2011.12英语六级听力:阻止荒漠化

40 percent of the world's land - home to about two billion people - is arid or semi-arid. The Karoo drylands are just one example of where the earth has dried up to such an extent, that it is no longer agriculturally productive.

Professor Timm Hoffman is the Director of the University of Cape Town's Plant Conservation Unit. He says land degradation is a problem world-wide.

"Research which has measured the changes in productivity over the last thirty years from satellites suggests that about 25% of the global surface has lost, or is losing productivity. This is measured in response to cultivation, in response to harvesting, resource-extraction, and as a result also of over-grazing."




According to the United Nations Conference on Desertification, 73% of Africa's drylands are affected by desertification.

South Africa is largely arid or semi-arid, and according to the South African National Biodiversity Institute, about a quarter of the country is severely degraded. This sometimes manifests as eroded gulleys following over-grazing of vegetation.

In the Eastern Cape province, over-grazing by non-indigenous angora goats farmed for mohair, has resulted in a large shrub known locally as spekboom being severely depleted.

Soil fertility and water-holding ability have been lost as a result. Only about 14% of the original healthy spekboom-rich thicket remains, as PhD student Marius van der Vyver explains.

"300 years of goat-browsing - injudicious goat-browsing - by land-owners has degraded most of the spekboom in the area. The area is naturally dominated by spekboom, which is what you see here behind me. And it is a very palatable shrub - goats love the stuff, also indigenous herbivores. But the goats, because of the numbers and the constancy of browsing, they depleted the area."

Van der Vyver's PhD is in the restoration of spekboom-dominated areas, much of which is now degraded land.

The shrub is very valuable in preventing desertification in the dry thicket landscape.

It grows quickly, and prevents erosion by binding the soil.

For these and more reasons, the South African government's Working For Land programme has for the last seven years, been restoring large tracts of degraded land, and already more than 2000 hectares have been replanted with spekboom.

Professor Richard Cowling of the Nelson Mandela Metropolitan University and the Restoration Research Group explains the value of reintroducing spekboom.

"It produces a huge amount of litter - leaf litter. It sheds lots of leaves. So if you put a little canister under spekboom you're going to pick up as many leaves as you would in some of the rainforests. And that enriches the soil enormously, and builds , which enables the soil to hold more moisture, so it's a self-augmenting process of building up an ecosystem that's really healthy. And spekboom can kick start that - it's a kind of an ecosystem engineer."

For a dry area plant, spekboom sequesters, or stores, a high amount of carbon.

The Restoration Research Group is working on accessing further funding for spekboom restoration from the carbon credit market.

Starting with early field trials by farmers, this method of restoration is now being implemented in nature reserves.

词汇讲解：

1. arid adj. 干旱的；干燥的
例句：The settlers irrigated the arid land.
移民们灌溉干燥的土地。

2. extent n. 长度, 面积, 范围；程度, 限度
例句：What's the extent of the damage?
损坏的程度如何?

3. measure vt.量出; 记录；估计, 估量；仔细考虑；(通过竞争, 冲突等)考验某事物, 较量
例句：We measured the distance.
我们测量了距离。

4. degrade vt.使降级, 使降低身份；使丢脸; 使陵削,剥蚀
例句：He degraded himself by cheating and telling lies.
他因欺骗、撒谎而损害了自己的人格。

5. erode v. 侵蚀, 腐蚀
例句：The sea erodes the rock.
海水侵蚀岩石。

6. deplete vt. 使大大的减少; 使空虚
例句：Our supplies of food are rather depleted.
我们的食品供应大大地减少了。

7. dominate v. 控制, 支配, 统治；在…中占首要地位
例句：The stronger man dominates the weaker.
强者支配弱者。

8. indigenous adj. 土生土长的；生来的, 固有的
例句：Kangaroos are indigenous to Australia.
袋鼠为澳大利亚本地的动物。

9. shed vt. 蜕皮, 树叶脱落, 蜕, 落
例句：Many trees shed their leaves in autumn.
许多树在秋天落叶。

10. enrich vt.使富有, 使富裕；充实, 使丰富
例句：Fertilizer enriches the soil.
肥料使土壤肥沃。

短语讲解：

1. The Karoo drylands are just one example of where the earth has dried up to such an extent, that it is no longer agriculturally productive.

dry up (使…)干涸
例句：The long drought dried up all the wells.
长期的干旱了。
no longer不再, 已不, 不复, 再也不
例句：The city's water supply is no longer adequate for its need.
这个城市的供水已不敷需求。

2. This is measured in response to cultivation, in response to harvesting, resource-extraction, and as a result also of over-grazing.

in response to对…做出反应
例句：She laughed in response to his jokes.
他的话引起她大笑。

3. In the Eastern Cape province, over-grazing by non-indigenous angora goats farmed for mohair, has resulted in a large shrub known locally as spekboom being severely depleted.

result in导致,结果是
例句：The flood resulted in a considerable reduction in production.
这次水灾造成相当大的减产。

4. So if you put a little canister under spekboom you're going to pick up as many leaves as you would in some of the rainforests.

pick up拾起, 捡起; 抬起
例句：I would have picked it up if I had noticed it.
我如果看见的话, 我早就把它拣起来了。

5. And that enriches the soil enormously, and builds , which enables the soil to hold more moisture, so it's a self-augmenting process of building up an ecosystem that's really healthy.

build up逐步建立,
例句：Many a large and big business has been built up from small ones.
很多大企业都是从小规模发展起来的。

6. The Restoration Research Group is working on accessing further funding for spekboom restoration from the carbon credit market.

work on致力于…
例句：He has been working on a new now.
近一年多来, 他一直在写一部新小说。