Littoral slope as a predictor of the maximum biomass of submerged macrophyte communities1,1

The hypothesis that the morphometric characteristics of the littoral zone of lakes are a major determinant of submerged macrophyte biomass was tested in Lake Memphremagog (Québec‐Vermont) by studying the relationship between maximum biomass of submerged macrophytes and physical and sediment characteristics of the littoral zone. The slope of the littoral zone accounted for 72% of the observed variability in maximum submerged macrophyte biomass (MSMB). By also incorporating sediment organic matter the variance explained was raised to 88% ( P < 0.0001). A model based on only slope as predictor of MSMB was improved by considering slopes ≷5.33%: urn:x-wiley:00243590:media:lno19863151072:lno19863151072-math-0001 The power of these two equations to predict the MSMB in a variety of temperate lakes was high ( r = 0.90, P < 0.0001). However, the temperate zone model overestimates the MSMB in highly turbid lakes where irradiance rather than slope is pre‐eminent and underestimates the biomass in semitropical and tropical lakes.