Changes in Soil Organic Carbon after Bamboo Afforestation in Cropland

This paper deals with the changing regularity of soil organic carbon(SOC) after afforestation in cropland,which showed:(1) in three years after afforestation,the contents of SOC were decreased in different soil profiles and the top soil profile(0～30 cm) was decreased more than that of the others;Three years later,due to the intensive management,the contents of SOC were increased quickly and up to nine years,the contents of SOC being larger than those of cropland;but twelve years later,the contents of SOC were decreased again because of the less intensive management.(2) The density of SOC showed almost the same tendency as the content of SOC;In three years,the density of SOC were decreased,later,the density of SOC was increased and in nine years,the density of SOC became larger than that of cropland;after nine yeas,the density of SOC were decreased again,but still more than those of cropland;(3) Three years after afforestation,the storage of SOC was decreased by 22%.After three years,the storage of SOC was increased gradually and in nine years,the storage of SOC became larger than that of cropland;In 12 years old stand,the storage of SOC was decreased,but larger than that of cropland.The content,density and storage of SOC all showed the tendency of decline,rising gradually,excessing and then decreasing.