沙地柏叶型变化的生态意义

沙地柏（Sabina vulgaris）的叶包括刺叶和鳞叶两种类型。本文探讨沙地柏刺叶与鳞叶的结构和功能差异的生态意义。结果表明：（1）刺叶的角质层厚度、表皮细胞大小、叶肉细胞表面积和维管束大小都显著小于鳞叶；（2）刺叶的组织密度和失水系数都明显大于鳞叶；（3）刺叶的净光合速度、蒸腾速率和胞间CO2／大气CO2比都显著大于鳞叶，而前者的水分利用效率显著低于后者。这些结果指示：沙地柏刺叶的光合产物积累和水分丧失量大于鳞叶，但前者的抗旱保水性、耐辐射能力和水分利用效率都低于后者。刺叶和鳞叶的结构和功能差异表明：沙地柏叶型变化在一定程度上具有适应意义。

Ecological Significance of Change of Leaf Form in Sabina vulgaris

Sabina vulgaris has two types of leaves (i. e. spine and scale leaves). This study examined the differences in structure and function between spine and scale leaves, and hence their ecological significance of change of leaf form in the species. (1) The spine leaves had smaller cuticle thickness, epidermis cell size, mesophyll cell surface area, and vascular bundle size than the scale leaves. (2) Both tissue density and coefficient of water loss were higher in the spine leaves than in the scale leaves. (3) The spine leaves had higher net photosynthesis rate, transpiration rate, and the ratio of substomatal CO 2 concentration to atmospheric CO 2 concentration than the scale leaves, but water use efficiency (WUE) was lower in the former than in the latter. Our results suggest that spine leaves had higher photosynthesis product accumulation and water loss than scale leaves, but both resistant-drought and resistant-radiation abilities and WUE were just opposite. Therefore, spine and scale leaves have different structure and function, which allows this species to adapt different environments.