A now outdated concept assumed these communities were stable and co-evolved. Plant communities were assumed to “partition” areas between forests, grasslands, and other vegetation types. And, plants within a community interacted mutualistically to help the community remain intact (relay floristics). We now know that plants compete, and the ones that gain initial advantage after a disturbance can dominate a community—and make the same area into different vegetation types. This changes complicate vegetation mapping. Following a disturbance, plant communities undergo times of rapid plant invasion, followed by exclusion of new stems when the growing space is becomes occupied. Later, other structures appear. Species diversity is generally highest during initial plant invasion (“stem exclusion stage”), lowest in the “stem exclusion stage”, and increases with different species in the later stages. All stages are needed in a landscape to protect biodiversity. Recent declines in forest species may be because stages have been excluded and because communities have been fragmented with roads and cities. All structures will be important for maintaining all species with climate changes.