Effects of vegetation restoration type on soil carbon,nitrogen,and microbial quantity in Guandi Mountain

Taking four vegetation restoration types,including abandoned land,Hippophae rhamnoides shrub,Larix principis-rupprechtii plantation,and mixed forest(mainly consisted of L.principis-rupprechtii,Betula platyphylla,Populus davidiana),in Guandi Mountain as test objects,this paper studied the seasonal variations of soil organic carbon,total nitrogen,NO-3-N,NH+4-N,and of the quantities of soil microbes relating to nitrogen metabolism(bacteria,actinomycetes,fungi,N-fixing bacteria,nitrifiers,and denitrifiers).In the four vegetation restoration types,an obvious seasonal variation was observed in the soil inorganic N content and microbial quantity,and the soil organic carbon,total nitrogen,NO-3-N,NH+4-N,and microbial population were decreased significantly with increasing soil depth.Compared with abandoned land,the soil organic carbon,total nitrogen,NO-3-N,NH+4-N,and microbial population in H.rhamnoides shrub,L.principis-rupprechtii plantation,and mixed forest were all higher,with the highest values in mixed forest,in which,soil carbon and nitrogen,and soil microbial population increased by 0.21%-2.05% and 0.09%-19.25%,respectively,soil fungi increased up to 19.25%,and soil inorganic nitrogen increased by 0.01%-0.49%.There were significant positive linear relationships between soil organic carbon,total N,NO-3-N,and NH+4-N and soil microbial population.In sum,vegetation restoration improved soil fertility,and the effect was most significant in mixed forest.