Winter climate change increases physiological stress in calcareous fen bryophytes

Area of Science:

• Ecology
• Wetland Science
• Plant Physiology

Background:

• Calcareous spring fens are rare, endangered global ecosystems.
• High-latitude fens face accelerated climate change, particularly warming winters and reduced snow cover.
• Snow cover is crucial insulation, protecting fen ecosystems from sub-zero temperatures.

Purpose of the Study:

• To assess the ecophysiological sensitivity of dominant fen bryophytes to changing climatic conditions.
• To investigate the impact of reduced snow cover on bryophyte physiology and community dynamics.
• To differentiate the responses of Campylium stellatum and Scorpidium scorpioides to simulated winter climate change.

Main Methods:

• Annual ecophysiological monitoring of C. stellatum and S. scorpioides.
• A snow removal experiment to simulate reduced winter insulation.
• Measurement of photosystem II efficiency (Fv/Fm) and pigment concentrations (chlorophylls, carotenoids).

Main Results:

• Bryophytes exhibited physiological stress (low Fv/Fm) in spring and highest pigment concentrations in autumn.
• Snow removal intensified physiological stress, reducing Fv/Fm and pigment concentrations.
• C. stellatum, a hummock inhabitant, showed greater sensitivity to snow removal than S. scorpioides, a hollow-dwelling species.

Conclusions:

• Winter climate change negatively impacts spring fen bryophytes through increased frost exposure and freeze-thaw cycles.
• Reduced snow cover exacerbates physiological stress and alters pigment composition in fen bryophytes.
• Differential species responses suggest potential shifts in bryophyte community structure under future climate scenarios.