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Ants Have Big Impact on Environment as "Ecosystem Engineers"

　　Research by the University of Exeter1 has revealed that ants have a big impact on their local environment as a result of their activity as "ecosystem engineers" and predators. The study, published in the Journal of Animal Ecology, found that ants have two distinct effects on their local environment.

　　Firstly, through moving of soil by nest building2 activity and by collecting food they affect the level of nutrients in the soil. This can indirectly impact the local populations of many animal groups, from decomposers to species much higher up the food chain.

　　Secondly, they prey on a wide range of other animals, including larger prey which can be attacked by vast numbers of ant workers.

　　Dirk Sanders, an author of the study from the university's Centre for Ecology and Conservation, said:"Ants are very effective predators which thrive in huge numbers. They're also very territorial3 and very aggressive, defending their resources and territory against other predators. All of this means they have a strong influence on their surrounding area."

　　"In this research, we studied for the first time how big this impact is and the subtleties of it. What we found is that despite being predators, their presence can also lead to an increase in density and diversity of other animal groups4. They genuinely play a key role in the local environment, having a big influence on the grassland food web," Sanders said.

　　The study, carried out in Germany, studied the impact of the presence of different combinations and densities of black garden ants and common red ants, both species which can be found across Europe, including in the UK. It found that a low density of ants in an area increased the diversity and density of other animals in the local area, particularly the density of herbivores and decomposers. At higher densities ants had no or the opposite effect, showing that predation is counteracting the positive influence.

　　Dr Frank van Veen, another author on the study, said:"What we find is that the impact of ants on soil nutrient levels has a positive effect on animal groups at low levels, but as the number of ants increases, their predatory impacts have the bigger effect — thereby counteracting the positive influence via ecosystem engineering."

　　Ants are important components of ecosystems not only because they constitute a great part of the animal biomass5 but also because they act as ecosystem engineers. Ant biodiversity6 is incredibly high and these organisms are highly responsive to human impact, which obviously reduces its richness. However, it is not clear how such disturbance damages the maintenance of ant services to the ecosystem. Ants are important in below ground processes8 through the alteration of the physical and chemical environment and through their effects on plants, microorganisms, and other soil organisms.

　　词汇：

　　predator /' predətə/ n.食肉动物

　　nutrient/' nju:triənt/ n .营养物;adj.营养的

　　decomposer/,di:kəm'pəuzə/ n.腐生物;分解体

　　prey/prei/ v.捕食;n.被捕食的动物

　　subtlety/ 'sʌtlti/ n ，微妙，精妙

　　herbivore/ 'hʒ:bivɔ: / n .食草动物

　　注释：

　　1.the University of Exeter ：埃克斯特大学。1851 年建校，位于英国西南部重要商业中心埃克斯特市，是英国的传统大学之一。

　　2. nest building ：筑巢

　　3. territorial ：领地的。在此用来形容蚂蚁的本性，即具有很强的领地意识，并且会竭尽全力保卫自己的领地。

　　4. an increase in density and diversity of other animal groups ：其他动物群体在数量和品种上的增长。

　　5. biomass ：物质名词，由bio和mass 两部分组成，意为“生物量”“生物质”。

　　6. biodiversity ：物质名词，由bio和diversity 两部分组成，意为“生物多样性”。

　　7.the maintenance of ant services to the ecosystem ：蚂蚁对生态系统的维护作用。

　　8. below ground processes ：土壤下面的(工作)过程，即影响生态环境的过程。

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