兰州北山半干旱区刺槐叶大小-数量权衡与坡向间的关系

Relationship between the trade-off of leaf size and number of Robinia pseudoacacia and slope aspects in semi-arid region in northern mountains of Lanzhou

权衡关系是生活史对策理论的基础,叶大小-数量的权衡关系对理解不同生境下植物生物量分配具有重要的意义。采用标准化主轴估计(standardized major axis estimation,SMA)方法,研究了西北半干旱区兰州市北山各坡向人工林刺槐叶数量和大小的生长关系。结果表明:随坡向由北坡向东坡、西坡和南坡转变,植物群落盖度、高度和土壤含水量逐渐减小,刺槐小枝单叶面积和单叶片干重逐渐减小,出叶强度逐渐增大;4个坡向刺槐小枝出叶强度与单叶面积、单叶片干重均呈显著的负相关关系(P<0.05),并存在接近-1的共同斜率;随坡向由北坡向东坡、西坡和南坡转变,出叶强度与单叶面积、单叶片干重四组关系的回归方程截距均逐渐减小。刺槐叶大小-数量的权衡关系,反映了植物功能性状对异质生境的响应和适应,以及植物资源分配的权衡机制。

Trade-offs are fundamental to life-history strategy theory, and the trade-off between leaf size and leaf number is important for understanding the plant biomass allocation under differ- ent habitats. Based on the method of standardized major axis estimation （SMA） , this paper stu- died the relationship between the leaf size and number of Robinia pseudoacacia plantations of dif- ferent slope aspects in northern mountains of Lanzhou in semi-arid region of Northwest China. The results indicated that with the change of the aspect from north to east, west and south, the cover and height of plant community and soil moisture declined, individual leaf area and individual lamina mass of R. pseudoacacia declined and the leafing intensity increased. Significant negative relationships between leafing intensity with indivi-dual leaf area and individual lamina mass were found in R. pseudoacacia in all aspects （P〈O.05） , and the common slope of the regressions was significantly close to -1. In addition, when the aspect changed from north to east, west and south, the four groups of y-intercepts in the scaling relationships of leafing intensity with individ- ual leaf area and individual lamina mass declined gradually. The trade-off between leaf size and leaf number with changes in slope aspect of the habitat reflected the response and adaptation of plant functional traits to heterogeneous habitats and the balance mechanism of plant resource allocation.