Ants as a Barometer of Ecological Change
At picnics, ants are pests. But they have their uses. In industries, such as mining, farming and forestry, they can help gauge the health of the environment by just crawling around and being antsy.
It has been recognized for decades that ants -- which are highly sensitive to ecological change --can provide a near-perfect barometer of the state of an ecosystem. Only certain species, for instance,will continue to thrive at a forest site that has been cleared of trees.46 And still others willmove in and take up residence.
By looking at which species populate a deforested area, scientists can determine how"stressed" the land is.47 Ants are used simply because they are so common and comprise so many species.
Where mine sites are being restored, for example, some ant species will recolonize the stripped land more quickly than others.48 Australian mining company Capricorn Coal Management has been successfully using ant surveys for years to determine the rate of recovery of land that it is replanting near its German Creek mine in Queensland.
Ant surveys also have been used with mine-site recovery projects in Africa and Brazil, where warm climates encourage dense and perse ant populations." We found it worked extremely well there." says Jonathan Majer, a professor of environmental biology. Yet the surveys are perfectly suited to climates throughout Asia, he says, because ants are so common throughout the region. As Majer puts it: "That's the great thing about ants."
Ant surveys are so highly-regarded as ecological indicators that governments worldwide accept their results when assessing the environmental impact of mining and tree harvesting.49
Why not? Because many companies can't afford the expense or the laboratory time needed to sift results for a comprehensive survey. The cost stems, also, from the scarcity of ant specialists.50
A. This allowed scientists to gauge the pace and progress of the ecological recovery.
B. Yet in other businesses, such as farming and property development, ant surveys aren't used widely.
C. Employing those people are expensive.
D. They do this by sorting the ants, counting their numbers and comparing the results with those of earlier surveys.
E. The evolution of ant species may have a strong impact on our ecosystem.
F. Others will die out for lack of food.
46.F。空格前讲的是只有某些物种将在没有树的森林里存活;空格后讲仍有其他物种将会迁入并占据住地。空白处的前后谈论的都是物种在没有树的森林里生存的情况，且都使用了将来时“will”，所以空格处也应谈及物种在森林里生存的情况，且时态也应该使用将来时。所有选项中只有F使用的是将来时态，且语义上也比较接近，故正确答案为F其他的将会因为缺少食物而死亡。从语法来看，空格前面的句子有certain species，空格后面的句子有still others，这一定是英语中的“some/certain…others…still others”的固定结构，也不难得出答案为F。
47.D。空格前讲的是科学家通过观察哪个物种在没有树的森林里生活来决定该区域所承受的“压力”，空白处后谈论的是使用蚂蚁仅仅因为它们很常见而且包含了很多物种，由此可知空白处谈论的是科学家利用蚂蚁这个物种进行观察，所以本题答案为选项D他们通过将蚂蚁分类、计算他们的数量和与早期研究作比较而做出决定。其中“doing this”中的“this”是指前面句子中的scientists can determine how“stressed”the land is。
48.A。空格前一句提到，在矿区生态恢复过程中，一些种类的蚂蚁就比其他种类的蚂蚁更快迁回到该片原先荒废的区域;空格后提到澳大利亚的一家矿业公司Capricorn Coal Management就成功使用针对蚂蚁的调查而测算出土地复原的速度，因而空格处谈论的还是蚂蚁和土地复原的话题。因而，选项A这使得科学家能够测算出生态恢复的速度和进程与前后衔接紧密，符合题意。其中，选项A中的ecological recovery与前面一句中的recolonize相呼应，也提示选项A的句子是前面句子的后续句。