Definition: I will explain what a plagioclimax community is. A long time ago, a pioneer species, for example, bacteria, would start to grow on a rock. Over time, a community of species - animals and plants - will begin to develop, but for plagioclimax - the community of species will not extend to a natural climax community because of external influences preventing this. For example, human activities - cutting down trees, cattle grazing on farmland, and people walking on dunes - prevent plants from growing naturally. This means a community of species will not develop into a natural climax community.