To determine the role lemmings play in structuring plant communities and their contribution to the 'greening of the Arctic', we measured plant cover and biomass in 50 + year old lemming exclosures and control plots in the coastal tundra near Barrow, Alaska. The response of plant functional types to herbivore exclusion varied among land cover types. In general, the abundance of lichens and bryophytes increased with the exclusion of lemmings, whereas graminoids decreased, although the magnitude of these responses varied among land cover types. These results suggest that sustained lemming activity promotes a higher biomass of vascular plant functional types than would be expected without their presence and highlights the importance of considering herbivory when interpreting patterns of greening in the Arctic. In light of the rapid environmental change ongoing in the Arctic and the potential regional to global implications of this change, further exploration regarding the long-term influence of arvicoline rodents on ecosystem function (e.g. carbon and energy balance) should be considered a research priority.

N = 4 for all land cover types. ANOVA results revealed that richness differed among land cover types (F2, 18 = 26.2, p < 0.0001), but exclosures and controls did not differ significantly (F1, 18 = 8.2, p = 0.5). The ANOVA results for the Shannon-Wiener Index revealed a significant treatment*land cover type interaction (F2, 18 = 4.6, p = 0.02). Data extracted in the frame of a joint ICSTI/PANGAEA IPY effort, see http://doi.pangaea.de/10.1594/PANGAEA.150150

Supplement to: Johnson, David R; Lara, Mark J; Shaver, Gauis R; Batzli, Go; Shaw, J D; Tweedie, Craig E (2011): Exclusion of brown lemmings reduces vascular plant cover and biomass in Arctic coastal tundra: resampling of a 50 + year herbivore exclosure experiment near Barrow, Alaska. Environmental Research Letters, 6(4), 045507