Compare primary and secondary succession. In Environment A, trees are growing back and some of the larger animals are returning to a logged forest. In Environment B, lichens and moss are growing on a rocky mountainside that was scraped bare as a glacier retreated. Now, hundreds of years later, some small grasses, shrubs, and animals live there. Which statement best describes both situations? Both environments are undergoing the same kind of succession. Environment A is undergoing succession, and Environment B is not. Both environments are undergoing succession, but different kinds. Environment A is not undergoing succession, and Environment B is. 9.