青海湖区紫花针茅草原封育导致的土壤养分时空变化特征

封育导致的生态系统恢复会体现在土壤恢复.以不同封育年限的青海湖区紫花针茅草原为对象,研究封育导致的土壤养分时空变化特征.结果表明:同一样地速效氮、速效磷和速效钾都表现为表层含量最高,显著高于第Ⅱ层,下面几层之间差异不显著;封育对速效养分含量影响不同,对速效钾含量影响不大,而速效磷含量大多显著提高,封育样地速效氮含量稍微高于对照样地.全量养分相比较,封育对土壤全钾和全磷含量影响不大,随土层加深全氮含量降低,封育导致土壤表层全氮含量升高(提高了19.9%).有机质含量随土层加深而降低,长期封育导致土壤有机质含量增加.相关分析表明,速效钾和全钾含量之间相关不显著,速效磷和全磷、速效氮和全氮含量都表现出显著相关,有机质和全量养分之间只有全氮表现出了显著相关.封育后土壤pH值略有升高;随着土层加深,土壤容重升高,但土壤容重变化不大.封育使草原土壤养分含量增加,但是养分的增加是一个非常缓慢的过程,对草原的保护还需继续加强.

Spatiotemporal Variation in Soil Nutrient of Stipa purpurea Steppe Fenced in the Qinghai Lake Region

Soil restoration is a major aspect of ecological restoration.The study was conducted in Stipa purpurea steppe fenced for years,to detect the spatiotemporal variation of soil nutrient after fencing.The results showed that in the same plot the contents of available N,P and K in surface layer significantly higher than those in the second layer,and there were no significant differences among the lower layers.Fencing had different effects on different available nutrients: It had little effect on available K,however,the content of available P was mostly higher than that of CK,and the content of available N was a bit higher than that of CK.Fencing had little effects on the content of total K and total P,while the content of total N decreased with soil depth,and was higher than that of CK in the surface layer after fencing(increased by 19.9%).The content of soil organic matter(SOM) decreased with soil depth,and long time fencing resulted in the elevation of SOM content.Correlation analysis showed that the contents of available K and total K had no significant correlation,the contents of available P and total P,available N and total N both showed significant correlation,and SOM only showed significant correlation with total nitrogen among total nutrients.And fencing resulted in slightly elevation of pH value;Soil bulk density increased with soil depth,but no significant difference was found between fencing and CK.Fencing resulted in elevation of soil nutrient,but it was a very slow course,so the protection for Stipa purpurea steppe should be preceded.