Abstract
Abstract. A good understanding of the interrelations between land cover alteration and changes in hydrologic conditions (e.g., soil moisture) as well as soil physicochemical properties (e.g., fine soil particles and nutrients) is crucial for maintaining the fragile hydrologic and environmental conditions of semiarid land, such as the Horqin Sandy Land in China, but is lacking in existing literature. The objectives of this study were to examine: (1) spatio-temporal variations of soil moisture and physicochemical properties in semiarid land; and (2) how those variations are influenced by land cover alteration. Using the data collected in a 9.71 km2 well-instrumented area of the Horqin Sandy Land, this study examined by visual examination and statistical analyses the spatio-temporal variations of soil moisture and physicochemical properties. The results indicated that for the study area, the soil moisture and physicochemical properties were dependent on local topography, soil texture, vegetation density, and human activity. Long-term reclamation for agriculture was found to reduce soil moisture by over 23 % and significantly (p-value < 0.05) lower the contents of soil organic matter, fine soil particles, and nutrients.
Highlights
Semiarid land, where precipitation is less than potential evapotranspiration (PET), such as the Horqin Sandy Land located between the Inner Mongolian Plateau and the Northeast China Plain (Fig. 1), usually has fragile hydrologic conditions that are very sensitive to land cover alteration from human activities
The annual average soil moisture at a location within the study area was dependent on the local topography as well as soil texture (Fig. 2), which is consistent with Zuo et al (2008)
Maintaining the fragile hydrologic conditions of semiarid land such as the Horqin Sandy Land is crucial for preventing desertification and environmental degradation
Summary
Semiarid land, where precipitation is less than potential evapotranspiration (PET), such as the Horqin Sandy Land located between the Inner Mongolian Plateau and the Northeast China Plain (Fig. 1), usually has fragile hydrologic conditions that are very sensitive to land cover alteration from human activities (e.g., cultivation; Ma and Fu, 2005; Fu et al., 2006). The fragility is characterized by measurable spatial and/or temporal changes in soil hydrologic (e.g., soil moisture) and physicochemical (e.g., soil fine particles, organic matter, and nutrients) properties (Nicolson et al, 1998; Dai et al, 2004; Held et al, 2005; Fu and Ma, 2008) These changes usually result in land desertification and environmental degradation (Hennessy and Kies, 1986; Okin et al, 2001; Fu et al, 2006), which in turn is likely to reduce grassland agricultural productivity, reduce usable water resources, and intensify sandstorms in terms of both occurrence and magnitude (Kertesz and Mika, 1999; Ma and Fu, 2007; Monger, 2010). A continuous 5-yr experiment in the semiarid Loess Plateau of China (Guo et al, 2010) indicated that the soil physicochemical properties were noticeably improved after cropland was converted back to grassland
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