Dinâmica de serrapilheira e mesofauna do solo em floresta tropical seca na Paraíba

Abstract

The cycles of litter contribution and action of edaphic organisms are fundamental in the process of biogeochemical cycling and the stability of the Caatinga biome. The research area is the Reserva Particular do Patrimônio Natural (RPPN), located in the municipality of Santa Terezinha (PB), where in 2003 seven transects were demarcated, 200 m apart, and 1.0 m x 1.0 m collectors were installed to evaluate the monthly deposition of litter. The study aimed to estimate the spatial and temporal variation of deposition, accumulation and decomposition of litter, and to evaluate the population of mesofauna that colonize the soil-litter compartments and the interference of climatic variables in the dynamics of these events. For the present study, the evaluations were carried out in two periods: period 1 from August/2018 to July/2019 and period 2 from August/2019 to July/2020. All intercepted material was separated into fractions (leaves, branches + bark, reproductive material and miscellaneous). The accumulation of litter on the forest floor was quantified using a metal frame with dimensions of 0.5 m x 0.5 m, to estimate the rate of litter decomposition. To evaluate edaphic mesofauna, metal rings (5.2 cm high and 4.8 cm in diameter) were used, removing four undeformed samples per transect each month for subsequent extraction of organisms in the Berlese-Tullgren apparatus. The average annual litter production via input in the collection boxes was 629.89 kg ha-1 in Period 1 (August/2018 to July/2019) and 352.38 kg ha -1 in Period 2 (August/2019 to July/2020). In the composition of the edaphic fauna, the orders of mites and collembola stood out, contributing 51.6% of the organisms extracted in Period 1 and 75.18% in Period 2. It is concluded that the fractions of leaves and branches were those that contributed most to the formation of the litter in both cycles.