Select from the seven phrases below the two phrases that correctly characterize northern Europe during the twelfth century and the three phrases that correctly characterize southern Europe. Two of the phrases will NOT be used. Write your answer choices in the spaces where they belong. You can either write the letter of your answer choice or you can copy the sentence. The Black Hills forest, the prairie riparian forest, and other forests of the western United States can be separated by the distinctly different combinations of species they comprise. Clements was challenged by another pioneer ecologist, Henry Gleason, who took the opposite view. it is largely an artifact of our perception, due to the illusion that nature, especially a complex system like a forest, seems so unchanging from one day to the next.