Question

    The African Continent has various habitat types, but savanna (热带草原) ecosystems cover approximately half. And where there is savanna, there is fire. "It's an important part of the ecology of the system," says University of Liverpool ecologist James R Probert. Burning allows grasses to take the lead by keeping taller bushes from occupying the land, Loss of grasses could push out species such as wildebeest (牛 羚 ), which are famous for their splendid annual migration.

A decade ago researchers put decreasing fires within Tanzania's Serengeti National Park down to the recovery of wildebeest population following an epidemic of rinderpest, a viral disease. When millions of wildebeest feed on grass, they remove fuel from the land, making fire less frequent and less severe.

But Probert and his colleagues found that even after wildebeest populations had stabilized by the mid-1990s, fires continued to decrease in the same area. Their analysis of satellite data showed that the region experienced a 40 percent reduction in wildfires between 2001 and 2014- in line with dramatic increases in farm animals in the area.

If you have lots of farm animals eating the grass, then you have less fire. That’s well known Probert says. "But I don’t think anybody had realized the degree of the decline in fire and linked it to farm animals before.”

This is a really interesting pattern, "says University of Guelph biologist John Fryxell, who was not involved in the study. He cautions, however, that 15 years' worth of data is still a fairly small amount of information from which to draw final conclusions. "What a short-term connection like that suggests is that there's something interesting here that could provide the grounds for a deeper experimental analysis, "he adds. That research could include artificially controlling fire frequency or grazing intensity (放牧强度) in certain areas and then monitoring the land's response over time.

1.What do we know about fires in savanna?

A.They only happen once in a decade.

B.They are harmful to the growth of grasses.

C.They help keep the balance of the ecosystem.

D.They guarantee the leading position of taller bushes.

2.According to Probert, what led to decreasing fires?

A.The spread of a disease. B.The increase in farm animals.

C.The change of the climate. D.The stability of wildebeest population.

3.What does John think of Probert's study?

A.It might help recover the land in savanna.

B.It could lead to further studies on savanna fire.

C.It has proven the link between fires and grasses.

D.It offers enough information for final conclusions.

4.What is the best title for the text?

A.Savanna Ecosystem. B.No More Farm Animals

C.Eating Away Fire. D.Controlling Wildfires

Answer

1.C

2.B

3.B

4.C

【解析】

这是一篇说明文。文章作者强调了草原火灾的重要性后分析了草原火灾次数减少的原因。

1.

推理判断题。根据文章第一段"It's an important part of the ecology of the system," says University of Liverpool ecologist James R Probert. Burning allows grasses to take the lead by keeping taller bushes from occupying the land. Loss of grasses could push out species such as wildebeest（利物浦大学的生态学家詹姆斯•R•普罗伯特说：“这是生态系统的重要组成部分。燃烧可以让草领先生长，防止高大的灌木丛占据土地。草的消失可能会导致像牛羚这样的物种灭绝）可知，燃烧可以给草的生长留出空间。如果不长草了会导致像牛羚这样的物种灭绝。因此可以判断，草原火灾有助于生态系统的平衡。故选C项。

2.

细节理解题。根据文章第三段Their analysis of satellite data showed that the region experienced a 40 percent reduction in wildfires between 2001 and 2014- in line with dramatic increases in farm animals in the area（他们对卫星数据的分析显示，2001年至2014年间，该地区的野火减少了40%，与该地区农场动物数量的急剧增加一致）可知，是农场动物数量的增加导致野火减少的。故选B项。

3.

推理判断题。根据最后一段What a short-term connection like that suggests is that there's something interesting here that could provide the grounds for a deeper experimental analysis（这种短期联系表明，这里有一些有趣的东西可以为更深入的实验分析提供依据）可知，John觉得Probert的研究数据可以被利用来对热带草原火灾进一步研究。故选B项。

4.

主旨大意题。根据文章第一段认为草原火灾对保持生态平衡很重要即： It's an important part of the ecology of the system。但是在文章的第二至第四段中提到了草原火灾次数减少的原因包括了an epidemic of rinderpest（一场牛羚瘟疫）和最重要的dramatic increases in farm animals in the area（地区农场动物数量的急剧增加）。综合分析可知，文章主要在讲消失的草原火灾。故选C项。