Heterogeneidade ambiental e regeneração natural em uma Floresta Ombrófila Mista Aluvial

Abstract

The main objective of this study was to determine the influence of environmental heterogeneity on the regenerative component of an Alluvial Araucaria Forest in the southern Santa Catarina State plateau region. The regenerated individuals were sampled within 48 plots allocated in three sectors: river, interior and edge. The survey of environmental variables was conducted in all plots, obtaining data of edaphic variables, topography, groundwater level, canopy cover, environmental impact and soil classification. A Principal Component Analysis was performed for the surveyed variables to identify environmental gradients. For the regenerative component, the influence of environmental sectors, related to river distance and soil classes, on floristic-structural organization was determined by generalized linear models. The organization of vegetation was verified using Principal Coordinates Analysis. The presence of indicator species was evaluated for the sectors with significant effect on vegetation. Cambisols predominated in the area, and the terrain is mostly flat and the soils are dystrophic, acidic, alic and with sandy loam to silt loam texture. One third of the plots presented water near the surface, indicating greater environmental selectivity in these places. The canopy was predominantly closed (91.16%) and the level of environmental impact was considered low. The division into sectors, defined by to the river distance, had a significant influence on the distribution pattern of species, and the edge sector showed the most distinctive floristic and structural composition, with 14 indicator species. The regenerative component demonstrated spatial variations that reflected the environmental heterogeneity according to sectors, with river distance determinant for the formation of floristic groups.