高寒草甸不同植被类型土壤全氮含量变化动态分析

The dynamics of soil total nitrogen content of different vegetation types on alpine Kobersia meadow

采用凯氏定氮法对高寒草甸不同植被类型土壤全氮进行季节动态测定分析,结果表明：在整个生长季中020cm层土壤全氮质量分数的顺序为：藏嵩草沼泽化草甸（Kobresia-swamp meadow）〉金露梅灌丛草甸（Dasiphoru fruticosa shrubs）〉人工燕麦草地（Avena sativa artificial grassland）〉矮嵩草草甸（Kobresia humilis meadow）〉矮嵩草退化草地（Kobresia humilis-degraded grassland）。原生植被草甸类型下单位面积土壤全氮含量远高于退化草地。藏嵩草沼泽化草甸土壤每平方米的全氮含量最高,达到0.712kg,金露梅草甸次之,两者之间差异性不显著（p〉0.05）;其他三种草地类型单位面积土壤全氮含量差异性显著（p〈0.05）;原生草甸矮嵩草草甸每平方米全氮平均含量为0.406kg,而退化的矮嵩草草地每平方米全氮平均含量为0.301kg,可以推算,土地退化导致土壤全氮流失的量为0.105kg,即高寒草地退化导致25.86%氮流失。随着季节的变化,土壤全氮质量分数随生长季均有所增加,最高值都出现在8月份,但各月份之间土壤全氮质量分数变化差异性不显著（p〉0.05）。原生植被0-10cm层土壤全氮含量高于10-20cm层,人工草地与退化草地差异性不显著。

we study the seasonal dynamics of soil total nitrogen content on the different vegetation types of alpine meadow through Kjeltec auto sampler system. The results showed： the soil total nitrogen concentration in 0～20 cm depths in whole growing season was： Kobresia-swamp meadow〉 Dasiphoru fruticosa shrubs 〉 Avena sativa l artificial grassland 〉 Kobresia humilis 〉 Kobresia humilis-deraded grassland. Soil total nitrogen content per unit area is much higher in the native vegetation type than in degraded vegetation types. The soil total nitrogen content of Kobresia-swamp meadow is the highest, and its value reached 0.712 kg.m～2. There is no significant difference for soil total N content between Kobresia-swamp meadow and Dasiphoru fruticosa shrubs. The soil total nitrogen content per unit area of Kobresia humilis meadow and Kobresia humilis-deraded grassland is 0.406 kg and 0.301 kg respectively. Compared with them, we can find alpine grassland degradation leading to loss of 25.86% soil nitrogen. With the seasonal changes, soil total nitrogen was increasingly, the highest values appear in the August, but there was no significant difference between adjacent month of soil total nitrogen change （p〉0.05）. In addition, soil total nitrogen content in native meadow was significantly higher in 0～10 cm depths than in 10～20 cm depths, there is no significant difference between 0～10cm depths and 10～20cm depths in artificial meadow and degradation meadow of soil total nitrogen content.