【目的】 探究浙江百山祖国家级自然保护区内不同海拔的杉木-针阔混交林根际土壤有机碳含量垂直分布差异,明确海拔变化条件下土壤有机碳活性组分的影响因素。【方法】以保护区内不同海拔(600、800、1 000、1 200 m)的杉木-针阔混交林为研究对象,在每个海拔林分设置3个样地,测定每个样地内0~20 cm土层土壤理化性质[土壤总有机碳(TOC)、全氮(TN)、全磷(TP)、土壤pH]、土壤酶活性及土壤有机碳组分含量等指标,分析根际土壤有机碳沿海拔的变化特征及影响因素,并计算土壤碳库管理指数(CMI)。【结果】杉木-针阔混交林根际土壤TOC、TN、TP含量随着海拔的上升逐渐增大,颗粒有机碳(POC)与总有机碳变化一致;易氧化有机碳(ROC)、矿质结合态有机碳(MOC)含量随海拔先上升后下降;根际土壤β-葡萄糖苷酶活性随海拔升高呈增加趋势;与海拔600 m处相比,其他3个海拔土壤CMI显著增加。根际土壤TOC、POC、ROC与TN含量呈显著正相关,与β-葡萄糖苷酶及多酚氧化酶活性呈显著正相关。根际和海拔的交互效应对土壤有机碳组分及酶活性无显著影响。冗余分析表明,TN是影响根际土壤活性有机碳组分及CMI的主要因子。【结论】海拔形成的小气候及土壤理化性质的改变是造成根际土壤活性有机碳组成海拔差异的重要因素,土壤氮含量是影响根际土壤活性有机碳的主导因子,高海拔区域内土壤碳库质量较高,应加强对高海拔地区植被的保护。

【Objective】 This research aims to investigate the differences in vertical distribution of rhizosphere soil organic carbon content in fir coniferous-broadleaved mixed forests at different altitudes in Baishanzu National Nature Reserve, Zhejiang Province, and to clarify the factors influencing the active components of organic carbon under altitudinal changes.【Method】The study was carried out in fir coniferous-broadleaved mixed forests at different altitude gradients (600, 800, 1 000 and 1 200 m) in the park, and three sample plots were set up in each altitude gradient. Soil properties [total organic carbon (TOC), total nitrogen (TN), total phosphorus (TP) and soil pH], soil enzyme activity and soil organic carbon content in soil layers of 0-20 cm were measured and analyzed in each sample plot. Analyzed the distribution characteristics of rhizosphere soil organic carbon along the altitude and the influencing factors, and calculated the soil carbon pool management index (CMI).【Result】TOC, TN and TP contents of the rhizosphere soil increased gradually with the rise of altitude, and the particulate organic carbon (POC) and TOC varied in the same way; the content of readily oxidizable organic carbon (ROC) and mineral-bound organic carbon (MOC) firstly increased and then decreased. The β-glucosidase activity of rhizosphere soil tended to increase with elevation. The soil carbon pool management index (CMI) of the other three elevation gradients significantly increased. The TOC, POC and ROC contents of rhizosphere soil were significantly positively correlated with TN, β-glucosidase and polyphenol oxidase were significantly positively correlated with TOC. The interaction effects of rhizosphere and elevation had no significant effect on soil organic carbon fractions and enzyme activities. Redundancy analysis showed that TN was the main factor affecting active organic carbon fractions and CMI. 【Conclusion】Climate and soil physicochemical changes brought about by altitude changes are important factors affecting the altitudinal differences in rhizosphere soil organic carbon, and soil nitrogen content is the dominant factor affecting active organic carbon in the rhizosphere soil.The quality of soil carbon pool in high-altitude areas is high, and the protection of vegetation in high-altitude areas should be strengthened.