土壤颗粒组分中氮含量及其与海拔和植被的关系

Nitrogen Content in Soil Particulate Fraction and Its Relationship to the Elevation and the Vegetation

研究祁连山北坡土壤颗粒组分中氮含量及其与海拔和植被的关系。结果表明：土壤颗粒组分比例、土壤颗粒氮比例、土壤颗粒氮含量和土壤颗粒组分氮含量都随海拔升高而差异不显著;就土壤颗粒组分比例而言,0～15cm土层在阳坡3800m处、阴坡3000、3200和3500m处较高,15～35cm土层在阴坡3200和3500m、半阴坡2800m处较高（p〈0.05）;就土壤颗粒氮比例而言,0～15cm土层在阴坡3000和3200m、阳坡3300和3800m处最高,15～35cm土层在阴坡3000m和阳坡3300m处最高;就土壤颗粒氮含量而言,0～15cm土层在阴坡3600m处最低,阳坡3800m和半阴坡2800m处较高,15～35cm土层在阴坡3400m、阳坡3300m处较高;就土壤颗粒组分氮含量而言,0～15cm土层在阴坡3400m、阳坡3300和3800m处较高,15～35cm土层在阴坡3400m、阳坡3300m处较高（p〈0.05）;植被对土壤颗粒组分比例、土壤颗粒氮比例、土壤颗粒组分氮含量和土壤颗粒氮含量的影响显著;就土壤颗粒组分比例而言,0～15cm土层在森林和灌丛草甸中较高,高寒草甸中较低,森林与灌丛草甸及干草原与荒漠草原中差异不显著,15～35cm土层在森林、灌丛草甸和干草原中较高,高寒草甸中最低,森林、灌丛草甸与干草原中差异不显著;就土壤颗粒氮比例而言,0～15cm土层在森林和高寒草甸中较高,灌丛草甸、荒漠草原与干草原中差异也不显著,15～35cm土层在森林和高寒草甸中较高,荒漠草原和干草原中最低;就土壤颗粒组分氮含量而言,各土层均在灌丛草甸中较高,干草原和荒漠草原中较低;就土壤颗粒氮含量而言,各土层均在森林和灌丛草甸中最高,干草原和荒漠草原中最低,森林、高寒草甸与灌丛草甸中差异不显著;土壤颗粒组分比例、土壤颗粒组分氮含量、土壤颗粒氮比例和土壤颗粒氮含量随土壤全氮含量增加而增加（p〈0.02）,土壤颗粒氮含量随颗粒组分氮含量极显著增加（p〈0.001）,土壤颗粒氮比例随土壤颗粒氮含量增加显著增加（p〈0.05）;祁连山北坡土壤中非保护性氮含量总体上随海拔升高而增加,森林和高寒草甸土壤中非保护性氮比例最高。

Nitrogen content of soil particulate fractions and its relationship to the vegetation and the elevation in Qilian Mountains were investigated. The results showed that the ratio of soil particulate fractions, soil particulate organic matter-nitrogen （PON） ratio, nitrogen content of soil particulate fractions, soil PON content did not significantly change with the altitude. The ratio of soil particulate fraction in 0 - 15 cm soil depth at 3 000 m,3 200 m and 3 500 m of shady slope, or 3 800 m of sunny slope, or that in 15 - 35 cm soil depth at 3 200 m, 3 500 m of shady slope, or 2 800 m of semi-shady slope was the highest among the all elevations slope aspects and soil depths. PON ratio in 0 - 15 cm soil depth at 3 000 m and 3 200 m of shady slope, or 3 300 m and 3 800 m of sunny slope, or that in 15 - 35 cm soil depth at 3 300 m of sunny slope, or 3 000 m of shady slope was also the highest. The nitrogen content of PON in 0 - 15 cm at 3 600 m of shady slope was the lowest, while the nitrogen content of PON in 0 - 15 cm at 3 800 m of sunny slope, or 2 800 m of half shady slope, or that in 15 - 35 cm at 3 400 m of shady slope, or 3 300 m of sunny slope was the highest. The nitrogen content of soil particulate fraction in 0 - 15 cm soil depth at 3 400 m of shady slope, or 3 300 m and 3 800 m of sunny slope,or that in 15 - 35 cm under 3 400 m of shady slope and 3 300 m of sunny slope was the highest. There were also significant effects of vegetation on the ratio of soil particulate fraction, the ratio of soil PON, soil PON and nitrogen content of soil particulate fraction. The ratio of soil particulate fraction in 0 - 15 cm soil depth forest or in shrub meadows was the highest, and the difference for this ratio between in forest and shrub meadows or between in desert steppe and arid steppe were not significant, and that in 15 - 35 cm soil depth in forest, shrub meadows or arid steppe was the highest. While there were no significant difference for the ratio of soil particulate fraction among in forest, shrub meadows and steppe. The ratio of PON in different soil depth in forest and alpine meadows were the highest, and there were no significant difference for the ratio among under shrub meadows, steppe and arid steppe in 0 - 15 cm soil depth, and the ratio in steppe or arid steppe in 15 - 35 cm soil depth were the lowest （p 〈 0.05）. The nitrogen content of soil particulate fraction in different soil depth in shrub meadows was the highest, and that in desert steppe or arid steppe was the lowest. The nitrogen content of soil PON in different soil depth under forest or shrub meadows was the highest, while that in desert steppe or arid steppe was the lowest, and there were no significant difference for the nitrogen content among forest, alpine meadows and shrub meadows. The ratio of soil particulate fraction, nitrogen content of soil particulate fraction, soil PON content and soil PON ratio all increased with increasing total soil nitrogen content （p 〈 0.02）, and soil PON content increased with increasing nitrogen content of soil particulate fraction （p 〈 0.001）, and ratio of soil PON increased with increasing soil PON content （p 〈 0.05）. The results showed that the soil unprotected soil nitrogen content increased with increasing elevation, generally, and unprotected soil nitrogen ratio in forest and meadows was the highest among the all different types of vegetations.