黄河北岸兰州段丘陵区土壤生态化学计量与空间变异

Spatial variation of ecological stoichiometry characteristics of hilly soil in Lanzhou section of Yellow River north shore

为探究黄河北岸兰州段丘陵区土壤碳、氮、磷含量及化学计量比的空间变异特征,基于12个样地数据,采集1 m剖面内不同发生层土壤进行土壤含水率(SWC)、pH、有机碳(SOC)、全氮(STN)和全磷(STP)的测定。分析了研究区土壤碳、氮、磷含量及其生态化学计量特征在植被和土层上的差异及空间变异特征。结果表明:(1)研究区SOC、STN、STP均值分别为4.53、0.74、0.13 g·kg^(-1),C∶N、C∶P、N∶P均值分别为7.85、55.17、8.40;(2)研究区SOC、STN、C∶N和N∶P的块基比C_(0)/(C_(0)+C)<0.25,主要受气候、植被、地形等自然因素影响;STP、C∶P则C/(C+C)>0.75,主要受退耕还草等人为因素影响;(3)研究区土壤整体受到氮限制,与此同时有机碳更为匮乏,磷则在短期内不会成为限制因子。在黄河流域兰州段北岸丘陵区北岸的生态治理与恢复中,应重视有机肥和氮肥的配置与施加,同时需减少人为干扰,这对于植被的快速恢复与养分的固定具有重要意义。

To understand the spatial variability of soil C,N and P contents and their stoichiometric ratios in the hilly area of Lanzhou on the north bank of the Yellow River Basin. Based on 12 sample plots,we measured soil water content(SWC),pH,soil organic carbon(SOC),total nitrogen(STN)and total phosphorus(STP)at a depth of 1m in 12 plots. Then,we had analyzed the difference of SOC,STN and STP contents and their eco-stoichiometry characteristics in the study area in terms of different vegetation and soil layers,as well as their spatial variability. Results show that:(1)The mean values of SOC,STN and STP in the study area were 4.53,0.74 and 0.13 g·kg^(-1),respectively. The mean values of C∶N,C∶P and N∶P were 7.85,55.17 and 8.40,respectively.(2)The ratios of nugget to soil C/(C+C)<0.25 of SOC,STN,C∶N and N∶P are influenced by natural factors such as climate,vegetation and topography in study area. The C_(0)/(C_(0)+C)>0.75 of STP and C∶P are influenced by anthropogenic factors likely fallowing and grassland restoration.(3)The study area is the most deficient in organic carbon and is limited by nitrogen,while phosphorus will not be a limiting factor in the short term. These results suggest that people should pay attention to the allocation and application of organic and nitrogen fertilizers in the subsequent ecological management and restoration activities,at the same time,people need to reduce human disturbance. All of this will be important for the rapid recovery of vegetation and fixation of soil nutrient in the hilly area of Lanzhou on the north bank of the Yellow River Basin.