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第51章 北极地区的苔原

These are the signs of the coming arctic winter:The color of the tundra changes as the water grasses turn brilliant red。The migratory birds gather in flocks along the coast and gradually drift southward。Most of the birds that have spent the brief summer on the tundra now disappear,leaving only the golden eagle,the gyrfalcon,the ptarmigan,and the snowy owl to brave the sunless northern winter。

As the lakes and ponds freeze over,a thin mantle of snow covers the sedge。Occasionally a young and inquisitive arctic fox may be seen loping across the tundra。The weasel and the lemming begin to change color;as the winter deepens,their coats will turn snow white。

During the first week in August the arctic sun dips below the horizon for the first time since May-it has not set all summer long。The gold and purple sunsets color the subfreezing waters of the Arctic Ocean。

By the end of September or early October the tundra is dark and seems deserted;winter has taken hold of the arctic for another nine long months。

这些都是北极地区冬季即将来临的征兆:随着水草变成艳红色,北极苔原的颜色也改变了;候鸟沿着海岸成群聚集,并逐渐南移;在苔原度过短暂夏天的大部分鸟类现已消失,只剩下金鹰、白隼、松鸡和雪白色的猫头鹰来迎接这没有太阳的北极之冬。

随着湖泊、水塘全部冰封,蓑衣草披上了薄薄的一层雪衣,也许偶而能见到一只好奇的北极幼狐慢跑着越过苔原。黄鼠狼和旅鼠开始改变颜色,随着深冬的来临,它们的毛皮将会变成雪白色。

8月的第一个星期,北极的太阳自5月以来第一次沉入地平线以下——整个夏天太阳都没有落山。金色和紫色的夕阳把冰点以下的北冰洋水染成了五颜六色。

9月底或10月初,苔原是黑暗的,似乎是一片荒芜;冬天在长达9个月的时光中又主宰了北极。

Tundra n。冻原,苔原(欧、亚、北美辽阔平坦的北极地带,不生树木,土壤下层常年冰冻)

Flock n。(同一种的羊或鸟的)一群:e。g。a flock of wild geese 一群雁flocks(of sheep)and herds(of cattle)羊群和牛群。

Drift v。飘移;漂流

Mantle n。覆盖物:e。g。hills with a mantle of snow 覆盖着一层雪的山

Inquisitive adj。爱管闲事的

Lope v。跳跃着大步跑

Weasel n。黄鼠狼

Dip v。向下倾斜

苔原也叫冻原,是生长在寒冷的永久冻土上的生物群落,是一种极端环境下的生物群落。苔原多处于极圈内的极地东风带内,风速极大,且有明显的极昼和极夜现象。苔原生物对极地的恶劣环境有很多特殊的适应。苔原植物多为多年生的常绿植物,可以充分利用短暂的营养期,而不必费时生长新叶和完成整个生命周期,但短暂的营养期使苔原植物生长得非常缓慢。