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Hi there! You're just in time.
嗨，大家好，来得正是时候。
Everyone at The Fort has been learning about redwood trees, the tallest trees in the world.
城堡的每个人都在学习世界上最高的树，也就是红杉树。
My friend Sam the Bat has been learning about them, too, and I was just about to check in with him.
我的朋友蝙蝠山姆也在学习红杉，我正准备向他汇报。
Let's see what he's up to today!
咱们看看他今天有什么打算！
Hi, Jessi!
嗨，杰西！
Hi, Sam! How is your redwood research going?
嗨，山姆！你的红杉研究进展如何？
Uh, it's going okay. I was just reading about the habitat that redwoods live in, but I'm a little confused by something.
呃，还行。我刚刚在看红杉的栖息地，不过我有点困惑。
Redwood trees tend to grow on the west coast of North America, mostly in California.
红杉树一般生长在北美西海岸，主要在加利福尼亚。
But that area of California has a dry season.
但加州的那个地区是旱季。
Every year, around the same time, it doesn't rain much, and the ground gets really dry.
大概在每年的同一个时间段，雨水很少，地面会变得非常干燥。
But redwood trees are plants, and I know that plants need water to survive.
但红杉是植物，我知道植物需要水才能生存。
I also know that most plants use their underground roots to get water.
我还知道大多数植物要利用它们在地下的根来获取水分。
So, I was wondering how such big trees can survive the dry season if there isn't as much water in the ground.
所以，我想知道，如果地面上没有水很少，那这样的大树是如何在旱季存活下来的呢。
My guess is that they don't really need their roots to drink water. They're just using something else.
我猜它们其实不需要根来获取水分，它们用了别的东西。
But I was talking to Squeaks about it, and his guess is that the redwood trees are getting secret water from somewhere.
但我和吱吱谈过这件事，他的想法是红杉树从某个地方得到了秘密的水。
So, who's right?
所以，谁对谁错呢？
Wow, you two have some great ideas about how redwoods survive the dry season. And you're both a bit right!
哇哦，你俩对红杉如何在旱季生存的想法很棒。而且，你俩都说对了一点点！
What? How?
啥？说来听听？
Well, Squeaks is right that redwood trees have a special source of water during the dry season.
吱吱说的没错，红杉树在旱季有一种特殊的水源。
And you're right that the redwoods use a different part of the plant to reach this water, instead of using their roots.
你也没说错，红杉会利用自己不同的部位来获取水分，而不只是它们的根。
Redwood trees can use their needles to soak up water.
红杉可以用针叶吸收水分。
Now, even in the dry season, plants soak up water through their roots. And they use it to help them grow and survive.
现在，即便在旱季，植物也会通过根部吸收水分，它们用水分来帮助自己成长和生存。
But their needles also come in handy.
但它们的针头也会派上用场。
They might not look like it, but needles are a type of leaf.
针叶是一种叶子，虽然看起来不太像。
And like all leaves, they're covered in teeny-tiny holes called stomata.
和所有的叶子一样，针叶上面全是一种被称为“气孔”的极小的洞。
You wouldn't really be able to see them without a microscope. But they're there, lots of them!
只有用显微镜才能看到。但它们就在那里，而且有很多！
And these hole-like structures have an important job: They let things in and out of the plant.
这些洞状结构有一个重要的作用：让东西进出植物。
Like, when it's hot outside, stomata let water vapor out of the plant, and that helps them cool down.
比如，当外面很热的时候，气孔会让水蒸气从植物中释放出来，这有助于它们降温。
It's like how when you get too hot, some of the water leaves your body as sweat. And that helps you cool down!
就像当你太热时，一些水会以汗水的形式离开你的身体，这能帮助你凉快下来！
Water vapor is a little different than the drops of sweat on your body, though.
水蒸气和你身体上的汗有一点不同。
Water vapor is the same thing as water.
水蒸气和水是同一种东西。
It's made of all the same stuff, but it looks a lot different because it's what's called a gas.
它们由相同的物质组成，但看起来很不一样，因为水蒸气是一种“气体”。
What does a gas look like?
气体是什么样子的？
Great question! Breathe into your wing, or breathe into your hand. What do you see?
问得好！对着你的翅膀呼吸，或者对着你的手呼吸。你看到什么了？
Nothing?
啥都没看到。
Exactly! Gases are invisible.
完全正确！气体是看不见的。
And believe it or not, you just breathed out a couple of gases, including some water vapor of your own!
信不信由你，你刚刚呼出了一些气体，里面有一些你的水蒸气！
So, when plant leaves or needles let out a bunch of water vapor, you can't normally see it.
所以，当植物的叶子或针叶释放水蒸气时，你通常是看不到的。
When water vapor leaves a plant through the leaves like this, it's called transpiration.
当水蒸气像这样通过叶子离开植物时，这就叫“蒸发”。
But transpiration gets rid of water. How can it help redwood trees get more water?
但是，蒸发是去除水分的，那它如何帮助红杉获得更多的水分呢？
Well, most of the time, plants use their leaves to let water vapor out.
嗯，大多数时候，植物用它们的叶子来释放水蒸气。
But when there isn't enough water being soaked up by the roots, a plant can use its leaves to let water vapor in from the air around them.
但是当根部没有吸收足够的水分时，植物还可以利用叶子让周围空气中的水蒸气进来。
This is called reverse transpiration, because it's like regular transpiration…just backward!
这叫做“反向蒸发”，因为它和普通的蒸发是一样的，只不过是向后！
And it's really great for plants that live in habitats like redwood forests. Can you guess why?
对于生活在红杉林等栖息地的植物来说，这一旦很好。你能猜到为什么吗？
Here's a hint: What do you notice about this picture of a redwood forest?
给你个提示：这张红杉林的照片里有什么？
Well, it looks really foggy there… wait, fog looks a lot like clouds. And clouds are made of water!
嗯，雾很大……等等，雾看起来很像云，云是由水构成的！
If all of that fog is water, the redwood trees should be able to suck it up with their needles using reverse transpiration!
如果所有的雾都是水，那么红杉就能利用它们的针叶用反向蒸发大法来吸收水分！
You got it! Nice work! Redwood trees usually live in places that are really foggy.
你说对了，很棒！红杉通常生长在雾很大的地方。
So even when the ground is dry, there can be enough extra water vapor in the air for plants to use reverse transpiration.
所以，即使地面干燥，但空气中还是有足够多的水蒸气供植物进行反向蒸发。
They'll open up the stomata on their needles and drink in the fog.
它们会打开针叶上的气孔，在雾中喝水。
The redwoods are still using their roots during the dry season, but since there isn't a lot of water in the ground, using their needles helps them get all the water they need.
红杉在旱季仍会利用它们的根，但由于地下的水很少，所以它们会利用针叶帮助自己获得所需的所有水分。
Thanks for the help, Jessi.
谢谢你的帮助，杰西。
It's really cool that redwood trees can drink water from the air, and not just the ground.
红杉不仅能从地上喝水，还能从空气中喝水，这真是太酷了。
And it's amazing that they can use their roots and their needles to get enough water.
神奇的是它们能用根和针叶获得足够的水。
Welp, see you later! I want to take a closer look at some of the leaves growing on the trees outside!
好了，再见！我想仔细看看外面树上长出的叶子！
Even if they aren't redwood needles, maybe they're doing something amazing, too! Bye, Jessi! Bye everybody!
即使它们不是红杉针，但或许也在做一些神奇的事情！再见，杰西！再见，大家！
Bye, Sam! I'm so glad that Sam is having fun learning about redwoods.
再见，山姆！很欣慰山姆在学习红杉上这么开心。
If you'd like to keep discovering more about redwoods and all things science with all of us here, make sure to hit the subscribe button below.
如果你想和我们一起继续发现更多关于红杉和所有科学的东西，一定要点击下面的订阅按钮。
We'll see you next time, here at The Fort.
我们下期见，沃斯堡等你哦。
