山东银莲花叶片形态结构对异质生境和海拔变化的响应

山东银莲花为一分布极其狭域的稀有物种,对海拔600 m以上的针阔混交林和山顶灌丛两种异质的生境都具有较高的适应性。为探索其适应策略,选择两种异质生境中的5个海拔梯度样带,采用常规石蜡切片法和显微观察技术,对叶片进行观察、分析和测量,通过比较叶片外部形态特征参数和内部解剖结构的差异,推测其叶片适应海拔和异质生境的响应策略。结果表明:为适应阴暗、潮湿的针阔混交林和干旱、强光照的山顶灌丛两种不同环境,山东银莲花分别表现出不同的适应策略。针阔混交林下,叶片的背腹表皮毛密度、比叶面积和气孔相对开度较山顶灌丛的大,而气孔密度、叶片厚度、栅栏组织和海绵组织的厚度较山顶灌丛的小;山顶灌丛植株叶片栅栏组织细胞排列较林下更加整齐紧密。两种生境中叶片腹面表皮毛的长度、气孔相对开度都随海拔的升高而减小,且差异明显;而叶片厚度、比叶面积、气孔指数等对600 m以上海拔变化未表现出明显的规律性。本研究将为山东银莲花的保护和利用提供理论基础及依据,为其他植物的相关研究提供参考。

Response of leaf morphology and structure of Anemone shikokiana to heterogeneous habitats and altitude changes

Anemone shikokiana is a rare species adapted to two heterogeneous habitats including conifer and broad-leaf mixed forest and shrubs of mountaintop at higher than 600 m elevation. In the present study, we chose five sample transects to explore the response mechanism of this species to heterogeneous habitats and altitude gradients. Leaves, which are plant organs with the largest surface area exposed to the sun and air, are the main photosynthetic organs and sensitive organs to environmental changes. The morphology and anatomical structure of the leaves in A. shikokiana were analyzed by the paraffin section method and microscopic technique. We observed the morphological characteristics of the leaves and epidermal hairs, measured the thickness of the leaves and mesophyll tissue, calculated their anatomical indices and stomatal parameters, and analyzed the correlation between these characteristics and the heterogeneous habitats or altitude. Compared with those of leaves from mountaintop shrubs, the density of upper and lower epidermal hairs, specific leaf area, and relative opening of the stoma of leaves from the conifer and broad-leaf mixed forest were greater, whereas stoma density, leaf thickness and palisade and spongy tissue thickness were lower. The length of upper epidermal hairs and relative opening of the stoma gradually decreased with increasing altitude. However, there was no obvious regularity between the other parameters measured and different altitude, such as palisade and spongy tissue thickness, specific leaf area, and stomatal index. This study provides a theoretical foundation for the protection and utilization of A. shikokiana and provide references for related research in other plants.