A Simulation Model for Growth of the Submersed Aquatic Macrophyte Sago Pondweed (Potamogeton pectinatus L.)

Abstract

Abstract : A simulation model for biomass dynamics of the submersed macrophyte Potamogeton pectinatus L. is presented. The model (POTAM) is based on carbon flow through the vegetation in meter-squared (m2) water columns. It includes descriptions of several factors that affect biomass dynamics, such as site characteristic changes in climate, temperature, water transparency, water level, pH, and oxygen effects on CO2 assimilation rate at light saturation, wintering strategies, mechanical control (removal of shoot biomass), and grazing. The characteristics of community and site can be easily modified by the user. POTAM incorporates insight into the processes affecting the dynamics of a sago pondweed community in relatively shallow, hard water (0.1-to 6-m depth; dissolved inorganic carbon concentration> 0.8 mmol and pH> 6), under ample supply of nitrogen and phosphorus in a pest-, disease-, and competitor-free environment under the prevailing weather conditions. It has been calibrated on data pertaining to a sago pondweed community in the Western Canal near Zandvoort, The Netherlands. At this site, growth starts from the subterranean tubers alone. Plant biomass usually peaks once a year, in July, and intensive downward transport of soluble carbohydrates occurs after anthesis, used for the formation of tubers that grow into the sediment. POTAM simulated the dynamics of plant and tuber biomass and tuber numbers in the Western Canal near Zaudvoort, The Netherlands, well over a period of 1 to 5 years. Starting from measured instead of nominal tuber size increased the similarity between simulated and measured plant data. The importance of several plant species- characteristic properties was explored, namely, of leaf surface:dry weight ratio, tuber bank density, anchorage depth, and presence/absence of wintering shoots.