Annual Absorption of Gaseous Air Pollutants by Mosses and Vascular Plants in Diverse Habitats

Abstract

Mosses are used as bioindicators of air pollution stress for plant communities because field studies of moss distribution around SO₂ sources show that they are more sensitive to gaseous pollution than vascular plants. Differences between moss and vascular plant sensitivity to SO₂ is thought to reflect greater SO₂ absorption by mosses; however, direct evidence supporting this hypothesis is limited.

This paper uses a general model of gaseous pollutant uptake to make comparisons between absorption of SO₂ for mosses and vascular plants. Annual SO₂ absorption is characterized for both types of plants for a number of diverse habitats in which the water status of plants would be expected to change with time. The estimation of SO₂ absorption showed how habitat or weather patterns may change absorption capacity of these two groups of plants.

We conclude that mosses are likely to absorb more SO₂ and other gaseous pollutants during the course of a year than are vascular plants. This was apparent with all habitats examined, from the tropics to the arctic tundra. The difference in annual SO₂ absorption between these types of plants varied with habitat and ranged from 400 to 4000-fold. This greater absorption potential for SO₂ occurs despite variations in annual moss water content being taken into account. SO₂ absorption calculated for mosses can help account for total sulphur content in mosses growing near SO₂ sources.