影响呼伦贝尔草原土壤有机碳空间变异的主导因素

Study on Dominant Factors Affecting Spatial Variation of Soil Organic Carbon in Hulunbuir Grassland

【背景】土壤有机碳(SOC)是草地生态系统全球碳循环中的关键组成部分。在气候变化和草地土壤退化的背景下,草地碳循环的研究引起了广泛的关注,特别是对草地SOC在不同时间和空间尺度上的动态和驱动因素的深入分析。然而,对草地SOC长期动态变化的估计和空间变异驱动因子分析目前主要基于遥感建模方法和模拟预测,而非直接测量。【目的】评估呼伦贝尔草原不同时期SOC空间变异因子的相对重要性及其变化特征。【方法】基于1980年全国第二次土壤调查数据,在2022年重复了呼伦贝尔草原第二次土壤调查的31个样点的土壤剖面,并通过建立多元线性模型和广义相加模型对这两个时期SOC变化及其驱动因子进行量化分析。【结果】1980—2022年,40年间呼伦贝尔草原SOC由17.25 g·kg^(-1)增加到17.62 g·kg^(-1),增加了0.37 g·kg^(-1)。气候因子的相对重要性从1980年的22.1%增加到2022年的72.9%。相比之下,地形和利用强度因子的相对重要性下降,分别从1980年的38.8%和39.2%下降到2022年的13.5%和13.5%。【结论】气候因子、地形和利用强度共同主导了呼伦贝尔草原土壤有机碳的空间变异。在过去的40多年里,影响草地SOC变化的气候因子已由次要贡献因素演变为主要控制因素。

【Background】Soil organic carbon(SOC)is a key component of the global carbon cycle in grassland ecosystems.In the context of climate change and grassland soil degradation,the study of the grassland carbon cycle has garnered extensive attention,particularly the in-depth analysis of the dynamics and driving factors of soil organic carbon in grasslands at different temporal and spatial scales.However,the estimation of long-term dynamic changes and the analysis of drivers for spatial variation in grassland SOC are primarily based on remote sensing modeling methods and simulation predictions,rather than direct measurements.【Objective】The aim of this study was to evaluate the relative importance of SOC spatial variation factors and their variation characteristics in different periods of Hulunbuir grassland.【Method】Based on the data of the second national soil survey in the 1980,the soil profiles of 31 sample sites in Hulunbuir grassland in 2022 were collected again,and the SOC changes and driving factors of Hulunbuir grassland were quantitatively analyzed in these two periods by establishing a multivariate linear model and a generalized additive model.【Result】From 1980 to 2022,the SOC of Hulunbuir grassland increased from 17.25 g·kg^(-1)to 17.62 g·kg^(-1)in 40 years,with an increase of 0.37 g·kg^(-1).The relative importance of climatic factors increased from 22.1%in the 1980 to 72.9%in 2022,compared with a decrease in the relative importance of the topography and utilization intensity factors,which decreased from 38.8%and 39.2%in the 1980 to 13.5%and 13.5%in 2022,respectively.【Conclusion】The climatic factors,topography and use intensity jointly dominated the spatial variation of soil organic carbon in Hulunbuir grassland.Over the past 40 years,the climate factors have evolved from a secondary contributor to grassland SOC change to a major controlling factor.