Glob. Change Biol. http://doi.org/2v7 (2015)
Deciduous shrubs are becoming increasingly common in arctic tundra landscapes, typically dominated by evergreens, graminoids and cryptogams. This shift in community composition could fuel carbon uptake in these systems, according to a one-year study of Alaskan tundra phenology.
Shannan Sweet, at Columbia University, and colleagues compared the phenology and productivity of two types of tundra in Alaska — one dominated by evergreens and graminoids and the other by deciduous shrubs — using remotely sensed measurements of canopy reflectance and numerical models. Canopies dominated by deciduous shrubs greened up faster, and reached the period of peak greenness 13 days earlier, than canopies dominated by evergreens and graminoids. As a result, the peak season in the deciduous canopies lasted an average of 10 days longer. Leaf area was also greater in these ecosystems.
The deciduous canopies took up three times more carbon over the course of the growing season than the evergreen- and graminoid-dominated canopies, due to the longer peak season and increased leaf area; peak season extension accounted for over 70% of this response. As such, the researchers suggest that future increases in deciduous shrub abundance in these systems could enhance tundra carbon gain.