Abstract: The dominance of non-Sphagnum mosses such as Polytrichum strictum has increased in some peatlands of NE China while the mechanism is not clear. We performed a one-year experiment in Hani Peatland with three mosses, Sphagnum palustre, S.magellanicum and P.strictum in two typical habitats with different water table depth. We tried to explore the effects of water table and neighbor on morphological traits including height increment, biomass production and side-shoot production and biochemical traits including carbon and nitrogen content and soluble sugar content. Two Sphagnum mosses both responded to water table drawdown with the increasing of side-shoot production and nitrogen content but decreasing height increment. S.magellanicum also responded with the decreasing of soluble sugar content. Except for the inhibitive effect on biomass production and the facilitation effect on side-shoot production, no other traits in P.strictum were affected by water table drawdown. In mixed culture, two Sphagnum species mutually promoted their height increment and biomass production. Side-shoot production in S.palustre and carbon content in S.magellanicum were negatively affected by neighbor P.strictum, while neither neighbor had any effects on P.strictum. Although P.strictum did not have a direct competition effect on two Sphagnum mosses, and by virtue of its good drought tolerance, it could still get the competitive advantage and realize population expansion in peatlands in the background of climate warming and water table drawdown resulted from disturbance by human beings.

Key words: Sphagnum, Polytrichum strictum, water table, soluble sugar content