Influence of Vegetation Types on Soil Organic C at Yangou Catchment in the Loess Hilly-gully Region
植被类型对黄土丘陵区流域土壤有机碳氮的影响

Reforestation plays an important role in soil conservation and soil carbon sequestration.Different vegetation types were established in a catchment due to soil loss control in the hilly-gully region of the Loess Plateau.Natural vegetation and replanted vegetation were selected based on typical sites of the Yangou catchment in the region.The community of vegetations selected at the site was identified.Soil organic carbon(SOC)and total soil N(TSN)under different vegetations are compared.For natural vegetations,SOC content under Liaodong oak tree(Q.liaotungensis Koidz.)was 29.5g/kg,Huangcimei(R.xanthina Lindl.)and Potentilla cryptottaeniae thorn(Sophora Davidii)varied from 11.6 to 21.3g/kg,and Iron rod wormwood(A.gmelinii Web.Ex Stechm.)( S.bungeana Trin)varied from 8.4 to 10.6g/kg.For replanted vegetations,SOC content under pure Robinia crop(Robinia pesudoacacia.L)varied from 5.53 to 11.9g/kg and small-leaf poplar(Populus simonii)from 12.8 to 18.4g/kg.SOC content under Hippophae rhamnoides L.subsp and wood of apricot for kernel were 8.7g/kg and 4.7g/kg,respectively.SOC in orchard(Malus pumila)varied from 3.4 to 3.9g/kg.When farmland converted to alfalfa(M.sativa L.),SOC content increased from3.4 to 4.2g/kg.For cropland,SOC varied from 3.3 to 4.8g/kg.Compared to arable soil,natural vegetation significantly influences surface SOC in the soil profiles,however,SOC in C horizon under natural vegetation was higher than that in arable soil.SOC distribution in arable slope land is significantly different from that under natural recovery of grasses,shrubs,woods and man-built vegetation.Soil C/N ratio increases in the order:orchard,arable land,grassland and woodland.In addition,there was a significant correlation between TSN and SOC at the catchment.