Regeneração natural do componente arbustivo-arbóreo e atributos do solo em áreas com diferentes altitudes no semiárido

Abstract

Understanding what drives this heterogeneity on a microscale in the forest physiognomy is critical to predict how forests will respond to global environmental change as well as develop conservation and management strategies that maximize the benefits of biodiversity. The objective of this research was to characterize the regenerating stratum of Shrub-tree communities, associating the environmental conditions to levels of soil and topographic gradient. Considering the region of Araripe as a landscape stratified in three environments: Lower (altitudes ≤ 600 m), Slope (600> to ≤ 750 m) and Plateau with altitudes above 750 m. For each environment, nine areas (B1, B2, B3, E1, E2, E3, C1, C2 and C3) were sampled with 20 plots of 5 x 10 m for measuring natural regeneration. Analyzes of the soil chemical attributes of the nine areas and the canonical analysis were made to discriminate which variables contributed most to the variance of the species, and what percentage of this variance is explained by the environmental variables. In the floristic of the nine areas, 4,974 regenerating individuals were inventoried, 1,433 in the Lower, 1303 in the Slope and 2,217 in the Plateau, belonging to 131 botanical species. The stratified areas in the environments of Lower, Slope and Plateau represent a floristic and structural variability of vegetal phytophysiognomies characteristic of dry or seasonally dry forests inserted in the semi-arid Pernambucano with high richness of shrub species of the natural regeneration of these communities. The region has a variability of environments with distinct microclimatic characteristics and following an altitude gradient. The areas of Lower have shallow soils, more fertile and with typologies of xerophytic vegetation. In the areas of Slope, more sandy soils and low fertility, with more shrub vegetation of small size and with low diversity and density. And finally, in the Plateau, there is a greater microclimatic variation, with wetter areas and variation of xerophilous vegetation and seasonal forest.