My PhD looks at reconstructing past catchment vegetation around small lakes in the Arctic and assessing the best ways this can be achieved.   As the Arctic becomes warmer, a process called “greening” is occurring where plants are migrating northwards into areas they could not previously survive in.  It is currently unknown how this migration of plants will affect the carbon cycle. Our NERC-funded project is looking at the role of Lakes in the Arctic Carbon Cycle (LAC) The species composition and carbon-fixing productivity of a lake depends on the vegetation surrounding it.  We want to know how lakes will change in response to the shift in vegetation we are starting to see in the Arctic.  One of the ways we can do this is by looking at the pollen and plant macrofossils preserved in lake sediment records to determine vegetation changes associated with past climate warming events.  Using models such as REVEALS and LOVE (Sugita, 2007) we aim to quantitatively reconstruct the regional and local vegetation.  Estimating how much pollen plants produce (Pollen Productivity Estimates, PPEs) is an essential input into these models, however the majority of current estimates are derived from European species.
So, last summer Mary, Pete and I headed off to the boreal forests and open tundra of Alaska to obtain the first PPEs from this region.

After a couple of days recovering from jet lag and getting all the kit together, we headed off down the Richardson Highway towards the Alaska Range.

The first half of the fieldwork focused on collecting samples and modern vegetation data from ten plots in the open tundra, largely along the Denali Highway, south of the Alaska Range.   The fieldwork methodology involved collecting moss polster samples which contain around 7-10 years of accumulated pollen.  The vegetation coverage was then recorded up to 100m around each sample.  This methodology allows us to distance-weight the vegetation around the plot.  To test the models and see how they represent the modern vegetation we also collected surface samples from three small lakes we named ourselves; Drop Down Pond, Oh that Pond! and Petty Pond.   At the end of a hard day’s work we retired to the camp site, surrounded by fantastic views of mountains and lakes, tundra vegetation and topped off by designated gravel camping areas, designed for your comfort!


The second half of the fieldwork focused on twelve sites in the boreal forests around Fairbanks.   This is where the exhaustion hit me and the mozzies got me!   The sites ranged from the beautiful and majestic birch and aspen forests to the dense mature spruce forest which often felt like we were navigating our way through a tangled jungle. Thankfully, we had an extra pair of hands come to the rescue and we were joined by Mary’s friend, Jessie.


All this data will eventually be fed into an Extended R-value (ERV) model which will estimate the PPEs for the taxa.  At the end of an intense four weeks we had hugged and measured over 800 trees and recorded 691,150.46m2 of vegetation and every mosquito bite was worth it.




Ruppert Lake.  Photo: K. Davies

Ruppert Lake. Photo: K. Davies

When the floatplane left us at Walker Lake, it was just the five of us and a large pile of camping and coring kit that would keep us busy for the next twelve days or so. As the humming of the engine and the waves died away things became very quiet for a moment and we were all awed by the view over Walker Lake against the backdrop of the Brooks Range. Welcome to one of the last wild places in the world! This quiet, contemplative moment only lasted briefly as a cloud of mosquitoes formed around us.

We had come to this place at the southern margin of the Brooks Range to core three lakes. We hoped that the sediments in those lakes would contain an environmental history of the past 10.000 years. Our NERC-funded project, Lakes and the Arctic Carbon cycle (LAC), had just started and we were going to investigate how large-scale changes in the landscape had influenced lakes in the past. As a result of changes in temperature and precipitation the vegetation in the Arctic has changed dramatically since the last ice age, going from tundra, to shrub-tundra to boreal forest. In turn, this led to an increase of soil development and nitrogen fixing by species like alder. We know how these processes work to some extent from previous research projects, but we don’t know yet how these developments on the landscape scale influence lakes. We want to know about lakes because they can play an important role in storing carbon in their sediments (dead plants and animals) or releasing it to the atmosphere (CO2 and CH4). By coring lakes we can create records of vegetation change using pollen and plant macrofossils that are preserved in the sediment. Next, we can compare these with records of in-lake changes using remains of diatoms (a group of algae), invertebrates and pigments. We can also look at the geochemistry of the sediments using techniques such as XRF scanning (X-rays of the cores), and stable isotope analysis (Check here for a great explanation of stable isotopes and another great science website!). This way we can try to understand how they are related to each other, which will also inform us about similar processes that are going on today as climate change strongly affects high latitude regions. By coring lakes across the Arctic we hope to get a larger picture, which is why colleagues have already cored lakes in Greenland and Siberia, and why we are here in Gates of the Arctic National Park, Alaska.

The park ranger had told us very clearly that we would have to keep a clean camp and to have different places for sleeping, cooking, and storing food. The reason for this is that food, fuel, and other human items like toothpaste smell irresistibly interesting to bears. It would perhaps have been nice to see a bear in the distance at some point, but we were so well equipped to keep bears away that the chance we’d see one was rather slim. We had bear-proof barrels to store our food, an electric fence around the stored food, at least one can of pepper spray each, jingling bells, a shotgun (and training to use it), and a motion sensor alarm (“Critter Gitter”). The latter gave us a couple of sleepless nights chasing off birds, branches, and perhaps (?) a bear. Twice, a moose came grazing when we were coring and one of our lakes was home to a beaver, but we never saw a bear during our trip.

The most unexpected thing we experienced in the arctic was the intense heat and baking sun. Which is great if you’re on holiday, but not ideal when you’re carrying several 20-30 kg kit packs half a mile uphill, wearing long sleeves and a mosquito net that prevents you to breathe in fresh air. But we really needed all of our equipment: two boats, boards and ropes to build a platform. The adjustable sediment corer with several meters of extension rods, liners, pistons, and cable. Tools and water sampling equipment. Material to extrude, wrap and package cores. Plus an extra boat to shuttle kit and people to and from the platform.

After taking several cores totalling 12 m of mud at Ruppert Lake, we moved everything another half a mile through thick brush to three previously unstudied lakes that we hoped would have enough sediment in them. At one lake we were successful in retrieving 2.25 m of sediment until we were stopped by a layer of coarse wood (for which we wanted to baptize the lake ‘Woody Bottom Pond’, but in the end gave it the much more exciting name ‘Lake 3’). In all, we brought back almost 25m of sediment weighing 150 kg, that will keep us and other project partners busy for a while.

There is one thing that is so easily forgotten when you’re focused on getting all the right cores. And that is to look around you, to take in the landscape, the reflection of the trees and the mountains in the water, the raven flying in the distance. Listen quietly to the silence, and draw in fresh air. The Arctic has always attracted me, perhaps because life seems more simple there, uncontaminated by the modern day rat race. You will need to survive, of course. Survive the cold and dark winters, the wild animals, the bugs, the alcohol. Call me a romantic fool, but life is different out there. And at the end of the day the most fantastic thing to do is bathing in the clear, cold, still water of Walker Lake. The midnight sun setting in warm purple colours below the mountain tops.