The full programme book (PDF) - Royal Geographical Society

T9
Holocene ecosystem functions in arctic lake catchments
E-J. Hopla 1 *, M. Van Hardenbroek 1 , M. Edwards 1 , P. Langdon 1 , A. Clark 1
1 Palaeoenvironmental Laboratory University of Southampton, Geography and Environment, University
of Southampton
The Arctic is sensitive to climate change and it is predicted that the region will experience
rapid changes with future global warming (Solomon et al, 2007). Vegetation is already
responding to increasing global temperatures by migrating northwards in a process called
“greening” (Jia et al. 2009; Forbes et al. 2010). It is currently unclear what the overall
result of greening will be on the carbon cycle. Lakes are an important geographical feature
in the Arctic and in light of future climate change understanding their ecosystem dynamics
of the past and present is of significant interest.
This project will primarily aim to reconstruct Holocene vegetation changes associated with
past climate warming events in 3 sets of small lake catchments in Alaska, Greenland and
Russia to help us to understand the long-term interactions between climate, vegetation
and in lake processes. Testing reproducibility of the signals in our records within and
between regions is a key element of the project. This poster focuses on two lakes within
the Brooks Range of Alaska (1-2 km apart), Ruppert Lake and Lake 3. Preliminary pollen
data at Lake 3 suggests a basal date of around 10,000 years BP with deciduous woodland
dominated by popular and birch. The vegetation shifts into forest tundra with an increase
in spruce followed by a rise in alder, which is consistent with previous research
undertaken at Ruppert Lake (Higuera et al. 2009). Alder is a nitrogen-fixing tree and it is
assumed that the introduction of this species into the catchment will have an effect on the
N and in turn the C cycle. Catchment fire disturbances have been recorded within the
charcoal record at Lake 3 and will be compared to pre-existing data from Ruppert Lake to
strengthen the current understanding of fire histories in the region, to investigate how
replicable these records are, and to link changes in fire regime to vegetation types and
nutrient cycling in soils.
Keywords: Holocene; arctic; lakes; pollen; carbon cycle
Forbes, B.C., Macias Fauria, M., and Zetterberg, P. (2009) Russian Arctic warming and ‘greening’ are
closely tracked by tundra shrub willows, Global Change Biology, 16 (5) 1542-1554
Higuera, P.E., Brubaker, L.B., Anderson, P.M., Sheng Hu, F and Brown, T.A. (2009) Vegetation
mediated the impacts of postglacial climate change on fire regimes in the south-central Brooks Range,
Alaska, Ecological Monographs, 79(2) 201-219
Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor and H.L. Miller (eds.)
(2007) Contribution of Working group I to the Fourth Assessment Report of the Intergovernmental
Panel on Climate Change, Cambridge University Press.
Jia, G.J., Epstein, H.E., and Walker, D.A. (2009) Vegetation greening in the Canadian arctic related to
decadal warming, J.Environ.Monit, 11, 2231-2238