积雪增加对青藏高原高寒草甸土壤磷有效性的影响

Effects of snow addition on soil phosphorus availability in an alpine meadow of the Tibetan Plateau

积雪增加引起土壤水热变化,进而可能改变草地生态系统土壤磷循环过程。本研究以青藏高原多年冻土区高寒草甸为研究对象,采用积雪栅栏诱导方式模拟积雪增加,分析测试了对照和积雪增加处理下土壤表层的水热特征、土壤理化性质和磷酸酶活性、土壤磷的有效性和组分特征。结果表明:1)积雪增加提高了生长季(5-9月)浅层(0~10 cm)土壤温度和湿度;2)积雪增加在0~10 cm、10~20 cm土层显著增加了土壤中全磷、有效磷、Al-P含量,降低了有机磷和Ca_(2)-P含量,Ca_(8)-P含量在0~10 cm土层降低,在10~20 cm土层增加;3)冗余分析表明,影响土壤磷形态的关键因子为土壤全氮、有机质和土壤水热状态。积雪增加通过改变土壤全氮含量、有机质含量和水热状态等土壤理化性质和土壤磷酸酶活性,提高土壤有机磷矿化速率,促进Ca_(8)-P和Al-P等缓效磷源释放更多的磷,提高土壤磷有效性。

Deeper snow cover in winter may change soil phosphorus cycling in alpine meadow grassland ecosystems through effects on soil temperature and moisture.A field experiment involving snow addition was conducted at an alpine meadow in the permafrost region of the Tibetan Plateau.Snow fences were used to contain snow to simulate increased depth of snow cover.The results showed:1)Snow addition significantly increased temperature and moisture in the top 0-10 cm soil horizon in the growing season(from May to September).2)Snow addition significantly increased soil total phosphorus,available phosphorus and Al-P in the 0-10 cm and 10-20 cm soil horizons,but decreased soil organic phosphorus and Ca_(2)-P contents.The Ca_(8)-P content decreased in the 0-10 cm soil depth and increased in the 10-20 cm soil depth.3)Redundancy analysis showed that the key factors affecting soil phosphorus forms were soil total nitrogen,organic matter and soil hydrothermal state.Therefore,it was confirmed that snow addition improved soil organic phosphate mineralization rate by changing soil physical and chemical properties,including total nitrogen content,organic matter content,hydrothermal state and soil phosphatase activity.Snow addition also promoted phosphorus release from slow-acting phosphorus sources such as Ca_(8)-P and Al-P,and improved soil phosphorus availability.