川西北高寒草甸生长季土壤氮素动态

研究了川西北高寒草甸生长季土壤氮素变化特征,结果表明:研究区0～40 cm土层在整个生长期内,有机质含量均高于60 g.kg-1,全氮含量高于2.83 g.kg-1,养分含量丰富.浅丘山地草甸土壤氮素随季节变化呈现增加的趋势,植被覆盖变化(浅丘山地灌丛)或退化程度增加(丘前阶地草甸)使得土壤氮素随季节呈现出先减少后缓慢增加的变化,但影响主要表现在0～30 cm土层中,并且越往表层,差异越大.川西北高寒草甸土壤C/N值偏小(<25),利于氮的矿化养分释放.由于研究样地中灌丛的出现,虽然没有引起明显的"沃岛"现象,但加大土壤养分空间异质性的趋势.

Dynamics of Soil Nitrogen Element of Alpine Meadow in Northwestern Sichuan during Growth Season

Seasonal dynamics of soil nitrogen element of the alpine meadow in the northweatern Sichuan Province were studied.Samples were taken from three neighboring typical alpine regions,shrubland meadow,upland meadow and terrace meadow in May,July and September.Soil organic matter,total nitrogen and available nitrogen were analyzed.The results showed that in 0~40 cm depth soil of three sites,organic matter content was higher than 60 g·kg-1,total nitrogen content was higher than 2.83 g·kg-1 in the whole growth period.The shrubs and the grazing made the nitrogen content change in different seasons,the effect mainly concentrated in the 0~30 cm depth of the soil,and the closer to the surface,the greater the difference.C/N ratio of alpine meadow soils was a little small(<25),which was good for the liberation of nitrogen mineralization.Because of research plots’ shrub,there was no obvious fertile island phenomenon,but the trend of nutrient spatial heterogeneity did increase.