A. I only
B. I and II only
C. I and III only
D. I, II and III
参考答案:
B
本题详细解析:
Both primary and secondary succession involve pioneer species (Statement I). Pioneer species are the first organisms to colonise an area during succession, regardless of whether it's primary or secondary succession.
The rate of succession can vary in both primary and secondary succession (Statement II). The rate can depend on various factors, including the environmental conditions and the specific organisms involved. Choice B is therefore, correct, and Choice A is incorrect as it only includes one of the true statements.
Primary succession begins in barren, lifeless environments, for example, when glaciers expose bare rock, whereas secondary succession occurs in areas with existing communities that have been disturbed, such as after forest fires. Statement III is, not true, making Choices C and D incorrect.
