TOEFL Reading: ETS-TOEFL阅读机经 - 1D4J3BC4GX1LB338L$

According to paragraph 4 one difference between the second and the third stage in forest development is that in the third stage A. there is more intraspecific competition than interspecific competition. B. the growth of understory and suppressed substory trees slows down. C. sudden changes in the environment are less frequent. D. the canopy becomes more complex.