Plant community

A plant community is a collection or association of plant species within a designated geographical unit, which forms a relatively uniform patch, distinguishable from neighboring patches of different vegetation types. The components of each plant community are influenced by soil type, topography, climate and human disturbance. In many cases there are several soil types present within a given plant community. This is because the soil type within an area is influenced by two factors, the rate at which water infiltrates or exits (via evapotranspiration) the soil, as well as the rate at which organic matter (any carbon-based compound within the environment, such as decaying plant matter) enters or decays from the soil. Plant communities are studied substantially by ecologists, due to providing information on the effects of dispersal, tolerance to environmental conditions, and response to disturbance of a variety of plant species, information valuable to the comprehension of various plant community dynamics. A plant community can be described floristically (the species of flowers or flora the plant community contains) and/or phytophysiognomically (the physical structure or appearance of the plant community). For example, a forest (a community of trees) includes the overstory, or upper tree layer of the canopy, as well as the understory, a layer consisting of trees and shrubs located beneath the canopy but above the forest floor. The understory can be further subdivided into the shrub layer, composed of vegetation and trees between a height of approximately one to five meters, the herbaceous layer, composed of vascular plants at a height of one meter or less, and sometimes also the moss layer, a layer of non-vascular bryophytes typically present at ground level (approximately 0.15 meters in height or less). In some cases of complex forests there is also a well-defined lower tree layer. A plant community is similar in concept to a vegetation type, with the former having more of an emphasis on the ecological association of species within it, and the latter on overall appearance by which it is readily recognized by a layperson.