5个原因说明森林的重要性

5个原因说明森林的重要性

Forests cover nearly a third of all land on Earth, providing vital organic infrastructure for some of the planet's densest, most diverse collections of life. They support countless species, including our own, yet we often seem oblivious of that. Humans now clear millions of acres from natural forests every year, especially in the tropics, letting deforestation threaten some of Earth's most valuable ecosystems.

森林覆盖了地球上近三分之一的土地，为地球上一些密度最大、种类最多的生命提供了重要的有机基础设施。它们支持着无数的物种，包括我们自己的物种，但我们似乎常常忽略了这一点。现在，人类每年从天然林中砍伐数百万英亩的土地，特别是在热带地区，这使得森林砍伐威胁到了地球上一些最有价值的生态系统。

Sunlight filters through a forest in Union Wood near Ballygawley, Ireland. (Photo: Mark Carthy/Shutterstock)

We tend to take forests for granted, underestimating how indispensable they still are for everyone on the planet. That would quickly change if they all disappeared, but since humanity might not survive that scenario, the lesson wouldn't be very useful by then. As the Once-ler finally realizes in Dr. Seuss' "The Lorax," a crisis like deforestation depends on indifference. "UNLESS someone like you cares a whole awful lot," Seuss wrote, "nothing is going to get better."

我们往往认为森林是理所当然的，低估了它们对地球上每个人来说仍然是多么不可或缺。如果它们全部消失，这种情况将很快发生变化，但由于人类可能无法在这种情况下生存下来，到那时，这一教训将不会非常有用。正如这位曾经的作家在苏斯博士的《洛拉克斯》(the Lorax)中最终意识到的那样，森林砍伐这样的危机取决于人们的漠不关心。“除非像你这样的人非常在乎，”苏斯写道，“否则一切都不会好起来。”

In hopes of shedding more light on what forests do for us, and how little we can afford to lose them, here are 5 reasons why forests are so important:

为了让人们更多地了解森林对我们的作用，以及我们失去森林的代价有多大，我们列出了森林如此重要的5个原因:

Morning mist shrouds a tropical forest at Kaeng Krachan National Park in Thailand. (Photo: Stephane Bidouze/Shutterstock)

1. They help us breathe.

它们帮助我们呼吸。

Forests pump out oxygen we need to live and absorb the carbon dioxide we exhale (or emit). A single mature, leafy tree is estimated to produce a day's supply of oxygen for anywhere from two to 10 people. Phytoplankton in the ocean are more prolific, providing half of Earth's oxygen, but forests are still a key source of quality air.

森林为我们提供生存所需的氧气，并吸收我们呼出(或排放)的二氧化碳。据估计，一棵成熟多叶的树每天能为两到十个人提供氧气。海洋中的浮游植物数量更多，为地球提供了一半的氧气，但森林仍然是优质空气的关键来源。

2. They're more than just trees.

它们不仅仅是树。

Nearly half of Earth's known species live in forests, including 80% of biodiversity on land. That variety is especially rich in tropical rainforests, but forests teem with life around the planet: Insects and worms work nutrients into soil, bees and birds spread pollen and seeds, and keystone species like wolves and big cats keep hungry herbivores in check. Biodiversity is a big deal, both for ecosystems and human economies, yet it's increasingly threatened around the world by deforestation.

地球上近一半的已知物种生活在森林中，包括80%的陆地生物多样性。这种物种在热带雨林中特别丰富，但在地球上，森林中充满了生命:昆虫和蠕虫将营养物质输送到土壤中，蜜蜂和鸟类传播花粉和种子，而狼和大猫等关键物种则控制着饥饿的食草动物。生物多样性对生态系统和人类经济来说都是一件大事，但它在世界各地正日益受到森林砍伐的威胁。

3. People live there, too.

人们也住在那里。

Some 300 million people live in forests worldwide, including an estimated 60 million indigenous people whose survival depends almost entirely on native woodlands. Many millions more live along or near forest fringes, but even just a scattering of urban trees can raise property values and reduce crime, among other benefits.

全世界约有3亿人生活在森林中，其中估计有6千万土著人民的生存几乎完全依赖于当地的林地。还有数百万人生活在森林边缘或附近，但即使只是城市树木的零星分布，也能提高财产价值，减少犯罪，还有其他好处。

The canopy towers above a coastal-plain forest in Italy's Nazionale del Circeo. (Photo: Nicola [CC BY 2.0]/Flickr)

4. They keep us cool.

它们使我们保持凉爽。

By growing a canopy to hog sunlight, trees also create vital oases of shade on the ground. Urban trees help buildings stay cool, reducing the need for electric fans or air conditioners, while large forests can tackle daunting tasks like curbing a city's "heat island" effect or regulating regional temperatures.

通过种植树冠来吸收阳光，树木也在地面上创造了重要的遮荫绿洲。城市树木可以帮助建筑物保持凉爽，减少对电风扇或空调的需求，而大片森林可以解决令人生畏的任务，比如抑制城市的“热岛效应”或调节地区温度。

5. They keep Earth cool.

它们使地球保持凉爽。

Erawan Falls flows through a rainforest in the Tenasserim Hills of western Thailand. (Photo: Shutterstock)

Trees also have another way to beat the heat: absorb CO2 that fuels global warming. Plants always need some CO2 for photosynthesis, but Earth's air is now so thick with extra emissions that forests fight global warming just by breathing. CO2 is stored in wood, leaves and soil, often for centuries.

树木还有另一种降温方法:吸收导致全球变暖的二氧化碳。植物进行光合作用总是需要一些二氧化碳，但现在地球的空气中含有大量的额外排放，森林仅靠呼吸就能对抗全球变暖。二氧化碳储存在木材、树叶和土壤中，通常可以保存几个世纪。