Seasonal growth of submersed macrophytes in lakes: The effects of biomass density and light competition

The long-term growth and succession of aquatic plant species in lakes have been documented in many field studies, but there has been little insight to quantify the mechanisms which determine the outcome of competitive growth. In this paper, a process-based macrophyte growth model is formulated and used to investigate the light limited growth of individual macrophyte species and of two species in competition. Closed form solutions for integral biomass production over 1 day are derived, reducing the time and depth resolution required for seasonal growth calculations. For growth in monoculture, seasonal biomass production is found to be most sensitive to the base growth and respiration rate coefficients and the temperature dependence of growth, and relatively insensitive to biomass density, and the half-saturation constant for light. The sensitivity of seasonal biomass production to basic physiological, morphological, and physical lake parameters is found to be significantly higher for growth in competition compared to growth in monoculture. For published growth parameter values, invasive species are predicted to suppress the growth of native species over a well-defined range of water depths and turbidities, largely by reaching the water surface early in the season and subsequently forming a dense surface canopy.