Soil Physical and Chemical Properties in Water Conservation Forest in Eastern Qinghai Province

Taking sixteen forest types in the loess hilly area of eastern Qinghai Province as research objects,the main vegetation types and soil physical properties(soil bulk density and porosity)and chemical properties(organic matter,N,P,and K)are analyzed.The changes in soil water holding capacity and soil fertility are studied.Results show that mixed forest have the minimum soil bulk density and the largest soil capillary porosity,and the mixed forest soil is loosen and porous and has the higher capability of water conservation and soil conservation.The distributions of soil organic matter,N,P,and K for different vegetation types are consistent,following the order of mixed forestconiferous forestbroadleaf forestshrubbarren hills.In different forest types,soil in Larix principis-rupprechii forest has the highest N content,while P and K contents are relatively low.Soil in Populus cathayana has the highest P content,while N and K content are relatively low.Soil in Betula platyphylla Suk—Betulautilis—Sabina przewalskii—Ricea asrerata(5∶2∶2∶1)mixed forest has the highest K content,while N and P contents are relatively low.In terms of comprehensive comparison,mixed forest well promotes the increases in soil organic matter,N,P,and K contents,improves soil nutrient status,and helps to sustain soil fertility.