珍稀植物华木莲的现代濒危机制:探析与展望

Endangered mechanisms of Sinomanglietia glauca: exploring and prospect

关键词:  华木莲, 濒危机制, 竞争驱赶, “林—窗”游击更新, 有效林窗, 保护生态学

Key words:  Sinomanglietia glauca, endangered mechanism, competitive exclusion, “Forest-Gap” guerilla regeneration model, effective gap, conservation ecology

摘要:

华木莲(Sinomanglietia glauca)在探讨木兰科系统演化与被子植物起源等方面具有重要科学价值,但其分布区域狭窄、种群规模较小,被列为我国濒危植物和极小种群植物。该文在系统综述华木莲生物生态学特性和更新维持机制的基础上,对华木莲的现代濒危原因进行了总结:(1)华木莲属古老残遗濒危植物,环境变迁、瓶颈效应、高频自交和遗传漂变,导致其遗传多样性下降、适应性差;(2)喜光喜肥的生物生态学特性和群落种间竞争驱赶作用,“林—窗”游击式更新是华木莲种群延续的重要方式,然而当前人类干扰导致有效林窗供给不足、种子传播效率下降、“游击”机会减少,更新难以完成;(3)毛竹扩张与林下箬竹过度增长严重影响华木莲开花结实,并妨碍其幼苗更新。今后应加强华木莲谱系地理与群落系统发育、群落环境对华木莲生长发育的影响及其应答、林窗更新机制与种子长距传播、群落结构调整与保护技术、遗传复壮与迁地保护等方面研究,为华木莲以及相似生物生态学特征的濒危植物保护提供理论指导。

Abstract:

Sinomanglietia glauca, a species with scientific value to reveal magnoliaceae evolution and the origin of an-giosperms, distributing discretely in Jiangxi and Hunan provinces, is catalogued as a rare and endangered plant and wild plant species with extremely small populations. The current endangered causes of S. glauca were systematically reviewed in light of its bioecological characteristics and regeneration mechanisms. The results were as follows:(1)As an ancient relic, history environmental change, the bottleneck effect, high frequency selfing and genetic drift, all could result in a decline in genetic diversity and poor adaptability for S. glauca.(2)“Forest-Gap” guerrilla regeneration model was an important way for this species surviving, due to its light- and nutrient-demanding characteristics, and exclusion stress from interspecific competition in community. However, this model was interrupted by insufficient forest gaps and lower seed dispersal efficiency, less chance to guerrilla.(3)Bamboo expansion and overgrowth seriously reduced S. glauca flowering and fruiting, and interfered seedlings recruitment. Anyhow, the main causes of threats to this resource are selfing genetic recession, interspecific competition exclusion, insufficient effective forest gaps. The information of endangered mechanism and protection eco-logy is still very weak, the following are hoped to be strengthened in the future: the phylogeography and community system development of S. glauca at the molecular-level, how environment factors affect the growth and development of S. glauca and its responses, “Forest-Gap” regeneration mechanism and seed long-distance dispersal, conservation technology by community adjustment, genetic rejuvenation and reintroduction. The review can provide theoretical guidance for S. glauca and other rare and endangered plants with similar bioecological characteristics.