本研究以农牧交错带4种典型人工植被(樟子松、油松、杨树、柠条锦鸡儿)为研究对象，以天然草地为对照，探讨农牧交错带典型人工植被群落0～100 cm 土层范围内土壤C、N、P含量及其化学计量比特征。结果表明:①草地、柠条、杨树、樟子松和油松的表层(0～20 cm)土壤有机碳(SOC)含量分别为7。72、7。16、4。16、15。59和15。84 g/kg，全氮(TN)含量分别为1。12、0。58、1。27、1。23和0。87 g/kg，全磷(TP)含量分别为0。24、0。20、0。31、0。14和0。25 g/kg，均低于我国表层土壤SOC、TN和TP平均水平，土壤肥力较低。②除杨树林外，各人工植被类型下土壤SOC含量均大于草地，表现为油松＞樟子松＞柠条＞草地＞杨树。杨树林的土壤TN和TP含量在各个土层深度均最高;油松在0～20 cm 土层中的土壤TN含量大于草地;樟子松的土壤TN含量在50～100 cm 土层中大于草地，柠条最低且始终低于草地。除杨树林外，其余人工植被的土壤TP含量均低于草地，油松林最低。各个土层中，不同人工植被的土壤C∶N和C∶P均大于草地，总体上均表现为油松＞樟子松＞柠条＞杨树＞草地;在0～20 cm 土层中，只有杨树林地的N∶P大于草地，而在20～100 cm中各植被的土壤N∶P比草地高。③本研究中的土壤C与N、P的相关性不显著，而土壤N与P呈极显著的正相关;SOC对C∶N和C∶P的相关系数绝对值最大，表明土壤C∶N和C∶P主要受SOC调控;而N∶P只与TN呈显著正相关，表明N∶P主要受TN调控。
Soil C,N and P Contents and Their Stoichiometry Under Different Artificial Vegetation Types in Agro-pastoral Zone of Northern China:A Case Study of Wuchuan County
This study investigated four typical artificial vegetation types(Pinus sylvestris,Pinus tabulaeformis,Populus L.and Caragana korshinskii)and grassland in the agro-pastoral transitional zone in order to explore the characteristics of soil carbon(C),nitrogen(N),phosphorus(P)and their stoichiometric ratios within the 0-100 cm soil layer.The results showed that:1)Topsoil(0-20 cm)organic carbon(SOC)contents of grassland,Caragana korshinskii,Populus L.,Pinus sylvestris,Pinus tabulaeformis were 7.72,7.16,4.16,15.59 and 15.84 g/kg,respectively;Total nitrogen(TN)contents were 1.12,0.58,1.27,1.23 and 0.87 g/kg,respectively;Total phosphorus(TP)contents were 0.24,0.20,0.31,0.14 and 0.25 g/kg,respectively.All were lower than those of the national average levels,indicating the lower soil fertility.2)SOC was in an order of Pinus tabulaeformis＞Pinus sylvestris＞Caragana korshinskii＞grassland＞Populus L.,TN and TP in the poplar forest were highest among different soil depths.TN of Pinus tabulaeformis in the 0-20 cm layer was higher than that under grassland.TN in the 50-100 cm layer under Pinus sylvestris was higher than that under the grassland,while TN under Caragana korshinskii was lowest and lower than that under the grassland.Except for the Populus L.forest,TP under other artificial vegetation were lower than that under the grassland,with Pinus tabulaeformis being the lowest.In each soil layer,C∶N and C∶P ratios under different artificial vegetation were higher than those under the grassland,generally in an order of Pinus tabulaeformis＞Pinus sylvestris＞Caragana korshinskii＞Populus L.＞grassland.In the 0-20 cm layer,only N∶P ratio of Populus L.exceeded that under the grassland,while in the 20-100 cm layer,N∶P ratios of all vegetation was higher than that under grassland.3)The correlation between soil C and N,P was not significant,while N and P showed a significant positive correlation.SOC had the highest correlation coefficient with C∶N and C∶P,indicating SOC was the primary regulator of C∶N and C∶P ratios,while N∶P was only significantly correlated with TN,suggesting that N∶P was mainly regulated by TN.
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