植被类型对黄土丘陵区流域土壤有机碳氮的影响

恢复植被是遏止水土流失和提高土壤有机碳氮(SOC,TSN)积累的重要措施。以黄土丘陵沟壑区燕沟流域为基础,分析了主要植被类型的SOC,TSN变化及其分布特征。结果表明,自然恢复的辽东栎群落SOC含量为29.5g/kg,其次为黄刺玫,狼牙刺群落11.6～21.3g/kg,铁杆蒿(+长芒草)群落为8.4～10.6g/kg。人工建造的刺槐林5.53～11.9g/kg,小叶杨12.8～18.4g/kg,沙棘群落为8.7g/kg,仁用杏为4.7g/kg,苹果园SOC含量3.4～3.9g/kg,退耕苜蓿为4.2g/kg,耕地3.3～4.8g/kg。自然恢复的灌丛群落和人工乔木群落可有效地改变坡面SOC含量与分布。土壤有机碳氮具有显著线性关系,而C/N比例和作用区间随着农田到林地的演变而变大。

Influence of Vegetation Types on Soil Organic C at Yangou Catchment in the Loess Hilly-gully Region

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.