Oxygen-deficiency and allelochemicals affect Sphagnum spore persistence in peatlands

Abstract

To test the effects of characteristic ecological gradients in peatlands including oxygen-deficiency and allelopathy on Sphagnum spore persistence. We determined the initial viability of Sphagnum spores and then stored the spores for 60 days, either dry, in ultrapure water, peatland surface water or Sphagnum water leachate (the latter two solutions rich in allelochemicals from Sphagnum). We varied oxygen concentration by injecting air at three different concentrations during the storage experiment. After retrieval from experimental storage, spore germinability index was assessed. Germinability index after air injection was lower than under oxygen-deficiency. Germinability index in the peatland surface water and Sphagnum leachate water was higher than in ultrapure water, under oxygen-deficiency. Overall, dissolved oxygen and high pH negatively affected spore germinability and, consequently, viability. These results indicate that once dispersed onto bryophyte substrates or waterlogged hollows, Sphagnum spores can maintain viability better than when exposed to dry conditions or in water without allelochemicals. Extreme longevity of Sphagnum spores may be attributed to the oxygen-deficient, waterlogged and acidic Sphagnum-dominated peatland habitat with allelopathic substrates.