Shading as a tool for <i>Sphagnum magellanicum</i> regeneration: scalable implications for peatland restoration in southern South America

Peatland degradation driven by the overharvesting of Sphagnum magellanicum threatens carbon storage and water regulation in Patagonia, southern Chile, and Argentina. Restoration could be facilitated through ex situ propagation. However, its ecological requirements, such as light availability, are poorly understood. Here we tested whether shading improves diaspore regeneration under controlled conditions aiming at the future restoration of degraded peatlands. Stem fragments from a Chilean peatland were used as diaspores and cultured for 11 weeks under Raschel mesh with different shading levels (0, 35, 70, and 80%). Regeneration (shoot number), shoot elongation, and pigment content were analyzed with generalized linear mixed models. The 35% and 70% shading increased shoot elongation compared with the control (no shading), whereas the 80% shading did not promote regeneration but produced shoots significantly longer than those of unshaded moss. All shaded treatments had higher chlorophyll a and b concentrations, while carotenoid and sphagnorubin levels were unaffected. These findings delineate a light range that maximizes diaspore establishment without inducing shade-avoidance stress. Thus, applying 35%–70% Raschel shading could serve as a practical method for ex situ production and field restoration of peatlands in Southern South America.