Efeito da regeneração de uma floresta tropical seca sobre a comunidade de artrópodes de serapilheira

Abstract

The loss of native forest areas is one of the results of the anthropic action in diverse environments. Occasionally degraded areas are abandoned and, in some cases, enter in natural regeneration process. The Tropical Dry Forests (TDF) represent a heavily endangered ecosystem and with part of their remnants represented by forests in succession. The litterfall has great importance in the successional process to shelter seed banks, to guarantee better conditions in the soil and to maintain diverse ecosystem services. The local fauna is an important component of the dynamics of the litter, acting in the breaking of the vegetal material which facilitates its decomposition, potentializing the process of nutrient cycling. Arthropods are strongly represented in terrestrial ecosystems presenting different eating habits, strategies of occupation of microhabitats and of fundraising, and can serve as indicators of the quality of the environment. This work aims to evaluate the effect of forest regeneration on the community of litter arthropods of a TDF. Assuming the hypothesis that the advance of the regeneration will favor the richness, relative abundance of species and the number of feeding guilds. Five plots (20 x 50m) were established at each stage of regeneration after abandonment (25, 45 and more than 60 years), in areas of TDF in Paraiba – Brazil. In each plot, litter arthropods were collected at 5 pre-set points using pitfall and mini-Winkler extractors in the dry and rainy season, totaling 150 samples. The pitfalls with water and detergent were installed close to the ground where they remained for 48 hours, then the collected material was stored in 70% alcohol recipients. The litter of an area of 1 m ² was collected and transferred to the mini-Winkler extractor, where it remained for 48h. The arthropods present in the litter were captured in a 70% alcohol pot present in the extractor, then the pots were stored in the laboratory for further sorting and identification. The diversity in the different plots was observed from the diversity profiles of Hill, for the different seasons. Beta diversity was calculated to understand the patterns of group substitution between areas. Functional characteristics were observed from the general survey of the characters related to feeding guilds and mouth parts, the similarity was analyzed from the Gower distance and a CWM was performed to measure the average abundance of characters in the community. The stages showed different patterns of abundance between dry and rainy seasons, the intermediate stage being generally richer and more diverse than the others. The beta diversity was relatively low, with 0.195 the Jaccard index between the three stages in the rainy season and 0.294 for the dry season. The most representative guild was the herbivores and the most common mouth parts was “chewing”, there being no significant difference in the distribution of the characters between the orders, a standard that should change when the identification is finished and consequently the functional characters are more specific than the current ones.