象科动物对当地森林生态系统的影响

现存的象科动物(Elephantidae)分为非洲草原象(Loxodonta africana)、非洲森林象(Loxodonta cyclotis)和亚洲象(Elephas maximus)3 种,作为森林生态系统的关键物种,它们对当地森林生态系统的影响非常复杂,在一定环境条件下,既可能是积极的作用,也可能是消极的作用。积极的作用包括:帮助植物传播种子;促进种子萌发;创造断层,维持群落多样性;为其他动物增加食物资源;为其他动物创造栖息地。消极的作用包括:使一些物种的种群数量减小;使森林变成灌木丛和草原等。而由于活动受限导致的种群密度过高是象科动物对森林生态系统产生消极作用的主要原因。当前象科动物的3 个物种均面临种群数量锐减和生存空间不断缩小的危机,为此迫切需要针对其对生物多样性和生态平衡的影响开展深入和全面的研究,并且应根据实际情况因地制宜地制定管理措施。

The impact on local forest ecosystem by elephants

Current taxonomy recognizes three extant species of elephants (Elephantidae), the African bush elephant Loxodonta africana, the African forest elephant Loxodonta cyclotis and the Asian elephant Elephas maximus. As large herbivores and an excellent keystone species, elephants can cause positive and/or negative impacts on their surrounding environments and these impacts can vary in both temporal and spatial scales. The positive impacts include: improved seed dispersal and germination; creating forest gaps and maintaining community diversity; and enriching food resources and habitat for other animals. The negative impacts include: causing biodiversity loss by reducing locally vulnerable species, and causing habitat degradation by transforming local plant communities from woodlands to shrub lands or grass lands. Population over-abundance by confinement to habitat islands due to habitat loss is mainly responsible for the negative impacts caused by elephants. Simply culling off elephants would not be an effective mitigation strategy to offset their negative impacts and is strongly discouraged. Rigorous scientific information on effective ways to evaluate and alleviate the negative impact of elephants and to guide proper management plans still is lacking. Local environmental conditions and site-specific objectives should be considered when developing management actions to curb the negative impact of elephants on woody vegetation. All elephant species, including African bush elephant, African forest elephant and Asian elephants, are currently facing severe population declines and habit loss. In order to save them from extinction, it is imperative to conduct more comprehensive research to better understand the relationship between elephants and the ecosystems in which they live.