在预计的气候变化情景中,辅助迁移可能在受威胁植物物种的异地保护中发挥重要作用,通过将它们转移到其本地分布之外的类似合适的栖息地。然而,目前尚不清楚稀有特有植物物种(REPS)是否有这样的栖息地,因为它们的栖息地非常有限。这项研究的目的是对REPSPiceamartineziiPatterson和PiceamexicanaMartínez进行种群规模评估,并评估潜在的物种分布及其在墨西哥和全球范围内辅助迁移的可能性。
我们进行了人口统计普查,实地调查寻找新的看台,并开发了最后一次冰川最大值(22,000年前)的分布模型,中全新世(6000年前),当前(1961-1990)和未来(2050和2070)时期,对于整个墨西哥领土(考虑到气候,土壤,地质和地形变量)以及所有全球陆地区域(仅基于气候)。
我们的人口普查显示,马氏疟原虫和墨西哥疟原虫的种群分别为89,266和39,059人,分别,包括已知的种群和新的林分。墨西哥的预测表明,过去的合适区域有点大,现在仅限于已知的人口和新的林分,到2050年,它们将在悲观的气候情景中消失,到2070年,稀缺的边缘区域(p=0.5-0.79)仅存于马氏疟原虫。世界范围的预测(仅基于气候变量)显示,2050年仅在墨西哥的边际区域很少。以及世界各地(墨西哥以外的所有地区)墨西哥疟原虫的几个大区域(p≥0.5),特别是在印度的喜马拉雅山和台湾的忠阳山,在当前和未来(2050年)条件下具有高度合适的(p≥0.8)气候栖息地。然而,那些合适的地区目前居住着其他特有的云杉:Piceasmithiana(Wall。)Boiss和PiceamorrisonicolaHayata,分别。
在墨西哥稀缺的边缘地点,只有马丁虫可以选择辅助迁移,墨西哥疟原虫的可能性将是大陆和跨大陆的易位。这给未来的异地保护计划带来了两个可能的问题:第一个问题与是否考虑辅助迁移到边缘地点有关,这些地点不涵盖该物种的主要栖息地要求;第二个问题是,当在其他地方发现合适的栖息地但其他特有物种居住时,应优先保护哪些物种(本地或外来物种)。这凸显了讨论新政策的必要性,应对预期的高物种灭绝率的国际合作准则和机制,与预计的气候变化有关。
In the projected climate change scenarios, assisted migration might play an important role in the ex situ conservation of the threatened plant species, by translocate them to similar suitable habitats outside their native distributions. However, it is unclear if such habitats will be available for the Rare Endemic Plant Species (REPS), because of their very restricted habitats. The aims of this study were to perform a population size assessment for the REPS
Picea martinezii Patterson and
Picea mexicana Martínez, and to evaluate the potential species distributions and their possibilities for assisted migration inside México and worldwide.
We performed demographic censuses, field surveys in search for new stands, and developed distribution models for Last Glacial Maximum (22,000 years ago), Middle Holocene (6,000 years ago), current (1961-1990) and future (2050 and 2070) periods, for the whole Mexican territory (considering climatic, soil, geologic and topographic variables) and for all global land areas (based only on climate).
Our censuses showed populations of 89,266 and 39,059 individuals for P. martinezii and P. mexicana, respectively, including known populations and new stands. Projections for México indicated somewhat larger suitable areas in the past, now restricted to the known populations and new stands, where they will disappear by 2050 in a pessimistic climatic scenario, and scarce marginal areas (p = 0.5-0.79) remaining only for P. martinezii by 2070. Worldwide projections (based only on climate variables) revealed few marginal areas in 2050 only in México for P. martinezii, and several large areas (p ≥ 0.5) for P. mexicana around the world (all outside México), especially on the Himalayas in India and the Chungyang mountains in Taiwan with highly suitable (p ≥ 0.8) climate habitats in current and future (2050) conditions. However, those suitable areas are currently inhabited by other endemic spruces:
Picea smithiana (Wall.) Boiss and
Picea morrisonicola Hayata, respectively.
Assisted migration would only be an option for P. martinezii on scarce marginal sites in México, and the possibilities for P. mexicana would be continental and transcontinental translocations. This rises two possible issues for future ex situ conservation programs: the first is related to whether or not consider assisted migration to marginal sites which do not cover the main habitat requirements for the species; the second is related to which species (the local or the foreign) should be prioritized for conservation when suitable habitat is found elsewhere but is inhabited by other endemic species. This highlights the necessity to discuss new policies, guidelines and mechanisms of international cooperation to deal with the expected high species extinction rates, linked to projected climate change.