多年冻土区土壤碳、氮的可变性及对深层土壤特性了解的缺乏限制了人们对气候变化响应的理解。为明确东北大兴安岭多年冻土区森林土壤有机碳、有效氮（铵态氮、硝态氮）含量分布特征，于2020年秋季（9月末）采集呼玛河流域三种类型多年冻土区（不连续多年冻土区、零星多年冻土区和岛状多年冻土区）16个1 m深的土壤剖面，基于结构方程模型探讨海拔、气候、冻土区类型和植被类型等环境变量对森林土壤有机碳和有效氮含量的影响。结果表明：土壤有机碳和硝态氮含量在不连续多年冻土区高于零星多年冻土区和岛状多年冻土区，土壤铵态氮含量在零星多年冻土区高于岛状多年冻土区和不连续多年冻土区；在垂直剖面上，随着土壤深度的增加，土壤有机碳和有效氮含量呈降低趋势，且土壤有机碳与有效氮之间呈显著的负相关关系（P<0.05）。结构方程模型表明，植被类型和年平均温度是土壤有机碳含量变化的主要控制因素，年均降水量对土壤有机碳含量变化的影响最弱；冻土区类型和植被类型是土壤铵态氮和硝态氮含量变化的主要控制因素。研究结果能够为未来准确模拟和估算呼玛河流域多年冻土区森林土壤碳氮储量提供一定的数据支撑。

As the main body of the terrestrial ecosystem， forest soil plays an irreplaceable role in the global carbon and nitrogen cycles. Under natural conditions， the distribution of forest soil organic carbon and available nitrogen is controlled by factors such as climate and vegetation. Climate usually affects soil water and heat conditions and the distribution patterns of vegetation. Vegetation affects soil carbon and nitrogen content through its own growth and litter decomposition. However， due to the significant regional variation in response to climate warming， limited field observations and large spatial heterogeneity， the understanding of soil organic carbon and available nitrogen content and spatial distribution patterns in the deep soil of different types of permafrost zones remains largely uncertain. At the same time， in the past century， the temperature in the Greater Hinggan Mountains has experienced a warming of more than 1 ℃， and the frozen soil has degraded from continuous permafrost zone to discontinuous permafrost zone， sporadic permafrost zone or island permafrost zone. At present， there is still a lack of research on the spatial distribution characteristics and influencing factors of soil organic carbon and available nitrogen in different types of permafrost zones in the Huma River basin. Therefore， this paper selects three types of permafrost zones in the Huma River basin （discontinuous permafrost zones， sporadic permafrost zones and island permafrost zones）. Based on the spatio-temporal transformation method， we explored the spatial variation characteristics of forest soil organic carbon and available nitrogen in the process of permafrost degradation and revealed the main controlling factors and relative contributions of forest soil organic carbon and available nitrogen in the watershed. In this study， forest soil was selected as the research object. In September 2020， 16 soil profiles with a depth of 0~100 cm were selected for sample collection in discontinuous permafrost zones， sporadic permafrost zones and island permafrost zones in the Huma River basin. The soil samples were collected vertically downward from the surface into 5 layers， 0~20 cm， 20~40 cm， 40~60 cm， 60~80 cm and 80~100 cm in sequence. Three replicates of soil samples were collected at different sides of the same depth of the profile， and a total of 240 soil samples were collected. Each sampling point records basic information such as elevation， longitude， latitude， and dominant species of above-ground and surface vegetation. The effects of environmental variables such as elevation， climate， permafrost zone type and vegetation type on forest soil organic carbon and available nitrogen content were discussed based on the structural equation model （SEM）. The results showed that the contents of soil organic carbon and nitrate nitrogen in the discontinuous permafrost zone were higher than those in sporadic permafrost zone and island permafrost zone， while soil ammonium nitrogen content in the sporadic permafrost zone was higher than that in island permafrost zone and discontinuous permafrost zone. In the vertical profile， the contents of soil organic carbon and available nitrogen contents tended to decrease with increasing soil depth， and there was a significant negative correlation between soil organic carbon and available nitrogen （P<0.05）. The structural equation model clarified that vegetation type and mean annual temperature were the main controlling factor for soil nitrate nitrogen content， and mean annual precipitation had the weakest effect on soil organic carbon content； permafrost zone type and vegetation type were the main controlling factors for soil ammonium nitrogen and nitrate nitrogen content. This study is helpful to understand the distribution patterns and main controlling factors of forest soil organic carbon and available nitrogen in different types of permafrost zones in the Huma River basin， and can provide certain data support for the accurate simulation and estimation of forest soil carbon and nitrogen storage in the watershed in the future.