Variation in soil infiltration properties under different land use/cover in the black soil region of Northeast China

Soil infiltration properties(SIPs)of infiltration rate and saturated hydraulic conductivity significantly affect hydrological and erosion processes,thus,knowledge of SIPs under different land use/cover are vital for land use management to control soil erosion for realizing the sustainable development of the small agricultural watershed.Nevertheless,few studies have been carried out to investigate the differences in SIPs and their dominant influencing factors between different land use/cover in the black soil region of Northeast China.Therefore,eight typical land use/cover were selected to clarify the variations in SIPs between different land use/cover and further identify their dominant influencing factors.SIPs of initial infiltration rate(IIR),steady infiltration rate(SIR),and saturated hydraulic conductivity(Ks)were determined under eight typical land use/cover(forestland,shrub land,grassland,longitudinal shelterbelt,transverse shelterbelt,agricultural road,and cropland of Zea mays L.and Glycine max(Linn.)Merr)using a tension disc infiltrometer with three pressure heads of−3,−1.5,and 0 cm.The results of one-way ANOVA analysis showed that SIPs varied greatly between different land use/cover.Shelterbelt plant with Populus L.had the maximum IIR,SIR,and Ks,and then followed by shrub land,agricultural road,cropland,grassland,and forestland.Spearman correlation analysis indicated that SIPs were significantly correlated with soil and vegetation properties.Redundancy analysis revealed that differences in SIPs between different land use/cover were dominantly attributed to the differences in soil texture,field capacity,and plant root mass density,which explained 79.36%of the total variation in SIPs.Among these dominant influencing factors,the results of structural equation model indicated that the indirect effects of plant root and soil texture played the most important role in variations of SIPs via affecting soil texture and pore characteristics.These results have significant implications for the precise prediction of watershed hydrological and erosion processes,also provide a scientific basis for guiding the distribution pattern of land use in the cultivated watershed.

Land surface roughness impacted by typical vegetation restoration projects on aeolian sandy lands in the Yarlung Zangbo River valley,southern Tibetan plateau

Aeolian sandy lands are widespread and desertification is recognized as one of the main environmental issues in the Yarlung Zangbo River valley,southern Tibetan plateau.The surface microtopographic var-iations induced by the near soil surface characteristics of plant communities are important compositions of land surface roughness,which likely influence wind erosion.This study was conducted to quantify the effects of typical vegetation restoration on land surface roughness on the aeolian sandy lands,and to identify the main influencing factors of land surface roughness in the Yarlung Zangbo River valley.Two bare sandy lands(as controls)and eight vegetated sandy lands with different restoration communities and ages were selected,and land surface roughness(LSR),as represented by surface microtopographic variations in this study,was measured by photogrammetric surveys.The results showed that LSR significantly increased by 7.9-16.8 times after vegetation restoration on the aeolian sandy lands,and varied among different restoration communities and ages.The mostly restored communities of Sophora moorcroftiana and Populus L.had greater LSR as compared to Artemisia wellbyi and Hedysarum scoparium.With succession from 6 to over 30 years,LSR gradually increased in the Sophora moorcroftiana restored sandy lands,but decreased in the Populus L restored sandy lands.The variations of LSR were mainly attributed to the differences in near soil surface characteristics of vegetation(plant stem diameter and coverage,and plant residue density)and biological soil crusts(coverage and thickness).Mixed plantation of Populus L and Sophora moorcroftiana was considered as the best restoration communities because of their effectiveness in increasing land surface roughness on the aeolian sandy lands in the Yarlung Zangbo River valley.The results would facilitate the understanding of the benefits of vegetation restoration in controlling wind erosion on the aeolian sandy lands.