Continuous Waterlogging May Not Facilitate Germinability Maintenance of Sphagnum Spores

Abstract

Burial depth within soil affects the survival of seeds and spores in ecosystems. However, burial depth effect on germinability of Sphagnum spores received little attention. In a peatland in Northeast China, we conducted a spore burial experiment using two hollow dwelling species, Sphagnum squarrosum and S. fallax. We hypothesised that i) S. squarrosum would show lower spore germinability than S. fallax because of its limited distribution in open area and ii) for both species there would be increased spore germinability along burial depth gradient because greater depth provides better conditions for spore preservation. After one-year spore burial, we conducted a laboratory germination bioassay to test spore germinability, determined by germination percentage (GP) and germination index (GI). Spore germinablity of S. squarrosum was >60% lower than S. fallax. Both species showed at least 40% higher germinability when buried in hollows than in hummocks. Overall spore germinability increased with burial depth with maximum germinability at 30 and 20 cm below the surface of hummocks and hollows respectively, where water table fluctuation occurred. We conclude that although hollows are better habitats for spore storage, continuous waterlogging may not be favourable for maintaining high germinability of Sphagnum spores.

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