纪录片《我们的地球》 第338期 广袤草原(3)(在线收听) |
Grasslands occur where rain is too sporadic for forests to exist. 降雨量不足以养育森林时就会出现草原。 The rain that a grassland needs to survive for a year might arrive all at once. 草原生长所需的年降雨量可能会一次来临。 Storms like these can release 12 inches of rain in 24 hours. 这样的暴雨在24小时内能达到300毫米降雨量。 Not much fun if you're out in it. 淋起来可不好受。 Eventually the earth can't soak up any more, and the grassland undergoes a radical change. 最终土壤无法继续吸收雨水,草原也完全变了样子。 Many plants would drown here, but grasses thrive. 许多植物会被淹死,而草本却会茁壮生长。 They grow so fast, their leaves quickly rise above the water and into the sunlight. 它们长得飞快,茎叶迅速伸出水面,沐浴在阳光下。 Here in southern Africa, water transforms one of the most remarkable grasslands on Earth, the Okavango. 在南非,降水能让世界上最奇特的草原之一改头换面,奥卡万戈三角洲。 Every year, 5,000 square miles of grassland are flooded. 每年都有近一万三千平方公里的草原被水淹没。 For one pride of lions, this poses a major problem. 对于狮群来说,这成了最大的问题。 |
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