Leaf litterfall, decomposition and nutrients release in a Seasonal Semideciduous Forest in Southern Brazil

Biogeochemical cycling study of ecosystems and their functioning are fundamental for planning conservation practices and management of forest remnants in Brazil. The objective of the study was to characterize the leaf litterfall production rate and the nutrients release via decomposition in a fragment of Seasonal Semideciduous Forest, in Southern Brazil, in advanced stage of regeneration. For two years, evaluations of litterfall and leaf litter decomposition (using the mass loss method with litterbags) were performed monthly, as well as their nutrient content analysis. Annual input of leaf litterfall was 4,532.7 kg ha-1 of dry matter, which promoted, for the two-year period, a supply of 195.5, 9.2 and 55.3 kg ha-1 of N, P and K, respectively. The litter nutrients use efficiency followed the decreasing order P > K > N. The annual decomposition constant for leaf litter was 1.16, reaching a half-life at 215 days, making 84.4% N, 72.7% P and 92.9% K available at the decomposition end of two years. In the two years of collection, the largest deposition rate of litter occurred in the spring, with the highest peak in October, indicating a seasonal deposition behavior. The forest fragment presents high production of leaf litter (66% leaves) and input of N. The rapid decomposition of leaf litter contributes to the release of nutrients over time, N and K initially, and P in the long run. P is limited due to the high efficiency of its use.