Effects of litter manipulation on soil respiration under short-term nitrogen addition in a subtropical evergreen forest

Nitrogen (N) availability is rapidly increasing in subtropical ecosystems, where litterfall is also accelerating and may substantially affect belowground carbon (C) storage and soil respiration (R-s). This study aims to detect how litter inputs affect R-s under N addition in a subtropical forest. We conducted a two-factor experiment (N addition and litter manipulation) in a subtropical Schima superba evergreen broad-leaved forest in eastern China. Three levels of N addition included low-N (50 kg N ha(-1) yr(-1)), high-N (100 kg N ha(-1) yr(-1)) and ambient N (0 kg N ha(-1) yr(-1)), and three levels of litter manipulation consisting of litter removal (NL), litter addition (DL) and Control litter input were conducted. Our results showed NL decreased R-s by 41% and 38% under low- and high-N additions, respectively, compared to Control litter input. DL decreased R-s by 24% compared to Control litter input under high-N addition. Furthermore, low- and high-N additions decreased the effect size of NL on R-s, whereas high-N addition decreased the effect size of DL on R-s in the study period, in both rainy and dry seasons. The effect of litter input alteration on R-s under N addition decreased, compared to R-s in Control litter input under N addition. Thus, the increase in R-s under N addition was alleviated, suggesting that soil organic C sequestration may benefit from increasing N deposition in the future. Further study is needed to clarify the effects of litter input alteration on R-s and soil C cycling under long-term N addition in subtropical forests.