Biodiversity supports ecosystem functioning and productivity, and makes ecosystems more resilient and resistant to changes. Ecosystem functions are due to the biological, geochemical and physical processes occurring within an ecosystem. They relate to the structural components (e.g. water, soil, atmosphere, and biota) and their interactions within and across ecosystems. Functions that are useful to human well-being are defined as ‘ecosystem services’. Lichenised fungi are complex and form diverse ‘functional organismic communities’. They can be regarded as individuals as well as microhabitats comprising a huge variety of coexisting fungal, algal and bacterial taxa or genotypes, pertaining to most different domains of life. Lichens and their symbionts underpin a great number of ecosystem functions (i.e., rock decomposition, soil formation, carbon, and nitrogen fixation), support the diversity of numerous organisms, e.g. through the provision of food, habitat, shelter, camouflage, or nesting material. Furthermore, they provide numerous direct and indirect ecosystem services, which are presented in detail in this overview. Examples are the provision of lichen secondary metabolites and other compounds for medicinal and other purposes, the use of lichens as bioindicators of environmental changes, and as inspiration source in the context of culture, arts and design. The aim of the present review is to give insight in the current knowledge on ecosystem functions provided by lichens, as well as to point out which of these are, directly or indirectly, of benefit for human beings. Lichens are often neglected in ecosystem service analyses and nature conservation management, mostly due to underestimation of their role and difficulties in identification. The primary agents and lichen traits involved in ecosystem processes are analysed, and possible approaches on how to quantify, estimate the value, model and map lichen ecosystem services are discussed. Keywords: Lichenised ascomycetes
Biodiversity
Ecosystem services
Ecosystem functions.