第三册第3篇：自然平衡

3 Balance of Nature 自然平衡

All the different plants and animals in a natural world are in a state of balance. This balance is achieved by the plants and animals interacting with each other and with their non-living surroundings. An example of a natural community is woodland, which is usually dominated by a particular species of plant, such as the oak tree in an oak wood. The oak tree in this example is therefore called the dominant¹ species but there are also many other types of plants, such as bushes, small trees, mosses², lichens³ and algae⁴.
自然界所有不同的植物和动物都处于平衡状态。这种平衡是通过植物和动物互相作用，以及它们与非生命环境互相影响取得的。例如，林地是一个自然生物群落，它通常由一特定种类的植物所主导，比方说橡树林里的橡树。此例中的橡树因而被称为优势物种，但也有许多其他种类的植物，像灌木、小树、苔藓、地衣和藻类。

The plants of a community use carbon dioxide, oxygen, water and nitrogen to build up their tissues using energy in the form of sunlight. The plant tissues form food for the plant-eating animals which are in turn eaten by the flesh-eating animals. Thus plants produce the basic food supply for all the animals of a community. The animals themselves are the consumers, and are either herbivores or carnivores.
植物群落利用二氧化碳、氧气、水和氮生成能吸取阳光能量的组织。植物组织成为食草动物的食物，食肉动物又以食草动物为食。这样植物为生物群落里的所有动物提供了基本的食物。动物自身是取食者，或为食草动物，或为食肉动物。

Examples of herbivores in a woodland community are rabbits, deer, mice, snails⁵, and insects. The herbivores are sometimes eaten by the carnivores. Woodland carnivores are of all sizes, from insects to animals like owls⁶, and foxes. Some carnivores feed on herbivores, some feed on the smaller carnivores, while some feed on both. These food relationships between the different members of the community are known as food chains or food webs. All food chains start with plants. The links of the chain are formed by the herbivores that eat the plants and the carnivores that feed on the herbivores.
举例来说，林地生物群落里的草食动物有兔子、鹿、老鼠，蜗牛以及昆虫，它们不时被食肉动物吃掉。林地里的食肉动物有大有小，从昆虫到猫头鹰和狐狸这样的动物。有些食肉动物捕食食草动物，有些吃更小的食肉动物，还有一些两种都吃。生物群落里不同物种间的食物关系称为食物链或食物网。所有的食物链均开始于植物。食物链的链环是以植物为生的食草动物和捕食食草动物的食肉动物。
 

1 dominant   

adj.支配的，统治的；占优势的；显性的；n.主因，要素，主要的人(或物)；显性基因

参考例句：

• The British were formerly dominant in India.英国人从前统治印度。
• She was a dominant figure in the French film industry.她在法国电影界是个举足轻重的人物。

2 mosses   

n. 藓类, 苔藓植物 名词moss的复数形式

参考例句：

• Ferns, mosses and fungi spread by means of spores. 蕨类植物、苔藓和真菌通过孢子传播蔓生。
• The only plants to be found in Antarctica are algae, mosses, and lichens. 在南极洲所发现的植物只有藻类、苔藓和地衣。

3 lichens   

n.地衣( lichen的名词复数 )

参考例句：

• The only plants to be found in Antarctica are algae, mosses, and lichens. 在南极洲所发现的植物只有藻类、苔藓和地衣。 来自辞典例句
• Litmus: Mixture of coloured organic compounds obtained from several species of lichens. 石蕊：从几种地衣类植物中获取的带色有机化合物的混合物。 来自互联网

4 algae   

n.水藻，海藻

参考例句：

• Most algae live in water.多数藻类生长在水中。
• Algae grow and spread quickly in the lake.湖中水藻滋蔓。

5 snails   

n.蜗牛；迟钝的人；蜗牛( snail的名词复数 )

参考例句：

• I think I'll try the snails for lunch—I'm feeling adventurous today. 我想我午餐要尝一下蜗牛——我今天很想冒险。 来自《简明英汉词典》
• Most snails have shells on their backs. 大多数蜗牛背上有壳。 来自《简明英汉词典》

6 owls   

n.猫头鹰( owl的名词复数 )

参考例句：

• 'Clumsy fellows,'said I; 'they must still be drunk as owls.' “这些笨蛋，”我说，“他们大概还醉得像死猪一样。” 来自英汉文学 - 金银岛
• The great majority of barn owls are reared in captivity. 大多数仓鸮都是笼养的。 来自辞典例句