In this multidisciplinary project we plan to study carbon mineralization in general and methane cycling in particular as a function of the glacial chronosequence and soil development. Recent studies have shown that sediments underneath glaciers and ice sheets represent large reservoirs of methane that add to the global emission of methane when the sediments are deglaciated.

The lake near the Kobbefjord Glacier is/has been very sensitive to glacial changes during the past thousands of years, and will be investigated for a) changes in water chemistry, biological communities; b) food chain dynamics by using stable isotopes (C, N); c) genetic changes in zooplankton, flagellates and bacteria; d) speed of changes in the biological communities as a response to dramatic temperature changes due to climate changes.

The catchment for the retreating Greenlandic ice cap is an ideal site to get further insight in the mechanisms behind regime shifts, the duration between shifts and the resilience towards the changes, since it is possible along the transect form the ice edge, to find areas of different ages. By analyzing physical-chemical variables and biological remains in different sediment layers from deep lakes we can evaluate the response of the lakes to former cold and warm periods through the Holocene, where the ice expanded and retreated.

The aim is to constrain ice fluctuations of the Greenland ice sheet and local glaciers and ice caps during the last 10.000 years using threshold lake records. The concept is that when a glacier is in the catchment of the threshold lake it receives meltwater and clastic sediments (silt/sand) whereas gytja is deposited when the glacier is retracted and outside the catchment. These changes can easily be observed and the clastic layers representing periods with an expanded ice position can be dated because the gytja layers contain organic material.

The retreating glacier in the bottom of the Godthåbsfjord provides a unique opportunity for examining patterns in the successional changes in central terrestrial ecosystem parameters, and to contrast and compare these too those from the limnic system. The present project will establish a transect going from the glacier front and outwards. Along this 5m wide and app. 5km long transect we will apply two approaches to characterize the development in the ecosystem (outlined below). Firstly, we will record plant species composition in all sediment-covered areas ((separated by >500m).

Future shrub expansion in Greenland is likely to be particularly pronounced in certain parts of the Godthåbsfjord area, while shrubs may not expand in other parts due to the strong climatic gradients (coast/inland, altitude, slope and aspect). On the basis of an existing GCRC project (6502), we propose to investigate the biomass, assemblage structure and seasonal dynamics of above‐ and below‐ground arthropod communities associated with existing vegetation plots (Figure 1). Among the existing plots, arthropods will be sampled in selected plots with low and high shrub dominance.

The ecosystems in western Greenland are strongly influenced by the composition of the plant communities, yet little is known about the effects of environmental variations on the vegetation composition. In order to understand the mechanisms that control the structure and resilience of the ecosystems it is therefore essential to better understand the factors that shape the local plant community composition.

Leg 2a: Resolute to Kugluktuk (05 September to 01 October)

Leg 1b: Pond Inlet to Resolute (12 August – 05 September)