In the previous chapter, we focused on the mechanisms that explain how bryophyte species are able to ‘travel’ across oceans and continents. The success in colonizing a new area, or the ability to persist within the same area in the long-term, depend, of course, on the ability of the species to cope with local environmental conditions. Bryophyte distributions are influenced by a variety of factors operating over a range of temporal and spatial scales (Rydin 2009) (Fig. 7.1), which are the focus of the present chapter.

Global ecology

A central thesis to plant ecology is that climate exerts the dominant control on the distribution of plants at the continental scale. In bryophytes, changes in communities depending on major climatic shifts during the Quaternary Era are evident from the succession of macro-remains preserved in peat. Each climatic phase had its characteristic range of habitats and these appear to have been colonized by bryophytes at a remarkable speed as soon as they developed and became available (Jonsgard & Birks 1995). Two macrofossil taxa are of particular significance in the interpretation of macro-climatic changes: Sphagnum spp. and Racomitrium lanuginosum.

The local distribution of R. lanuginosum is controlled by its preference for cold, wet climates (Tallis 1995). By contrast, the occurrence of Sphagnum largely depends on water availability. In the Holarctic, for example, Sphagnum bogs are strictly restricted to areas experiencing an annual moisture balance > 0 (Gignac et al. 2000).