西藏安多草地退化对植物生物量和土壤养分的影响

以西藏安多县原生小嵩草(Kobresia pygmaea)草甸草原与退化小嵩草草甸草原2种类型草地为研究对象,对其草地的地上和地下生物量、土壤的有机碳、全氮、全磷、有效氮和有效磷含量进行研究,了解退化对草地植物生物量和基本养分含量的影响。结果表明,退化小嵩草草甸草原的地上、地下以及总生物量均显著下降,地上0~10、10~20cm土层生物量和总生物量分别相当于小嵩草草甸草的80.9%、22.1%,15.8%和20.0%;2种类型草地土壤的全量和有效碳氮磷含量均较低,退化对土壤全量和有效养分的影响并不一致,退化导致0~10和10~20cm土层的有机碳、全氮和全磷含量均显著升高,而导致0~10和10~20cm土层的有效氮和有效磷含量均显著降低,2种类型草地随着土层的加深,土壤有机碳、全氮、全磷、有效氮和有效磷含量没有明显差异。

Effect of grassland degradation on the plant biomass and soil nutrients in Anduo County,Tibetan

Two types grassland,Kobresia pygmaea meadow steppe and degraded Kobresia pygmaea meadow steppe were selected to study the effect of alpine meadow degradation on biomass and soil nutrients,and the a-bove ground biomass,root biomass and soil organic carbon,total N,total P,available N and available P were de-termined.The results showed that the above ground,root and total biomass all decreased significantly,and the a-bove ground biomass,0~10 cm,10~20 cm and total biomass of the degraded grassland were 80.9%,22.1%, 15.8% and 20.0% of the Kobresia pygmaea meadow steppe respectively.The total and available nutrients of the two grassland types were all at a lower level.The effects of degradation on soil total nutrients and available nutrients were not consistent.Soil organic carbon,total N and total P in 0~10 cm and 10~20 cm soil depth both increased significantly,but the available N and available P in 0~10 cm and 10~20 cm soil depth both decreased significantly after degradation.In addition to total N in the degraded grassland,there were no significant differ-ence in soil organic carbon,total N,total P,available N and available P of different soil depth both the two grass-land types.