A. A forest is cleared for farmland, and eventually, various vegetables grow in place of the forest.
B. A glacier melts, and barren rock is exposed, which is eventually covered by small autotrophs.
C. Eventually, one tree species and an herbivorous bird species outnumber other organisms.
D. A population of large herbivores migrates after consuming most of the grass in an area.
参考答案:
B
本题详细解析:
Choice B starts with a barren, lifeless environment, the bare rock, and progresses as pioneer species like autotrophs (such as algae or lichens) colonise the area. The death and decay of these organisms, as well as other factors, leads to soil development. Plants may begin to grow, and animal species eventually immigrate to the area. Choice B is, therefore, correct.
Although a forest being cleared by humans is an example of a disturbance caused by a biotic factor (humans), the growth of agricultural plants is a controlled and managed process, not ecological succession. Choice A is, therefore, incorrect. Choice C is a partial description of a climax community, which tends to be dominated by fewer species as a result of competition, leading to a decrease in biodiversity. These few species utilise a significant proportion of the habitat's resources. Choice D is incorrect as it is an example of migration. Some species migrate from area to area, consuming significant proportions of the available food and then moving on to a new location in search of more food.
