State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, Shaanxi 710061, China; CAS Center for Excellence in Quaternary Science and Global Change, Xi'an, Shaanxi 710061, China.
State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, Shaanxi 710061, China; CAS Center for Excellence in Quaternary Science and Global Change, Xi'an, Shaanxi 710061, China; Interdisciplinary Research Center of Earth Science Frontier, Beijing Normal University, Beijing 100875, China; Department of Earth and Environmental Sciences, Xi'an Jiaotong University, Xi'an 710049, China.
Sci Total Environ. 2021 Feb 10;755(Pt 2):142444. doi: 10.1016/j.scitotenv.2020.142444. Epub 2020 Sep 24.
The introduction of exotic plants and improper management strategies with regard to plant species can change the soil-water balance of deep soils, which in turn results in the formation of a dried soil layer (DSL) within the soil profile. The Loess Plateau (LP) of China has a complex terrain; however, only a few studies have evaluated the effects of the gully-induced DSL patterns, especially in hilly and gully regions of the northern LP. In this study, we collected soil-water content data to a depth of 5 m at 40 sampling sites in a slope-gully system to investigate and characterize DSLs and their spatial patterns. Results show that the DSL indices vary greatly in different slope positions. The thickness of DSLs (DSLT) and quantitative index (QI) in the gully were significantly (p < 0.05) higher than those in the non-gully areas. The relative contribution of soil properties was higher than those of terrain factors in the gully, whereas the contribution of terrain factors was higher than those of soil properties under shrubland. Gullies contributed to the complex spatial DSL patterns in the slope-gully system. Partial least squares regression (PLSR) was used to detect the relative significance of 10 selected environmental factors that affect spatial DSL patterns. Variable importance in projection (VIP) demonstrated that soil properties, especially Clay and Silt content, significantly influenced the DSL formation depth (DSLFD), DSLT, and QI. Land-use and slope position were the most important factors that influenced the mean soil-water content (SWC) within DSLs (DSL-SWC), which exhibited the highest VIP values. PLSR models simulated DSL indices accurately in DSL-SWC; the values for variation in response (R) and goodness of prediction (Q) were 0.94 and 0.92, respectively. Therefore, our findings provide a helpful base reference for DSL management and reclamation of hill and gully regions of the LP.
外来植物的引入和物种管理策略的不当会改变深层土壤的水土平衡，从而导致土壤剖面中形成干涸土壤层（DSL）。中国黄土高原（LP）地形复杂，但仅有少数研究评估了沟壑诱发的 DSL 模式的影响，特别是在 LP 北部的丘陵和沟壑地区。本研究在一个坡沟系统中 40 个采样点采集了至 5 m 深处的土壤水分含量数据，以调查和描述 DSL 及其空间格局。结果表明，不同坡位的 DSL 指数差异很大。沟内 DSL 厚度（DSLT）和定量指数（QI）明显（p < 0.05）高于非沟区。在沟内，土壤性质的相对贡献高于地形因素，而在灌丛下，地形因素的贡献高于土壤性质。沟谷促进了坡沟系统中复杂的空间 DSL 格局。偏最小二乘回归（PLSR）用于检测 10 个选定环境因子对空间 DSL 格局的相对重要性。变量重要性投影（VIP）表明，土壤性质，特别是粘土和粉土含量，对 DSL 形成深度（DSLFD）、DSLT 和 QI 有显著影响。土地利用和坡位是影响 DSL 内平均土壤水分含量（DSL-SWC）的最重要因素，其 VIP 值最高。PLSR 模型准确模拟了 DSL 指数在 DSL-SWC 中的变化，响应变异（R）和预测精度（Q）的值分别为 0.94 和 0.92。因此，本研究结果为 LP 丘陵沟壑区 DSL 管理和复垦提供了有益的参考。
