Due to the necessity of nature to fill every niche with efficient use of sunlight and soil, plants naturally partition those resources through a succession of species. After a disturbance or as soil has become exposed to the environment through some geological event, plants begin to occupy the new niche. At first the pioneer plants take hold. Dandelions, grasses, and an assortment of plants commonly called weeds begin to cover the soil and put down roots. Flat and broad leaved plants cover the soil and limit the growth of other plants. Some root structures are fibrous growing laterally while others are deep and vertical. Even at this early stage the plants are partitioning the soil so that each gets its needs met. New plants of similar route structure are out-competed by the plants that are established. Only the plants that can find a niche that is not occupied will have a chance at survival.
Excerpt from APS 5101 Polyculture Design University of Minnesota, June - July, 2013