Introduction

Modern textbooks in general ecology contain very few, if any, bryophyte examples of patterns and processes such as population and metapopulation dynamics, dispersal, competition, herbivory, and species richness variation. A question then arises: can we freely adapt theories developed from studies of vascular plants or even animals and apply them to bryophytes? In this chapter I give examples of population and community-level processes based on bryophyte studies, and discuss how life history, morphology and physiology of bryophytes can help us to understand population dynamics, community diversity, and species composition.

Bryophytes are important in terms of species richness and cover in many habitats, and also for ecosystem functions. Most obvious is the role of Sphagnum as peat former. A calculation based on an average peat depth of 2 m indicates that the amount of carbon in northern hemisphere peatlands is 320 Gt, about 44% of the amount held in the atmosphere as carbon dioxide (Rydin & Jeglum 2006; see Chapter 9, this volume). Another example is the finding that nitrogen-fixation by the cyanobacterium Nostoc associated with Pleurozium schreberi contributes substantially to the nutrient budget of boreal forests (DeLuca et al. 2002). An illustration of the community importance of bryophytes is their contribution to biodiversity in many ecosystems at northern latitudes. As an example, Sweden hosts c. 0.8% of the world's vascular plant species, and 7.5% of the bryophytes (Table 10.1).