Relationship between soil water content and soil particle size on typical slopes of the Loess Plateau during a drought year

Xiao Zhang; Wenwu Zhao; Lixin Wang; Yuanxin Liu; Yue Liu; Qiang Feng

doi:10.1016/j.scitotenv.2018.08.211

Relationship between soil water content and soil particle size on typical slopes of the Loess Plateau during a drought year

Sci Total Environ. 2019 Jan 15:648:943-954. doi: 10.1016/j.scitotenv.2018.08.211. Epub 2018 Aug 18.

Authors

Xiao Zhang¹, Wenwu Zhao², Lixin Wang³, Yuanxin Liu⁴, Yue Liu⁵, Qiang Feng⁶

Affiliations

¹ State Key Laboratory of Earth Surface Processes and Resource Ecology, Faculty of Geographical Science, Beijing Normal University, Beijing 100875, China; Institute of Land Surface System and Sustainable Development, Faculty of Geographical Science, Beijing Normal University, Beijing 100875, China; Department of Earth Sciences, Indiana University-Purdue University Indianapolis (IUPUI), Indianapolis, IN 46202, USA.
² State Key Laboratory of Earth Surface Processes and Resource Ecology, Faculty of Geographical Science, Beijing Normal University, Beijing 100875, China; Institute of Land Surface System and Sustainable Development, Faculty of Geographical Science, Beijing Normal University, Beijing 100875, China. Electronic address: zhaoww@bnu.edu.cn.
³ Department of Earth Sciences, Indiana University-Purdue University Indianapolis (IUPUI), Indianapolis, IN 46202, USA. Electronic address: lxwang@iupui.edu.
⁴ State Key Laboratory of Earth Surface Processes and Resource Ecology, Faculty of Geographical Science, Beijing Normal University, Beijing 100875, China; State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.. Electronic address: yuanxinliu@rcees.ac.cn.
⁵ State Key Laboratory of Earth Surface Processes and Resource Ecology, Faculty of Geographical Science, Beijing Normal University, Beijing 100875, China; Institute of Land Surface System and Sustainable Development, Faculty of Geographical Science, Beijing Normal University, Beijing 100875, China. Electronic address: 201531190025@mail.bnu.edu.cn.
⁶ State Key Laboratory of Earth Surface Processes and Resource Ecology, Faculty of Geographical Science, Beijing Normal University, Beijing 100875, China; College of Forestry, Shanxi Agricultural University, Taigu, Shanxi 030801, China. Electronic address: 201231190029@mail.bnu.edu.cn.

PMID: 30144762
DOI: 10.1016/j.scitotenv.2018.08.211

Abstract

In the context of global climate change as well as local climate warming and drying on the Loess Plateau of China, understanding the relationship between soil particle size and soil water distribution during years of atypical precipitation is important. In this study, fractal geometry theory is used to describe the mechanical composition and texture of soils to improve our understanding of hydropedology and ecohydrology in the critical zone on the Loess Plateau. One grassland slope and two shrubland slopes were selected in the hilly and gully region of the Loess Plateau, and soils were sampled along hillslope transects at depths of 0-500 cm. Fractal theory and redundancy analysis (RDA) were used to identify relationships between the fractal dimension of soil particle-size distributions and the corresponding van Genuchten parameters for the soil-water-characteristic curves. The oven-drying method was used to measure soil water content, and the high-speed centrifugation method was used to generate soil-water-characteristic curves. The results show that (1) the soil water that can be used by Caragana korshinskii during a drought year is distributed below 2 m from the surface, whereas the soil water that can be used by grass is below 1.2 m; (2) Caragana korshinskii promotes the conservation of fine soil particles more than does natural restored grass, and the soil particle-size distribution fractal dimension changes with depth and position; and (3) soil hydraulic properties correlate strongly with soil pedological properties such as bulk density and the soil particle-size distribution fractal dimension. These results provide a case study of the relationships among soil distributions, hydrologic and geomorphic processes for vegetation restoration in drylands with a thick vadose zone. More studies on soil property changes are needed to provide case studies and empirical support for ecological restoration in the Loess Plateau of China.

Keywords: Drought year; Fractal dimension; Loess plateau; Particle-size distribution; Soil-water characteristic curve.