The interactive effects of temperature and moisture on nitrogen fixation in two temperate-arctic mosses
- 299 Downloads
Nitrogen (N) fixation in moss-cyanobacteria associations is one of the main sources of ‘new’ N in pristine ecosystems like subarctic and arctic tundra. This fundamental ecosystem process is driven by temperature as well as by moisture. Yet, the effects of temperature and moisture stress on N2 fixation in mosses under controlled conditions have rarely been investigated separately, rendering the interactive effects of the two climatic factors on N2 fixation unknown. Here, we tested the interactive effects of temperature and moisture on N2 fixation in the two most dominant moss species in a temperate heath, subarctic tundra and arctic tundra: Pleurozium schreberi and Tomentypnum nitens. Mosses with different moisture levels (25, 50, 100%) were kept at different temperatures (10, 20, 30 °C) and N2 fixation was measured at different times after exposure to these conditions. T. nitens had the highest nitrogenase activity and this increased with moisture content, while effects were moderate for P. schreberi. Nitrogenase activity increased with temperature in all mosses, and the temperature optimum (Topt) was between 20 °C and 30 °C for all mosses. Quick acclimatization towards higher temperatures occurred. Our results suggest that the contemporary and not the historical climate govern the response of moss-associated N2 fixation to changes in the abiotic environment. Thus, climate change will have substantial impacts on N2 fixation in dominant mosses in temperate, subarctic and arctic habitats.
KeywordsAcetylene reduction Arctic Climate change Cyanobacteria Drought Heathland
Funding was provided by the Danish Council for Independent Research and FP7 Marie Curie Actions “COFUND” (Grant ID: DFF—1325-00025), as well as from the Danish Council for Independent Research “Research Project 1” (Grant ID: DFF—6108-00089), and the Danish National Research Foundation (Center for Permafrost, CENPERM DNRF100). We thank Gosha Sylvester and Maja Holm Wahlgren for assistance with laboratory analyses at the University of Copenhagen, and Abisko Scientific Research Station for logistics and access to climate data.
- Antropova TA (1974) Temperature adaptation studies on the cells of some bryophyte species. Tsitologiia 16:38–42Google Scholar
- Belnap J (2001) Factors influencing nitrogen fixation and nitrogen release in biological soil crusts. In: Belnap J, Lange OL (ed) Biological soil crusts: structure, function, and management. Ecological studies, vol 150, pp 241–261. Springer, HeidelbergGoogle Scholar
- Ellermann T, Andersen HV, Bossi R et al. (2011) Atmosfærisk deposition. Århus Universitet, pp 18–38, NOVANAGoogle Scholar
- Glime JM (2007) Bryophyte Ecology. Volume 1. Physiological Ecology. Ebook sponsored by Michigan Technological University and the International Association of Bryologists. http://www.bryoecol.mtu.edu/. Accessed 01 June 2015
- Granhall U (1981) Biological nitrogen fixation in relation to environmental factors and functioning of natural ecosystems. In: Clark FE, Rosswall T (eds) Terrestrial nitrogen cycles, vol 33. Swedish Natural Research Council, Stockholm, pp 131–144Google Scholar
- Isichei AO (1980) Nitrogen fixation by blue-green algae soil cursts in Bigerian svanna. In: Rosswall T (ed) Nitrogen cycling in West African ecosystems. NFR, Stockholm, pp 191–199Google Scholar
- Karlsson GP, Akselsson C, Hellsten S, Karlsson PE, Malm G (2009) Övervakning av luftföroreningar norra Sverige—mätningar och moddellering. Svenska Miljöinstitut IVL rapport B1851. Lund UniversityGoogle Scholar
- Kershaw KA (1985) Physiological ecology of lichens. Cambridge University Press, LondonGoogle Scholar
- Li Y, Glime JM (1990) Growth and nutrient ecology of two Sphagnum species. Hikobia 10:445–451Google Scholar
- Stewart WDP, Smapaio MJ, Isichei AO, Sylvester-Bradley R (1977) Nitrogen fixation by soil algae of temperate and tropical soils. In: Döbereiner J, Burris RH, Hollaender A, Franco AA, Neyra CA, Scott DB (eds) Limitations and potential for biological nitrogen fixation in the tropics. Plenum Press, New York, pp 41–63Google Scholar