Análise da vegetação e organismos edáficos em áreas de caatinga sob pastejo e aspectos socioeconômicos e ambientais de São João do Cariri-PB.

Abstract

The objective of this research was to evaluate the interference of goat grazing on the vegetation, the rate of evolution of CO2, abundance, richness and diversity of soil fauna and its dynamics in rainy and dry seasons, and assess the socioeconomic and environmental aspects of São João do Cariri - PB. The research was lead in the “Fazenda Experimental Bacia Escola/CCA/UFPB” in São João do Cariri - PB, from January to December of 2008, in three contiguous areas of caatinga, correspondent to treatments T1 (10 animals – 1 animal/3200 m2), ), T2 (5 animals – 1 animal/6400 m2) and T3 (Control = without animals). The area of the experiment is of 9.6 ha, being divided in three areas of 3.2 ha each. In each treatment there was fulfilled a floristic and phytosociologic survey in 30 parcels of (10x10 m) in a distance of 20 m from each other, being written down: the species, the height and the diameter of the individuals with Circumference at the Height of Base (CAB) 3 cm and height 1 m. We have done monthly determinations of carbon dioxide (CO2), distribution of the macro and mesofauna, carbon, organic matter, water content of the ground and kinetic of CO2 to each two hours (05 AM to 5 PM). We applied 355 questionnaires to the 60 farms of São João do Cariri - PB, following in the same area used by the Community Health Agents. In three areas of caatinga families with a greater number of species in shrub-tree layer are: Cactaceae and Euphorbiaceae, and the species Croton Sonderianus is the one that has a bigger relative density and species of higher importance in the three areas are: Croton sonderianus, Caesalpinia pyramidalis Pilosocereus gounellei, Aspidosperma pyrifolium and Jatropha mollisssima. Species that were common in the three areas were: Aspidosperma pyrifolium, Opuntia palmadora, Pilosocereus gounellei, Caesalpinia pyramidalis, Croton sonderianus, Jatropha mollisssima and Sida sp. The floristic similarity was high for the three areas, with Jaccard indexes higher than 0.25, but the diversity was very next, with similar richness of species, with emphasis on Sida sp. The dominant groups of soil macro fauna were: Hymenoptera, Diptera, Acarina, Coleoptera and Araneae and of soil mesofauna were Acarina, Collembola, Protura and Diptera. The greatest abundance of the macro fauna was found in areas under grazing and mesofauna in the areas with lower grazing pressure with 5 animals. The variation of the abundance and richness of groups are higher in the rainy season and in the end of the season, the groups of macro fauna tend to increase. The CO2 emissions showed temporal variation with higher peak of release during the rainy season, being higher in the area II with 5 animals and the rate of CO2 varied throughout the day depending on the meteorological elements, with a tendency to release more in the afternoon. The socioeconomic activity of the majority of the population in rural area is agriculture with production of traditional crops as maize and beans for family consumption and small livestock production, with a predominance of beef cattle, sheep and goats of mixed breed. The species Pilosocereus gounellei, Opuntia palmadora, Cereus jamacaru, and Manihot glaziovi are more used to feed the goats, however, the primary use of the Caatinga is the removal of timber for firewood and fences. The edaphic organisms widely found by landowners in the areas of forest, plantation and native pasture are: Hymenoptera, Araneae, Scorpiones), Isoptera and Coleoptera.