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Plant-soil-herbivore interactions in the Arctic

Feedback to the carbon cycle
We study the interactions between the plants, soil and herbivores in a high arctic environment. We primarily focus on how grazing affects the ecosystem carbon cycle and fluxes of the greenhouse gases carbon dioxide, methane and nitrous oxide.

Arctic ecosystems are important sinks for carbon dioxide (CO2) and hold considerable amounts of the world's total pool of soil organic carbon. Climate warming is proceeding faster in the Arctic than elsewhere on Earth. Plant-soil-herbivore interactions have potentially large consequences for a variety of ecosystem processes such as carbon sequestration, greenhouse gas production/emission and plant diversity and community composition.

 

Muskoxen grazing outside an exclosure established at the study site in Zackenberg Valley, Greenland.
Muskoxen grazing outside an exclosure established at the study site in Zackenberg Valley, Greenland.

 

We aim to elucidate 1) How grazing by muskoxen affects the carbon sequestration and allocation patterns in an Arctic wetland, 2) How grazing affects greenhouse gas production and fluxes, 3) How grazing effects the composition of vascular plant species of key importance to greenhouse gas production and emission, and 4) How grazing may modulate effects of a changing climate on carbon sequestration and greenhouse gas fluxes.

To address the aims we will use a combination of in situ field measurements and detailed analysis in the laboratories using novel isotope techniques. The field site is a fen located in the Zackenberg valley (74°30'N / 21°00'W) in Northeast Greenland, close to the Zackenberg Research Station. The project can be divided into three different sub-experiments as listed below.

Field exclosures

In the summer 2010 five blocks where established (by Niels Martin Schmidt and Mads Forchhammer from NERI) in the Zackenberg valley. Each block consists of three 100 m2 squares, i.e. a control, a snow fence and an exclosure preventing muskoxen grazing. To determine greenhouse gas fluxes, pore-water concentrations of labile carbon compounds (e.g. organic acids) and to monitor physical parameters we established two 40x40 cm measuring plots within each square. On these plots, measurements will be carried out throughout the field seasons in years to come to determine both the direct and long-term effect of grazing on the ecosystem.

 

Instrumentation placed inside a transparent chamber is used to measures greenhouse gas fluxes from the soil inside one of the exclosures.
Instrumentation placed inside a transparent chamber is used to measures greenhouse gas fluxes from the soil inside one of the exclosures.

Field experiments

At another location in the fen (similar vegetation composition and soil properties), five smaller blocks are established. These block consist of a control and a treatment where we simulate grazing by clipping the vegetation 5 cm above ground two to three times during the growing season. The same measurements are performed as in the exclosure experiment described above.

Laboratory experiments

Here monoliths (intact samples of peat and moss and sedge vegetation) are taken from the Zackenberg valley fen and transported back to the laboratory at Lund University. In the laboratory the monoliths will be grown under carefully controlled environmental conditions and subjected to detailed studies, of the link between grazing, pore-water chemistry and greenhouse gas fluxes, using novel isotope techniques.

 

 

Researchers

Julie Maria Falk

Niels Martin Schmidt

Torben R. Christensen

Lena Ström

 

Contact point: Lena Ström

lena.strom [at] nateko.lu.se

 

LUCCI - Lund University Centre for studies of Carbon Cycle and Climate Interactions

Department of Physical Geography and Ecosystem Science

Lund University

Sölvegatan 12

S-223 62 Lund, Sweden