Early colonisation of high arctic substrates exposed by glacier retreat.
Whilst the retreat of glacial ice may be sad for lovers of the Arctic it heralds new opportunities for terrestrial plant species and associated microorganisms. By surveying the expedition’s ‘home’ area for plant species distribution and ground cover, a detailed picture will be obtained of the colonisation of land that has been recently exposed by glacier retreat. Soil samples taken from these areas will be also be tested for microbiological colonists, as well as gas fluxes and chemical composition, so that a complete picture may be built up of the combined processes of biological invasion and carbon accumulation on land exposed by retreating glaciers.
Accelerated retreat of glaciers in response to climate warming in the Arctic is becoming increasingly well documented. Glacier retreat results in the exposure of virgin surfaces for colonisation by both macroscopic plant life and microorganisms. Furthermore, the ages of these exposed surfaces can be dated, using aerial and satellite images of the extent of individual glaciers. This provides chronosequences of surfaces which, as in the classic studies by Crocker and Major in the Glacier Bay area of Alaska, can provide valuable insights into the interlinked processes of vegetation growth and alteration of the colonised substrate.
Perhaps the most important aspect of this process is the accumulation of carbon, in the form of organic matter, in the exposed substrate. This can be a slow process, though the rate can be estimated from examination of the sequences of substrates left behind by glacier retreat. A major concern in a warming arctic environment is the predicted acceleration in loss of carbon from peats as tundra surface temperatures increase. This loss could be balanced, to some extent, by the increased area of land available for organic matter accumulation as glaciers retreat. However, the potential for carbon accumulation in freshly exposed substrates will depend on the speed and extent to which colonisation by microorganisms and vegetation occurs. It will also depend on the fluxes of carbon-containing gases, mainly CO2 and CH4, from the surface – recent research in the Canadian Rockies has shown that these fluxes are linked to the microbial communities in glacial sediments.
This project aims to estimate the potential for carbon accumulation in the wake of glacial retreat based on field studies in the Bockfjorden area in 2016. We will examine the initial stages of colonisation of substrates exposed by glacier retreat of the Adolfbre Nygaardbre and Schjelderupbre glaciers. Field studies will involve systematic mapping of all macroscopic vegetation including lichens, bryophytes and vascular plant species. GPS will be used in combination with field identification to provide georeferenced data that will be mapped on return to the UK. Herbarium specimens may be taken to assist with positive identification of species, especially bryophytes. Gas fluxes will be measured in-situ using closed chambers, with gas samples being brought to the UK for analysis of CO2 and CH4 from which flux calculations can be made. Soil samples will also be taken systematically throughout the survey area.
These will be returned to the UK for chemical and microbiological analysis: the latter will focus on the distribution of major functional groups of soil microbes, using Biolog, MicroResp(TM) and TRFLP methods. Data from these analyses will be combined with geographic distributions of macroscopic species within a GIS to provide a comprehensive picture of the early biological colonisation and carbon accumulation potential of high Arctic substrates exposed by glacier retreat.