【摘要】 氮和磷作为植物体内重要的生命元素,在植物群落的生长发育过程中发挥着重要的作用。为了明确祁连山亚高山灌丛林叶面积指数与冠层氮、磷之间的关系,本文通过对祁连山亚高山灌丛林不同植被类型(箭叶锦鸡儿、高山吉拉柳、金露梅)及不同放牧处理(羊群、牦牛,未放牧)条件下灌丛群落的叶面积指数(LAI)与叶片氮积累量(TFN)、叶片磷积累量(TFP)比较发现,在整个亚高山灌丛群落中,LAI与TFN和TFP之间都有较强的相关性,并且TFN和TFP比值的变化表明不同植被类型叶片的生长都受到N、P的共同限制,只是随着LAI的增加,高山吉拉柳主要受到氮素的限制,箭叶锦鸡儿主要受到磷素的限制,而金露梅则受到N、P的共同限制;在不同放牧条件下,单位面积LAI对应的TFN的值较高而TFP的值较低,说明动物通过对植被的啃食可能会改变群落的模式,在一定程度上限制磷的摄入。LAI、N、P之间的耦合关系表明了亚高山灌丛群落的LAI在物种组成、放牧和冠层密度上存在差异,但仍然受到N和P的约束。研究结果有利于探索水分限制条件下祁连山灌丛林生态系统植物叶片与养分元素之间关系,对于研究干旱区高寒灌丛生态系统在全球气候变化中的作用及其对全球气候变化的响应与反馈,具有重要的理论价值和实践意义。更多还原

【Abstract】 As the important life elements in plants, Nitrogen(N) and Phosphorus(P) play important roles in the growth and development of plant communities. In order to clarify the relationship between the leaf area index of subalpine shrub forests in the Qilian Mountains and the canopy N and P, different vegetation types(Dasiphora fruticosa, Caragana jubata, Salix cupularis S. oritrepha) and different grazing treatments were adopted to study. Then the total foliar nitrogen(TFN), total foliar phosphorus(TFP), and the leaf area index(LAI) of subalpine scrub forest communities were compared under different conditions(sheep, yaks, and ungrazed) to find that LAI was strongly correlated with both TFN and TFP across communities, and also within different plant types(Dasiphora fruticosa, Caragana jubata, Salix cupularis S. oritrepha) and grazing treatments(sheep, yaks, and ungrazed). Across almost the entire range of LAI values and contrasting communities, in the TFN:TFP ratios it indicated co-limitation by N and P in almost all communities. However, the increase of LAI, Salix cupularis was and Caragana jubata mainly limited by N and P, respectively, but Dasiphora fruticosa was co-limited by N and P. Under different grazing conditions, the value of TFN corresponding to LAI per unit area was higher and the value of TFP was lower, suggesting that the animal might change the pattern of the community through grazing of vegetation and limit the phosphorus intake to some extent. This relationship between LAI, N and P in subalpine scrub forest suggests where in LAI remains similarly constrained by N and P despite differences in species composition, grazing and canopy density.更多还原