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 (Rs). This study aims to detect how litter inputs affect Rs 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 Rs by 41% and 38% under low- and high-N additions, respectively, compared to Control litter input. DL decreased Rs by 24% compared to Control litter input under high-N addition. Furthermore, low- and high-N additions decreased the effect size of NL on Rs, whereas high-N addition decreased the effect size of DL on Rs in the study period, in both rainy and dry seasons. The effect of litter input alteration on Rs under N addition decreased, compared to Rs in Control litter input under N addition. Thus, the increase in Rs 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 Rs and soil C cycling under long-term N addition in subtropical forests.