关键词: 土柱置换, 武夷山, 土壤呼吸, 土壤微生物量碳, 可溶性有机碳

Abstract: Subtropical areas are subjected to rapid climatic change owing to anthropogenic activities, which could potentially affect soil respiration. In this study, a coniferous forest (CF) at 1442 m and an evergreen broad-leaved forest (EBF) at 645 m were selected as research objects in the Wuyishan National Park, Fujian Province, China. The effects of simulated warming (soil monoliths transferred from CF to EBF) and cooling (soil monoliths transferred from EBF to CF) on soil carbon processes were explored using a reciprocal soil monoliths translocation experiment. The microclimate, soil respiration, soil organic carbon, soil total nitrogen and soil labile organic carbon were measured for in situ and transferred treatments at both elevations. The results showed that soils experienced warming had higher temperature and lower moisture. In contrast, soils experienced cooling had lower temperature and higher moisture. Simulated warming substantially-increased soil respiration by 99.6% and significantly decreased temperature sensitivity (Q₁₀) compared with the CF incubated in situ. Simulated cooling substantially reduced soil respiration by 43.3% and increased Q₁₀ compared with the EBF incubatedin situ. Soil temperature was the factor driving changes in soil respiration, whereas soil moisture had no relationship with soil respiration (P>0.05). At the end of the experiment, soil organic carbon contents of the EBF and CF were increased by 12% and 10%, respectively, which might be related to the decomposition of dead roots and leaf litter. The soil organic carbon content decreased slightly under both the warming and cooling treatments, which could be explained by the differences in intensity of soil respiration. At the end of the experiment, warming reduced soil microbial biomass carbon, but increased dissolved organic carbon. In contrast, cooling increased soil microbial biomass carbon and decreased dissolved organic carbon, indicating that soil labile organic C may not respond equally to warming and cooling. Therefore, the responses of soil respiration to warming and cooling should be considered for the construction of climate change response models when both warming and cooling are involved in the climate change.

Key words: translocation of soil monolith, Wuyi Mountain, soil respiration, soil microbial biomass carbon, dissolved organic carbon.