Serviços ecossistêmicos de estoques de carbono e retenção da água em solos em diferentes estado de conservação na caatinga

Abstract

In the drylands, goods and services offered by the soil are altered by inappropriate land use and management practices that compromise the functionality of ecosystems, whose actions result in high rates of degradation, water changes and alteration of soil organic carbon content. This study aimed to evaluate soil water retention and soil organic carbon dynamics and their relationships with ecosystem services of support, regulation, and provisioning in a dry forest located in the Paraíba state, Brazil. Three areas with different land uses and vegetation were chosen: Fazenda São Paulo dos Dantas (FASP) with intermediate vegetation complexity composed of forests and woods (60%) and agricultural areas (40%); the Private Natural Heritage Reserve (RPPN) Fazenda Almas with highly complex vegetation with 90% of its area covered by forests; and an area located in São João do Cariri (SJC) with low vegetation complexity with about 75% of its soils degraded. To carry out this study, a homogeneous sampling grid was used with 25 points in each area, in a total of 75 points. In each quadrant, trenches were opened and both disturbed and undisturbed samples were collected at depths of 0-10, 10-20 and 20-30 cm, totaling 225 samples. Granulometric analysis, soil density, particle density, total porosity, pore classes, organic matter and carbon content were performed. To identify the variability and the degree of spatial dependence of organic carbon, geostatistics and kriging were used. Soil water retention (CRA) curves were estimated by the pedotransfer function (FPT), using the fourth level of the Tomasella function. For statistical analysis, Tukey's mean test at 5% probability and principal component analysis (PCA) were used. The COS grades and stock in FASP were higher than the other areas at all depths. According to FPT estimates, SJC is the area with the greatest potential to retain greater amounts of water due to the high content of clay and organic matter, however, this area does not have the required characteristics to retain water due to the high degree of compaction, smaller porous space and higher soil density. It can be concluded that the area with physical characteristics with the greatest potential to retain water is FASP with the greatest capacity to offer various soil ecosystem services.