Habitat requirements for establishment of Sphagnum from spores

1 The ecological significance of the spore in perennial bryophytes has been questioned. In Sphagnum, protonemata have rarely been observed in the field and P-concentrations in natural waters are insufficient for spore establishment. 2 We determined requirements for establishment of Sphagnum spores in growth chamber experiments. Up to 17 species were tested on peat with various natural substrates added and with different mire waters. In a field experiment, the effect of cover of nutrient depleted Eriophorum-litter was also tested. 3 There were large differences between substrates. and establishment appeared to be limited by the amount of phosphate released. Added moose dung or litter of Betula pubescens promoted establishment well above the low level seen on peat alone, or with added litter from Pinus sylvestris. 4 Species differed slightly in response to different mire waters and to added substrates, but these differences could not be attributed to the natural habitat of the species or their breeding system. There was a weak negative relationship between spore size and establishment success. 5 In the field experiment, about 1% of the sown, viable spores established in the presence of moose dung or Betula litter. With moose dung there was an indication that protonemata and plants of other bryophytes had a negative effect on the establishment of Sphagnum. 6 Nutrient release from litter and cover provided by vascular plants are needed to generate safe sites for the establishment of Sphagnum from spores, especially on wet, acidic and relatively nutrient-poor soils and peat. Recruitment from spores may therefore be important in Sphagnum, particularly following disturbance.