樟子松人工林生长对土壤碳氮磷化学计量的影响

Effect of Pinus sylvestris var.mongolica Plantation Growth on Stoichiometry of Soil Carbon,Nitrogen and Phosphorus

以科尔沁沙地不同生长期(幼林、中龄林、成熟林、过熟林)的樟子松人工林为对象,研究0~100 cm层土壤碳氮磷化学计量随林龄的变化规律。结果表明:樟子松人工林土壤C/N含量表现为过熟林>中林龄>幼林龄>成熟林,C/P含量表现为过熟林>幼林龄>中林龄>成熟林,N/P随着林龄增加先降低后升高,C/P、C/N、N/P含量最低值均出现在生长速度最快的成熟林,最高值均出现在过熟林。表明沙地樟子松人工林在成熟林以前,土壤磷含量满足樟子松人工林的生长需求。在过熟林阶段碳含量出现累积,土壤磷增长量低于碳增长量,致使过熟林时期樟子松人工林增长速率下降,磷成为过熟林时期樟子松生长限制因子。

Based on the Pinussylvestris plantation in different growth stages(young forest,middle-aged forest,mature forest and over-mature forest)in Horqin Sandy Land,the change rules of soil carbon,nitrogen and phosphorus stoichiometry with forest age in the 0-100 cm layer were investigated in this paper.The results demonstrated that the value of C/N in the P.sylvestris plantation soil was over-mature forest>middle-aged forest>young forest>mature forest,the value of C/P was over-mature forest>young forest>middle-aged forest>mature forest,and N/P firstly decreased and then increased with the forest age.The lowest C/P,C/N and N/P ratios appeared in the mature forest stage,and the highest ratios in the over-mature forest stage,suggesting that before the mature forest stage,soil phosphorus contents can meet the growth needs of the P.sylvestris plantation.In the over-mature forest stage,carbon content accumulated and the growth of phosphorus was lower than that of carbon,which led to the decline in the growth rate of P.sylvestris plantation.Therefore,phosphorus became the growth-limiting factors of P.sylvestris at the over-mature forest stage.