| Resource & environmental sciences |
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| Contents and ecological stoichiometry characteristics of soil carbon, nitrogen and phosphorus in wetlands of Ningxia plain |
| BO Xiaoyan, MI Wenbao, XU Hao, ZHANG Xueyi, MI Nan, SONG Yongyong |
| (1. School of Agriculture, Ningxia University, Yinchuan 750021, China; 2. Ningxia Polytechnic, Yinchuan 750021, China; 3. School of Resource and Environmental Sciences, Ningxia University, Yinchuan 750021, China; 4. Institute of Desertification Control, Ningxia Academy of Agricultural and Forestry Sciences, Yinchuan 750021, China; 5. Ningxia Key Lab for Meteorological Disaster Prevention and Reduction, Yinchuan 750002, China) |
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Abstract Ecological stoichiometry is a comprehensive and effective method to learn the relationship and regularity of the elements in the biogeochemical cycle and the ecological process. The ecological stoichiometry of carbon (C), nitrogen (N) and phosphorus (P) are significant in ecological systems. Soil C, N and P in wetlands significantly affected the productivity of the ecosystem, which are also important indicators of environmental status of wetland. At present, the research on C, N and P of wetlands is more concentrated on eastern part of China. Fewer research were focused on the characteristics of ecological stoichiometry of wetland in arid and semi-arid regions of Northwest China. The study area in this paper is Ningxia plain, which located in the arid area of Northwest China. As the Yellow River run through the plain, wetlands are widely distributed in this region. Due to the influence of agricultural irrigation and other factors, the eutrophication of wetland is a concerned problem, and the distribution of C, N and P of the wetlands have their unique characteristics. In order to clarify the spatial distribution characteristics of soil nutrients and its influencing factors in wetland of Ningxia plain, the combination of “3S” technologies (remote sensing, geographical information system, and global positioning system), typical sampling and laboratory determination were used, nine plots of the wetlands soil in Yellow River, lakes and marshes were sampled, and the content of soils ［soil organic carbon (SOC), N and P］ and their stoichiometric ratios were measured. The distribution characteristics of SOC, N and P were further analyzed. The results indicated that the average values of SOC, TN and TP in wetland soil of Ningxia plain are 9.61 mg/g, 0.94 mg/g and 0.45 mg/g, respectively. SOC are significantly correlated with TN and TP (P<0.05). SOC and TN are cumulative in surface 10-20 cm layer cross the longitudinal section of all plots. TP content is stable a cross the longitudinal section. The contents of SOC, TN and TP of the nine plots in northern and southern side of the plain are higher than the middle part. The spatial distribution characteristics of C/N and C/P are similar, both show higher in middle plain and lower in northern and southern sides of the plain. The N/P ratios in northern and southern sides of the plain are higher than that in the middle part of the plain. Among different wetlands, the highest TN, TP and N/P were observed in lakes, the highest SOC, C/N and C/P were observed in marshes, and lowest SOC, TN, TP, C/P and N/P were observed in rivers. The SOC, TN and TP of rivers showed a higher spatial variation over the plain. The contents of C, N and P and their stoichiometric ratios are impacted by environmental factors including wetland origin, vegetation type, soil properties and human activities including tourism, urban construction, industrial and agricultural pollutions. Soil C and P are key factors that determining the differences of C/N and C/P, and the C/P and N/P were more influenced by the moisture and salinity of soil. The typical stoichiometry property of C, N and P of Ningxia wetlands is that the C/P value is significantly lower than the average value of China, indicating that the organic phosphorus of microorganisms were mineralized in this region.
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Published: 20 January 2016
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宁夏平原不同类型湿地土壤碳氮磷含量及其生态化学计量学特征
为了阐明宁夏平原不同类型湿地土壤养分的空间分布特征及其影响因素,采用“3S”技术,即遥感技术(remote sensing,RS)、地理信息系统(geographical information system,GIS)、全球定位系统(global positioning system,GPS)和典型样地采样及实验室测定相结合的方法,对宁夏平原河流、湖泊、沼泽3类不同类型典型湿地不同土层深度土壤有机碳(soil organic carbon,SOC)、全氮(total nitrogen,TN)和全磷(total phosphorus,TP)含量及其生态化学计量学特征进行了分析。结果表明:1)SOC、TN含量在垂直剖面上呈“表聚性”分布；TP含量在垂直剖面上变化较小。9个典型湿地从南向北,土壤SOC、TN、TP含量整体呈先减少后增加的变化趋势,即中部低,南北高；C/N比和C/P比空间变化趋势一致,整体上均呈现先增加后减少的趋势,即中部高南北低；N/P整体上呈先减少后增加的趋势,即中部低南北高。2)从湿地类型来看,土壤TN、TP含量和N/P比湖泊湿地最高,SOC含量、C/N比和C/P比沼泽湿地最高,河流湿地SOC、TN、TP含量与C/P比和N/P比均最低。河流湿地土壤SOC、TN、TP含量在水平空间上的差异性最大。3)C、N、P含量及其生态化学计量特征受湿地成因、植被、土壤理化性质等环境因子，和旅游、城市建设、工农业污染等人类活动因子的多重影响。土壤C和P含量是决定C/N比和C/P比差异的关键因子,同时土壤C/P比和N/P比受含水量和盐度的影响大。
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