Oceanic bryophytes in Atlantic oakwoods

Abstract

Summary The oceanic bryophyte element of the vegetation of British and Irish Atlantic oakwoods is not only the richest bryophyte flora in Europe, it is also one of the richest bryophyte floras in the world. The oceanic climate and the buffering provided by the tree canopy are critical in maintaining the constant humidity and equable temperatures which provide the basis for this diversity. Though the initial impression of these woodlands is of a homogeneous green carpet over both rocks and trees, most good woodlands will have over 200 different species of moss and liverwort, many of which are very specific as regards micro-habitat. Within the woodlands, a recently glaciated landscape gives much exposed rock of different aspect, texture and chemistry, and also turbulent burns in deep ravines which enhance the humidity. These niches are exploited by different bryophyte communities which may contain a number of species that are very rare in European terms and for which we have a special responsibility. Any management plans for these woodlands should take account of this variety of micro-habitat, and monitoring of the effects on bryophyte populations of any resulting change in the structure of ground vegetation is vital.