Models of aquatic plant productivity: a review of the factors that influence growth

Models that simulate production of rooted macrophytes and macroalgae in aquatic systems aid in developing hypotheses about the feedback mechanisms that influence plant growth and allow water resource managers to predict how plants will respond to changes in water quality management regimes. Light availability, water temperature, water velocity, and phosphorus, nitrogen and dissolved inorganic carbon concentrations are the environmental factors most often modelled to influence plant photosynthesis, respiration, washout and decay. The algorithms used to describe these relationships are reviewed, with emphasis placed on aquatic plants in freshwater ecosystems. The factors influencing photosynthesis in aquatic plants have been well-described with mechanistic or theoretical equations. However, research is needed to better describe mathematically the mechanisms involved in plant respiration, washout and decay. Due to the complexity of the interaction of environmental factors influencing plant growth, empirical relationships are unavoidable in productivity models and they can provide useful insight into ecosystem 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 environmental conditions. (C) 1997 Elsevier Science B.V.