易分解有机碳输入量对武夷山不同林型土壤激发效应的影响

土壤有机碳库是陆地生态系统中最大的碳储量库，其微小的变化也能使大气中CO₂浓度发生巨大的改变，植物来源碳的输入能通过激发效应促进或抑制土壤有机碳（SOC）的分解，对SOC的动态平衡产生影响。以武夷山三个林型（阔叶林、马尾松林、针阔混交林）土壤为研究对象，通过向土壤中添加不同量的¹³C标记葡萄糖（0、100、200、400 mg C/kg）研究易分解有机碳输入量对不同林型土壤激发效应的影响，并在此基础上探讨易分解有机碳输入量对土壤激发效应影响的作用机理。结果表明，葡萄糖输入对土壤激发效应的影响与葡萄糖输入量和林型有关。葡萄糖的输入均抑制了三个林型SOC的分解（即，呈现负的激发效应）。阔叶林土壤和针阔混交林土壤激效应强度随着葡萄糖输入量的增加而增加，而马尾松林土壤的激发效应强度对葡萄糖输入量的响应并不明显。然而在马尾松林土壤中由葡萄糖所引起的激发效应强度显著高于其他两种林型土壤。研究结果表明，易分解有机碳的输入可以抑制SOC的矿化，形成负激发效应，阔叶林土壤的激发效应强度与土壤可利用氮、葡萄糖添加量与微生物碳量比值有关，而针阔混交林与马尾松林土壤的激发效应强度分别与土壤中的放线菌和真菌有关。

Impacts of labile organic carbon input on the priming effect of three forest soils in Wuyi Mountain

Soil organic carbon pool is the largest carbon pool in the terrestrial ecosystem, and thus its small change can result in a significant change in atmospheric CO₂ concentration. The input of plant-derived carbon can accelerate or mitigate the decomposition of soil organic carbon (SOC) through the priming effect, and eventually affect SOC balance. To investigate the impacts of labile organic carbon input on the priming effect and clarify the underlying mechanisms, a ¹³C labeling experiment with different amount of glucose inputs (0, 100, 200 and 400 mg C/kg) were carried out in this study. The experimental soils were collected from three different forest soils (the evergreen broadleaf forest, broadleaf and coniferous mixed forest, and Pinus massoniana forest) in Wuyi Mountain. The results showed that the impacts of glucose input on the priming effect were dependent on both the amount of glucose input and forest type. The input of glucose inhibited the decomposition of SOC in the three forest soils (i.e., a negative priming effect). The magnitude of the priming increased with increasing the input of glucose in the broad-leaved forest and coniferous and broad-leaved mixed forest, whereas the response of the priming magnitude to the glucose input was not significant in Pinus massoniana forest soil. However, the priming effect in Pinus massoniana forest soil was significantly higher than that in the other two forest soils. The results indicated that the input of labile organic carbon could inhibit the mineralization of SOC and formed a negative excitation effect. The priming effect in broad-leaved forest soil was related to soil available N and the ratio of glucose application rate to microbial biomass carbon, while the priming effects in coniferous and broad-leaved mixed forest and Pinus massoniana forest soil were related to actinomycetes and fungi, respectively.