Sensitivity of mosses to sulfur dioxide

Area of Science:

• Environmental Science
• Botany
• Ecology

Background:

• Sulfur dioxide (SO2) is a major air pollutant impacting ecosystems.
• Bryophytes, like mosses, are sensitive bioindicators of environmental stress.
• Previous studies indicate SO2 affects plant physiology, but species-specific responses and life stage sensitivities are less understood.

Purpose of the Study:

• To determine the differential sensitivity of seven North American moss species to sulfur dioxide (SO2) fumigation.
• To investigate the SO2 tolerance of different life stages (protonema, young gametophores, mature gametophores) in Polytrichum ohioense.
• To elucidate the mechanisms behind observed moss-impoverished zones near SO2 emission sources.

Main Methods:

• Controlled fumigation experiments exposing seven North American moss species to SO2 concentrations from 0.5 to 4.0 ppm.
• Cultured gametophytes of Polytrichum ohioense were fumigated with SO2 at concentrations ranging from 0.1 to 4.0 ppm for 8 hours.
• Comparative analysis of species sensitivity and life-stage specific responses to SO2 exposure.

Main Results:

• Significant differential responses were observed among the seven moss species to SO2 fumigation.
• Leucobryum glaucum and Dicranum scoparium exhibited the highest sensitivity, while Dicranella heterophylla, Polytrichum ohioense, and Pottia truncata were most resistant.
• In Polytrichum ohioense, protonema and young gametophores were highly sensitive, killed by 0.2 ppm SO2, whereas mature gametophores tolerated up to 4.0 ppm SO2.

Conclusions:

• Moss species exhibit varying tolerance levels to sulfur dioxide pollution.
• The high sensitivity of moss protonema and young gametophores to SO2 suggests that impaired reproduction, not direct damage to mature plants, is the primary cause of moss reduction near SO2 sources.
• These findings highlight the importance of considering life stage-specific sensitivities when assessing the ecological impact of air pollutants on bryophyte communities.