绿色星球（2022）

只有在发生降雨时
and only wakes up and grows for a brief period,
才会短时间苏醒并成长
if and when there is a fall of rain.
我曾亲眼见过很多植物采取这种缓慢生长策略
I've seen evidence of this "grow slow" strategy for myself.
40年前 我曾到美国加州的莫哈维沙漠
40 years ago, I came here to California's Mojave Desert
寻找一株特定的植物
to visit one particular plant.
三齿团香木的繁衍策略
An individual creosote bush
往往不是通过开花结果
tends to spread not by setting seeds
来产生下一代的
and producing a new generation,
而是会从基部周围长出新的茎干
but by sending out new stems around its base.
这株植物的生长应该始于1万到1万2千年前
This plant started growing between 10,000 and 12,000 years ago.
这是1982年的影像
That was in 1982.
人们通过仔细的测量发现 这株植物这些年来的生长量
Since then, careful measurement has shown that it has increased
还不到3厘米
its size by less than one inch.
这种植物的耐旱能力非常惊人
Its ability to endure is truly extraordinary.
三齿团香木能够非常高效地收集稀少的降雨
So efficient is creosote at collecting what little rain
其它植物很少能与之匹敌
falls here, that few other plants can compete with it.
因此 经过了1万2千年的时间
As a result, over the last 12,000 years,
这株植物已经完全主宰了这片区域
it's come to completely dominate this landscape.
墨西哥北部的奇瓦瓦沙漠
The Chihuahuan Desert in north Mexico.
在这里 有一种特殊的植物把等待策略发挥到了极致
Here, one particular plant plays the waiting game so well
以至于生命中的大部分时间看起来像枯死的植物
that it spends much of its life looking dead
当然也就不会被动物吃掉
and certainly not worth eating.
它能以假死状态存活将近10年时间
And it can survive like this for a decade.
这就是鳞叶卷柏
This is the resurrection plant.
它属于卷柏科
It's a kind of moss.
几乎没有什么根 当然也不能储存很多水分
It barely has roots, and it certainly can't store much water,
但它可以移♥动♥
but it can travel.
在经历了特别长时间的干旱之后
After a particularly long drought...
它就会脱离了它的根
..it breaks away from its roots...
变成...
..and becomes...
风滚草
..a tumbleweed.
它不停地穿越荒漠
Blowing across the desert,
可以在一周内移♥动♥一公里多
it can travel a mile in a week.
运气好的话 还可能会找到水源
With luck, it may find water.
些许雨水就能让它焕发生机
Just a shower of rain can bring it back to life.
它的叶子在吸收水分之后就会展开
As its fronds soak up the water, they unfurl.
重重保护下的内芯
In its protected centre,
仍然有绿色的组织
it still has green cells
它可以吸收水分和阳光
which absorb both the water and sunlight
并迅速制♥造♥出植株所需的能量 重新开始生长
and rapidly produce the food it needs to resume its growth.
只要能获得水分 它就能继续生长
It will grow for just as long as there is moisture...
如果环境湿度降低
..but when that disappears...
它又会卷成一团
..it closes up once more
再次踏上旅程
and resumes its travels.
在美国犹他州的峡谷地
Here in the Canyonlands of Utah
生长着一种植物
lives a plant that has developed
它们与当地动物共享这片荒漠
a finely-balanced relationship
动植物间建立起了和谐的共生关系
with the animals with which it shares this dramatic desert.
这里偶尔会下雨
Rain does occasionally fall here
把尘土变成泥土
and turns dust into mud.
但这不会持续很长的时间
But that doesn't last long.
一个短暂的机会之窗打开了
A brief window of opportunity opens.
埋藏在土壤中数年之久的种子
Seeds that have been buried for years
现在终于见到了阳光
may now be exposed to light
并活了过来
and come to life.
这是土狼烟草
This is coyote tobacco.
在短短几周内 它就长到一米高
In just a few weeks, it grows a metre tall
还开出了数十朵鲜花
and produces dozens of flowers.
夜晚的空气中飘荡着它浓郁的花香
The night air becomes heavy with their fragrance.
很快 它们就吸引了天蛾
Soon, they attract hawk moths
前来吸食花蜜
which sip their nectar,
并在这过程中给花朵传粉
and in doing so, pollinate them.
但天蛾也会在它们身上产卵
But the moths also lay their eggs on them.
很快 卵孵化成幼虫
Soon, the caterpillars have hatched
开始咀嚼叶片
and are munching the leaves.
植物的组织液因此暴露在干燥的空气中
Their nibbles expose the plant's sap to the drying air.
但是土狼烟草有自己的防御机制
But the tobacco plant has a defence.
受到攻击的叶子会产生尼古丁
The leaves under attack produce nicotine.
这种化学物质可以麻痹天蛾幼虫
This chemical sedates the caterpillars
并让它们变得行动迟缓
and slows them down.
此外 尼古丁还能让幼虫散发出一种特殊的气味
And what is more, it makes them give off a particular scent...
召唤其它动物
..one that summons others
前来支援
to come to the plant's aid.
其中包括
Big-eyed bugs,
两毫米长的迷你杀手 大眼长蝽
miniature assassins, only two millimetres long...
和鞭尾蜥蜴
..and whiptail lizards.
无论体型大小 它们都会以毛毛虫为食
Big or small, they make a meal of the caterpillars.
策略非常有效
It's certainly effective...
但情况远不止看起来那么简单
..but there's more to this strategy than meets the eye.
当土狼烟草的叶子受到天蛾幼虫攻击时
When the leaf of a tobacco plant is attacked by a caterpillar,
所有其余的叶子都会做好防御的准备
all the rest of the leaves prepare to defend themselves.
但是这边的叶子怎么知道
But how does this leaf know
另外一边的叶子受到攻击呢？
that that leaf there is under attack?
好吧 美国当地的科学家
Well, scientists here in the United States
已经对这几株土狼烟草进行了特殊的基因改造
have specially genetically modified these tobacco plants
在特殊灯光的照射下
so that under special lighting conditions,
这台显微镜可以准确地告诉我们发生了什么
this microscope can show us exactly what is going on.
一会我要攻击这株植物其中一片叶子
I'm going to attack one of the leaves of this plant
用这些镊子
with these tweezers which, to the plant,
让它感觉就像被毛毛虫啃咬一样
will seem as if it's being nibbled by a caterpillar.
遭受攻击的叶片
Signals are being transmitted along the veins
通过叶脉与植物其它部分相连 它可以进行信♥号♥♥传递
that link the leaf to the rest of the plant.
这就像一套简化版的神经系统
It's rather like a very simple nervous system.
整株植物
From that initial injury,
从最先受到攻击的叶子得到信息 了解到有危险发生
the whole of this little plant is aware that something has happened.
这种信♥号♥♥ 将警报传递给所有的叶子
This signal warns each leaf of the danger,
这样其它叶子在受到攻击时
so that it is ready to produce nicotine
就可以立即生产尼古丁
the moment it's attacked.
土狼烟草凭借这套防御系统
With this defence at the ready,
得以继续生长
the tobacco plant can continue to grow
直到最终结籽
until eventually, it produces seeds.
荒漠中的植物
It's particularly important in deserts
必须尽量扩大种子的扩散范围
for seeds to be distributed as widely as possible
这样才会使部分种子有接触水源的机会
so that some will have a chance of reaching moisture.
沙漠中有一种非常理想的媒介可以帮它们实现这一目标
And deserts have an excellent agent to help them do that -
就是风
the wind.
很多种子都已经演化出利用风力的策略
Many seeds have adaptations to help them exploit it.
有些外壳可以防止内核出现磨损
They have shell to protect the seeds within from abrasion
有些则有“翅膀”能乘风而行
or wings to help them catch the air.
随着白天气温升高
As the temperature rises throughout the day,
沙漠中的风越来越大
desert winds increase in strength.
在亚利桑那州这里
Here in Arizona,
时常有大风肆虐 人们将其称为“哈布沙暴”
the land is regularly swept by what is known as a haboob.
这是一种巨大的沙尘暴
It's a giant sandstorm,
但实际上 也是一场种子风暴
but also, in effect, a seed storm.
数以百万计的种子被卷入空中
Countless millions of them are swept up into the air.
这些种子可以随风飘行数千公里
Some seeds can travel thousands of miles on the wind...
最终种子可能到达最偏僻的荒漠
..so that plants may eventually reach even the most isolated desert.
有些种子飘落到了一个岛屿上
Some have landed on an island
这座岛位于玻利维亚境内 全球最大的盐滩中间
in the middle of the world's largest salt flat in Bolivia.
有的飘到了加拉帕戈斯群岛 在最近喷发形成的火山灰中发芽
In the Galapagos, they sprout on fields of recently-erupted lava.
它们甚至到达了所有地点中最荒凉的地方之一
They've even reached one of the most inhospitable of all sites -
圣佩德罗马蒂尔小岛
the tiny island of San Pedro Martir,
这是墨西哥沿海的
a scorched, lonely rock
一座贫瘠的岩石岛
off the coast of Mexico.
这里是摩天柱属植物武伦柱的家
This is the home of the giant cardon,
一种体型巨大的仙人掌
a species of huge cactus
重量可达12吨♥
that can weigh up to 12 tonnes.
它们能在岛上茁壮成长 是因为这里有出色的伙伴
They're able to thrive here because of an extraordinary partnership...
棕色鲣鸟和蓝脚鲣鸟
..with brown and blue-footed boobies.