Relief and edaphoclimatic conditions as influencing agents of C[O.sub.2] release in Alagoas Caatinga, Brazil

The release of carbon dioxide (C[O.sub.2]) occurs through soil respiration. However, release of C[O.sub.2] from soil to the atmosphere is subject to interference from agents such as relief, edaphic and climatic conditions. Thus, this research aimed to quantify edaphic respiration related to edaphoclimatic factors in a toposequence area in Caatinga of Delmiro Gouveia, Alagoas, Brazil. The research was conducted from February 2013 to June 2014, with bimonthly collections during day and night. The soil C[O.sub.2] losses, temperature measurements, soil water content and rainfall were quantified. We verified that, independent of the evaluated points, C[O.sub.2] release was higher at night. Half-slope and shoulder were the areas with the highest emissions. Additionally, the C[O.sub.2] emissions presented annual variation, increasing with the availability of soil water and showing peaks of release in the rainy season. Soil and air temperature had no direct influence on soil C[O.sub.2] release; however, the highest C[O.sub.2] emissions occurred when temperatures were moderate and stable. Therefore, the conservation of this unique Brazilian biome is necessary because the impacts of its disturbance can increase the level of C[O.sub.2] released from the soil, increasing the amount of C[O.sub.2]in the atmosphere. Additional keywords: Brazilian semi-arid, rainfall, soil carbon dioxide, soil moisture, soil temperature. Received 12 June 2019, accepted 9 December 2019, published online 3 February 2020
Introduction Caatinga is the predominant vegetation type of the semi-arid region of north-eastern Brazil. Due to its heterogeneity and the significant number of rare and endemic species in the Caatinga, [...]