黄土高原常见树种比叶重及其与光合能力的关系

用鲜叶重与叶面积之比得出叶比重,对刺槐、紫穗槐、柠条、山杨、沙棘、狼牙刺和黄蔷薇等7个树种的比叶重及其与光合能力的关系进行研究,结果表明:7个树种各自的叶鲜重与叶面积之间都显著相关,比叶重随生长发育节律的变动而表现出明显的季节变化,说明不同树种之间养分利用及贮藏方式存在差异.生长季平均比叶重沙棘>柠条>刺槐>狼牙刺>紫穗槐>山杨>黄蔷薇,不同树种及同树种不同季节比叶重变化速率不同,反映了树种之间及不同季节叶片发育过程的差异.刺槐、柠条、山杨和紫穗槐的比叶重(x)与光合速率(Y)相关显著,光合速率随比叶重的增加而提高,模拟回归方程刺槐呈指数函数型,山杨为一次线性函数.柠条和紫穗槐的相关曲线呈二次抛物线型,临界点之前光合能力随比叶重的增加而提高,超高临界点则光合速率下降.黄蔷薇、狼牙刺和沙棘的比叶重与光合速率之间相关不显著.

The Specific Leaf Weight of Some Common Tree Species in Loess Plateau Area and Its Relationship with Photosynthetic Capacity

The specific leaf weight values(SLW-fresh weight of leaves/area of leaves) of 7 common tree species grown in loess plateau area, i.e., Robinia pseudoacacia, Amorpha fruticosa, Caragana korshinskii,Populus davidiana,Hippophae rhamnoides,Sophora japonica and Rosa hugonis were calculated and the relationship between the SLW value and photosynthetic capacity of the leaves was studied. It was showed by the results that there was significant correlation between the leaf area and the fresh leaf weight for these 7 tree species, and the SLW showed significant variation along with the seasons. These variations were closely related with the growth rhythm and the differences in nutrients utilization and storage patterns for different tree species. In growing season, the order of average SLW value was Hippophae rhamnoides > Caragana korshinskii > Robinia pseudoacacia > Sophora japonica > Amorpha fruticosa > Populus davidiana > Rosa hugonis. The SLW differed among these 7 tree species and the value of SLW for the same tree species also varied with the time, reflecting the differences in leaf development process for different tree species and in different seasons. It was found out that the SLW values of Robinia pseudoacacia,Caragana korshinskii, Populus davidiana and Amorpha fruticosa were significantly positively related to the photosynthetic capacity of the leaves, i.e., the photosynthetic capacity increased along with the increment of SLW value, the regression relationship for Robinia pseudoacacia could be expressed as exponential function, and for Populus davidiana was a linear function. The regression formulae between SLW and photosynthetic capacity for Caragana korshinskii and Amorpha fruticosa were quadratic functions. Under the critical point of SLW, the photosynthetic capacity increased as the SLW increased, but it decreased when the SLW was over the critical point. There was no significant relationship between the SLW and photosynthetic capacity for Rosa hugonis, Sophora japonica and Hippophae rhamnoides.