生境丧失对具有似Allee效应集合种群的影响及对策——以江苏盐城为例

似Allee效应对物种续存是潜在的扰动因素,稀有物种更易受其影响,可能增加生存于破碎化栖息地中的珍稀物种的死亡风险;但似Allee效应对多物种集合种群续存的影响及其在珍稀物种保护中的应用未能引起足够重视。将似Allee效应引入集合种群动力模式,建立了生境丧失下具有似Allee效应的n-珍稀物种的集合种群模式,并以江苏盐城滩涂湿地中的29种珍稀物种为研究实例。研究结果表明:(1)似Allee效应导致n-物种集合种群多度作长期变周期振荡,原本竞争共存物种可能无法继续共存,甚至灭绝。(2)似Allee效应增强对次强种及劣势种的生存极为不利,导致次强物种由强至弱灭绝,劣势物种由弱至强依次灭绝。(3)盐城天然湿地丧失29%后,11种劣势物种的集合种群由弱到强将最终依次灭绝,灭绝迟豫时间为304～890a,这些物种即Hanski所指的"活死者"。(4)适度增加栖息地面积是保护珍稀物种多样性的有效方法之一,在盐城现存3200km2的天然湿地基础上适度增加1801～2064km2左右栖息地面积,可以有效保护29种濒危物种的多样性,同时应注意结合针对具体物种的保护措施来提高濒危物种多度。研究结果对物种多样性保护及自然保护区建设具有重要的理论指导意义。

Impact of wetland loss on metapopulation with the Allee-like effect and the strategy: a study case of Yancheng in Jiangsu Province

The Allee-like effect is a destabilizing factor in species persistence.Rare animals are more susceptible to the effect as it will increase extinction risk of those rare living in fragmented habitats.But so far there is still no adequate attention paid to its influence on multi-metapopulation and its application for rare biological conservation.In this paper,the Allee-like effect is introduced into a dynamical metapopulation model of multi-species under habitat loss to study the 29 rare species living in Yancheng wetland of Jiangsu Province.By means of numerical simulation,we demonstrate that:(1) Allee-like effects result in periodic fluctuation of metapopulation abundance of multi-species so that coexistence may become impossible and species could even go extinction.(2) Severe Allee-like effect is disadvantageous to the persistence of several sub-dominant and inferior metapopulation,and the severer the Allee-like effect is,the shorter the extinction time will be.(3) In the case of 29% of Natural wetlands lost in Yancheng,the metapopulation of 11 rare species will go extinct from the poorest to stronger with a time delay of 304-890 years in response to the past habitat loss,and these bound to extinction are the typical 'living dead' as named by Hanski.(4) As for the reservation strategies,an adding of about 1801-2064 km2 habitat restoration would effectively guarantee the persistence of all the 29 kinds of rare metapopulation on the base of the existing 3200km2 natural wetlands,and at the same time,other protection measures should be taken to increase the metapopulation abundance of those rare species.Our results can be helpful for species diversity conservation and provide theoretical guidance to nature reserve construction.