不同生境毁坏速度下的物种灭绝机制

The mechanism of species extinction under habitat destruction at different rates

已有似Levins的多物种模型,在研究生境毁坏的影响时,一方面主要集中在对瞬间毁坏影响的研究,另一方面主要研究生境毁坏对强物种影响的研究。在Tilman的多物种竞争共存模型的基础上,同时考虑了生境毁坏直接效应和生境毁坏时间异质性,提出了全新的普适的多物种竞争共存的非自治动力模式。通过模拟物种灭绝对不同速度的生境毁坏时间异质性的响应发现:(1)物种灭绝既存在强物种由强到弱的灭绝,也存在弱物种由弱到强的灭绝。同时,弱物种灭绝机制进一步分为弱物种瞬间集体灭绝,以及较长时间由弱到强的灭绝。(2)生境毁坏速度越快,物种灭绝的时间越短,弱物种灭绝的越多,因此,生境毁坏速度越慢,越有利于弱物种的长期续存。(3)最强物种的多度越大,强-强物种抵御生境毁坏的能力越强,而弱-弱物种抵御生境毁坏的能力越弱,集体灭绝的弱-弱物种就越多。最强物种的多度大的群落(如温带森林),主要发生的是弱-弱物种灭绝,而最强物种多度小的群落(如热带雨林)同时发生强-强和弱-弱物种的灭绝。因此,争对不同结构的集合种群,不同的保护对象,应采取不同的管理策略。

Habitat destruction is the primary cause of population, metapopulation and species extinction worldwide. The speeds of habitat destruction and species extinction reach the climax during the past 200 years because of rapid human population growth and advances in technology. The growing rates of this destructive process urge the development of a conceptual framework aiming at understanding the responses of ecosystems to habitat destruction. Many metapopulation models have simulated the consequences of habitat destruction on species diversity and gained many developments. However, those models focus on the effects of instantaneous destruction on species extinction and metapopulation dynamics and ignore the temporal heterogeneity of habitat destruction. So, we have developed a new universal non-autonomous dynamical model of multiple species competition-coexistence, and simulated the responses of species diversity to the temporal heterogeneity of habitat destruction at different rates. The results show that： 1 ） there is not only the extinction of superior competitors ranked from the best to the poorest, but also the extinction of inferior competitors from the poorest to the best. Moreover, extinction of inferior competitors can be further classified into two types ： one is the short-time and mass extinction of inferior competitors, the other is the long-time extinction of inferior competitors from the poorest to the best. 2） The slower habitat destruction is, the more favorable it is to species persistence; 3 ） when q （abundance of the best competitor） is bigger, thernost superior competitors are more vulnerable to extinction; when q is smaller, the most superior competitors and the most inferior competitors are both vulnerable to extinction.