Response of plant communities to environmental conditions: disturbances or constraints

Abstract

In aquatic environments, disturbances can be floods, which induce flow velocities sufficient to cause erosion of the substrate and the uprooting of plant communities, or that promote alluvial deposits. Thus they create heterogeneity of habitats, which results in a wide variety of plant communities whose composition is related to the variability of the intensity of exchanges hydrological, quality and origin of waters. The species develop strategies adapted to the fluctuating water levels with variable intensity and frequency. In rivers not subject to flooding, plant communities that are expanding are organized as a sequence of vegetation according to a gradient of natural trophic level upstream downstream. Physical or chemical impairments (morphological changes in the bed, hydroelectric impoundment) change or even destroy this sequence. It shows that plant communities may be descriptors of hydrological functioning of the watercourse and/or biondicators of physical or chemical impairments.