Deposição, acúmulo e decomposição de serapilheira em área de caatinga preservada.

Abstract

In any forest ecosystem there is a strong interaction between vegetation and soil, which is expressed in the organic matter input and output cyclical process. The cycling of nutrients through litter is considered the most important means of transfer of essential elements of the vegetation to the ground. The present study aimed to estimate the production, accumulation and decomposition rate of litter in the Conservation Unit, in the semi-arid of Paraiba. To evaluate the litterfall we used 20 l.Om x 1.0 m, with bottom of nylon mesh, and the collections were done monthly. The litter was collected in separate ffactions leaves, branches, reproductive material, and miscellaneous. To quantify the stock of accumulated litter we used metal frame with dimensions of 0.5m x 0.5 m, which was launched at random. The decomposition rate of litter was estimated by annual litterfall and annual average accumulated litter. We also calculated the average time of renovation estimated by 1 / K and the time required for decomposition of 50% and 95% of the litter. The experimental design used for analysis of the deposition of the litter was in randomized blocks with 20 repetitions with a factorial arrangement of treatments in 15 x 3, and comparison of means by Tukey test. The total deposition of litter in three periods during the study was 3275.20 kg ha-1, the fraction contributing 72.9% leaf, twig with 14.6%, 12.3% with reproductive material and Miscellaneous with 0 8%. The decomposition coefficient obtained was 0.58. We conclude, therefore, that in all periods studied, the leaf fraction formed the highest percentage in the litter. Litterfall in the caatinga followed the order: leaf> branch> reproductive material> miscellaneous. The decomposition of litter in the caatinga is slower than in rainforest.