Abstract: Nitrogen (N) and phosphorous (P) are vital elements and have crucial impacts on the productivity of terrestrial ecosystem. Ecological stoichiometry of plant N and P provides an efficient way for understanding plant nutrient utilization. Based on field investigation, dominant herbaceous species in a pine and oak mixed forest were assured and their stoichiometric characteristics were analyzed. Results indicated as follows. Casual species could be found frequently in the forest. The mean concentrations of N, P and N:P ratio in the leaves of dominant herbaceous species were (17.51±3.01) mg·g^-1, (1.74±0.79 ) mg·g^-1and (11.67±4.01), respectively. Relationships between the concentrations of N and P in the leaves of dominant herbaceous species were explored by linear regression. The N:P ratio generally negatively related to the concentration of P. Both Carex lanceolata and Deyeuxia sylvatica were limited by soil available N in their growing processes. In contrast, Astilbe chinensis growth was unlimited by either soil available N or P. These results suggested forest thinning promoted litter decomposition and increased the productivity of herbaceous species in the pine-oak mixed forest.

Key words: Pine and oak mixed forest, Nitrogen, Phosphorus, Nutrient limitation, Ecological stoichiometry

摘要： 氮(N)和磷(P)是影响陆地生态系统生产力的重要元素,而植物氮磷(N-P)生态化学计量特征为研究植物的养分利用状况提供了有效途径。研究林下草本优势种叶片N,P元素含量,可为判断其生长限制性元素及探索提高其生产力的途径提供参考依据。以秦岭松栎混交林内优势草本为研究对象,在群落调查的基础上,确定秦岭山地松栎混交林内草本优势种,分析优势草本叶片N,P化学计量特征。结果表明:林内草本偶见种较多;优势草本叶中N,P含量和N:P比的均值分别为(17.51±3.01) mg·g^-1,(1.74±0.79) mg·g^-1和(11.67±4.01);优势草本叶片中N与P的含量间存在线性关系;随着草本叶片中P含量增加,N:P比总体呈下降趋势;研究区松栎混交林内草本优势种披针叶苔草(Carex lanceolata)和野青茅(Deyeuxia sylvatica)生长受土壤中可利用的N限制,升麻(Astilbe chinensis)不受土壤中可利用的N,P含量限制;开展森林抚育,促进凋落物分解有利于提高松栎混交林内草本生产力。

关键词: 松栎混交林, N, P, 养分限制, 生态化学计量