| Abstrakt: |
Background and objective Withdrawing crop production to restore ecological functions of the loess plateau in northwestern China has greatly increased vegetation coverage since 1999, but there is a lack of understanding of how subsoil water content responded to such land use changes. The purpose of this paper is to fill this knowledge gap. Method Soil water content in the depths from the soil surface to 1000 cm was measured from slopped farmland, grassland and jujube orchard at a small watershed in the Yuanzegou waterhead in a loess hilly region. Result The average moisture content in the 0-1 000 cm soil in different ecosystems was ranked in the order of jujube orchard < grassland < sloping farmland. In the 0-200 cm soil, soil water content in the farmland, grassland and jujube orchard increased with depth first followed by a decline, with their average water content across the soil profile being 11.91%, 11.23% and 9.99%, respectively. In the depth from 200 to 1000 cm, soil water content decreased asymptotically with depth, with the average soil water content over the profile being 11.77%, 11.62% and 9.96% for the farmland, grassland and jujube orchard, respectively. Water stored in the 200-1 000 cm soils was ranked in the order of farmland > grassland >jujube orchard, with their associated average value being 148.78 mm, 145.28 mm and 121.11 mm, respectively. Waters stored in the farmland and grassland were comparable, both being significantly higher than that in the jujube orchard (p<0.05). Jujube took up more water from the 200-1 000 cm soil than the grasses (p<0.05), with the water consumed by the jujube ranging from 21.67 mm to 32.97 mm compared to -4.47 mm to 10.32 mm used by the grasses. Subsoil water content was positively correlated with clay while negatively related to sand particles and organic carbon mass fraction, all at significant levels.Conclusion Withdrawing crop production significantly reduced soil water content and water storage in the subsoil, especially when returning to forests. Jujube took a significant amount of water from the subsoil, followed by the grasses. Therefore, managing vegetation coverage after sparing cropped land is critical to restoring ecological functions of the hilly loess landscape in northwestern China. [ABSTRACT FROM AUTHOR] |
