Monday, August 22, 2011

Microtopography. Microheterogeneity. Microbiology. - Dave Graham

Nine flights in Alaska last week reminded me how far the tundra spans in this state that is 14-times the size of Tennessee. Polygonal features cover the ground like a giant jigsaw puzzle.

Standing in the middle of the Barrow Environmental Observatory (BEO), you can see for miles in any direction. Only the much-welcome power lines break up the landscape. The largest permafrost degradation features rise only ~80 cm from the surrounding troughs. But a few centimeters make all the difference to the fauna, and probably the microbes as well. Liquid water is precious for the cotton grass in saturated depressions and the rootless sphagnum moss that forms tight clusters in moist terrain. Microtopography begets microheterogeneity.

While polygons and vegetation stand out from above, the subsurface is a bustling metropolis of microbial activity. The temperature drops from a chilly 4 degrees C (air) to 3.5 degrees C (surface water) to 2 degrees C (dry ground). Microbes in this cold active layer busily degrade dying plant material, but we know much less about the microbes that are degrading old, long-buried biomass from the thawing permafrost of high-centered polygons. The nutrients and gasses released by this microbial activity are key to understanding the tundra’s future vegetation and climate. I would expect the variations in microtopography and water distribution to have a huge effect on microbial heterogeneity. I look forward to returning during ‘drilling season’ to sample cores of this hidden world.