ISSN 1000-3665 CN 11-2202/P

    黄土高原中北部灌-草区土壤干层特征分析及其环境驱动因素模型构建

    Characteristics of dried soil layer and environmental driving factor modeling in the north-central shrub-grassland region of the Loess Plateau

    • 摘要: 当前黄土高原中北部部分地区存在人工植被“生态水文错配”,进而引发土壤干燥化问题,现有研究对区域土壤干层的空间分布模拟较为薄弱,难以支撑对土壤干层及土壤水资源可持续性的进一步精细化研究。为量化黄土高原中北部灌−草区土壤干层的空间分布,明确驱动土壤干层形成的控制性环境因素,构建土壤干层预测模型,研究通过野外调查乔木林地、灌木林地、草地和农地共111个样地0~500 cm土壤剖面,结合土壤干层厚度、土壤干层内含水率和土壤水分亏缺度3个指标,收集5类环境参数,阐明和揭示了黄土高原中北部灌-草区区域土壤干层的空间特征及影响驱动因素,利用传统统计和随机森林、支持向量机、BP神经网络3种经典机器学习方法构建了土壤干层空间分布的预测模型。结果表明:(1)黄土高原中北部灌-草区0~500 cm剖面普遍存在土壤干层发育,平均厚度为312 cm,平均土壤干层内含水率为9.05%,平均水分亏缺度为0.59;(2)植被状况是影响区域土壤干层分布的决定性因素,而田间持水量是影响土壤干层内含水率的关键因素;(3)机器学习方法能够较好地预测土壤干层的空间分布,尤其是BP神经网络(除土壤干层厚度)和支持向量机方法。研究量化了黄土高原中北部灌−草区土壤干层的空间分布,并明确了植被状况、土壤性质和气象条件是影响土壤干层的关键环境因素。此外,机器学习模型的预测结果为这些发现提供了拓展研究的可能性,有助于在更广泛的区域进行土壤干层的管理和预测。

       

      Abstract: The eco-hydrological mismatch between artificial vegetation and available soil water resources in parts of the north-central Loess Plateau has resulted in widespread soil desiccation and the formation of dried soil layers (DSLs). However, limited knowledge of the spatial distribution of DSLs constrains the assessment of soil water sustainability. To quantify the spatial distribution of DSLs in the shrub-grassland regions of the Loess Plateau, identify the dominant environmental factors driving DSL formation, and develop predictive models for DSLs, this study conducted field investigations across 111 sample plots (including farmland, grassland, forestland, and shrubland) to analyze 0–5 m soil profiles. Three key indicators were evaluated: dried soil layer thickness, soil water content within the dried soil layer, and soil water deficit. A total of five types of environmental factors were collected to elucidate the spatial characteristics and driving factors of DSLs in the shrub–grassland regions. Traditional statistical methods and three classical machine learning algorithms were employed to construct predictive models for DSL spatial distribution. The results reveal widespread development of DSLs (0–500 cm depth) in the shrub-grassland regions, with an average DSL thickness of 312 cm, an average soil water content within the DSL of 9.05%, and a mean soil water deficit of 0.59. Vegetation status is identified as the decisive factor influencing the spatial distribution of DSLs, while field capacity emerges as the critical determinant of soil water content in the DSL. Machine learning methods demonstrate strong predictive performance for DSL spatial distribution, particularly the back propagation neural network (BPNN) (except for DSL thickness) and support vector machine (SVM) models. This study quantitatively characterized the spatial patterns of DSLs in the shrub-grassland regions of the Loess Plateau and established vegetation status, soil properties, and meteorological factors as key environmental drivers. Furthermore, the predictive capabilities of machine learning models offer potential for spatial analysis of these findings, enabling improved management and forecasting of soil desiccation across broader regions.

       

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