陇中地区温性草原土壤化学计量特征对气候因子的响应

Response of soil stoichiometric characteristics to climatic factors in temperate steppe of Longzhong region,China

以陇中地区温性草原为对象,研究气候因子(年降水量和年均温)与不同深度(0~5、5~10、10~20、20~30、30~50、50~70和70~100 cm)土壤有机碳(C)、氮(N)、磷(P)含量及其化学计量特征的关系。结果表明:随土壤深度的增加,陇中温性草原土壤C、N含量及C∶P、N∶P逐渐降低,分别从21.88 g·kg^(-1)、1.84 g·kg^(-1)、33.6和3.1下降至7.67 g·kg^(-1)、0.59 g·kg^(-1)、12.5和1.0,而土壤C∶N呈增加趋势,从12.2增加到13.9,土壤P含量保持稳定,平均为0.61 g·kg^(-1)。土壤C、N含量及C∶P、N∶P与年降水量呈显著正相关,与年均温呈显著负相关;土壤P含量及C∶N与年降水量和年均温的相关性不显著。随土壤深度的增加,年降水量和年均温对土壤C、N、P含量变化的总解释度先下降后升高,对土壤C∶P、N∶P、C∶N变化的总解释度无显著变化。陇中温性草原土壤碳氮磷含量的变化主要受年降水量的影响,年降水量和年均温对不同深度土壤C、N、P含量及C∶N、C∶P、N∶P变化的影响和相对贡献存在差异。

We explored the relationship between climate factors(mean annual precipitation and mean annual temperature)and the contents and stoichiometry of soil carbon(C),nitrogen(N),and phosphorus(P)at different soil depths(0-5,5-10,10-20,20-30,30-50,50-70,and 70-100 cm)temperate steppe of Longzhong.The results showed with the increases of soil depth,soil C,N contents,C:P,and N:P gradually decreased from 21.88 g·kg~(-1),1.84 g·kg~(-1),33.6 and 3.1 to 7.67 g·kg~(-1),0.59 g·kg~(-1),12.5 and 1.0,respectively.Soil C:N showed an increasing trend from 12.2 to 13.9,while soil P content remained stable with an average of 0.61 g·kg~(-1).Soil C,N,C:P,and N:P were significantly positively correlated with mean annual precipitation and negatively correlated with mean annual temperature.Soil P content and C:N were not correlated with mean annual precipita-tion and mean annual temperature.With the increases of soil depth,the total explanatory power of the changes in soil C,N and P contents by mean annual precipitation and mean annual temperature decreased and then increased,and that in soil C:P,N:P and C:N did not change significantly.The changes of soil C,N and P contents on the temperature steppe were mainly influenced by mean annual precipitation.The effects and relative contributions of mean annual precipitation and mean annual temperature on the variations of soil nutrient contents and stoichiometry of C,N and P differed at different soil depths.