title: Water isotopes in desiccating lichens.
abstract: The stable isotopic composition of water is routinely used as a tracer to study water exchange processes in vascular plants and ecosystems. To date, no study has focussed on isotope processes in non-vascular, poikilohydric organisms such as lichens and bryophytes. To understand basic isotope exchange processes of non-vascular plants, thallus water isotopic composition was studied in various green-algal lichens exposed to desiccation. The study indicates that lichens equilibrate with the isotopic composition of surrounding water vapour. A model was developed as a proof of concept that accounts for the specific water relations of these poikilohydric organisms. The approach incorporates first their variable thallus water potential and second a compartmentation of the thallus water into two isotopically distinct but connected water pools. Moreover, the results represent first steps towards the development of poikilohydric organisms as a recorder of ambient vapour isotopic composition.
authors.affiliation: Department of Experimental Ecology, University of Kaiserslautern, P.O. Box 3049, Erwin-Schroedinger-Str. 14/262, 67653, Kaiserslautern, Germany. Britta.Hartard@Forst.bwl.de
authors.forename: Britta
authors.initials: B
authors.lastname: Hartard
authors.forename: Matthias
authors.initials: M
authors.lastname: Cuntz
authors.forename: Cristina
authors.initials: C
authors.lastname: Máguas
authors.forename: Michael
authors.initials: M
authors.lastname: Lakatos
mesh_terms: D002245:Carbon Dioxide / Q000378:metabolism; D019069:Cell Respiration; D005591:Chemical Fractionation; D003890:Desiccation; D008011:Lichens / Q000378:metabolism*; D008954:Models, Biological; D010103:Oxygen Isotopes; D018515:Plant Leaves / Q000166:cytology / Q000378:metabolism; D013997:Time Factors; D014867:Water / Q000032:analysis*
chemical_list: D010103:Oxygen Isotopes; D014867:Water; D002245:Carbon Dioxide