MODELS OF AQUATIC PLANT PRODUCTIVITY - A REVIEW OF THE FACTORS THAT INFLUENCE GROWTH

Models that simulate production of rooted macrophytes and macroalgae i n aquatic systems aid in developing hypotheses about the feedback mech anisms that influence plant growth and allow water resource managers t o predict how plants will respond to changes in water quality manageme nt regimes. Light availability, water temperature, water velocity, and phosphorus, nitrogen and dissolved inorganic carbon concentrations ar e the environmental factors most often modelled to influence plant pho tosynthesis, respiration, washout and decay. The algorithms used to de scribe these relationships are reviewed, with emphasis placed on aquat ic plants in freshwater ecosystems. The factors influencing photosynth esis in aquatic plants have been well-described with mechanistic or th eoretical equations. However, research is needed to better describe ma thematically the mechanisms involved in plant respiration, washout and decay. Due to the complexity of the interaction of environmental fact ors influencing plant growth, empirical relationships are unavoidable in productivity models and they can provide useful insight into ecosys tem dynamics. However, the robustness of macrophyte simulation models is largely dependent on the rigour with which they are calibrated and verified against natural data representing a broad range of environmen tal conditions. (C) 1997 Elsevier Science B.V.