Estoque de serapilheira e nutrientes na borda e no interior de um fragmento de floresta estacional subtropical na região do bioma pampa

Abstract

The state of Rio Grande do Sul where the Pampa biome, since its colonization, was subjected to an accelerated process of deforestation, due to a strong agricultural tradition, currently generating a forest scene with several fragments of native forest, with different degrees disturbance, especially in biotic and abiotic factors on their edges, causing changes in litter production and seed bank, which guarantees forest regeneration. Due to the lack of studies in these ecosystems, this study aimed to analyze the edge effects in the fragment, analyzing litter production and reproductive material. The work was performed in a Subtropical Seasonal Forest fragment within the municipality of Vila Nova do Sul. For the study, four sites were marked in the fragment, towards the inner edge of the fragment: 0-10 m (10 samples), 10-20 m (10 samples), 20-50 m (15 samples) and 50-100 m ( 25 samples), totaling 60 samples of litter. The samples were formed by the organic mat on the ground, collected with a wooden frame 25 cm x 25 cm, collected in the seasons of autumn and winter. Were separated into fractions: leaves, twigs <1 cm, unidentified waste and reproductive material composed of seeds. The results obtained for the litter in the autumn season indicated that there was no significant difference between the edge and the interior of the fragment, but in the winter season was no significant difference between the inside and the edge of the fragment. The accumulated litter on the ground is responsible for a large supply of nutrients, especially Ca and N with 55% to 32% in the autumn season. For the micronutrients, Fe and Mn were the highest values in the autumn season. Regarding the number of seeds, a significant difference between the edge and the interior according to the Tukey test in the autumn season and also in the winter season. This information collaborate to understand the ecological relationships that exist in the forest, providing support for the guidance of recovery plans and restoration of fragmented areas of native forests in the region.