Relationships between Arctic shrub dynamics and topographically derived hydrologiccharacteristics

Abstract

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 patternof positive change in shrub cover across the North Slope of Alaska. The greatest amounts ofchange occurred in valley slopes and floodplains. We studied the association between shrubcover change and topographically derived hydrologic characteristics in five areas innorthern 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 arepreferentially expanding into areas of higher topographic wetness index (TWI) valueswhere the potential for moisture accumulation or drainage is greater. In addition, we foundthat floodplain shrub development was strongly associated with high TWI values and adecreasing average distance between shrubs and the river bank. This suggests aninteracting influence of substrate removal and stabilization as a consequence of increasedvegetation cover.