Plant Physiological Ecology & Biogeochemistry
The focus of the Plant Physiological Ecology & Biogeochemistry research group is on climate change effects and anthropogenic impact on organisms, plant physiological and biogeochemical processes in natural and semi-natural ecosystems, mainly in the temperate and arctic zone. For more details regarding potential projects, internship etc., please see below, and feel free to contact Anders Michelsen.
Professor Anders Michelsen (Group leader)
Post doc Signe Lett
Post doc Marianne Koranda
PhD Student Laura Helene Rasmussen
PhD Student Emily Pickering Pedersen
Emil Sherman Andersen, Anne Marie Stevnsvig, Else Pedersen,
Elisabeth Larsen Kolstad, Julie Pedersen Festersen,
Kristine Skov, Maj Sofie Paornak D Christensen,
Simone Windfeldt-Schmidt, Frederik Grande Zimmermann,
Agnieszka Rzepczynska, Anna Polaskova, Maya Anne Nissen Olsen
The fields of research are within general and physiological ecology in terrestrial systems, including interactions between the ecosystem components, and the biodiversity of soil organisms and plants. Major approaches include investigation of plant physiological and biogeochemical responses to natural environmental variation and to global and regional environmental changes and disturbances (e.g. climate change, UV-B radiation and land use). We also study the interactions between aboveground processes such as photosynthesis, the relation to tissue chemistry, and to belowground processes, such as nutrient mineralisation and uptake by plants. The main approach of the research is experimental and generally has a process as well as an organism/population component. It spans over a hierarchy of temporal and spatial levels such as studies of
• use of stable isotopes in ecology
• gas exchange at leaf and whole plant level
• nutrient mineralisation, plant nutrient uptake and soil-microbe-plant-interactions
• nitrogen flow and carbon cycling, at community, ecosystem and landscape level
The research takes place in arctic and temperate ecosystem types. The group is using the facilities in the Ecological-Chemical Laboratory, the Isotope Ratio Mass Spectrometry and the Ecophysiology Laboratory. Field work takes place in Denmark, Sweden (Abisko), Greenland (Zackenberg, Disko), and elsewhere.
Current externally funded research projects include
• Nitrogen fixation as a key function in contrasting ecosystems: Climatic and molecular controls (2016-2019)
• CENPERM -Center for Permafrost (2012-2022)
Current and future M.Sc/PhD/post doc projects may address questions as
• Does permafrost thaw lead to enhanced nutrient availability and plant N uptake?
• How far does ammonia emission from farms affect plants and sensitive ecosystems?
• Does climate change affect microbial and plant uptake of nitrogen?
• What is the role of ericoid and ectomycorrhizal fungi for carbon balance in northern ecosystems?
• Will arctic and danish heath ecosystems be future sources or sinks for CO2?
• Is more methane emitted from plants, soil and litter when temperatures increase?
• To which extent does N2 fixation by microorganisms associated with plants lead to nitrogen enrichment in other ecosystem compartments?
The Ecological-Chemical Laboratory
The Ecological-Chemical Laboratory carries out high precision physical and chemical analyses of soils, plants, gases and liquids. The laboratory is fully updated in analytical equipment and takes on analytical tasks for the scientific staff at the Dept. of Biology as well as for external reseachers. For instance we analyze:
Plant species composition
Elements as C,N, P and heavy metals in soil, plants and liquids
Secondary metabolites as tannins and flavonoids
15N og 13C natural abundance and enrichment
Photosynthesis with Licor 6400XT
CH4, CO2 and BVOC
Microbial biomass CNP
Ergosterol, PLFA, Biolog plates
Screening for mycorrhiza fungi
The analytical equipment includes:
Hitachi U-2000 and U-2010 Spectrophotometers
Shimadzu Total Organic Carbon Analyzer TOC/TN
Perkin Elmer Atomic Absorption Spectrophotometer
Shimadzu GC-17A Gas Chromatograph
Fiastar 5000 Flow Analyzer
LECO TruSpec Carbon Nitrogen Determinator
Eltra CS 500 Total Carbon Determinator
Aquatec 5400 Analyzer
EuroVector Elemental Analyzer EA3028-HT
Micromass IsoPrime Isotope Ratio Mass Spectrometre
Agilent GC/MS with thermal desorption
Picarro isotopic greenhouse gas analyser
Center for Permafrost
Professor Anders Michelsen, Terrestrial Ecology Section, is one of the principal investigators from Dept. of Biology in Center for Permafrost, CENPERM, which is funded with100 mio. DKK by Danish National Research Foundation (Danmarks Grundforskningsfond). The center is funded for 10 years (2012-2021) and investigates the interactions between microorganisms, soil and plants in relation to permafrost dynamics and trace gas emission. The Center is a close collaboration between Dept. of Geosciences and Dept. of Biology at University of Copenhagen. Other participants from Dept. of Biology includes Kathrin Rousk, Helge Ro-Poulsen and Riikka Rinnan,Terrestrial Ecology Section, and Anders Priemé, Section of Microbiology. See www.cenperm.ku.dk
Nitrogen fixation stimulates plants
With climate change shrubs and trees expand northwards in the Subarctic: New results show that also more nitrogen may be fixed from the air.
Enhanced nitrogen fixation stimulates plant growth. Fixation of nitrogen from the air is in tundra to a high degree performed by cyanobacteria associated with mosses, and this process is promoted by warming in northern Scandinavia. However, as taller shrubs expand into the tundra, nutrients in their leaf litter will either promote or reduce the nitrogen fixation, depending upon which shrub species that will dominate. This has recently been shown by scientists Kathrin Rousk and Anders Michelsen from Center for Permafrost and Department of Biology at University of Copenhagen, and published in the widely recognized scientific journal Global Change Biology.
Mosses in subarctic tundra are colonized by bacteria that fix atmospheric nitrogen (N2), and together, they can contribute 50% to total ecosystem N input. Despite this key role, the effects of climate warming and increased litter input as a result of shrub expansion on N2 fixation in mosses are ambiguous.
To aid in predicting the role of moss-associated N2 fixation in a warmer, future climate, we modeled N2 fixation throughout the snow-free period in subarctic tundra. We used data from a field experiment close to the Abisko Scientific Research Station in Northern Sweden, in which climate change was simulated with open top chambers to increase the air and soil temperature, and with addition of plant litter from willow and birch-shrubs.
N2 fixation was highest in the warmed and in the birch litter addition plots (around 3 kg N ha-1 yr-1), while the willow litter additions lead to decreased N2 fixation rates (less than 2 kg N ha-1 yr-1). Warming will lead to increased N2 fixation rates in mosses, while the consequences of further shrub expansion will depend on the dominant shrub invading: the expansion of willow will likely limit the N input via N2 fixation, whereas a predominance of birch shrubs will increase N2 fixation and with that, N supply to the ecosystem. The amount of N that is fixed is important because it influences how much CO2 that plants are able to acquire through photosynthesis, and hence it impacts the carbon balance.
Rousk K., Michelsen A. (2016) Ecosystem nitrogen fixation throughout the snow-free period in subarctic tundra: Effects of willow and birch litter addition and warming.
Global Change Biology
Arctic vegetation is getting higher!
Arctic vegetation is increasing in height and cover due to warming. Research published in Nature Climate Change shows that shrubs, grasses and forbs are getting taller while bare soil is reduced. In the circumpolar study, which included experimental sites run by the Physiological Ecology group, changes in vegetation structure and composition from 1980 to 2010 was recorded in 158 sites across the tundra, and related to observed temperature changes. Link to paper and more information (danish only).
Phys Ecol Courses
The group teaches in the courses:
Arctic biology, General ecology, Experimental design and statistical analysis in biology, Biological experiments: design and analysis, Experimental design and methodology in ecology, Methodology and sampling in environmental management, Plant ecophysiology, Terrestrial ecosystem processes and global change