Long-Term Nitrogen Addition Decreases Soil Carbon Mineralization in an N-Rich Primary Tropical Forest

Anthropogenic elevated nitrogen (N) deposition has an accelerated terrestrial N cycle, shaping soil carbon dynamics and storage through altering organic mineralization processes. However, it remains unclear how long-term high affects in tropical forests. To address this question, we established a experiment N-rich lowland forest of Southern China with additions such as NH4NO3 0 (Control), 50 (Low-N), 100 (Medium-N) 150 (High-N) kg ha−1 yr−1, laboratory incubation experiment, used to explore the response therein. The results showed that 15 years significantly decreased rates. During period from 14th day 56th day, average decreases CO2 emission rates were 18%, 33% 47% low-N, medium-N high-N treatments, respectively, compared Control. These negative effects primarily aroused by reduced microbial biomass modified functions (e.g., decrease bacteria relative abundance), which could be attributed N-addition-induced acidification potential phosphorus limitation forest. We further found greatly increased soil-dissolved (DOC), there relationships between DOC, indicating consumption on soil-soluble pool may decrease. suggests can increase stability benefit sequestration This study help us understand microbes control cycling sink tropics under both dioxide future.