Primary production and primary producers

The distribution of plant species and their productivity in a fluvial hydro-system is dependent on the complex interactions between hydrodynamic processes (e.g. flow velocity, shear stress, the nature and stability of the substrate etc.), hydrochemical processes (e.g. nutrient cycling, pH etc.) and the use of solar energy by their photosynthetic processes (influenced in turn by water transparency, shade etc.). Diverse adaptive strategies permit plant communities to colonize a range of patches in the fluvial unit, but they are sensitive environmental indicators (Naiman and Décamps, 1990). However, environmental changes affecting plant distributions in fluvial hydrosystems are now recognized as complex phenomena, giving rise to transient states in plant communities which may persist for decades.