陕西省森林群落乔灌草叶片和凋落物C、N、P生态化学计量特征

C,N,P stoichiometric characteristics of tree,shrub,herb leaves and litter in forest community of Shaanxi Province,China

研究陕西省121个森林群落中乔叶、灌叶、草叶和凋落物4个层次的C、N、P化学计量学特征及其变异性,分析了各层次间及其与地理因子间的关系.结果表明:乔叶C、N含量最高,草叶P含量最高,凋落物C、N、P含量均最低.乔叶、灌叶、草叶和凋落物的C∶N∶P分别为439.4∶14.2∶1、599.2∶13.5∶1、416.5∶13.3∶1、504.8∶15.5∶1,乔叶、灌叶、草叶N∶P值差异不显著,但均与凋落物N∶P值差异显著,表明不同生活型活体植物叶片的N∶P值具有一定的稳定性.与N含量相比,C和P含量在各层次间表现出更好的相关性;C、N、P含量及其比值在草叶与乔叶之间较在灌叶与乔叶之间表现出更好的相关性;凋落物与乔叶和草叶之间C、N、P含量均表现出显著正相关,与灌叶只在P含量之间存在显著正相关.灌叶N、P含量随纬度增加而增加,草叶N、P含量随经度增加而降低,海拔对叶片和凋落物C、N、P含量及其比值的影响较小,只有乔叶N∶P与海拔之间存在显著负相关.各地理因子对草叶的影响大小表现为经度>纬度>海拔,对乔叶、灌叶和凋落物的影响大小表现为纬度>经度>海拔.

A total of 121 sampling sites were selected to study the C, N, P stoichiometric characteristics among the leaves of tree, shrub, herb and the litter of the majority forest community of Shaanxi Province, China. We also studied their relationships with geographical factors. The results showed that C, N concentrations were highest in tree leaf, P concentration was highest in herb leaf, and the C, N, P concentrations were lowest in litter. Leaf C ： N ： P ratios of tree, shrub, herb leaves and litter were 439.4 ： 14.2 ： 1, 599.2 ： 13.5 ： 1, 416.5 ： 13.3 ： 1, 504.8 ： 15.5 ： 1, respectively. The N：P ratios of tree, shrub and herb leaves were not significantly different, but they were all significantly higher than that of litter layer, indicating N ： P ratio of different living life forms＇ leaves was stable. Compared with N, C and P had better relationships in each layer, and the relationships of leaf C, N, P stoichiometry between tree and herb leaves were better than those between tree and shrub leaves. The correlations of C, N, P stoichiometry between litter and the tree or herb leaves were highly significantly positive, and the correlations of P stoichiometry between litter and shrub leaves were highly significantly positive. Shrub leaf N, P concentration increased with the increasing latitude, and herb leaf N, P concentrations decreased with the increasing longitude. Compared with the longitude and latitude, the effect of altitude was smaller, and only tree lear N ： P decreased wltn the increasing latitude. Multivariate linear regression analysis results showed that the influence of geographical factors on herb leaf was longitude 〉 latitude 〉 altitude, while was latitude 〉 longitude 〉 altitude for tree, shrub leaves and litter.