中蒙边境不同纬度草原土壤化学计量特征

Characteristics of stoichiometry in soil of grassland at different latitudes on China-Mongolia border

为揭示不同纬度草原土壤碳(C)、氮(N)、磷(P)元素的空间分异特征,以我国中蒙边境草原(二连浩特市、东乌旗和新巴尔虎右旗)为研究区,通过对不同土层(0~10、10~20、20~30 cm)的C、N、P元素含量及其化学计量比的空间分布特征的研究,探讨影响草原土壤化学计量空间变化的主要因子。结果表明:(1)在0~30 cm的土层范围内,3个地区草原土壤中有机碳、全氮和全磷的含量随着纬度升高逐渐增加,均表现为新巴尔虎右旗>东乌旗>二连浩特市。同一地区表层土壤的有机碳和全氮含量高于下层,而不同土层间全磷含量变异性不大。(2)同一地区不同土层之间C/N、C/P、N/P和C/N/P差异不显著(P>0.05);相同土层土壤C/N、C/P、C/N/P则表现出纬度差异性,C/N表现为东乌旗>新巴尔虎右旗>二连浩特市,C/P表现为新巴尔虎右旗>东乌旗>二连浩特市,而C/N/P表现为二连浩特市>东乌旗>新巴尔虎右旗。随着土层深度的增加,3个区域的土壤N/P呈现不同的变化趋势,其中二连浩特市土壤N/P呈先增加后降低的趋势,东乌旗地区土壤N/P则呈逐渐降低的趋势,新巴尔虎右旗地区土壤N/P则表现为先降低后增加的趋势。(3)纬度、降水量、温度和pH值是影响土壤化学计量比变化的重要因素,其中C/P、N/P与纬度呈极显著正相关(P<0.01),C/P和N/P与pH值、降水量、温度均呈显著负相关(P<0.05),C/N/P与纬度呈显著负相关(P<0.05),而与pH和温度呈显著正相关(P<0.05)。研究结果为探讨中蒙边境不同纬度草原土壤养分平衡和草原生态系统的可持续发展提供参考。

In order to reveal the soil carbon(C),nitrogen(N),phosphorus(P)spatial distribution characteristics in grassland soils of different latitudes,the grasslands on China-Mongolia border(Erenhot City,East Ujimqin Banner and Xin Barag Right Banner)were selected as the study areas.The spatial distribution characteristics of C,N and P elements in different soil layers(0~10,10~20,20~30 cm)in the grassland were analyzed to discuss the main factors influencing the spatial variation of soil stoichiometric.The results showed that:(1)Within the range of 0~30 cm layer,the contents of organic carbon,total nitrogen and total phosphorus in the soil of the three grassland areas gradually increased with the increase of latitude,which were all shown as Xin Barag Right Banner>East Ujimqin Banner>Erenhot City.The content of organic carbon and total nitrogen in the topsoil of the same area was higher than that in the lower layer,but the variation of total phosphorus content in different soil layers was not significant.(2)There was no significant difference in C/N,C/P,N/P,C/N/P between different soil layers in the same area(P>0.05).The C/N,C/P and C/N/P of same soil layer in different grasslands showed latitude differences.C/N of each layer of soil from high to low was in the order of East Ujimqin Banner>Xin Barag Right Banner>Erenhot City,while C/P of each soil layer showed as Xin Barag Right Banner>East Ujimqin Banner>Erenhot City,however,C/N/P of each soil layer ranked as Erenhot City>East Ujimqin Banner>Xin Barag Right Banner.With the increase of soil depth,N/P in the three areas showed different trends:Erenhot City showed an increasing trend first and then decreased;East Ujimqin Banner showed a gradually decreasing trend;Xin Barag Right Banner showed a decreasing trend first and then increased.(3)Latitude,precipitation,temperature,and soil pH were the important factors that affected the change of soil stoichiometric.C/P and N/P was significantly positively correlated with latitude(P<0.01),while C/P and N/P were significantly negatively correlated with soil pH,precipitation and temperature(P<0.05).C/N/P had a significantly negative correlation with latitude(P<0.05),but a significantly positive correlation with soil pH and temperature(P<0.05).Results of the study can provide references for the discussion of soil nutrient balance and sustainable development of grassland ecosystem in different latitudes of the border between China and Mongolia.