Wednesday, June 19, 2013

Science on the tundra

There is no shortage of science being conducted on the lakes, streams, and terrestrial ecosystems that surround Toolik Lake. That was obvious in the presentations this morning and reinforced in our series of site visits this afternoon.

Two field tours were planned. The first involved a short walk along wooden boardwalk near the upper reach of Toolik Lake itself and then up a short slope to a dry heath location. It is here that Gus Shaver spent 30 minutes or so talking about the geologic history of the area. There is a strong interaction between geology, topography, climate, and the types of vegetation found in this area. It was emphasized that the bedrock geology of the North Slope is complex. Toolik lake is within the Kuparuk River drainage. There are no glaciers in the Kuparuk drainage due to Atigun Gorge that separates this area from the mountains of the Brooks range. All water that discharges from the Kuparuk comes from snow fall and precipitation.


Gus brought along a couple of tile probes so people could push them into the soil and determine depth of the active layer. This early in the season, the active layer was found to be only a few centimeters thick. Seeing is believing so we dug a small pit and removed the a portion of the tussock tundra. An organic layer was present and, as suggested by the tile probe, was very shallow and underlaid by ice and frozen soil.

Gus then took us a short distance to see the plastic greenhouses that he is widely known for having built to warm tundra vegetation more than 20 years ago. He and his colleagues have drawn many conclusions from these studies, including the fact that warming causes an increase in shrub productivity. Such results confirm what many have suggested is a greening of the Arctic and an increase in shrubiness of the tundra that has been seen over the last 50 years in Alaska and elsewhere.


Having seen experiments being conducted in terrestrial ecosystems we jumped in a couple of vans and headed just north of Toolik Lake to the Kuparuk River. Construction along the Dalton Highway slowed our progress, but we did make it to our destination within an hour. There ,we heard about a phosphorus fertilization study that had been conducted on the Kuparuk River beginning in 1983. A pretty ambitious study that has now been going in one form or another ever since. Breck Bowden and his colleagues reported that phosphorus additions had affected a number of important processes over the years; productivity, nutrient cycling, and bryophytes and insect community structure. There were implications of these changes for fish populations. Questions of food web dynamics were raised and an interesting discussion followed.

Tomorrow Gus will take Rich and me to a few other sites where he has established experimental studies in the past. There are also small-scale warming studies being conducted in the area using the ITEX chamber design and I would like to see those up close. There are ITEX chambers in Barrow, but plant communities are so different between the two locations that I'd like to see those chambers in action here where the abundance of shrubs is higher.