Characterizing Sphagnum spectral physiology across a 3000km latitudinal transect.

Bryophytes contribute significantly to carbon cycling and net ecosystem productivity on a global scale. Sphagnum bogs alone account for one third of all terrestrial carbon storage. Despite the significance of Sphagnum to global carbon cycling, the physiology of the genus remains poorly characterized. Assessments of spectral physiology, such as reflectance and chlorophyll fluorescence can be measured from a remote setting and provide estimates of relative photosynthetic capacity. In this work, we studied the spectral physiology of Sphagnum samples collected from ten sites distributed across a 3000km transect in North America. The reflectance and chlorophyll fluorescence responses of Sphagnum differed significantly between the latitudinal sites. While these results suggest that Sphagnums’ photosynthetic physiology depends on latitudinal origin, the directionality of this variation was mildly correlated with latitude. Generalized additive models explained differences in spectral physiology between the latitudinal sites more effectively than linear regression. Discriminant analysis of Sphagnum reflective and chlorophyll fluorescence responses classified Sphagnum by latitudinal sites of origin with high accuracy. These models also effectively distinguished Sphagnum from both vascular and nonvascular plant taxa