THE ROLE OF REPRODUCTION FOR PERSISTENCE OF BRYOPHYTE POPULATIONS IN TRANSIENT AND STABLE HABITATS

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  Many bryophytes occur in habitats which are of limited size and duration. Consequently, a bryophyte population shows dynamics at two levels: within-habitat and between-habitat. Whereas vegetative growth and competition are primary processes at the within-habitat level, reproductive processes (including dispersal by gemmae) are crucial for the between-habitat level. Simulation studies show that knowledge of parameters of the habitat (habitat size and duration, mean distance between habitats, spatial arrangement and number of habitats) is indispensable for assessment of the role of reproduction in bryophytes. Information on these parameters is largely missing. An analysis of the British moss flora showed a strong relationship between frequency of propagule formation and habitat; mosses in small (or less contiguous) and unstable habitats show more frequent propagule formation. Without a detailed knowledge on remaining parameters of species biology and habitat, these relationships are difficult to interpret.

  The method of persistence of a species is important also in evolutionary considerations. Life strategies in bryophytes are syndromes of interrelated adaptations to different habitats. These relationships to the habitat (both at within patch and between patch levels) form an intriguing subject for the study in evolution of bryophytes.