Seasonal dynamics of litter stability, composition, and microbial properties in a semiarid tropical dry forest

Litter influences carbon flow in tropical dry forests by mediating energy and nutrient exchange between plants and soil. In the Caatinga, seasonal climate effects control litter production, quality, and decomposition, yet the microbiological regulation of these processes remains unclear. This study examined the seasonal changes in litter chemical composition, microbiological properties, and stability in native Caatinga vegetation. Six bimonthly soil samplings were conducted under native dry forest belonging to the Instituto Agronômico de Pernambuco (NF 1 ) and native dry forest from a private farm (NF 2 ). During the dry season, litter mass (1178 kg ha −1 ) and carbon stocks (404 kg ha −1 ) increased, along with renewal times (131 days) and residence times (143 days). The decomposition rate and return coefficient dropped by 61.9% and 22.7% during the same season, accompanied by a sharp decrease in moisture content from 96.2% in the rainy season to 4.9% in the dry season, indicating slower microbial decomposition under unfavorable moisture and temperature conditions. Basal respiration (1259 mg kg −1 ), microbial carbon biomass (1178 mg kg −1 ), microbial and mineralization quotients (0.47% and 0.48% day −1 ), and carbon use efficiency (0.06) also increased during the dry season, suggesting enhanced microbial activity and efficiency and indicating carbon preservation under water stress. Spatial differences in vegetation and litter affected microbial efficiency and organic matter recalcitrance, showing that plant diversity influences how decomposition responds to seasonal variation. Overall, seasonality shapes interactions between litter and microbes in the Caatinga, regulating carbon and nutrient flow and helping these semiarid ecosystems stay resilient.