VOA标准英语2013--Fighting Fire with Fire

 

Fighting Fire with Fire

In African savannahs, or grasslands², wildfires can either be destructive or beneficial. It all depends on when those fires occur. Scientists at the World Agroforestry Center have developed a system to determine the best time to set the savannahs ablaze³.

Savannahs stretch across many parts of Africa. But scientists concentrated their research on grassland¹ conditions similar to the Sahel and South Sudan. When wildfires spread uncontrolled, the heat and flames can cause damage on several levels.

“Many components⁴ of the ecosystem⁵ can be affected⁶. The biodiversity itself, the soil composition and structure and gas emission⁷ and greenhouse gas emission into the atmosphere,” said Cheikh Mbow, senior climate change scientist with the World Agroforestry Center in Nairobi, Kenya.

“Fire is seen as one of the biggest drivers of deforestation in some ecosystems⁸. And it contributes widely to the reduction of the ecosystem services, which [are] the basis of most of the livelihoods⁹ in Africa in poverty conditions. So we are worrying about fire because of the many impacts and implications for the human beings.”

Fires in savannahs are common.

“If you look at African images from [a] satellite in the dry season, it appears that most of the ecosystem, which has some level of dryness, will have fires on a regular basis. There have been many attempts in the past, since colonial time actually, to, sort of, ban fire in our ecosystem, but they never succeeded. They never succeeded because fire is a tool,” said Mbow.

Fire is used as a tool by local populations, for instance, when they’re gathering¹⁰ honey, clearing land or desiring new vegetation growth. Mbow says nearly all of the fires in the savannahs are caused by humans. Nature plays a very small role.

“The conditions in which natural fire can occur [are] when lightning happens, for instance. In Africa, when lightning happens in these tropical areas that’s a period during which we have rain. It’s wet. When it’s raining, that’s the time we have lightning, and it’s very unlikely that when it’s raining fire can take place,” he said.

With climate change, he said, there’s concern the savannahs will become even more dry, making destructive wildfires much more likely.

That’s why scientists at the World Agroforestry Center and their partners developed a system to pinpoint¹¹ the best times to intentionally¹² set fires. It’s known as early burning. It consumes layers of biomass before they build-up to highly combustible¹³ levels. Efforts to prevent fires altogether can actually make things worse.

“If you protect this area for five years, let’s say, or 10 years, you’ll have a dangerous amount of biomass. Fire not only consumes the biomass, it also destroys all the characteristics of the ecosystem, which makes this ecosystem viable¹⁴. I’m thinking about microorganisms in the soil, small animals. So it’s a bit dangerous to over protect the ecosystem,” he said.

So an early burn, Mbow said, needs to be done when the conditions are just right – not too wet or not too dry. Fires intentionally set at that time not only consume the biomass, but prevent dangerous fires later in the season.

“There are many factors in determining fires. The one factor is the grass moisture, but also the grass load. The biomass load is extremely important. The second important factor is the atmospheric¹⁵ parameters¹⁶ – air temperature and wind. And the third one is the topography. If you are in heavy conditions, it’s very risky¹⁷ sometimes to use fire. As they go uphill they become stronger and very difficult to control. So there are many, many aspects which should be in consideration. And there is no silver bullet or one-size-fits-all situation.”

The early burns are generally fast moving and stay mainly on the surface. They cause only minor¹⁸ damage to trees, soil nutrients¹⁹ or microorganisms.

The recommendations for controlled fires in African grasslands can be found in the February issue of the Journal for Arid²⁰ Environments. Mbow said that he hopes African governments will consider implementing²¹ them. However, he added, few countries on the continent currently have resources for fire management.

1 grassland   

n.牧场，草地，草原

参考例句：

• There is a reach of grassland in the distance.远处是连绵一片的草原。
• The snowstorm swept the vast expanse of grassland.暴风雪袭击了辽阔的草原。

2 grasslands   

n.草原，牧场( grassland的名词复数 )

参考例句：

• Songs were heard ringing loud and clear over the grasslands. 草原上扬起清亮激越的歌声。 来自《现代汉英综合大词典》
• Grasslands have been broken and planted to wheat. 草原已经开垦出来，种上了小麦。 来自《简明英汉词典》

3 ablaze   

adj.着火的，燃烧的；闪耀的，灯火辉煌的

参考例句：

• The main street was ablaze with lights in the evening.晚上，那条主要街道灯火辉煌。
• Forests are sometimes set ablaze by lightning.森林有时因雷击而起火。

4 components   

（机器、设备等的）构成要素，零件，成分； 成分( component的名词复数 )； [物理化学]组分； [数学]分量； （混合物的）组成部分

参考例句：

• the components of a machine 机器部件
• Our chemistry teacher often reduces a compound to its components in lab. 在实验室中化学老师常把化合物分解为各种成分。

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 affected   

adj.不自然的，假装的

参考例句：

• She showed an affected interest in our subject.她假装对我们的课题感到兴趣。
• His manners are affected.他的态度不自然。

7 emission   

n.发出物，散发物；发出，散发

参考例句：

• Rigorous measures will be taken to reduce the total pollutant emission.采取严格有力措施，降低污染物排放总量。
• Finally,the way to effectively control particulate emission is pointed out.最后，指出有效降低颗粒排放的方向。

8 ecosystems   

n.生态系统( ecosystem的名词复数 )

参考例句：

• There are highly sensitive and delicately balanced ecosystems in the forest. 森林里有高度敏感、灵敏平衡的各种生态系统。 来自《简明英汉词典》
• Madagascar's ecosystems range from rainforest to semi-desert. 马达加斯加生态系统类型多样，从雨林到半荒漠等不一而足。 来自辞典例句

9 livelihoods   

生计，谋生之道( livelihood的名词复数 )

参考例句：

• First came the earliest individualistic pioneers who depended on hunting and fishing for their livelihoods. 走在最前面的是早期的个人主义先驱者，他们靠狩猎捕鱼为生。 来自英汉非文学 - 政府文件
• With little influence over policies, their traditional livelihoods are threatened. 因为马赛族人对政策的影响力太小，他们的传统生计受到了威胁。

10 gathering   

n.集会，聚会，聚集

参考例句：

• He called on Mr. White to speak at the gathering.他请怀特先生在集会上讲话。
• He is on the wing gathering material for his novels.他正忙于为他的小说收集资料。

11 pinpoint   

vt.准确地确定；用针标出…的精确位置

参考例句：

• It is difficult to pinpoint when water problems of the modern age began.很难准确地指出，现代用水的问题是什么时候出现的。
• I could pinpoint his precise location on a map.我能在地图上指明他的准确位置。

12 intentionally   

ad.故意地，有意地

参考例句：

• I didn't say it intentionally. 我是无心说的。
• The local authority ruled that he had made himself intentionally homeless and was therefore not entitled to be rehoused. 当地政府裁定他是有意居无定所，因此没有资格再获得提供住房。

13 combustible   

a. 易燃的,可燃的; n. 易燃物,可燃物

参考例句：

• Don't smoke near combustible materials. 别在易燃的材料附近吸烟。
• We mustn't take combustible goods aboard. 我们不可带易燃品上车。

14 viable   

adj.可行的，切实可行的，能活下去的

参考例句：

• The scheme is economically viable.这个计划从经济效益来看是可行的。
• The economy of the country is not viable.这个国家经济是难以维持的。

15 atmospheric   

adj.大气的，空气的；大气层的；大气所引起的

参考例句：

• Sea surface temperatures and atmospheric circulation are strongly coupled.海洋表面温度与大气环流是密切相关的。
• Clouds return radiant energy to the surface primarily via the atmospheric window.云主要通过大气窗区向地表辐射能量。

16 parameters   

因素，特征； 界限； （限定性的）因素( parameter的名词复数 )； 参量； 参项； 决定因素

参考例句：

• We have to work within the parameters of time. 我们的工作受时间所限。
• See parameters.cpp for a compilable example. This is part of the Spirit distribution. 可编译例子见parameters.cpp.这是Spirit分发包的组成部分。

17 risky   

adj.有风险的，冒险的

参考例句：

• It may be risky but we will chance it anyhow.这可能有危险，但我们无论如何要冒一冒险。
• He is well aware how risky this investment is.他心里对这项投资的风险十分清楚。

18 minor   

adj.较小(少)的，较次要的；n.辅修学科；vi.辅修

参考例句：

• The young actor was given a minor part in the new play.年轻的男演员在这出新戏里被分派担任一个小角色。
• I gave him a minor share of my wealth.我把小部分财产给了他。

19 nutrients   

n.（食品或化学品）营养物，营养品( nutrient的名词复数 )

参考例句：

• a lack of essential nutrients 基本营养的缺乏
• Nutrients are absorbed into the bloodstream. 营养素被吸收进血液。 来自《简明英汉词典》

20 arid   

adj.干旱的；(土地)贫瘠的

参考例句：

• These trees will shield off arid winds and protect the fields.这些树能挡住旱风,保护农田。
• There are serious problems of land degradation in some arid zones.在一些干旱地带存在严重的土地退化问题。

21 implementing   

v.实现( implement的现在分词 )；执行；贯彻；使生效

参考例句：

• -- Implementing a comprehensive drug control strategy. ――实行综合治理的禁毒战略。 来自汉英非文学 - 白皮书
• He was in no hurry about implementing his unshakable principle. 他并不急于实行他那不可动摇的原则。 来自辞典例句