Shrubs, Runoff and Erosion in Arctic Alaska Foothills
Tape, K.D., Verbyla, D. and Welker, J.M. 2011. Twentieth century erosion in Arctic Alaska foothills: The influence of shrubs, runoff, and permafrost. Journal of Geophysical Research 116: 10.1029/2011JG001795.
Working with time series imagery obtained from Landsat thematic mapper data covering the period 1986-2009, Tape et al. examined the landscape pattern of tall shrub distribution and expansion in the Arctic foothills, located on the north side of the Brooks Range, Alaska, while they studied sediments obtained from cores of four lakes near the Chandler River on the central North Slope of Alaska (where shrub expansion is occurring), in order to compare relationships among shrub cover, erosion and runoff over the past quarter-century. And what did they find?
The three researchers say their results reveal "a background decline in erosion (collectively, in 3 cores) since 1980, superimposed by episodic erosional events (in 1 core)," and they state that "the background decline in erosion is associated with trends of increasing shrubs and declining peak runoff events."
Tape et al. conclude that "in contrast to the positive feedbacks associated with shrub expansion and climate (Chapin et al., 2005; Mack et al., 2004; Sturm et al., 2005; Swann et al., 2010)" - which tend to enhance local warming - their results "suggest a negative feedback from shrubs stabilizing soil (including carbon)," which is a very positive result.
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