Impacts of land-use changes on soil respiration in the semi-arid region of Brazil

Soil respiration represents the largest flux of CO2 emission from terrestrial ecosystems, being affected by land-use changes and soil properties. There are few studies investigating the response of soil respiration to land-use changes in the Caatinga biome. This study aimed to measure soil respiration from Caatinga vegetation and degraded pasture, to verify the effect of land-use changes on soil respiration. Measurements of soil respiration were performed using the infrared gas analyzer method over nine months (in rainy and dry seasons), in Caatinga and degraded pasture in the semi-arid region of Pernambuco. The soil moisture, soil temperature, soil organic carbon (SOC), Normalized Difference Vegetation Index (NDVI), and climatic variables were also measured. Soil organic carbon and NDVI were higher in Caatinga than in degraded pasture, while the inverse occurred with soil temperature. The soil respiration showed a clear seasonal variation, with the highest values occurring in the wet season, being positively correlated with soil moisture and negatively with soil temperature. Soil respiration was significantly higher in the Caatinga (8.0 ton ha(-1) yr(-1) of C) than in degraded pasture (3.7 ton ha(-1) yr(-1) of C). These higher values of soil respiration in Caatinga were due to lower soil temperature and higher SOC, and can be seen as indicators of good environmental quality.