Padrões de habitat e traços funcionais: impacto da fragmentação florestal sobre diferentes assembleias no bioma Pampa

Abstract

Ecotonal forests in contact with native grasslands in the Pampa biome constitute important genetic banks and sources of research about the ecology of plant and animal species, providing essential information for the conservation, restoration, and recovery of ecosystems. In the present study, we evaluated the possible effects of fragmentation, regarding the formation of different habitats conditioned by edge and interior environments and by environmental variables, on the occupation patterns and functional traits of three assemblages: arboreal-shrub component, associated species, and mammals. In three remnants of different sizes: a reference area (RPPN Boa Vista, 243.3 ha) and two smaller fragments (A1-2.6 ha and A2-10.8 ha), inserted in an interhabitat matrix (65 ha) of commercial exploitation of Eucalyptus sp., in Serra do Sudeste, extreme south of Brazil. In the first article, we investigate floristic patterns and possible evidence of the impact of fragmentation on the ecotonal forest in the Brazilian Pampa. The influence of the floristic contact zone, fragmentation, and habitats conditioned by environments and environmental variables on the phytosociological and floristic patterns of the arboreal-shrubby component was observed. Thirty-one families, 50 genera, and 64 species were identified. The most representative families are Myrtaceae, Salicaceae, Lauraceae, and Sapindaceae, with emphasis on the species Podocarpus lambertii. Terrain slope, altitude, and density of regenerants were the environmental variables with the greatest influence on the arboreal-shrub component. In the second article, we investigate the occupation pattern and habitat preferences regarding functional traits of the arborealshrub component, and environmental variables, in three different functional groups of associated species: bryophytes/lichens, vascular epiphytes/pteridophytes, and climbing plants. Bryophytes/lichens prefer the interior of forests, flat and lower altitude areas, with thick and low trees, with a rough and persistent bark. Vascular epiphytes/pteridophytes prefer the interior of forests, high and shallow areas, with thick trees, with rough and exfoliating bark. Climbing plants prefer edge habitats, sloping areas, with lower altitude and greater canopy openness, are little dependent on functional traits, and less sensitive to edge effects and habitat fragmentation. In the third article, we analyze the pattern of use and occupation of habitats by the assemblage of wild native mammals, through the use of camera traps. Eighteen species were recorded, being Nasua nausa and Mazama gouazoubira the most abundants. Different patterns of use by the species were found, some well adapted to forest habitats and others tolerant to the productive matrix. Environmental and vegetation variables had a greater influence on functional traits than on the structure of the mammal assemblage. Finally, our data suggest that the maintenance of diversity for the three studied assemblages is made possible by larger areas of native vegetation, especially for more demanding species, but that connectivity in the landscape is made possible by small vegetation nucleus and by the permeability of the interhabitat matrix, promoting habitat diversity and quality, and influencing local ecological dynamics. They also point out that the effects of fragmentation act differently on different assemblages, even in the same habitat, and that the isolated analysis of a component can lead to conclusions unrepresentative of the ecosystem. And these are fundamental characteristic to define importance and fragility levels of ecosystems in ecological contact zones, where the greatest natural diversity conditions the need for habitats diversity, influencing the conservation measures and strategies to be taken.