College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi 712100, China.
School of Environmental Sciences, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
Sci Total Environ. 2022 Mar 10;811:152172. doi: 10.1016/j.scitotenv.2021.152172. Epub 2021 Dec 6.
Identifying the variability and predominant factors affecting soil water (SW) is essential in regions with thick vadose zones and deep-rooted plants. This information is needed to clarify the balance between water availability and plant water demand. We collected 9263 soil samples from 128 profiles of 7-25 m deep soil under different climates (arid, semiarid and subhumid), soil textures and plant types (shallow or deep roots) in China's Loess Plateau. The factors dominating the horizontal and vertical variability of SW were identified using a multimodel inference approach and stepwise regression analysis. Horizontally, the mean water content and storage increased while the water deficits decreased from the northwest to the southeast. Vertically, mean water content and storage are highest in the relatively stable layer, followed by rapidly changing layers and active layers. Plant age and soil clay content dominate the horizontally varied SW, while plant age and normalized difference vegetation index (NDVI) dominate the vertical variability of SW. However, the dominant factors appeared to differ with climate and plant type. It was determined that for climate, soil clay content and plant age in arid regions, precipitation and plant age in semiarid regions, NDVI and plant age in subhumid regions were important factors. For plants, the dominant factors are NDVI and precipitation under shallow-rooted plants; however, NDVI and plant age were dominant under deep-rooted plants. The dominance of plant age highlighted the impact of vegetation patterns on SW, especially for deep-rooted plants, which should be taken into account when managing water resources and ecosystem rehabilitation in degraded regions.
在具有厚的包气带和深根植物的地区，确定影响土壤水 (SW) 的可变性和主要因素至关重要。这些信息对于澄清水供应和植物水分需求之间的平衡是必要的。我们在中国黄土高原的不同气候（干旱、半干旱和亚湿润）、土壤质地和植物类型（浅根或深根）的 128 个 7-25 米深土壤剖面中收集了 9263 个土壤样本。使用多模型推理方法和逐步回归分析确定了影响 SW 水平和垂直变化的主要因素。水平方向上，从西北到东南，平均含水量和储量增加，而水分亏缺减少。垂直方向上，相对稳定层的平均含水量和储量最高，其次是快速变化层和活跃层。植物年龄和土壤粘粒含量主导着水平变化的 SW，而植物年龄和归一化差异植被指数 (NDVI) 主导着 SW 的垂直变化。然而，主导因素似乎因气候和植物类型而异。结果表明，对于气候，干旱地区的土壤粘粒含量和植物年龄，半干旱地区的降水和植物年龄，亚湿润地区的 NDVI 和植物年龄是重要因素。对于植物来说，浅根植物的主导因素是 NDVI 和降水，而深根植物的主导因素是 NDVI 和植物年龄。植物年龄的主导地位突显了植被模式对 SW 的影响，特别是对于深根植物，在管理退化地区的水资源和生态系统恢复时应考虑到这一点。
