Análise comparativa da produção de serapilheira e macrofauna em áreas de caatinga.

Abstract

The production of litter, as well as its decomposition, are essential processes for the natural regeneration of an area. The present study had as objective to evaluate the deposition, accumulation and decomposition of litter and characterize the macrofauna of the soil, in Caatinga vegetation, in different successional stages. The experiment was carried out at the Fazenda Cachoeira de São Porfírio, in Várzea-PB, in three areas, characterized as: initial, medium and advanced stages of natural regeneration. For the deposited litter collection, 24 collectors of 1.0m x 1.0m were randomly distributed in each área. The collections were performed monthly during the 24-month period. The litter accumulated in the soil was estimated in quarterly collections, and nine samples were collected in each experimental area, using a 0.5 m x 0.5 m cast metal frame, randomly cast in the areas. The litter decomposition rate was estimated by means of an equation and from the value of k, the average renewal time estimated by 1 / ke and the time required for decomposition of 50% (t 0.5) and 95 % (t0.05) of the litter, also estimated by equation. For the evaluation of the macrofauna of the soil used adapted traps of the PROVID type, consisting of a PET bottle with a capacity of 2 L, containing four openings, one at each cardinal point, in the form of windows measuring 2 cm x 2 cm in order to allow the entry of soil organisms. During the experiment the litter production was higher according to the level of successional natural regeneration. The contribution of litter increased with the advancement of the successional stage. In the months that followed the rainy season, there was a higher production of litter, regardless of the successional stage. The litter decomposition presented a decomposition coefficient (k) of less than 1 for all areas and throughout the evaluated period. The Shannon and Pielou indices evidenced the low diversity in the study areas and the dominance of the Hymenoptera and Coleoptera classes in the dry and rainy periods, respectively, throughout the study.