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在祁连山东段南麓设置实验样带,研究了植被生产力、土壤有机质和全氮等在不同海拔的分布状况及其影响因素.结果表明:海拔3 200 m开始到海拔4 300 m山顶,沿海拔升高年平均气温按0.51℃.100 m-1递减率下降.海拔3 200~3 800 m间植被生产力随海拔升高而降低.土壤有机质和全氮含量沿海拔从3 200 m开始下降至3 400 m后开始急剧上升,在海拔3 600 m处最高,而后又迅速下降;土壤有机质和全氮在土壤剖面中的垂直分布趋势一致,表层土壤有机质和全氮含量高,随深度加深而降低.土壤碳氮比介于6~14之间,相对较低,利于土壤腐殖质化和有机氮矿.土壤碳氮比沿海拔的升高先增加后减小,在土壤剖面中的分布随海拔的不同而有所差异.土壤有机质含量和全氮含量和气候因子、植被类型及放牧利用有关.
The experimental transects were set up at the southern foot of the eastern section of the Qilian Mountains to study the distribution and influencing factors of vegetation productivity, soil organic matter and total nitrogen at different altitudes.The results showed that the altitude from 3 200 m to the top of 4 300 m above sea level, The annual average temperature decreased with decreasing rate of 0.51 ℃ .100 m-1. The productivity of vegetation decreased with the altitude increasing from 3 200 to 3 800 m. The content of soil organic matter and total nitrogen decreased from 3 200 m to 3 After 400 m, it began to rise sharply and reached the highest at an altitude of 3 600 m, and then dropped rapidly again. The vertical distribution of soil organic matter and total nitrogen in the soil profile was consistent, and the content of organic matter and total nitrogen in the topsoil decreased with the deepening of the depth. Soil carbon to nitrogen ratio is between 6 and 14, which is relatively low, which is conducive to humus and organic nitrogen mineralization.Carbon and nitrogen ratio increases first and then decreases along the altitude, and distribution in the soil profile varies with altitude While the differences of soil organic matter content and total nitrogen content were related with climatic factors, vegetation types and grazing use.