Phases of Vegetational Zones Classification of Natural Ponds and Lakes in the Glaciated Prairie Region Phases of Vegetational Zones In ponds and lakes with undisturbed bottom soils, most of the vegetational zones are each represented by two or three distinct phases that frequently alternate when there are appropriate fluctuations in water level or changes in intensity or frequency of certain land-use practices. Within each vegetational zone of a pond or lake, two or three phases may occur at the same time. Normal emergent phase. Plant growth extends above the water surface or dry bottom soil an often forms a canopy or overstory.
Subdominant species occur under the emergent cover.
Open water without vegetation or without emergent plants extending above the water surface may occur in all zones. Drawdown bare-soil phase. As surface water in the open-water phase gradually recedes and disappears, expanses of bare mud flats, which often become dry, are exposed. Natural drawdown emergent phase. Undisturbed areas with emergent drawdown vegetation are considered to be in this phase.