The vegetation physionomy and cover can show patterns of diversity and composition of the edaphic community, depending on the quantity and quality of litter in a specific habitat. The objective of this study was to evaluate the effect of the vegetation gradient formed by Graminoid Field (GRF), Cerrado Sensu Stricto (CSS), Cerradão (CRD) and Semideciduous Seasonal Forest (SSF) on density, diversity and composition of the edaphic fauna community in two seasons of the year, in the Sete Cidades National Park (Piauí state). For fauna sampling, a total of eight pitfall traps, distanced 10 m, were placed in each area in the central part of each system, where they remained for seven days. In the wet period, there was a tendency to increase the number of individuals as a function of the complexity of the vegetation formation, with the inverse occurring in the dry period. It was verified an environmental variation of the climatic factors temperature and humidity according to the vegetal formation, contributing to a heterogeneous distribution of the fauna. The GRF formation presented a significantly lower value of average richness only in the dry period. Regarding the variables of diversity and uniformity, they did not show drastic variations in relation to the vegetation gradient studied. The dominant groups in the vegetation gradient were Formicidae, Coleoptera, Aranae, Acari and Collembola, with reduction of the number of Coleoptera in the dry season. Principal component analysis (PCA) revealed greater differences in the composition of the communities between the vegetation formations for the rainy season. At this time, the formations SSF and CRD were associated to a greater diversity of invertebrates than CSS and GRF, demonstrating the influence of the vegetation complexity on the soil fauna community.Keywords: Savanna, seasonality, species diversity, soil invertebrates, successional stage. Fauna edáfica em um gradiente vegetacional no Parque Nacional de Sete Cidades ResumoA fisionomia e cobertura vegetal podem mostrar padrões de diversidade e composição da comunidade edáfica, em função da quantidade e qualidade da serapilheira em determinado habitat específico. O presente trabalho teve por objetivo avaliar o efeito do gradiente vegetacional formado por Campo Graminóide (CGR), Cerrado Sensu Stricto (CSS), Cerradão (CRD) e Floresta Estacional Semidecídua (FES) sobre a densidade, diversidade e composição da comunidade da fauna edáfica em duas épocas do ano do Parque Nacional de Sete Cidades (PI). Para amostragem da fauna foram colocadas um total de oito armadilhas do tipo Pit-fall, distanciadas por 10 m, em cada área na parte central de cada sistema, onde permaneceram por sete dias. No período úmido houve uma tendência a aumento do número de indivíduos conforme a complexidade da formação vegetal e o inverso ocorreu no período seco. Verificou-se uma variação ambiental dos fatores climáticos temperatura e umidade conforme a formação vegetal contribuindo para uma distribuição heterogênea da fauna. Apenas no período ...

The objective of this study was to evaluate the physical attributes of an oxisol under soybean monoculture, eucalyptus monoculture, and pasture and native forest conditions at depths of 0-0.20 and 0.20-0.40 m. Disturbed and undisturbed soil samples were collected to perform physical analyses. Specific analyses included texture, soil density, macroporosity, microporosity, total porosity, aggregate stability index, weighted mean diameter, percentage of aggregates with a diameter of >2.00 mm, and soil penetration resistance (PR). The data were analyzed using the Tukey's test for the comparison of mean values and multivariate analysis. Different uses and management of the soil affected its physical attributes, resulting in the deterioration of soil quality in the soybean and pasture areas. Soil management systems in pasture and soybean areas also resulted in higher soil density and lower soil porosity. The eucalyptus monoculture showed soil aggregation equal to that of the native forest. There was a sharp increase in soil PR beyond the 0.15-m deep layer in the pasture and soybean management systems. Multivariate analysis identified variables that correlated with each type of soil management and the effects of changes in soil characteristics.

Vegetation cover may show diversity and composition patterns of the soil invertebrate community, as a function of litter quantity and quality in a specific habitat. The objective of this work was to characterize the distribution of edaphic fauna in different monocultures. The study was carried out at Chapada Grande farm in Regeneração, PI. Four monoculture areas were chosen: no-tillage soybean, eucalyptus, pasture, and a preserved native cerrado forest. Soil fauna was collected in a dry and wet period by pitfall traps containing 4% formaldehyde. The edaphic fauna was evaluated by the number of individuals per trap per day, average richness and richness, Shannon diversity index and Pielou uniformity index. Data were submitted to analysis of variance and multivariate Principal Component Analysis (PCA). The highest number of individuals per day trap and of average richness were registered in the pasture, eucalyptus and forest areas in both periods, while soybean showed lower values with predominance of Coleoptera and Formicidae groups. The pasture and forest areas showed of higher Shannon index values in the two evaluated seasons, probably due to higher contributions organic residues in the soil that favors the shelter, feeding and reproduction conditions. Regarding the Pielou index, the soybean system showed higher values in this variable. The Aranae, Coleoptera, Formicidae and Diptera groups predominated in the humid period, while Coleoptera and Formicidae predominated in the dry period. Systems that generate greater accumulation of residues harbor a greater diversity of invertebrates of the edaphic fauna. Seasonality had an effect on all variables analyzed and the wet period showed more expressive values.

The use of different legume species, as green manure, may affect differently soil biological and chemical properties. The aim of this study was to evaluate the effect of four legumes species used as green manure on soil biological and chemical properties in short-term. We evaluated the following legume species: Crotalaria, Cajanus, Mucuna and Canavalia. The study was arranged in a completely randomised design with four replicates. The plants were incorporated into the soil (0-20 cm) by harrow and the chemical and biological properties were evaluated 30 and 60 days from the incorporation. Soil chemical and biological properties showed different trends according to legume species used. Soil P and K contents were highest in plot with Crotalaria, while soil Ca content was highest in plot with Mucuna. Soil microbial biomass was higher in plot with Mucuna as compared with others green manure species. Fluorescein diacetate hydrolysis was higher in plots with Mucuna and Canavalia than the others plots. Our results supported the hypothesis that different types of legume used as green manure affect differently the biological and chemical properties of soil. In this case, Mucuna was more effective to improve soil biological properties, while Crotalaria seems to be more efficient in the improvement of chemical properties.