Science Question for Monday, February 22nd, 2016
Abandoned cornfields have been the sites of investigations concerning ecological succession, the orderly progression of changes in the plant and/or animal life of an area over time (see Figure 1).
(Note: The plants are ordered according to their appearance during ecological succession.)
During the early stages of succession, the principal community (living unit) that dominates is the pioneer community. Pioneer plants are depicted in Figure 2.
The final stage of ecological succession is characterized by the presence of theclimax community, the oak-hickory forest. Figure 3 depicts the gradual change from pine to hardwoods.
Figures adapted from Eugene P. Odum, Fundamentals of Ecology. ©1971 by Saunders College Publishing/Holt, Rinehart, and Winston, Inc.
On the basis of the data presented in Figure 1, approximately 80 years after the abandonment of cropland, the land would contain:
A. pine seedlings only.
B. oak-hickory hardwood forests only.
C. early invading species like horseweed, aster, and broomsedge.
D. large pine trees with an understory of hardwood trees.
準確謎底：D
The best answer is D. Figure 1 indicates the community type that was present at various times following abandonment.
According to Figure 1, 80 years after abandonment, a pine forest existed on the abandoned land and a hardwood understory was also present. Thus, D is the correct answer.
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