科学美国人60秒 SSS 森林起火引发北方气候谜团(1)

This is 60 Second Science, I’m Emily Schwing.

这里是60秒科学，我是艾米丽·施温。

The boreal forest is the largest terrestrial biome in the world. It covers 14 percent of the land on earth.

北方森林是世界上最大的陆地生物群落。 它占地球陆地面积的14%。

And, today, I’m here with my dogs on the north side of Denali National Park and Preserve.

今天，我和我的狗狗们来到了德纳里国家公园和保护区的北边。

I’m walking my dogs through the boreal forest.

我带着我的狗穿过北方森林。

It’s also known as taiga that covers 1.3 billion acres of the earth's surface.

它也被称为针叶林，其覆盖了地球表面13亿英亩的面积。

This forest is actually really beautiful.

这片森林美轮美奂。

There’s these black spruce trees....

这是黑云杉树林....

They’re stumpy, sometimes really short and goring¹ in different directions.

这些树木粗短，有时非常短，而且朝不同的方向生长。

There’s lichen² that hangs off of the dead branches, bright green lichen.

枯枝上布满青苔，鲜绿色的青苔。

Today, there’s a skim of snow on the ground overtop of this feather moss³ that just covers the forest floor.

今天，一层飞雪覆盖在羽毛苔藓上，下面覆盖着森林地面。

There's a magpie⁴ on a tree branch right in front of me....

在我面前的树枝上有一只喜鹊....

Wildfire is a normal part of the lifecycle for a boreal forest, but as the climate warms, this ecosystem⁵ is becoming increasingly vulnerable.

野火是北方森林生命周期中正常的一部分，但随着气候变暖，这个生态系统变得越来越脆弱。

That vulnerability risks turning this forest from carbon sink into a carbon source.

这种脆弱性有可能使这片森林从碳转变成成碳源。

When the boreal forest burns, it has the potential to release gigatons of carbon into the atmosphere.

当北方森林燃烧时，它有可能向大气中释放数十亿吨的碳。

Much of that carbon is actually in the forest floor.

大部分的碳实际上都在森林的地面上。

Jill Johnstone has been studying boreal forest ecology for decades.

吉尔·约翰斯通几十年来一直在研究北方森林生态学。

She does research through Canada’s Yukon University, and with the University of Alaska, Fairbanks.

她在加拿大育空大学和阿拉斯加费尔班克斯大学进行研究。

It's this undecomposed plant remains⁶ that accumulate through time.

这些未分解的植物残渣会随着时间积累。

And when a fire comes through the forest, it can just singe⁷ the surface of those accumulated plant remains, or it can burn deeply into them like a severe burn combusts most of that forest floor.

当一场大火穿过森林时，它只会烧焦那些堆积的植物残渣的表面，或者它可以像严重的起火一样深深地燃烧进森林的大部分地面。

That results in a pulse of released carbon into the atmosphere in the form of smoke and other aerosols⁸ and small carbon dioxide molecules⁹.

其结果是碳以烟雾、其他气溶胶和二氧化碳小分子的形式释放到大气中。

And so that carbon is essentially¹⁰ lost from storage that burns away.

所以碳本质上是在储存过程中消耗掉的。

This past spring, a group of scientists released their findings from a 15-year study that looked at how boreal forests regenerate¹¹ after wildfire.

今年春天，一组科学家公布了他们对北方森林野火后如何再生的15年研究的发现。

Johnstone was a co-author.

约翰斯通是作者之一。

Well, one of the things that we've been noticing in the past couple of decades is that fires are burning differently in the boreal forest than we understand them to have burned in the past.

在过去的几十年里，我们注意到的一件事是，在北方森林中燃烧的大火与我们过去所理解的不同。

And as a result of that, how the forest regenerates¹² is changing.

因此，森林再生的方式也在改变。

Black spruce and fir are the dominant¹³ tree species in the boreal forest.

黑云杉和冷杉是北方森林的优势树种。

These trees are coniferous. They’re good at withstanding cold and they grow really slowly.

这些树是针叶树。它们很擅长抵御寒冷，而且生长得很慢。

Particularly fires that burn deep into the forest floor and they change the seed beds and that affects which tree species regenerate well.

特别是燃烧到森林地表深处的大火，它们改变了苗床，影响了哪些树种的再生。

And as a result we're seeing that recovering process shifting to what we call alternative trajectories¹⁴.

结果，我们看到恢复过程转变为我们所说的替代轨迹。

A changing climate means fires are becoming more severe.

气候变化意味着火灾变得越来越严重。

It’s burning off the organic layer of soils that support species like black spruce.

它正在燃烧土壤的有机层，而这些有机层正是黑云杉等物种赖以生存的土壤。

So after a severe fire, the environment is better suited for deciduous¹⁵ tree species like birch and aspen to get a foothold. These trees grow much faster.

所以在一场严重的火灾之后，环境更适合像桦树和白杨这样的落叶树种找到立足点。 这些树长得更快。

And here’s where Johnstone and her colleagues discovered an unexpected twist.

约翰斯通和她的同事在这里发现了一个意外变化。

Even though extreme fires are burning up those carbon rich layers of organic soil and releasing that carbon into the atmosphere in the short term—what grows back is even more carbon hungry than what came before it.

尽管极端的大火正在燃烧那些富含碳的有机土壤层，并在短期内将碳释放到大气中，但生长回来的植物比之前的植物更需要碳。

Johnstone says this new kind of boreal forest is storing carbon four times faster than it would have before it burned.

约翰斯通表示，这种新型北方森林储存碳的速度是起火前的四倍。

1 goring   

v.（动物）用角撞伤，用牙刺破( gore的现在分词 )

参考例句：

• General Goring spoke for about two hours. 戈林将军的发言持续了大约两个小时。 来自英汉非文学 - 新闻报道
• Always do they talk that way with their arrogance before a goring. 他们挨牛角之前，总是这样吹大牛。 来自辞典例句

2 lichen   

n.地衣, 青苔

参考例句：

• The stone stairway was covered with lichen.那石级长满了地衣。
• There is carpet-like lichen all over the moist corner of the wall.潮湿的墙角上布满了地毯般的绿色苔藓。

3 moss   

n.苔，藓，地衣

参考例句：

• Moss grows on a rock.苔藓生在石头上。
• He was found asleep on a pillow of leaves and moss.有人看见他枕着树叶和苔藓睡着了。

4 magpie   

n.喜欢收藏物品的人，喜鹊，饶舌者

参考例句：

• Now and then a magpie would call.不时有喜鹊的叫声。
• This young man is really a magpie.这个年轻人真是饶舌。

5 ecosystem   

n.生态系统

参考例句：

• This destroyed the ecosystem of the island.这样破坏了岛上的生态系统。
• We all have an interest in maintaining the integrity of the ecosystem.维持生态系统的完整是我们共同的利益。

6 remains   

n.剩余物，残留物；遗体，遗迹

参考例句：

• He ate the remains of food hungrily.他狼吞虎咽地吃剩余的食物。
• The remains of the meal were fed to the dog.残羹剩饭喂狗了。

7 singe   

v.(轻微地)烧焦；烫焦；烤焦

参考例句：

• If the iron is too hot you'll singe that nightdress.如果熨斗过热，你会把睡衣烫焦。
• It is also important to singe knitted cloth to obtain a smooth surface.对针织物进行烧毛处理以获得光洁的表面也是很重要的。

8 aerosols   

n.气溶胶( aerosol的名词复数 )；喷雾剂；（气体中的）浮粒；喷雾器

参考例句：

• Aerosols are present throughout the atmosphere. 气溶胶存在于整个大气层。 来自辞典例句
• Deodorants are available as aerosols or roll-ons. 除臭剂有喷雾装或滚抹装。 来自辞典例句

9 molecules   

分子( molecule的名词复数 )

参考例句：

• The structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。
• Inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里，大分子裂变为小分子。

10 essentially   

adv.本质上，实质上，基本上

参考例句：

• Really great men are essentially modest.真正的伟人大都很谦虚。
• She is an essentially selfish person.她本质上是个自私自利的人。

11 regenerate   

vt.使恢复，使新生；vi.恢复，再生；adj.恢复的

参考例句：

• Their aim is to regenerate British industry.他们的目的是复兴英国的工业。
• Although it is not easy,you have the power to regenerate your life.尽管这不容易，但你有使生活重获新生的能力。

12 regenerates   

n.新生，再生( regenerate的名词复数 )v.新生，再生( regenerate的第三人称单数 )

参考例句：

• This activity regenerates some of the ATP lost in proton reduction. 这一反应可以使在质子还原过程中丢失的某些ATP再生。 来自辞典例句
• Level 2-Heals all allied Heroes for 300 HP. Fully Regenerates converted creeps. 二级-治疗地图上所有的友方英雄300点的生命，完全恢复皈依你的单位。 来自互联网

13 dominant   

adj.支配的，统治的；占优势的；显性的；n.主因，要素，主要的人(或物)；显性基因

参考例句：

• The British were formerly dominant in India.英国人从前统治印度。
• She was a dominant figure in the French film industry.她在法国电影界是个举足轻重的人物。

14 trajectories   

n.弹道( trajectory的名词复数 )；轨道；轨线；常角轨道

参考例句：

• To answer this question, we need to plot trajectories of principal stresses. 为了回答这个问题，我们尚须画出主应力迹线图。 来自辞典例句
• In the space program the theory is used to determine spaceship trajectories. 在空间计划中，这个理论用于确定飞船的轨道。 来自辞典例句

15 deciduous   

adj.非永久的；短暂的；脱落的；落叶的

参考例句：

• Overgrown deciduous shrubs can be cut back at this time of year.过于繁茂的落叶灌木可以在每年的这个时候修剪。
• Deciduous trees shed their leaves in autumn.落叶树木在秋天落叶。