Abstract: Soil greenhouse gas (GHG) emissions contribute profoundly to global warming; however, how plant detritus input alters GHG emissions is poorly understood. Here, we used detritus input and removal treatments (i.e., DIRT: control, CK; double litter, DL; no roots with double litter, NRDL; no litter, NL; no roots, NR; no roots and no litter, NRNL) to assess the effects of litter and root inputs on soil CO₂, CH₄, and N₂O fluxes in soils in a coniferous (Pinus yunnanensis) and a broad-leaf forest (Quercus pannosa) in a subalpine region in southwestern China. Litter addition increased CO₂ emissions on average 22.22%, but did not significantly alter CH₄ uptake and N₂O emission compared to the CK. Litter removal (NL and NRNL) significantly reduced CO₂ emissions on average 30.22% and N₂O emissions on average 31.16% from both forest soils, but did not significantly affect soil CH₄ uptake. Root removal (NR and NRNL) generally decreased these three soil GHG fluxes. Changes in β-1,4-glucosidase (BG) involved in C and phospholipid fatty acid (PLFAs) biomass were projected to influence CO₂ emissions, while soil microclimates (temperature and moisture) combined with BG activity mainly regulated CH₄ uptake. Alterations in dissolved organic nitrogen, microbial biomass nitrogen and BG were mainly responsible for changes in N₂O emissions. Interestingly, coniferous forest soil seemed to promote CH₄ uptake more than the broad-leaf forest soil, but CO₂ and N₂O fluxes were not significantly affected by the forest types. As expected, litter addition significantly increased the warming potential, while litter removal relatively lowered it. These findings revealed the divergent roles of plant detritus input and forest type in shaping soil GHG fluxes, thereby providing insights into forest management and predicting contributions of subalpine forests to global warming.

Key words: Detritus input and removal treatment, Edaphic properties, Microbial activities, Soil greenhouse gas, Subalpine forests