大裂谷：美丽的非洲心脏（2010）

3000万年前
30 million years ago,
非洲茂密的热带丛林
tropical Africa was covered in dense jungle.
但已经没剩多少了
But not any more.
在东非
Here in East Africa,
森林已经销声匿迹
the forest has all but vanished,
一个完全不同的自然生态
a changed landscape that is the stage
草原正上演着最壮丽的野生动物的故事
for the most epic wildlife story on the continent.
还有森林
And it begins in the forest.
黑猩猩完全适应了树上的生活
Chimpanzees are perfectly adapted for life in the trees.
它们采集树上所有能吃的食物
They gather almost all their food from the canopy.
这些黑猩猩生活在乌干达的Kyambura峡谷
But these chimps live in the Kyambura Gorge of Uganda,
有时，它们也会开始一段奇异的旅程
and will sometimes embark on an unusual journey.
它们的家园，在这片狭长的林地
Their home, in this narrow strip of forest,
周边是广袤开阔的稀树草原
is surrounded by vast, open savannas...
..富饶的草原郁郁葱葱
..mile after mile of rich, grass-covered plains.
黑猩猩在森林和草原之间的边缘生活
Living on the border between forest and savanna means the chimps
有时它们也会很兴奋地进入草原觅食
sometimes venture into this new and exciting habitat in search of food.
但它们并不喜欢开放型的草原
But they don't feel comfortable in the open grasslands,
所以它们只会觅食几个小时，然后便匆匆返回森林
so only forage for a few hours at a time before returning to the forest.
然而，对于无数的其他物种，这是新的栖息地
However, for countless other species, this new habitat,
东非平原，已经成为它们生存的根本所在
the East African plains, has become fundamental to their survival.
那么如何才能在非洲这片瞬息万变的土地上活得精彩呢?
So how did this part of Africa change so dramatically?
3000万年前，当丛林仍然笼罩的非洲大♥陆♥
30 million years ago, when the jungle still shrouded the continent,
一个巨大的熔岩柱推动着东非高原
a vast plume of molten lava pushed up beneath the plateau of East Africa.
在巨大的压力下，地壳开始裂开
The Earth's crust cracked under the strain,
形成了非洲大裂谷
creating Africa's Great Rift.
大量的火山岩沿着裂缝喷发
Great volcanoes sprang up along the rift,
并引发了连锁反应
and triggered a chain of events
永远的改变了自然生态的面貌
that changed the face of the landscape for ever.
RUMBLING
RUMBLING
伦盖伊火山现在还是一座活火山
Ol Doinyo Lengai is still an active volcano.
马赛人称之为“上帝之山”
Its Masai name means "Mountain of the Gods".
它最近一次爆发的火山灰像地毯一样把下面的草原铺盖了厚厚一层
Its latest eruption covered the plains below in a blanket of thick ash.
火山灰对周围的植被有着深远的影响
Ash has a profound effect on the surrounding vegetation.
它像混凝土一样坚硬
It dries harder than concrete.
树根顽强的透过如此坚实的土地来吸收养分
It's so solid that tree roots struggle to grow through it.
东非大裂谷巨大的沟壑
Huge swathes of East Africa's Great Rift
覆盖着树抗性火山灰...
are covered in tree-resistant volcanic ash...
..在从东侧的坦桑尼亚北部延伸到肯尼亚
..stretching on the east side from Tanzania into northern Kenya,
并沿着较短的西部裂谷一直到达乌干达峡谷谷底
and along the arm of the shorter Western Rift up the valley floor of Uganda.
上升的裂谷不仅创造了高耸的火山
The rising rift valley not only created towering volcanoes,
还激起了一系列壮观的山脉群
it forced up great chains of mountains like these,
强大的鲁文佐里山
the mighty Ruwenzori.
它们高耸入云3英里
They stand three miles high,
像所有大裂谷高原
and like all the great highlands of the Rift,
它们对当地的气候，有着巨大的影响
they have a huge effect on the local weather
也就是说，对周围的植被也有影响
and, in turn, the surrounding vegetation.
云雾从刚果河流域的丛林湿地
Mist and cloud rolls in from the drenched jungles of the Congo Basin
径直飘到西部的鲁文佐里山
that lie directly west of the Ruwenzori.
温暖潮湿的空气直往山上串升
Warm, moist air rises up the mountains.
因此，冷却后凝结成的雨水，最后落在山坡上
As it does, it cools, so most of the moisture falls on the slopes,
和东部平原的部分地方
and little rain reaches the plains to the east.
大裂谷和火山灰的独特组合限制了降雨的区域
It's the Rift's unique combination of restricted rain and volcanic ash
就凝聚在海湾的森林
that keeps the forests at bay.
但其他的地方现在是一个杀戮战场
But the space left behind is now a battleground.
为了争当平原的霸主，两者之间时刻进行着无休止的争斗
Two determined colonisers fight to stake their claim on the plains.
有一个相当小的竞争者
One competitor is rather small and unassuming -
草...
grass...
RUSTLING
..它的竞争者大树，仍然存活在大草原上...
..its challenger the only tree that still holds out for its place in the savannas...
..非洲刺树-相思树
..the thorn tree of Africa- the acacia.
它能够存活，是因为它的根基很浅
It's able to cope because its shallow roots
可以从地面的泥土中提取水分
can extract any moisture from the soil above the hard ash pan...
..细小的叶子可以减少因蒸发而丢失水分
..and its tiny leaves reduce water lost by evaporation.
它很成功，并能张到6米高
It's so successful, it can grow six metres tall.
而且是肉食动物所需要的
But it has a predator to match.
相思树的小叶子营养不多
The acacia's small leaves are nutritious enough
不足以满足世界上最高的动物...
to support the world's tallest antelope...
..它高耸的身形，可以到达别的动物无法触及的高度
..lofty enough to exploit a niche that no others can reach.
对于相思树的树冠，不仅可以自上而下的吃
But the acacia crown is not only attacked from the top down,
而且可以自下而上的吃
but also from the bottom up.
非洲瞪羚有很适合的骨骼
The gerenuk has a skeleton that's adapted
使它可以每天都站立着吃食物
to enable it to spend all day standing on its hind legs.
但是高度并不是解决相思树的唯一途径
But height isn't the only key to unlock the acacia's defences.
地克羚羊是非洲最矮小的羚羊之一
The dik-dik is one of Africa's shortest antelopes.
它够不着很高的冠，只能在地面
It can't reach the high crown, and at ground level,
长满刺的相思树是它们的最爱
the acacia thorns are at their fiercest.
但地克羚羊的小脑袋很适合在荆棘间觅食
But the dik-dik's tiny head fits perfectly between the spikes,
因此，相思树的各个角度都遭到了攻击
and so the acacia is attacked from every angle.
相思树几乎可以解决这种啃咬带来的影响
The acacia can just about cope with the impact of nibblers like these,
但有一个重量级的家伙可不是来吃点心的
but there's one heavyweight that does more than just snack.
LOW-PITCHED RUMBLING
相思树幼苗被连根拔起
Seedling acacias are simply annihilated
由世界上最重的素食主义者
by the world's heaviest vegetarian.
但是，大树可能也并不安全
But adult trees aren't safe, either.
大象的鼻子不太适合选择单片叶子
The elephant's trunk is sensitive enough to select individual leaves...
..但足以折断树枝
..but strong enough to rip off entire branches.
它可以用象牙和鼻子举起很重的木头
The combination of tusk and trunk makes short work of heavy wood...
..重达3吨♥的庞大身躯看上去像推土机一样
..and a three-tonne body makes an effective bulldozer.
一头非洲大象只需一天就能彻底解决一棵大树
A single African elephant can flatten a tree a day.
同时，在裂谷大草原上的大象超过15万头...
And in the savannas of the Rift, the herds number over 150,000...
..完全能够消灭整片相思树林地
..capable of wiping out entire acacia woodlands.
这种规模的破坏在草原上至关重要
Landscape gardening on this scale plays an important role
这是在帮助相思树的竞争对手——草
in helping the acacia's competitor, grass.
大象50%食物来自于草，因此它也是在为自身的利益
Grass makes up over 50% of an elephant's diet, so it's in their own interests
而清除树木，以增长草的生长空间
to clear the trees and maintain space for grass to grow.
草不像其他植物，它长有穿透力很强的根
Grass, unlike other plants, grows from its roots instead of the tip.
这使得它的再生能力惊人
This gives it astonishing powers of regeneration.
同时也意味着它几乎可以不断生长 -
It also means it can be almost constantly cropped -
永无止尽的供给食物
a never-ending supply of food.
这种坚不可摧的植物接管了大裂谷平原
This indestructible plant has taken over the Rift Valley plains.
它拥有最大的数量和多样性
It supports the greatest numbers and diversity
在大型食草动物的世界里
of large grazers in the world.
SNORTING
但它有一个缺陷
But there is a downside.
草很快的生长, 因此食草动物才有大量的草消耗
Grass is hard to process, so grazers have to consume vast amounts.
那是一个大群体，大群体需要一个大草原
That means big guts, and big guts need a big body.
食草动物每天吃草的时间长达16个小时
A diet of grass also means eating for up to 16 hours per day,
只留下很少的时间去做其他的事情
and that leaves little time for the other important tasks.
这些是乌干达赤羚
These are Uganda kob,
西部裂谷最多的羚羊
the most abundant antelope in the Western Rift Valley.
发现它们时，它们都沉溺于惊人而复杂的求偶仪式
Somehow they find time to indulge in a surprisingly complex mating ritual.
赤羚有一个专门的繁殖地, 它们都知道的竞偶场
The kob have a dedicated mating ground, known as a lek.
雄赤羚聚集在一起，展示它自己的势力
It's where males gather to flaunt themselves,
并在前来的雌性中挑选伴侣
and the females turn up to pick a mate.
雄性要占有最佳地点
The males want to hold the best spot.
为了赢得它，必须加倍努力
To win it, they have to fight.
这可以给所有雌性留下深刻印象
It's all to impress the ladies,
它们选择伴侣时都很挑剔
who are very picky when it comes to choosing the right mate.
雌性会选择有最佳血统的雄性♥交♥配
The females are after the buck with the best blood -
最强壮的雄赤羚,拥有最令人羡慕的地位
the strongest male, holding the most coveted position
求偶时的优先权
right in the middle of the lek.
雌性选择了它的配偶,然后允许雄性
The female chooses her mate, and then allows him
测试它的荷尔蒙气味，以确认它准备交♥配♥
to test her scent for hormones to confirm she's ready to mate.
雌性的发♥情♥期只有20天左右
A female comes into season every 20 days or so,
但交♥配♥只需要几个小时
but is only receptive for a couple of hours,
因此它们没有多少时间调情
so there's not much time for flirting.
交♥配♥结束. 基因延续完成
Job done. The exchange of genes is complete.
WHISTLING CALL
CALLS AGAIN
现在，雌性缓和了拥护者的保护
Now the female can relax under the protection of her champion.
它有一个在选择后的较似有的因素
There is a selfish reason behind her choice.
强壮的雄性中间其实是最安全的地方