Aquatic macrophytes as limnological indicators

Species of submersed and floating-leaved aquatic macrophytes have been place in a series based on their patterns of occurrence in an ordination of floristic lists. Two chemical parameters from lake water analyses are correlated with the species assemblage in individual lakes and trophic categories are defined on the quantitative chemical characteristics of lake waters. The range and limiting tolerance of solute content for many aquatic species are described and related to these trophic categories. Restiction towards eutrophic conditions is considered as an obligate relatinship reflecting physiological demands. Some dystrophic and oligotrophic species are shown to have wide tolerance and are thought to be excluded from sites of higher trophic status by competition rather than physiological limitation.