An Integrated Assessment of the Influences of Upland Thermal-Erosional Features on Landscape Structure and Function in the Foothills of the Brooks Range, Alaska

We established the Arctic System Science/Thermokarst (ARCSS/TK) project in 2008 with the intent to use a systems approach to address hypotheses about how upland thermo-erosional features influence the structure and function of the foothill and mountainous landscape in the vicinity of the Brooks Range in arctic Alaska. We found that the common thermo-erosional features in this region are thaw slumps, thermo-erosional gullies, and active layer detachment slides. These features significantly redistribute and reduce soil carbon and nutrients. Sediments and nutrients are exported from thermo-erosional features and may impact streams and lakes. In general, productivity was greater in streams and lakes influenced by thermokarst inputs; that is, nutrient stimulation outweighed sediment interference. In either case, however, these effects are transitory on the timescale over which these thermo-erosional features form, stabilize, and revegetate. Our estimate of the rates at which carbon and nutrients accumulate after these thermo-erosional features stabilize is much faster based on field measurements than our estimates based on model predictions, suggesting that alternative sources of C and nutrients must be available. These features are numerous in the current landscape (~4/km2 in the area of this study) and are likely to be important as agents of nutrient redistribution across the arctic landscape.