Influence of Two Common Bryophytes on Acidity and Divalent Cation Concentrations in Standing Spring Water

Abstract

This laboratory experiment examines the influence of two common mosses on the pH and solute dynamics of water from a spring brook. Bivariate analysis of variance tests (MANOVA) revealed significant changes in concentrations of H+ and the combined variable, divalent cations (Ca++ & Mg++) over a three week incubation period in microcosms containing Thuidium delicatulum and Brachythecium rivulare, mosses commonly found in low order woodland streams. Divalent cation concentrations in the presence of moss were 36% higher, on average, than in similar microcosms with moss absent. In microcosms containing decomposing wood, W concentrations were 15% lower in the presence of moss. There were approximately 7 mg of divalent cations in every gram of moss tissue (AFDM), while a gram of wood contained 1-2 mg of divalent cations, values similar to those reported elsewhere in the literature. I suggest reversed cation exchange is the mechanism responsible for elevated divalent cation concentrations and changes in solute dynamics. A hypothesis concerning expected responses of fungal enzymes to the observed changes in solute dynamics is discussed.