Dynamics of litter nutrient return in Xishuangbanna tropical rainforest from 2005 to 2015 under the disturbance of extreme dry weather

This 11-year longitudinal study (2005-2015) investigated biomass dynamics and nutrient return patterns of litterfall in Xishuangbanna tropical rainforest, China, elucidating forest nutrient cycling mechanisms under extreme drought stress and informing climate-resilient ecosystem management. Through standardized plot monitoring and elemental analysis (C, N, P, K, S, Ca, Mg), we revealed: (1) Significant interannual variability in total litter production (7.52-11.90 t/ha, mean 9.59±0.30 t/ha), with extreme drought year 2010 showing 44% higher yield than normal years (2005, 2015). Leaf litter dominated consistently (60.12%), serving as the primary nutrient carrier; (2) Bimodal seasonal patterns featuring a spring peak (April) and summer trough (July-September), synchronized with phenological responses to climatic extremes; (3) Stable nutrient hierarchy (C>Ca>N>K>Mg>S>P) yet elevated C/N (+19%) and C/P (+31%) ratios under drought, indicating modified decomposition potential; (4) Climate-driven nutrient acceleration with 28% increase in annual returns (2005-2015), predominantly through leaf pathways (62-68% contribution). Strong correlations with monthly temperature (r=0.58, p<0.05) and humidity (r=-0.74, p<0.01) unveiled a "stress-induced nutrient pump" mechanism where drought accelerates foliar turnover. These findings propose leaf litter dynamics as a critical climate adaptation strategy in tropical forests. We emphasize integrating climate-sensitive litter monitoring into management frameworks, recommending establishment of early-warning systems based on litterfall indicators to enhance ecosystem resilience under global change scenarios.