneity; while the South, it reveals the more consistent importance of maintaining past conditions. The gradients of topography and climate stability had positive effects independent of scale. The current preservation areas of the Atlantic Forest have proved to be quite efficient in conserving taxonomic wealth and taxonomic and phylogenetic endemisms. However, the areas with the highest phylogenetic diversity values are outside the protected areas. Although they were not10 created for that initial purpose, the ecosystem service of maintaining the carbon stock below and above ground is also well represented in current conservation areas. An expansion of 9.3 percent of protected areas (according to our cut) to 17% would double the average performance of protecting tree biodiversity and carbon stocks. Regardless of the low correlation between biodiversity and ecosystem services, the prioritization solutions we propose to allow the choice of different spatial arrangements for the expansion of preservation areas, including several win-win solutions.