Study On Sphagnum Persistent Spore Banks In Two Peatlands Form China And Canada

A persistent sexual propagule bank (seeds and spores) is important forpopulation regeneration and maintenance of genetic diversity. Sphagnum spores havea predicted longevity of centuries. However, prediction has not been tested, and howhabitat affects spore viability in peatlands is still unknown.In this study, we drilled peat cores from hommock and hollow respectively intwo peatland of China and Canada. We tested Sphagnum spore viability at variousdepths in peat cores, dated by137Cs and210Pb dating, to determine time since burialfor spores in corresponding layers in Hani peatland and Canadian Mer-Bleue peatland,hummocks and hollows. Our aims were:1) to look for direct evidences thatSphagnum can form a long-term persistent spore bank;2) to estimate longevity ofSphagnum spores by establishing a model about the relationship between viability andburial time in Sphagnum spores; and3) To explore how the habitat differences affectsphagnum spores vitality and life. The main conclusions in this study are as follows:(1) Recently, the production of Sphagnum spores is volatile in peatlands. Bycontrast, the annual number of spore production is the highest in Hani peatlandhommock and it is the lowest in hollow. The Sphagnum spore production inMer-Bleue peatland is lower than Hani peatland.(2) This study is the first direct evidence that Sphagnum spores may be viable formore than4centuries and it definitely demonstrates that Sphagnum can form along-term persistent spore bank in peatlands. This is the highest longevitydemonstrated for bryophyte spores. And the vitality of spores decreased with theincrease of the burial time in the peatland.(3) Model calculated that the Sphagnum spores may survive for more than threemillenniums in nature. By contrast, the Sphagnum spores have higher viability inhollow habitat in minerotrophic peatlands.(4) The long-term persistent spore bank may have an important role forSphagnum population persistence under the current climate change. Once a majordisturbance, Sphagnum spores which survive the disturbance may germinate tore-establish the habitat.