ABSTRACT
A project to restore a degraded area must firstly reestablish organic soil matter and nutrient cycling process. In order to evaluate the influence of indigenous tree plantations on changings in soil fertility and organic matter dynamics, an experiment was installed at the Poço das Antas Biological Reserve, an Atlantic Rain Forest remnant of ca. 5,200. Six treatments involved mature forests (F), 8-year-old mixed plantations of indigenous tree species (P), and abandoned pastures (G), at both the flooding (V) and the sloping (M) areas of the Reserve. The experimental design was completely randomized. Soil samples were collected at the layers 0-2.5cm; 2-5-7.5cm; and 7.5-20cm to evaluate soil pH, and Al, Ca+Mg, P, K, C and N contents. The PV treatment showed higher values for the exchangeable cátions, C and soil organic matter (SOM) contents, indicating high cycling rates and biological activity. Soil stability was considered to be high in all treatments, since C:N ratio was lower than 12:1. Organic matter fragmentation showed a higher amount of fulvic acids (FA), humic acids (HA) and humin (HU) in the PV treatment, for the three soil layers. The plantation on the sloping areas (PM) showed the highest values of (FA+HA)/HU ratio, suggesting a lower stability condition. Results suggest indigenous tree plantations have great potential to restore nutrient cycling and soil organic matter contents in short term period in areas where forests have been converted into pastures. Techniques to accelerate the development of trees plantation on the sloping areas must be adopted.
Keywords:
homogeneous plantings; soil fertility; humic substances