青藏高原种植紫穗槐对土壤养分的响应

选取在西藏拉萨地区人工种植的两龄紫穗槐为研究对象,探讨了灌丛内与灌丛外土壤各种形态氮素、全磷、有机碳的含量特征及土壤pH的差异。结果表明,1)相对于灌丛外土壤,灌丛内土壤的全氮、铵态氮、硝态氮分别平均高23.44%,13.95%和37.60%,土壤全磷平均高19.57%,土壤有机碳平均高44.21%,土壤pH值平均低1.69%。2)灌丛内与灌丛外土壤的全氮、铵态氮、硝态氮、全磷、有机碳、pH均差异显著(P<0.05)。3)垂直方向上,灌丛内和灌丛外在10~20 cm土层的全氮、铵态氮、硝态氮、全磷均为最高,有机碳和pH则随土层深度增加而递减。4)土壤各营养元素之间表现为不同程度的相关性,土壤有机碳与铵态氮呈极显著正相关关系(P<0.01),与全磷呈显著正相关关系(P<0.05);全氮与全磷呈极显著正相关关系(P<0.01);铵态氮与全磷呈极显著正相关关系(P<0.01)。

Response of Amorpha fruiticosa planting to soil nutrients in the Tibetan Plateau

The two years old Amorpha fruticosa planted in the southwest of the Tibetan Plateau, Lhasa was selected to study the various forms of nitrogen, total phosphorus, contents of organic carbon and pH changes in both IC (in the crown) and OC (out of crown). 1) Total nitrogen, ammonium and nitrate in IC were 23.44%, 13.95% and 37.6% higher respectively than those in OC. Soil total phosphorus in IC was 19.57% higher, soil organic carbon in IC was 44.21% higher and soil pH was lower by 1.69 units than the average. 2) There were significant (P<0.05) differences in the contents of soil total nitrogen, ammonium, nitrate, total phosphorus, organic carbon and soil pH between IC and OC. 3) In a vertical direction, the contents of total nitrogen, ammonium, nitrate and total phosphorus reached a maximum value at a depth of 10-20 cm in soils. The contents of organic carbon and pH reduced with increasing depth. 4) A linear relation was shown between the organic carbon and total nitrogen, ammonium nitrogen, total phosphorus in IC.