Basal soil respiration in land use and cover systems in a caatinga enclaves moist forest

Abstract

Deforestation and the disorderly exploitation of natural resources for agricultural expansion occurred at an accelerated pace in the Brejo microregion of the state of Paraíba, Brazil, which resulted in abandonment and erosion of the soil in a large part of the region. In view of this scenario, the present study was undertaken to investigate the soil respiration in systems involving different forms of land use and cover in caatinga enclaves moist forests (Brejo de Altitude areas). The study was conducted in four land use and cover systems, namely, pasture, mandala agriculture, agroforestry system, and forest. Microbial activity was estimated by quantifying the carbon dioxide (CO2) released in the soil respiration process, from the soil surface, and captured by KOH solution. Soil temperature (°C) and water content (%) were monitored simultaneously with the analysis of soil respiration. The forms of land use and cover have a direct effect on the metabolic activity of soil organisms, and climatic factors such as soil temperature and moisture influence the dynamics of organic matter decomposition and, consequently, the release of CO2. The production of CO2 is higher at night than during the day, regardless of the analyzed systems. Among the evaluated areas, the forest showed the lowest CO2 emissions, so it was considered a CO2 receptor in contrast to the pasture area, which functioned as a CO2 emitter. Management techniques that reduce surface temperature and increase organic matter should be prioritized to promote soil biota.