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Soil water content (SWC) is a critical variable in studies of hydrological processes and the soil–plant–atmosphere continuum, especially in arid and semi-arid regions such as the Loess Plateau. Knowledge of the effects of vegetation types on soil water dynamics would aid in understanding the mechanisms responsible for water shortages and addressing the problem of poor long-term vegetation recovery. To evaluate the response of soil water storage (SWS) to different land use types during long-term natural vegetation succession, we examined soil moisture under different land use types (grassland, shrubland and forestland) at different times (2005 and 2014) in the Ziwuling forest region, located in the central part of the Loess Plateau, China. Our results showed that vegetation type had a significant effect on SWS in the 0–500 cm soil layer. The SWS in grassland and shrubland was significantly higher in August 2014 than in August 2005, but the pattern was reversed for forestland. In the same year, the SWS was highest in grassland, intermediate in shrubland, and lowest in forestland. SWS and SWC showed a highly significant and positive relationship in the 0–60 cm soil layers ( P < 0.01), and both soil bulk density (BD) and soil total nitrogen (TN) showed a significant relationship with SWS. In addition, the SWC and soil total porosity (TP) showed a significant positive relationship in the 0–20 cm soil layer ( P < 0.05). These results are expected to provide insights into land water management and inform efforts to estimate the productivity and sustainability of semiarid ecosystems. [ABSTRACT FROM AUTHOR]

Secondary succession can recover the properties of degraded soil. The moisture stored in different soil layers is recognized as an important driver of the productivity and sustainability of semi-arid terrestrial ecosystems, and land-use change has a significant effect on the global carbon (C) cycle through changing soil C accumulation rates. To evaluate the response of soil water storage (SWS) and soil organic carbon storage (SOCS) to long-term natural vegetation succession (∼150 a) and the coupling interaction between them, we examined the soil moisture and soil organic carbon content in the land for different restoration ages in the Ziwuling Forest region located in the central part of the Loess Plateau, China. Our results showed that the SWS decreased and the SOCS increased with long-term natural vegetation restoration. The SOCS decreased along with the increase in the soil depth, and it was highest in the topsoil (0–20 cm). In addition, the soil depth at which the SWS intensely varied and at which the SOCS tended to be stable moved downward and upward, respectively, with the vegetation succession. Furthermore, the correlation between SWS and SOCS was significant (P < 0.05) in the long-term restoration and gradually weakened with the increase in the soil depth and the vegetation restoration stages. Clay, silt, sand, total porosity (TP), inactive porosity (IP), aeration porosity (AP) and capillary porosity (CP) were important factors that influenced the coupling interaction of SWS and SOCS at the grass restoration stages (<50 a), and BD influenced this interaction in the shrub and early forest restoration stages (<130 a). The effect of soil physical factors on the interaction of SWS and SOCS gradually weakened during the vegetation restoration succession. These results are expected to help improve the understanding of the response of deep soil water and soil organic carbon to long-term natural vegetation restoration and to provide insights into the coupling interaction between soil water and soil organic carbon influenced by vegetation. [ABSTRACT FROM AUTHOR]

Soil water is a key terrestrial water resource, particularly in arid and semi-arid regions of the world such as the Loess Plateau of China. Information on the dynamics of soil moisture following vegetation restoration is essential for managing water resources and can be helpful for adjusting relevant government policies. To evaluate the response of soil water storage (SWS) to long-term natural vegetation succession (~ 160 a), we examined the soil moisture for different restoration ages in the Ziwuling forest region, which is located in the central part of the Loess Plateau. Our results showed that the SWS decreased with long-term natural vegetation restoration. The bulk density (BD), soil water content (SWC), and clay and silt content presented similar trends to those of the SWS throughout the entire vegetation succession. The SWS was significantly and positively correlated with the SWC and aeration porosity ( P < 0.05). The SWC was lower in the upper soils (0–50 cm) than in the deeper soils (> 50 cm) at every restoration stage, as was the SWS; however, the SWS in the 200–300 cm soil layer was the highest (164.61–212.80 mm) compared to other layers in all restoration stages. These results are expected to help improve the understanding of the response of deep soil water to long-term natural vegetation restoration and to provide insights into the dynamics of deep soil water influenced by vegetation. [ABSTRACT FROM AUTHOR]

Secondary vegetation succession on abandoned cropland significantly influences soil C-pool dynamics in arid and semi-arid region. Much work on soil C-pool dynamics has been focused on soil organic carbon (SOC), whereas considerably less attention has been given on soil inorganic carbon (SIC). Moreover, the relationship between SOC and SIC during natural succession is unclear. The objective of this research was to investigate SOC and SIC storage dynamics in natural restored grassland following cropland abandonment. We measured SOC and SIC content in paired grassland and cropland sites in the Gaoqiao watershed on the Loess Plateau, China. The grassland sites were established on cropland abandoned for 5, 13, 24, and 32 years. Top soil OC was significantly higher after 10-year restoration, especially in the 0–5 cm soil depths; deeper soil OC was lower in younger grasslands (< 20 yr), and significantly higher in older grasslands (> 20 yr). SIC was significantly higher after abandonment, but varied largely among successional grasslands. SOC storage (SOCs) decreased in the younger grassland (5 yr), and SOCs (0–100 cm) was significantly higher after 10-year restoration. SIC storage (SICs) increased after abandonment in the 0–100 cm soil depth, but showed various magnitudes among restored grasslands. SIC storage (SICs) originally contained most part of STC storage (STCs), and grass restoration after cropland abandonment led to higher SOCs/STCs ratio and lower SICs/STCs ratio. Our results indicate that grass restoration enhanced the accumulation of SOC and SIC storages, but with inverse proportional contributions to STC storage. We suggest that SIC should be as much focused as SOC during grass restoration in the arid Loess Plateau. [ABSTRACT FROM AUTHOR]