Seasonal variation of deep soil moisture under different land uses on the semi-arid Loess Plateau of China

ABSTRACTSoil moisture is a key issue for eco-hydrological research in arid and semi-arid regions, and is primarily concerned with water availability for vegetation. Shallow and deep soil moisture occurs according to the maximum infiltration depth. Soil moisture has three-dimensional characteristics: inter-layer variability, horizontal heterogeneity and temporal variability. Soil moisture is affected by various factors including terrain, soil characteristics, climate and vegetation, and the effects of these change with time (e.g., rainfall patterns) and space (e.g., soil depth). In arid and semi-arid regions, deep soil moisture is of particular importance to vegetation restoration and the evaluation of vegetation sustainability; however, accurate prediction of the spatial distribution of deep soil moisture in the Loess Plateau of China still faces numerous challenges. Therefore, future research should focus on the mechanisms, models and scale effects of soil moisture, particularly for deep soil moisture.

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Deep soil moisture limits the sustainable vegetation restoration in arid and semi-arid Loess Plateau

Geoderma ◽

10.1016/j.geoderma.2021.115122 ◽

2021 ◽

Vol 399 ◽

pp. 115122

Author(s):

Bin-Bin Li ◽

Pan-Pan Li ◽

Wan-Tao Zhang ◽

Jing-Yi Ji ◽

Guo-Bin Liu ◽

...

Keyword(s):

Soil Moisture ◽

Loess Plateau ◽

Vegetation Restoration ◽

Deep Soil ◽

Semi Arid

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Effects of topographic domain and land use on spatial variability of deep soil moisture in the semi-arid Loess Plateau of China

Hydrology Research ◽

10.2166/nh.2019.221 ◽

2019 ◽

Vol 50 (5) ◽

pp. 1281-1292 ◽

Cited By ~ 2

Author(s):

Bowei Yu ◽

Gaohuan Liu ◽

Qingsheng Liu ◽

Chong Huang ◽

He Li

Keyword(s):

Land Use ◽

Soil Moisture ◽

Spatial Variability ◽

Loess Plateau ◽

Hydrological Cycle ◽

Loess Soil ◽

Slope Aspect ◽

Deep Soil ◽

Positive Correlations ◽

Semi Arid

Abstract Deep soil moisture is fundamental to hydrological cycle and ecosystem sustainability in arid and semi-arid regions. This study examined the combined effects of topographic domain and land use on the spatial variability of deep soil moisture (0–5 m) on the semi-arid Loess Plateau of China. Our results showed that deep soil moisture was generally temporally stable due to the thick loess soil in the plateau region. The depth-averaged soil moisture was slightly lower in the gully domain compared to the hillslope domain but was dependent on the soil depths. Soil moisture variability was clearly larger in the gully domain when compared with that in the hillslope domain in the 0–5 m profile. The mean soil moisture contents in comparable soil depths were lower in forestland than in grassland (and farmland), particularly in the hillslope domain. Land uses had similar vertical distribution characteristics of deep soil moisture for each topographic domain. Soil moisture showed highly significant positive correlations with slope aspect in the hillslope domain and with profile curvature in the gully domain.

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Spatial variations of shallow and deep soil moisture in the semi-arid Loess Plateau, China

Hydrology and Earth System Sciences ◽

10.5194/hess-16-3199-2012 ◽

2012 ◽

Vol 16 (9) ◽

pp. 3199-3217 ◽

Cited By ~ 49

Author(s):

L. Yang ◽

W. Wei ◽

L. Chen ◽

F. Jia ◽

B. Mo

Keyword(s):

Soil Moisture ◽

Loess Plateau ◽

Sampling Site ◽

Spatial Variations ◽

Slope Position ◽

Slope Aspect ◽

Deep Soil ◽

Soil Layers ◽

Vegetation Growth ◽

Semi Arid

Abstract. Soil moisture in deep soil layers is an important relatively stable water resource for vegetation growth in the semi-arid Loess Plateau of China. Characterizing the spatial variations of deep soil moisture with respect to the topographic conditions has significant importance for vegetation restoration. In this study, we focused on analyzing the spatial variations and factors influencing soil moisture content (SMC) in shallow (0–2 m) and deep (2–8 m) soil layers, based on soil moisture observations in the Longtan watershed, Dingxi, Gansu province. The vegetation type of each sampling site for each comparison is same and varies by different positions, gradients, or aspects. The following discoveries were captured: (1) in comparison with shallow SMC, slope position and slope aspect may affect shallow soil moisture more than deep layers, while slope gradient affects both shallow and deep soil moisture significantly. This indicates that a great difference in deep soil hydrological processes between shallow and deep soil moisture remains that can be attributed to the introduced vegetation and topography. (2) A clear negative relationship exists between vegetation growth condition and deep soil moisture, which indicates that plants under different growing conditions may differ in consuming soil moisture, thus causing higher spatial variations in deep soil moisture. (3) The dynamic role of slope position and slope aspect on deep soil moisture has been changed due to large-scale plantation in semi-arid environment. Consequently, vegetation growth conditions and slope gradients may become the key factors dominating the spatial variations in deep soil moisture.

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Response of deep soil moisture to land use and afforestation in the semi-arid Loess Plateau, China

Journal of Hydrology ◽

10.1016/j.jhydrol.2012.09.041 ◽

2012 ◽

Vol 475 ◽

pp. 111-122 ◽

Cited By ~ 112

Author(s):

Lei Yang ◽

Wei Wei ◽

Liding Chen ◽

Baoru Mo

Keyword(s):

Land Use ◽

Soil Moisture ◽

Loess Plateau ◽

Deep Soil ◽

Semi Arid

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Variations of deep soil moisture under different vegetation types and influencing factors in a watershed of the Loess Plateau, China

Hydrology and Earth System Sciences ◽

10.5194/hess-20-3309-2016 ◽

2016 ◽

Vol 20 (8) ◽

pp. 3309-3323 ◽

Cited By ~ 35

Author(s):

Xuening Fang ◽

Wenwu Zhao ◽

Lixin Wang ◽

Qiang Feng ◽

Jingyi Ding ◽

...

Keyword(s):

Soil Moisture ◽

Influencing Factors ◽

Loess Plateau ◽

Vegetation Restoration ◽

Native Vegetation ◽

Watershed Scale ◽

Vegetation Types ◽

Deep Soil ◽

Soil Layers ◽

Management Measures

Abstract. Soil moisture in deep soil layers is a relatively stable water resource for vegetation growth in the semi-arid Loess Plateau of China. Characterizing the variations in deep soil moisture and its influencing factors at a moderate watershed scale is important to ensure the sustainability of vegetation restoration efforts. In this study, we focus on analyzing the variations and factors that influence the deep soil moisture (DSM) in 80–500 cm soil layers based on a soil moisture survey of the Ansai watershed in Yan'an in Shanxi Province. Our results can be divided into four main findings. (1) At the watershed scale, higher variations in the DSM occurred at 120–140 and 480–500 cm in the vertical direction. At the comparable depths, the variation in the DSM under native vegetation was much lower than that in human-managed vegetation and introduced vegetation. (2) The DSM in native vegetation and human-managed vegetation was significantly higher than that in introduced vegetation, and different degrees of soil desiccation occurred under all the introduced vegetation types. Caragana korshinskii and black locust caused the most serious desiccation. (3) Taking the DSM conditions of native vegetation as a reference, the DSM in this watershed could be divided into three layers: (i) a rainfall transpiration layer (80–220 cm); (ii) a transition layer (220–400 cm); and (iii) a stable layer (400–500 cm). (4) The factors influencing DSM at the watershed scale varied with vegetation types. The main local controls of the DSM variations were the soil particle composition and mean annual rainfall; human agricultural management measures can alter the soil bulk density, which contributes to higher DSM in farmland and apple orchards. The plant growth conditions, planting density, and litter water holding capacity of introduced vegetation showed significant relationships with the DSM. The results of this study are of practical significance for vegetation restoration strategies, especially for the choice of vegetation types, planting zones, and proper human management measures.

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Effects of Long-Term Vegetation Restoration on Distribution of Deep Soil Moisture in Semi-arid Northwest of China

Journal of soil science and plant nutrition ◽

10.1007/s42729-020-00280-4 ◽

2020 ◽

Vol 20 (4) ◽

pp. 2123-2132

Author(s):

Limei Wang ◽

Aisheng Ma ◽

Hong Zhang ◽

Jianguo Zhang ◽

Qiang Dong ◽

...

Keyword(s):

Soil Moisture ◽

Vegetation Restoration ◽

Deep Soil ◽

Semi Arid

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Effects of two typical revegetation methods on soil moisture in the semi-arid Loess Plateau, China

Hydrology Research ◽

10.2166/nh.2019.011 ◽

2019 ◽

Vol 50 (5) ◽

pp. 1453-1462

Author(s):

Qian Zhao ◽

Lei Yang ◽

Xin Wang ◽

Runcheng Bi ◽

Qindi Zhang

Keyword(s):

Soil Moisture ◽

Loess Plateau ◽

Temporal Variations ◽

Chinese Loess Plateau ◽

Deep Soil ◽

Chinese Loess ◽

Soil Desiccation ◽

Native Grasslands ◽

First Choice ◽

Natural Revegetation

Abstract Understanding the effects of vegetation on soil moisture is vital to the ecosystem restoration in water-restricted areas. For this study, the effects of introduced revegetation and natural revegetation on soil water (0–1.8 m) were investigated in the Chinese Loess Plateau, which was based on an in situ vegetation removal experiment and two years of soil moisture monitoring. The results indicated that under introduced revegetation, pasture grassland had lower soil moisture but higher temporal variations over the growing season. Compared with abandoned farmlands and native grasslands under natural revegetation, pasture grasslands revealed greater negative effects on deep soil moisture (1–1.8 m), which was difficult to recover following soil desiccation. In contrast, for abandoned farmlands and native grasslands, the surface soil moisture (0–0.4 m) was mainly impacted, which was easily replenished through rainfall events. These outcomes implied that natural revegetation, rather than introduced revegetation, should be the first choice in water-limited regions toward the rehabilitation of degraded ecosystems.

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