Dinâmica da serrapilheira e repartição da água de chuva por espécies da caatinga.

Abstract

The study of nutrient cycling is of fundamental importance in understanding the structure and function of forest ecosystems, especially in disturbed areas of the caatinga, where there is limited information about its dynamics. This study aimed to assess nutrient cycling through litter and contribution of caatinga species in the distribution of rainwater. Sampling was done monthly for twelve months in four areas: degraded, successional primary stage, secondary stage and late stage. We installed 72 collectors of 1.0 mx 1.0 m, with nylon fabric background in three areas. Litter deposited was fractionated into leaves, twigs, reproductive structures and miscellaneous, dried and weighed. To assess the stock of accumulated litter we used metal frame with dimensions of 0.5 mx 0.5 m, thrown randomly and collected monthly, taken to the laboratory for oven drying and weighed. To evaluate the decomposition, 40g of litter were placed in nylon bags (litterbags) mesh 1 mm ², dimensions 20.0 x 20.0 cm, being distributed on the soil surface and removed monthly, cleaned, dried and weighed. To evaluate the contribution of rainfall we used interceptometers installed 1.0 m above the ground surface, distributed under the canopy of six species of the caatinga, which evaluated the stemflow through collecting system installed around the stems of these species. The deposition of litter in the primary stage was 1874.71 kg ha-1 year-1; ha1ano 2005.38 kg-1 in the secondary stage; 2999.96 71 kg ha-1year-1 in the late stage. The fraction of leaves was the largest contributor to the formation of litter in three stages evaluated in the primary stage area showed higher accumulation of leaf litter decomposition and has been sluggish during the dry period. We conclude that the deposition of litter showed seasonal characteristics, with the accumulation of litter obeying the order primary stage> late stage > secondary stage. The decomposition of litter accumulated and renewal is faster in the area in late successional stage; internal Rainfall is higher in species with aerial structure consisting of leaflets, like the Jurema, especially in more concentrated rainfall events, The stemflow is of fundamental importance for the hydrological cycling especially those species with larger diameter and without bifurcation.