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Letting nature heal itself

The ecosystems destroyed by the deadly earthquake in May formed over the course of millennia. But their natural recovery will take only decades, writes ecologist Jiang Gaoming.

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The May 12 earthquake in Wenchuan killed more than 69,000 people. The tremors also caused landslides, uprooted vegetation and destroyed natural ecosystems. The government not only has to rebuild homes, but also repair damaged ecosystems.

Plant populations develop in one of two types of succession (the process by which ecosystems develop and change over time), those of dry or moist environments. These types of succession both create soil through physical, chemical and biological processes, before diversifying and ultimately forming a robust ecosystem. But this takes time: it can take two millennia or more to create a centimetre of soil. The ecosystems in the quake-hit area of Sichuan date from ancient times, and are the result of xerarch, or dry, succession. But ecosystems – like biological organisms – can adapt to their environments and help themselves. Even after an earthquake, as long as there are seeds, roots and soil, an ecosystem can quickly restore itself. And these secondary successions require decades, rather than millenia. All it requires is “enclosure”, which keeps the soil secure, while seeds and spores take root. Nature can heal itself.

On September 21, 1999, over 2,000 lives were lost to the 7.3 magnitude Chichi earthquake in Taiwan. By November 2001, areas with thick soil around the base of the hills were already covered by grass and bushes. Trees were starting to appear and plants were growing from crevices in the rocks. The local government had decided to let nature take its course. Some badly damaged buildings were even left as a memorial and a museum was constructed as a centre for research and education.

There are many other examples of damaged ecosystems healing naturally. Forty-five years ago in Hong Kong, agricultural activity stopped on a hillside farm and a luxuriant forest grew in its place. This is now Kadoorie Farm and Botanic Garden. At the turn of the twentieth century a town in Shaanxi province was home to 10,000 people and a major producer of food steamers made from local wood. But transportation problems meant the town was abandoned and the trees grew back naturally until forests covered the entire area. It is now part of the Foping Nature Reserve, where trees grow to a half-metre in diameter and pandas feast on the abundant bamboo. After an area in the Taixing Mountains, Shanxi province, was enclosed for five years, natural vegetation recovered, at 5.8% of the cost of creating an artificial forest. Enclosure creates mixed forests of grass, bushes and trees that are able to better absorb water, prevent soil loss, improve the local climate, reduce the risk of flooding and landslides and protect biodiversity.

For the last eight years, my research group has been studying the recovery of a damaged ecosystem in on the edge of the desert in Inner Mongolia. An area of 40,000 mu (around 27 kilometres) of sandy grasslands have now been restored to its condition in the 1960s. As the vegetation recovered, wild animals returned. Surrounding areas followed suit and the sand dunes are now covered with a healthy layer of vegetation. Earlier this month a group of Al-Jazeera reporters visited the site to find an example of a damaged ecosystem, but they spent the whole day driving and could not find one. In the end they had to use a small sand dune as a background. We tried planting trees and aerial seeding, but ultimately gave up. Instead we worked on changing the habits of local herders, improving land productivity and providing more employment opportunities – leaving nature to take care of the ecosystem.

Restoring the quake-hit ecosystems is a question of balancing the interests of the local people and the environment. Rural methane projects can reduce the number of locals taking firewood from the mountainsides. The use of straw as fodder will reduce the use of land for grazing and ensure that vegetation can grow. In Sihai township and Dazhuangke village, in Beijing, they now have forestry coverage of 85% or more, compared to the 30% they had 15 years ago. Back then, land was used very inefficiently: one person would use 20 mu of forest just for firewood. With those pressures on the ecosystem, no amount of spending on reforestation will succeed. Then the government opted to relocate the population and pay those who remained to tend the forest and provide coal. This reduced the pressures on the ecosystem and it was able to recover naturally.

When an ecosystem has not been pushed past certain limits, it is able to recover on its own. Human intervention should only be supplementary, including after an earthquake. This is particularly the case for sandy grasslands, grasslands, deserts, the mountains of the south and the northern sides of mountains in the north. In these areas soil remains and the water, light, heat and nutrients needed are available. It is even more appropriate in sparsely-populated areas, where it can avoid money being wasted on ineffective manual efforts, such as creating forests in arid areas.

The creation of nature reserves should be model to allow damaged ecosystems to recover. Funding can start at the national level; centrally-funded nature reserves can enforce environmental protection laws and spur the local economy. This will solve the problems of reserves being run commercially. When national reserves are funded, local governments will be able to adopt the same model and provide the funds for nature reserves from their own budgets. The first projects should be established in nature reserves hit by the quake; these can then become models for other areas.

 

Jiang Gaoming is a professor and Ph.D. tutor at the Chinese Academy of Sciences’ Institute of Botany. He is also vice secretary-general of the UNESCO China-MAB (Man and the Biosphere) Committee and a member of the UNESCO MAB Urban Group. He is known for his concepts of “urban vegetation” and allowing damaged ecosystems to recover naturally.

 

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评论通过管理员审核后翻译成中文或英文。 最大字符 1200。

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评论 comments

Default avatar
匿名 | Anonymous

天和人的分工

我同意蒋先生的观点,人的任务是救人,生态的事情就交给自然吧,不然很容易帮倒忙,而且容易产生更多贪污。

Division of work between the Nature and Human

I agree with Mr. Jiang. As human beings our task is to save other human beings of our kind.

Leave the ecosystems to the nature. We could easily do more damage than help if we insist on interfering the natural course, not to mention the possible corruption during our interference.

(This comment was translated by Zheng Shen)

Default avatar
匿名 | Anonymous

自wxai

这都是专业内的评论,非常赞!

from wxai

Professional comments, bravo!

translated by Lijin Zeng

Default avatar
匿名 | Anonymous

恢复过程可能漫长

正如蒋高明教授指出的,如果以农耕,伐木与用火为形式的人为压力被最小化,那么只要给予其足够的时间,土地是有可能自然恢复的。然而,中国南方的一些土地在经过长达两百年的恢复后,修复效果依然不明显。其中原因可能是当地的人为压力并未被解除。这种土地破坏不但在历史上一些艺术品上有所反映,而且在实地现场也仍然存在。

请看:http://fas.org/blog/china/wp-content/uploads/2008/03/art.pdf

Walter Parham [email protected]
(本评论由Zheng Shen翻译)

Recovery can be slow

Where human pressures such as farming, wood cutting, and fire can be minimized, natural restoration of land has a chance given sufficient time just as Professor Gaoming Jiang points out. Some degraded lands of South China however show only slight recovery even after 200 years where such pressures have not been removed. This land damage is reflected in some historic art works as well as on site today. (See)http://fas.org/blog/china/wp-content/uploads/2008/03/art.pdf.

Walter Parham
[email protected]

Default avatar
匿名 | Anonymous

黄石国家公园的生态恢复

几个星期前我去了美国黄石国家森林公园。1988年那里发生一场森林大火,现在还有许多过火林木。还有许多的树木已长到从1英尺到20英尺高。这是因为松塔里面是松树种子,外面被覆着一层胶。发生森林大火时,外面的胶被融化掉,里面的种子便四散开去。这是又一个大自然自我恢复生息的例子。有些森林火灾是由于闪电引起的,不幸的是1988年的大火是由于一颗烟蒂引起的。Sustainablejohn
(本评论由Yang bin翻译)

Recovery in Yellowstone

I was in Yellowstone National Park a few weeks ago. In 1988, a big forest fire occurred, and you can still see many burnt trees. You can also see many trees growing in already from 1 to 20 feet tall. This is because seeds were contained in the pine cones, sealed by a glue. When the fire happened, it melted the glue and the seeds fell all over the ground. Another example of Mother Nature watching out for herself. Some fires are caused naturally by lightning, unfortunately they traced the big 1988 fire to a cigarette butt.

sustainablejohn

Default avatar
匿名 | Anonymous

黄石是另一回事

美国很多地区的生物是长期以来适应于野火的,有的植物种子甚至必须经过火烧才能发芽。

所以这跟本文讨论的问题有差别。
(本评论由Lijin Zeng翻译)

In case of Yellowstone

The Biota there has been adapted to fire, some plant seeds actually have to go through the fire to be able to germinate.

In that case it's just another story.

Default avatar
匿名 | Anonymous

尊重自然规律是根本道理

蒋文讲的这个理念是对的。生态系统和生物多样性的恢复都应该强调自然规律。熊猫保护根本在于其栖息地的保护。卧龙也应该是这个道理。我们不应该再着力于侵占更多的野外栖息地来重建和扩大饲养基地。应该通过这次地震,加紧制订或修订熊猫放归野外的计划。这才是迁地保护(ex-situ conservation)的根本目的。野生动物主管部门的侧重点是自然保护,不该是“产业化”。

the key is to follow the principles of nature

Mr. Jiang made a good point in his article. The preservation of ecosystems and the restoration of biodiversity should follow the principles of nature. Protection of giant pandas essentially comes down to protection of their habitats. The same applies to Wolong National Nature Reserve. We must not seize any more wildlife habitat in order to rebuild and expand giant panda rehabilitation bases. As part of our responses to the Sichuan Earthquake, we ought to step up or revise the formulation of plans for returning giant pandas to the wild. This is the ultimate goal of ex-situ conservation. The governmental wildlife protection agencies should emphasize protecting natural reserves, not industrializing natural reserves.

(Comment translated by Yang bin)