Environmental gradients have been shown to influence the distribution of forest bryophytes in New Zealand, but no studies to date have measured physiological responses of these bryophyte species to environmental stress. Physiological differences between mosses and liverworts, and different growth forms of each, may lead to distinctive physiological mechanisms for dealing with damage induced by stress. Understanding the variation of species’ stress responses could help us better predict species interactions, distributions, and vulnerability to global change. We collected samples of 13 common forest-dwelling bryophyte species in spring and summer at three sites spanning an elevation gradient of 107 – 360 m a.s.l. in southern New Zealand. We used five protein biomarkers to assess oxidative stress responses of these species to elevation and season – one damage marker (protein carbonyls) and four defense markers (superoxide dismutase, catalase, glutathione reductase, and glutathione peroxidase).
Results/Conclusions
For the nine species (seven mosses and two liverworts) observed across the elevation gradient, we found that damage increased with elevation in all mosses and one liverwort, with significantly higher protein carbonyl concentration at high than low elevation. This increased damage was accompanied by increases in defense markers (i.e. significantly higher concentrations of most enzymes) for five moss species and the liverwort. We found that damage increased from spring to summer for seven moss species (i.e. significantly higher protein carbonyl concentration), and this was accompanied by increases in defense markers (i.e. significantly higher enzyme concentrations). The three liverwort species showed no effect of season on damage (i.e. no difference in protein carbonyl concentration), but one liverwort species had greater concentrations of defense markers in summer than in spring. Our results suggest that New Zealand mosses and liverworts exhibit similar physiological responses to stress along some environmental gradients (e.g. elevation) but not others (e.g. season). Future work examining how morphology and physiology together influence oxidative stress responses of these species would further help disentangle how environmental tolerances influence their distributions.