不同郁闭度对野外回归的梓叶槭幼树形态和生理特征的影响

濒危植物野外回归是扩大极小种群野生植物种群的有效途径。适宜的回归生境是物种生长的必要条件, 研究植物的生理生态特征对不同野外回归生境的适应性, 是科学评价濒危物种种群回归生境适宜性的关键指标。本文以野外回归的极小种群野生植物梓叶槭(Acer catalpifolium)为研究对象, 探讨了无遮荫、林缘、林隙以及林下(郁闭度由小到大) 4种不同光照条件对梓叶槭幼树的形态特征、光合特征、类黄酮指数及叶绿素含量等的影响。结果表明: (1)随着郁闭度的增大, 梓叶槭幼树的基径、冠幅以及新生枝条数量产生差异, 均呈现先增大后减小的趋势; (2)在林缘生境中, 梓叶槭幼树的单叶面积及单叶质量均最大, 比叶面积随着郁闭度的增大而增大; (3)随着郁闭度的增大, 梓叶槭叶片胞间CO₂浓度、蒸腾速率及气孔导度均呈现先减小后增大的趋势, 叶绿素含量呈现上升趋势, 类黄酮指数则呈现先增大后减小的趋势。综上可知, 林缘适宜的光照条件更适合梓叶槭野外回归。这一结果可为梓叶槭以及其他极小种群野生植物的回归生境适宜性的探索研究提供借鉴。

Physiological and morphological effects of different canopy densities on reintroduced Acer catalpifolium

The reintroduction of an endangered plant is an effective way to increase its wild plant populations. Suitable habitat is a necessary condition for reintroduced species to survive. Studying the adaptability of a plant’s physiology to different habitats prior to reintroduction is key for evaluating how successful the endangered species would be in each habitat. In this study, Acer catalpifolium, a Wild Plant with Extremely Small Populations (WPESP), was studied to explore the effects of habitat conditions on the morphological traits, photosynthetic characteristics, flavonoid index and chlorophyll contents of A. catalpifolium seedlings. The habitat conditions, no shading, forest edge, gap and understory, are ordered in a gradient from low to high canopy density. The results show that: (1) The change in canopy density correlated with the differences in base diameter, crown width and number of new branches. (2) The maximum single leaf area and single leaf mass were found in the forest edge habitat, and the specific leaf area increased as canopy density increased. (3) With increasing canopy density, intercellular CO₂ concentration, transpiration rate and stomatal conductance of A. catalpifolium showed an initial decrease before increasing. In contrast, the flavonoid index showed an initial increase before decreasing. Chlorophyll content showed a consistent upward trend. In summary, the light conditions of forest edge habitat make it more suitable than the other habitats in this study for the reintroduction of A. catalpifolium. This study establishes a theoretical and practical basis for field reintroductions of A. catalpifolium, and provides significant guidance for exploring suitable habitat for the reintroduction of other Wild Plant with Extremely Small Populations.