摘要:Shrub expansion is a global phenomenon that is gaining increased attention in the Arctic.
Recent work employing the use of oblique aerial photographs suggested a consistent pattern
of positive change in shrub cover across the North Slope of Alaska. The greatest amounts of
change occurred in valley slopes and floodplains. We studied the association between shrub
cover change and topographically derived hydrologic characteristics in five areas in
northern Alaska between the 1970s and 2000s. Change in total shrub cover ranged from − 0.65% to 46.56%. Change in floodplain shrub cover ranged from 3.38% to 76.22%. Shrubs are
preferentially expanding into areas of higher topographic wetness index (TWI) values
where the potential for moisture accumulation or drainage is greater. In addition, we found
that floodplain shrub development was strongly associated with high TWI values and a
decreasing average distance between shrubs and the river bank. This suggests an
interacting influence of substrate removal and stabilization as a consequence of increased
vegetation cover.