Li Jia-Yu, Lyu Mao-Kui, Li Xiao-Jie, Jiang Yong-Meng, Xie Jin-Sheng
College of Geographical Science, Fujian Normal University, Fuzhou 350007, China.
Key Laboratory for Humid Subtropical Eco-geographical Processes of the Ministry of Education, Fujian Normal University, Fuzhou 350007, China.
Ying Yong Sheng Tai Xue Bao. 2021 Apr;32(4):1250-1258. doi: 10.13287/j.1001-9332.202104.022.
Moisture is an important factor affecting the priming effect of soil organic carbon (SOC). However, empirical evidence for its effect in mountain meadows soil is lacking. We conducted a 126-day laboratory incubation experiment with the high altitude (2130 m) mountain meadow soil in Wuyi Mountain, by adding C-labelled glucose combined with controlling soil moisture (30% and 60% of field water capacity, FWC). The CO concentration and C-CO abundance were measured regularly to examine the differences of SOC mineralization and priming effects under different water conditions and the driving factors. Our results showed that SOC mineralization rate increased with increasing soil water content. The priming effect of meadow soil with different soil moisture showed a decreasing trend with the increases of incubation time. The priming effect in soils with low FWC soil was significantly greater than that with high FWC. At the end of incubation, the cumulative priming effect of low FWC soil was 61.4% higher than that of high FWC soil. Compared with low FWC soil, high FWC soil released more CO from glucose, and the ratio of cumulative primed carbon to glucose mineralization under low FWC was significantly higher than that under high FWC soil, indicating that soil microorganisms under the high FWC condition might preferentially mineralize more glucose than SOC and consequently lower priming effect. Therefore, the priming effect under high FWC was smaller than that under low FWC. There was a significant positive relationship between priming effect and microbial biomass carbon, microbial biomass carbon/microbial biomass nitrogen, and NH-N, indicating that soil microbial biomass and composition could be changed under low FWC condition. The improved microbial "nitrogen-mining" would increase priming effect. Consequently, the decline of soil moisture of mountain meadow induced by global climate change may increase the priming effect of carbon, with consequences on carbon loss.
水分是影响土壤有机碳（SOC）激发效应的重要因素。然而，关于其在山地草甸土壤中作用的实证证据尚缺。我们对武夷山高海拔（2130米）山地草甸土壤进行了为期126天的实验室培养实验，添加了碳标记葡萄糖并控制土壤湿度（田间持水量的30%和60%）。定期测量CO浓度和C-CO丰度，以研究不同水分条件下SOC矿化和激发效应的差异及驱动因素。结果表明，SOC矿化率随土壤含水量增加而升高。不同土壤湿度的草甸土壤激发效应随培养时间延长呈下降趋势。低田间持水量土壤的激发效应显著大于高田间持水量土壤。培养结束时，低田间持水量土壤的累积激发效应比高田间持水量土壤高61.4%。与低田间持水量土壤相比，高田间持水量土壤从葡萄糖中释放的CO更多，低田间持水量条件下累积激发碳与葡萄糖矿化的比值显著高于高田间持水量土壤，表明高田间持水量条件下土壤微生物可能优先矿化更多葡萄糖而非SOC，从而降低激发效应。因此，高田间持水量下的激发效应小于低田间持水量下的激发效应。激发效应与微生物生物量碳、微生物生物量碳/微生物生物量氮和NH-N之间存在显著正相关，表明低田间持水量条件下土壤微生物生物量和组成可能发生变化。微生物“氮挖掘”的改善会增加激发效应。因此，全球气候变化导致的山地草甸土壤水分下降可能会增加碳的激发效应，进而影响碳损失。
