41. B 42. D 51. D 52. B

43. C 53. D

44. A 54. A

45. D 55. C

46. A

47. B 48. C 49. B 50. A

2020奉贤一模

Ecology is a complicated thing. Given the facts that elephant damage often kills trees and bush fires often kill trees, it would be 41 to assume that a combination of the two would make things worse. Contrary to this assumption, 42 , as the recently-published research by Benjamin Wigley shows, if a tree has already been damaged, fire can 43 help to make things better.

One common way in which elephants harm trees is by stripping(剥) them of their bark(树皮). Dr Wigley, who did indeed start from the obvious 44 , set off to find out how much worse bush fires would make the effects of this bark stripping. To serve this purpose, he set up a study in the Kruger National Park. Since 1954, the Kruger has been the site of experiments in which plots of land have been burned 45 , to understand the effects of fire on plain ecology. In these experiments, Dr Wigley looked at trees in three different zones, in one of which, the trees were burned every year; in the second, they were burned every other year, while the third zone, by contrast, was actively 46 fire. To keep things consistent, he looked at the fate of the same tree species, the marula(马鲁拉树), in all three zones. He picked marulas because they are particular 47 of elephant activity. Their fruit are delicious, and prized by elephants and people alike. But elephants also seem to enjoy eating their bark. In July 2016 he and his colleagues identified 20 marulas in every zone and used special tools to 48 from each of them a circular section of bark 5 cm in diameter. Having imposed this damage, they 49 the wounds over the course of the following two years, to see what would happen. To their 50 , they discovered that the wounds of trees in fire zones recovered far better than those of trees that had seen no fires at all. Wounded trees in the annual burn zone re-grew 98% of their lost 51 during the two years of the study. Those living in the biennial(两年一次的) burn zone re-grew 92% of it. But those in the zone where fires were 52 re-grew only 72%.

The researchers also found something else when they were measuring the trees’ wounds: ants. Ten of the 20 trees in the fire-prevention zone developed ant colonies in their wounds. The ants in question were a species that is known to damage trees and is supposed to 53 tissue healing. By contrast, only five trees in the biennial burn zone and three in the annual zone developed ants’

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