SPHAGNUM DESICCATION TOLERANCE

Peatland restoration techniques currently developed in eastern Canada involve the reintroduction of Sphagnum fragments on the bare post-harv ested peat substrate in order to restablish a moss carpet. The reintro duced fragments, or diaspores, are exposed to desiccation and heat in summer. To evaluate Sphagnum desiccation tolerance, isolated stems of three species (Sphagnum fallax. S. fuscum and S. magellanicum) were ai r-dried (T similar to 20 degrees C, relative humidity similar to 60%) for various lengths of time. Results showed that, under these conditio ns, Sphagnum fragments can survive up to 14 days without water. In gen eral, S. fallax and S. magellanicum resisted better to desiccation tha n S. fuscum. However, for all species studied, desiccation delayed the onset of regeneration. In a second experiment, stems from six species (S. angustifolium, S. fallax, S. fuscum, S. magellanicum, S. nemoreum and S. papillosum) were oven dried for 48 hours at 20 degrees C, 30 d egrees C, 40 degrees C, 50 degrees C, 60 degrees C or 70 degrees C in order to evaluate their resistance to heat. As for desiccation toleran ce, heat tolerance varied between species. S. fallax was the only spec ies that survived a 48 hour period at 30 degrees C. Hence temperature acid water availability are important factors for the survival and gro wth of Sphagnlon diaspores introduced on bare prat.