Composição florística e fitossociológica da caatinga relacionada à dinâmica dos organismos do solo, na Estação Ecológica Curral do Meio, semiárido de Alagoas

Abstract

The Semiarid of Alagoas apresents variety of floristic and faunistic richness that can be explored. Studying the dynamics of this environment is necessary for understanding the processes of structuring the terrestrial ecosystems and the management and conservation of the Caatinga. In this sense, the present work aimed to rate the floristic and phytosociological composition of the Caatinga vegetation related to the soil organisms dynamics, in Ecological Station Curral do Meio, Semiarid region of Alagoas. It was delimited 1 ha, subdivided into 100 plots of 10 m x 10 m, where the floristic-phytosociological survey was performed by the contiguous plots method. Each sampled individual was annotated to Circumference at Base Height (CBH) ≥ 9 cm and height ≥ 1.0 m of all individuals sampled. For the characterization of the tree-shrub community structure of each species, the phytosociological parameters were calculated. For the evaluation of the diversity of floristic species was used the Shannon-Weaver diversity index, for the spatial distribution of the species was applied the MacGuinnes Index (AGI). To quantify the similarity of the communities was elaborated a grouping dendogram using the Jaccard Similarity. A mapping of the dominant plant species was also carried out, using GPS Map 76CSx to plot the spots of each plant and elaborated a map of the distribution of the plants. In order to collect the edaphic macrofauna, Provid traps were made with PET bottles, with a capacity of 2 L and 4 holes of 2x2 cm, kept in the field for 96 hours, containing 200 mL of 5% detergent solution and 5 drops of Formol A. P. The organisms caught longer than 2 mm were quantified and identified at the level of the taxonomic group. For evaluation of the mesofauna were collected samples of soil+ litter the use of metal rings (diameter = 4.8 cm and height = 5 cm) at 0-5 cm depth for extraction of the edaphic organisms. The samples were installed in the modified Berlese-Tullgren extractor battery and the organisms with a length of 0.2 to 2.0 mm were quantified and identified in a binocular loupe. The organisms of the macrofauna and mesofauna of the soil were evaluated quantitatively by the number of individuals and qualitatively by the Shannon Diversity Index (H) and by the Equability Pielou Index (e). Rainfall data, soil temperature measurements and soil water content were also determined, both at depths of 10 cm, besides carbon and soil organic matter determinations. The most abundant plant species are Bauhina cheilantha (Bong.) D. Dietr. (Mororó), Aspidosperma pyrifolium Mart. (Pereiro), Capparis flexuosa (L.) L. (Brave beans), Anadenanthera colubrina (Vell.) Brenan (Angico of stone) and Mimosa hexandra Michele. (White hawthorn); The families with the highest number of species are Mimosaceae and Fabaceae, with Fabaceae having the highest number of individuals; The Caatinga plant species sampled have potential for medicinal use, fuel, human food, ornamentation, wood (construction), tannin and forage production; The most abundant soil macrofauna taxonomic group is Hymenoptera, standing out the occurrende of Coleoptera and Araneae, evidenced by the lower diversity and uniformity; The most abundant soil mesofauna taxonomic groups are Acarina and Collembola, evidenced by the low values of the Shannon and Pielou indexes; The richness, abundance, diversity and uniformity of the organisms of the soil macrofauna and mesofauna oscillate according to the edaphoclimatic variations; The rich biodiversity of plant and faunal species, together with the high levels of carbon and soil organic matter, found in the experimental area in Ecological Station Curral do Meio, indicates that is in good condition.