地球脉动（2006）

行星地球
我们星球上1/3的陆地是沙漠
A third of the land on our planet is desert.
这些地球脸上的大伤疤看似毫无生机
These great scars on the face of the Earth appear to be lifeless,
然而令人吃惊的是并非如此
but surprisingly none are.
在所有沙漠中 生命总能以某些方式闪现
In all of them life manages somehow to keep a precarious hold.
沙 漠
沙漠并非都是炎热的
Not all deserts are hot.
英配解说：大卫·爱登堡
西伯利亚的寒风以50英里的时速
Fifty-mile-an-hour winds blowing in from Siberia
夹杂着风雪横扫蒙古戈壁沙漠
bring snow to the Gobi Desert in Mongolia.
虽然夏季气温高达50℃
From a summer high of 50 degrees centigrade
但是到了冬至却能降至零下40℃
the temperature in midwinter can drop to minus 40,
使得这里成为一片最荒凉的沙漠
making this one of the harshest deserts of all.
只有少许动物能适应 这种极端的气候变化
Few animals can survive these extreme changes.
野双峰驼
Wild Bactrian camels,
一种地球上最稀有的哺乳动物
one of the rarest mammals on the planet.
可能也是最坚韧的动物
And perhaps the hardiest.
它们最大的困难莫过于缺水
Their biggest problem is the lack of water,
尤其是现在——冬天
particularly now, in winter,
那里仅有的一点水也结成了冰
when the little there is is locked up as ice.
奇怪的是 这里的雪永远都不会融化
Surprisingly, snow here never melts.
又冷又干的空气使它们无法解冻
The air is just too cold and too dry for it to do so.
阳光把它们直接变成了水蒸气
The sun's rays turn it straight into vapour.
它们升华了
It evaporates.
可是这是唯一的水源
But it is the only source of water,
所以双峰驼只能吃雪
so Bactrian camels eat it.
在世界上其它地方
Elsewhere in the world
一只骆驼找到水坑后 能一次喝下200升水
a camel at a waterhole can drink as much as 200 litres during a single visit.
但在这里的饮水策略却是少而频繁
Here the strategy is to take little and often.
这当然有充分的理由
And with good reason,
因为肚子里装满雪将是致命的
for filling the stomach with snow could be fatal.
骆驼必须限定自己 每天只能吃10升左右的雪
The camels must limit themselves to the equivalent of just 10 litres a day.
冬季是交♥配♥时节
Winter is the time for breeding.
这种奇怪的表演是公双峰驼 吸引路过的母骆驼的一种方式
This extraordinary performance is a male Bactrian camel's way of attracting the attention of a passing female.
在夏天 骆驼不能远离水坑
In summer the camels can't stray far from waterholes.
可是现在 遍地都是唾手可得的雪
But now, with mouthfuls of snow lying everywhere
它们便能长途跋涉寻找配偶
they can travel widely in search of mates.
今天 这些沙漠专家的 野生数量已不足1000只
Today less than a thousand of these desert specialists remain in the wild.
戈壁尽管环境险恶 却是它们最后的据点
The Gobi, hostile though it is, is their last stronghold.
别的沙漠都和戈壁不太一样
There's no other desert quite like the Gobi,
为什么这里会成为沙漠呢
but why is this place a desert?
这里有一个简单而又重要的原因
There is one simple and massive cause -
喜马拉雅山脉
the Himalayas.
从南方过来的暖湿气流 撞上了这面巨大的屏障
Clouds blowing from the south hit this gigantic barrier.
在被迫抬升的过程中
As they're forced upwards
水汽在山坡上逐渐凝结
so they empty their moisture on the mountain slopes,
只有一小部分到达另一边的土地
leaving little for the land on the other side.
从太空中看 沙漠非常显眼
From the space deserts are very conspicuous.
绵延数百英里的沙丘像是一条条皱边花纹
Dunes of sand hundreds of miles long streak their surface.
由于没有植被覆盖
With no cloak of vegetation to conceal them
赤♥裸♥的岩石显露出奇特的造型
strange formations are exposed in the naked rock.
非洲的撒哈拉沙漠是世界上最大的沙漠
Africa's Sahara is the largest desert of all.
它的面♥积♥相当于美国
It's the size of the United States
也是全世界最大的沙尘源
and the biggest source of sand and dust in the entire world.
如此巨大的沙暴出现时毫无征兆
Sandstorms like these appear without warning
所到之处能见度骤降为零 几天内横扫的地区比英国还大
and reduce visibility for days over areas the size of Britain.
单峰驼——只有一个肉峰的骆驼 顶着沙暴大步行走
Dromedaries, single-humped camels, take these storms in their stride.
最重的沙子只能离开地面几米
The heaviest sand rises only a few metres above the ground,
但是尘埃却能被吹上5000多米高的天空
but the dust can be blown 5,000 metres up into the sky.
夹杂着沙粒的强风
The ferocious wind, armed with grains of sand,
塑造了各种沙漠地形
is the agent that shapes all deserts.
爬行动物的皮肤覆盖着鳞甲 能抵御刺痛的沙粒
Reptiles have armoured scaly skins that protect them from the stinging grains.
而昆虫则得遭受猛烈“炮火”的轰击
For insects the bombardment can be very severe indeed.
唯一的藏身之处当然是在沙子下面
The only escape is below the surface.
随着风的起落、侵蚀和旋绕
As the winds rise and fall, swallow and eddy
沙子被堆成了一座座沙丘
so they pile the sand into dunes.
这些沙漠布景可宽达数百英里
These sand scenes can be hundreds of miles across.
在纳♥米♥比♥亚♥ 风塑造了 一些世界上最大的沙丘
In Namibia the winds have built some of the biggest dunes in the world.
这些巨型沙丘高达300多米
Star dunes like these can be 300 metres high.
斜坡上吹起的沙粒 在沙丘顶部的边棱处飞扬
Grains, swept up the flanks, are blown off the crests of the ridges
所以沙丘移♥动♥的部分只是顶部
so it's only the tops that are moving.
这些沙丘的主体 可能已有5000多年未曾移♥动♥
The main body of these dunes may not have shifted for 5,000 years.
岩石很难抵挡风沙持续不断的摧残
Few rocks can resist the continuous blast of the sand carrying wind.
这些石头如今矗立在埃及的白色沙漠中
These outcrops are standing in Egypt's White Desert.
但它们也坚持不了多久
But they will not do so for much longer.
它们正被无情地凿碎 变成更多的沙粒
They're being inexorably chiseled away and turned into more sand.
现在 这些严重侵蚀的石块 已被放逐在沙海之中
Now lumps of heavily eroded rocks have been marooned in a sea of sand.
这些高达100多米的锯齿般的石锥
These jagged pyramids a hundred metres tall
曾经是一整块岩石高地的一部分
were once part of a continuous rocky plateau.
强悍的风沙最终将使它们完全消失
The blasting sand will eventually eliminate them altogether.
风的无情力量总是使沙漠的面貌不断改变
The relentless power of the wind ensures that the face of a desert is continually changing.
但是有一样东西永远都会存在
But there is one constant presence -
沙漠的太阳
the desert sun.
太阳的热力使水蒸发
The sun's heat and power to evaporate water
这对所有生活在这里的动物的 身体和习性都有极其深远的影响
has had a profound effect on the bodies and habits of everything that lives here.
在这里 太阳将会成为杀手
This sun potentially is a killer.
红大袋鼠必须意识到这一点
And the red kangaroos must acknowledge that.
此时 太阳还未升起
Right now, while the sun is low,
并没有直接危及到生命
there's no immediate cause for concern.
但是这种情况不会持续多久
But this situation won't last long.
澳大利亚是世界上最干旱的大♥陆♥ 整个白天酷热难当
Australia is the world's most arid continent with blistering daytime temperatures.
每过一小时 气温就将升高5℃
Every hour the temperature rises by five degrees centigrade.
热度很快就会达到临界点
Soon the heat will reach a critical point.
任何一只呆在外面的袋鼠 都将面临中暑的威胁
Any kangaroo out in the open is in serious danger of overheating.
待到阳光最毒辣之时 地面温度已升高至70℃
In the full sun the temperature on the ground soars to 70 degrees.
到了正午 太阳的炙焰 迫使它们不得不寻找庇荫处
By midday the radiation is so intense they must take shelter.
在树荫下 它们虽然避开了太阳的能量
In the shade they're shielded from much of the sun's energy
但它们的体温仍在升高
but their body temperature can still rise.
所以它们将唾液抹在前臂上
So they lick saliva on to their forearms
那里的血管网比较贴近皮肤表层
where there is a network of blood vessels close to the surface of the skin
因此 当唾液蒸发时 血液也能得到冷却
and, as the saliva evaporates, their blood is cooled.
这幅热影像能证明这种方法非常有效
This thermal image shows just how effective the process is.
身上蓝色的部分是较冷的部位
The blue areas on the body are the cooler parts.
唾液干了之后还得重新抹上
As the saliva dries it has to be replaced
袋鼠真正排放出去的体液也就是这些
and this is a real drain on the kangaroo's body fluids.
即使是在树荫下 土地照样被烤得火热
Even in the shade the earth is baking hot
于是袋鼠刨去灼烫的表层沙土
so the kangaroos dig away the warmed topsoil
贴近下面较冷的地面
to get at the cooler ground beneath.
通过呆在树荫下 并利用舔唾液的方法控制体温
By staying in the shade and licking to control their body temperature
袋鼠便能熬过一天中最热的时段
kangaroos manage to get through the hottest part of the day
而不至于中暑
without heat stroke.
但是对于大多数沙漠动物来说
But for the majority of desert animals
光凭这些手段还不足以在此生存
this strategy would not be enough for survival.
非洲的耳廓狐长有奇特的大耳 它们能散发热量
The extraordinary ears of the fennec foxes of Africa radiate heat
不过动物也有其它保持凉爽的方法
but the animals have another way of keeping cool.
它们白天呆在地下
They spend their days underground
直到日落之后才会出现
and only emerge at sunset.
夜晚的情况变得很不一样
Darkness brings huge changes.
在撒哈拉沙漠中 晚上的气温会下降整整30℃
In the Sahara the temperature can drop as much as 30 degrees during the night,
在如此凉爽的时候 小耳廓狐也能尽情玩耍
so it's cool enough to allow these desert fox cubs to play.
此时各种各样的动物都开始现身
All sorts of creatures now appear
包括一些意想不到的动物
including some really unexpected ones.
蟾蜍长着透水的皮肤
Toads have permeable skins
若是在白天的高温下 它们很快就会因为脱水而死
and would quickly die from desiccation out in the daytime heat.
所以只有到了晚上它们才能离开庇护所
It's only now that they can leave shelter.
蝎子也是同样的情况
The same is true for scorpions,
尽管它们的外壳其实并不透水
even though their shells are actually watertight.
事实上 大多数小型沙漠动物 都是夜行动物
In fact, most small desert creatures are nocturnal.
所以只有此时你才能判断 沙漠中究竟有多少生物
so it's only now that you can judge just how much life there can be in the desert.
可是水分在晚上也会损耗 必须在什么时候想办法补充
But moisture, lost even at night, has to be replaced sometime somehow
这一问题支配着所有沙漠动物的生活
and that problem dominates the lives of all desert dwellers.