Editing Lichen (section)

====Miniature ecosystem and holobiont theory====
Symbiosis in lichens is so well-balanced that lichens have been considered to be relatively self-contained miniature ecosystems in and of themselves.<ref name=TT>{{cite journal|pmid=21134099|year=2011|last1=Casano|first1=L. M.|title=Two ''Trebouxia'' algae with different physiological performances are ever-present in lichen thalli of ''Ramalina farinacea''. Coexistence versus competition?|journal=Environmental Microbiology|volume=13|issue=3|pages=806–818|last2=Del Campo|first2=E. M.|last3=García-Breijo|first3=F. J.|last4=Reig-Armiñana|first4=J|last5=Gasulla|first5=F|last6=Del Hoyo|first6=A|last7=Guéra|first7=A|last8=Barreno|first8=E|doi=10.1111/j.1462-2920.2010.02386.x|bibcode=2011EnvMi..13..806C |hdl=10251/60269|type=Submitted manuscript|hdl-access=free}}
</ref><ref name="FESM">[[Rosmarie Honegger|Honegger, R.]] (1991) ''Fungal evolution: symbiosis and morphogenesis, Symbiosis as a Source of Evolutionary Innovation'', Margulis, L., and Fester, R. (eds). Cambridge, MA, US: The MIT Press, pp. 319–340.</ref> It is thought that lichens may be even more complex symbiotic systems that include non-photosynthetic bacterial communities performing other functions as partners in a [[holobiont]].<ref name=SSSFD>{{cite journal |pmid=19554038|year=2009|last1=Grube|first1=M|title=Species-specific structural and functional diversity of bacterial communities in lichen symbioses|journal=The ISME Journal |volume=3 |issue=9 |pages=1105–1115 |last2=Cardinale|first2=M|last3=De Castro|first3=J. V. Jr.|last4=Müller|first4=H|last5=Berg|first5=G|doi=10.1038/ismej.2009.63|bibcode=2009ISMEJ...3.1105G |doi-access=free}}</ref><ref name=NPB>Barreno, E., Herrera-Campos, M., García-Breijo, F., Gasulla, F., and Reig-Armiñana, J. (2008) [https://www.researchgate.net/publication/258264055 "Non photosynthetic bacteria associated to cortical structures on Ramalina and ''Usnea'' thalli from Mexico"]. Asilomar, Pacific Grove, CA, USA: Abstracts IAL 6- ABLS Joint Meeting.</ref>

Many lichens are very sensitive to environmental disturbances and can be used to cheaply<ref name=LLHE>{{cite web |last1=Speer |first1=Brian R |author2=Ben Waggoner |title=Lichens: Life History & Ecology |url=http://www.ucmp.berkeley.edu/fungi/lichens/lichenlh.html |publisher=University of California Museum of Paleontology |date=May 1997 |access-date=28 April 2015 |archive-url=https://web.archive.org/web/20150502160300/http://www.ucmp.berkeley.edu/fungi/lichens/lichenlh.html |archive-date=2 May 2015 |url-status=live }}</ref> assess [[air pollution]],<ref name=ferry/><ref name=rosehawksworth/><ref name=Hawksworthrose1976/> [[ozone]] depletion, and metal contamination. Lichens have been used in making [[dye]]s, perfumes ([[oakmoss]]),<ref name=OMAO>{{cite web|url=http://www.victorie-inc.us/oakmoss.html|title=Oak Moss Absolute Oil, Evernia prunastri, Perfume Fixative|access-date=19 September 2014|archive-url=https://web.archive.org/web/20141225173039/http://www.victorie-inc.us/oakmoss.html|archive-date=25 December 2014|url-status=live}}</ref> and in [[traditional medicine]]s. A few lichen species are eaten by insects<ref name=LLHE/> or larger animals, such as reindeer.<ref>{{cite journal|doi=10.1111/j.1600-0587.1984.tb01138.x |title=Wild reindeer foraging-niche organization |journal=Ecography |volume=7 |issue=4 |page=345 |year=1984 |last1=Skogland |first1=Terje |bibcode=1984Ecogr...7..345S }}</ref> Lichens are widely used as environmental indicators or bio-indicators. When air is very badly polluted with sulphur dioxide, there may be no lichens present; only some green algae can tolerate those conditions. If the air is clean, then shrubby, hairy and leafy lichens become abundant. A few lichen species can tolerate fairly high levels of pollution, and are commonly found in urban areas, on pavements, walls and tree bark. The most sensitive lichens are shrubby and leafy, while the most tolerant lichens are all crusty in appearance. Since industrialisation, many of the shrubby and leafy lichens such as ''[[Ramalina]]'', ''[[Usnea]]'' and ''[[Lobaria]]'' species have very limited ranges, often being confined to the areas which have the cleanest air.