Variabilidade espacial de atributos físicos e entomofauna do solo em área no interior da Região Oeste do Pará

Abstract

The use of geostatistical analysis, helps to assist in the identification of spatial patterns of soil, allowing the consideration of the edaphic fauna present, influencing the indication of better management alternatives. Thus, this study aimed to evaluate the spatial variability of soil physical attributes with the local entomofauna, considering an area of fallow and native forest located in Santarém, western Pará. Sampling grids were assembled by collecting soil samples at depths 0 - 20 cm and 20 - 40 cm, totaling 49 samples per depth and a total of 98 samples per area, to assess the attributes: soil and soil particle density, macro and micro porosity, total porosity, gravimetric and volumetric moisture and resistance to soil penetration, and the collection of entomofauna was performed at each sampling point, with pitfall traps. Descriptive statistics, Principal Components Analysis (PCA) and Geostatistical Analysis were performed, with adjustment of semivariogram models for the characteristics of physical soil attributes using interpolation by Ordinary Kriging and, for the analysis of entomofauna, the covariogram models for the families were tested in order to find the model with the most appropriate parameters, with interpolation by Poisson Kriging. A total of 3,098 insects were collected, of which 1,710 were collected in the Native Forest and 1,388 in the fallow area, from 45 families, belonging to twelve orders. The Native Forest area presented a Shannon-Wiener index (H') of 2.68 and the fallow area of 2.31. The P The Pielou's Equitability index was 0.72 for the Native Forest and 0.61 for the fallow area. In the PCA analysis, 5 families were found to be associated with macroporosity, total porosity and soil moisture in the Native Forest area. In the fallow area 6 families showed greater proximity to the soil characteristics volumetric and gravimetric moisture, and also macroporosity and total porosity. This interaction can consider these organisms as indicators of soil quality, as they are influenced by anthropic practices, which generates a reduction of individuals in some areas, highlighting the influence of physical characteristics of the soil. For the physical attributes of the soil, the models of semivariograms matern, spherical, Gaussian and cubic were the best fits studied in the area of Native Forest, while in the fallow area the Gaussian, spherical, exponential, cubic and matern models were the best fits. In the edaphic fauna, the circular, exponential, cubic, spherical and Gaussian models were adjusted. In the analysis of the spatial dependence index (SDI) in the Native Forest area 10 families showed strong dependence, while in the fallow area there were 7 families. It was possible to observe the families that were most associated with the characteristics of moisture and porosity of the soil on the maps of interpolation by kriging.