Regeneração de espécies arbóreas e fauna do solo em diferentes ambientes no Semiárido da Paraíba.

Abstract

The semi-arid northeastern region is mostly covered by the Caatinga, and this vegetation is influenced by environmental conditions in which influences the diverse flora and fauna. The floristic composition of the herbaceous, shrubs and trees provide food for the animals, raw material for various purposes and keeps the seed bank as a reserve for maintenance of vegetation. The natural regeneration processes that occur in this biome depend on the sequence of the mechanisms responsible for depositing seeds in the soil seed bank formation and development of these seedlings and into grown trees. These processes are related to the presence of seed carrying tree in the areas or nearby, to the conditions of land use and climatic factors, which can affect the properties of the soil and the organisms richness of mesofauna and macrofauna soil that play an important role in the decomposition of the organic, contributing to the functionality of natural ecosystems. This study aimed to evaluate the seed bank in the soil and quantify organisms of the mesofauna and macrofauna soil in areas with different management in semiarid region of Paraíba : 1 ) Planting of Craibeira (Tabebuia áurea (Silva Manso) Benth. & Hook.f. ex S.Moore,), ( 2 ) degraded area without any woody vegetation , and ( 3 ) Planting of jurema branca (Piptadenia stipulacea (Benth) Ducke), sabiá (Mimosa caesalpiniifolia Benth) e jurema preta (Mimosa tenuiflora (Willd.) Poiret). The seed bank study was conducted by collecting five samples of litter and soil in each area, stored at the nursery UFCG , Campus de Patos , where they remained for about 90 days under shading and manual irrigation for counting and identification of emerging individuals. The total number of plants was compared between areas through the χ2 test at p < 0.05, and floristic diversity and species richness were assessed using the Shannon - Wiener index ( H ' ) and evenness of Uniformity ( e') . It was found in all three areas the dominance of seeds of herbaceous species. The degraded area had the highest density of grass seed, greater number of families and species, but lower diversity, while the planting area of craibeiras had the highest number of seeds of tree species and herbaceous seed stock and diversity were similar to those found in the planting area jurema and sabia. For capturing of the macrofauna we used PROVID traps, and every 45 days we collected soil+litter samples to determine the mesofauna, using metal rings with subsequent extraction of invertebrates present in the sample by the type of modified Berlese Tullgren equipment. The greater abundance of macrofauna organisms was observed in the area with planting of craibeiras while the planting area with jurema / sabia showed higher abundance of the mesofauna organisms. The largest groups of macrofauna abundance in different areas and periods , in order of decreasing density, were Hymenoptera, Coleoptera and Aranea . As for the mesofauna , groups Collembola and Acarina experienced seasonal fluctuations with the greatest diversity of Collembola and Acarina lower diversity recorded in the period of greatest water regime in the soil.