基于现代生态位理论的濒危物种辅助移植研究：以不同海拔分布范围的兰科植物为例

The modem concept of ecological niche is central in predicting ecological responses to rapid environmental change. Assisted colonization-the movement of a species by humans to habitats at higher latitudes or higher elevations beyond its native range that are predicted to be suitable under future climatic conditions-has recently developed as a conservation measure. Since assisted colonization involved expansion of species into new range, and may be triggered by concerns other than climate change, guiding and evaluating the practice under the contemporary ecological niche frame work make will not only benefit the conservation actions, but provide a fruitful ground for testing and improving the theory itself. A unique "experiment", moving orchids beyond their elevational ranges, forms the basis for our proposal to evaluate assisted colonization in light of climate change using contemporary niche theory. We propose to examine the demographic-based niche limits on selected climatic and biotic variables for six of the upward translocated orchid species in Guangxi. Three of the six species have restricted, low elevational ranges (<700 m a.s.l.), while the other three have wide elevational ranges (350-1200m). The translocation site was higher than the natural elevational range for the three low elevation species. We will quantify the recruitment and persistent niches use a combination of field and lab experiments, with treatments represent elevational variations and climate change scenarios. The proposed study will overcome the above shortcomings and provide us a mechanistic understanding on why a species will succeed or fail in a new range expansion. In addition, the effects of climate change on strongly symbiotic-dependent species are understudied. The proposed study will fill this gap as the proposed study species, similar to other members of the family (Orchidaceae), have complex, life-cycle dependent, symbiotic relationships with animal pollinators and/or mycorrhizal fungi. Finally, results from this study will provide guidance to future managed relocation of endangered species.

全球变暖正迫使物种逐渐向高纬度或高海拔地区迁移。然而，许多物种受自身扩散能力和破碎的生境所限无法通过迁移来适应气候变化。如何缓解这些物种的灭绝风险成为物种保护实践者和生态学家们关注的热点，辅助移植正是在此前提下应运而生的一种新兴保育概念和措施。辅助移植倡导将无法自然迁移的濒危物种人工迁至当前分布区外的高纬度/海拔地区。然而，辅助移植是否能够成为一种行之有效的物种保护手段尚缺乏研究实例。现代生态位理论做为阐述物种分布机理的理论，可对辅助移植的可行性进行科学评价。本课题基于在广西已经开展了6年辅助移植的多种野生兰科植物，选择其中3种窄幅种和3种宽幅种进一步开展相关实验，研究物种的驻留生态位和更新生态位，探索位于高海拔的迁居地为辅助移植物种提供适宜生态位的可能性和所需条件。本项目对我们理解在气候变化背景下物种分布可能发生变化的机理提供研究案例，从而为开展濒危物种的辅助移植提供指导和借鉴。

全球变暖正迫使物种逐渐向高纬度或高海拔地区迁移。然而，许多物种受自身扩散能力和破碎的生境所限无法通过迁移来适应气候变化。如何缓解这些物种的灭绝风险成为物种保护实践者和生态学家们关注的热点，辅助移植正是在此前提下应运而生的一种新兴保育概念和措施。辅助移植倡导将无法自然迁移的濒危物种人工迁至当前分布区外的高纬度/海拔地区。然而，辅助移植是否能够成为一种行之有效的物种保护手段还是一个未知数。现代生态位理论做为阐述物种分布机理的理论，可对辅助移植的可行性进行科学评价。Holt在2009从以种群动态为基础的Hutchinson现代生态位理论发展出更新生态位（establishment / recruitment niche）和驻留生态位（persistence niche）两个概念，进一步完善了现代生态位理论。驻留生态位指能够为非种子、非幼苗植物个体提供存活的足够条件，而更新生态位则指为植物提供适宜的结籽、种子萌发和幼苗生长等条件。.本课题利用在广西已进行的野生兰科植物的辅助移植，选择其中3种窄幅种和2种宽幅种进一步开展相关实验，探索研究物种的驻留和更新生态位。数据显示以种群成年个体生存率和成年个体获取共生真菌的能力揭示了雅长自然保护区濒危兰科植物驻留生态位，研究表明兰科植物对极端气候事件的抵抗和恢复能力是决定驻留生态位宽窄的主要因子。.以种群结实率为指标揭示了雅长自然保护区濒危兰科植物更新生态位，研究表明有效传粉者的存在与否是兰科植物迁移种群有无更新生态位的主要因子。典型代表有由蝴蝶传粉的银带虾脊兰，更新生态位比其他几种兰花的更新生态位要狭窄，在雅长的迁移接收地（～海拔1000m）无传粉蝴蝶，不能自然结实，从而无法更新。.本研究以兰科植物为研究对象，采取种群动态综合分析为主的研究手段确定目标种在高、底两个海拔梯度的驻留生态位和更新生态位，解释濒危物种辅助移植的成败机理。本研究对未来全球的濒危物种辅助移植的行动与研究均有重要参考价值性。