The Greening at the Forest-Tundra Ecotone in Subarctic Quebec
Ropars, P. and Boudreau, S. 2012. Shrub expansion at the forest-tundra ecotone: spatial heterogeneity linked to local topography. Environmental Research Letters 7: 10.1088/1748-9326/7/1/015501.
The efforts of the two researchers revealed that "both hilltops and terraces recorded an increase in shrub cover," and they say that "the increase was significantly greater on terraces than on hilltops (21.6% versus 11.6%)," while further noting that "this finding corroborates other studies using a similar method conducted in different regions of the Arctic," including Alaska (Sturm et al., 2001; Tape et al., 2006), northern Quebec (Tremblay, 2010), Russia (Forbes et al., 2010) and studies which revealed a major increase of the NDVI over the last few decades (Jia et al., 2003; Verbyla, 2008).
Ropars and Boudreau conclude their report by stating that "according to ground truthing, the shrub cover densification is associated mainly with an increase of Betula glandulosa Michx" - more commonly known as dwarf birch - and by noting that "the numerous seedlings observed during the ground truthing suggest that shrub densification should continue in the future," as, we would add, the warming- and CO2-induced greening of planet Earth continues!
Forbes, B.C., Fauria, M.M. and Zetterberg, P. 2010. Russian Arctic warming and greening are closely tracked by tundra shrub willows. Global Change Biology 16: 1542-1554.
Goetz, S.J., Bunn, A.G., Fiske, G.J. and Houghton, R.A. 2005. Satellite-observed photosynthetic trends across boreal North America associated with climate and fire disturbance. Proceedings of the National Academy of Sciences 102: 13,521-13,525.
Jia, G.S.J., Epstein, H.E. and Walker, D.A. 2003. Greening of Arctic Alaska, 1981-2001. Geophysical Research Letters 30: 10.1029/2003GL018268.
Myneni, R.B., Keeling, C.D., Tucker, C.J., Asrar, G. and Nemani, R.R. 1997. Increased plant growth in the northern high latitudes from 1981 to 1991. Nature 386: 698-702.
Myneni, R.B., Tucker, C.J., Asrar, G. and Keeling, C.D. 1998. Interannual variations in satellite-sensed vegetation index data from 1981 to 1991. Journal of Geophysical Research 103: 6145-6160.
Olthof, I. and Pouliot, D. 2010. Treeline vegetation composition and change in Canada's western Subarctic from AVHRR and canopy reflectance modeling. Remote Sensing of the Environment 114: 805-815.
Silapaswan, C.S., Verbyla, D.L. and McGuire, A.D. 2001. Land cover change on the Seward Peninsula: the use of remote sensing to evaluate the potential influences of climate warming on historical vegetation dynamics. Canadian Journal of Remote Sensing 27: 542-554.
Sturm, M., Racine, C. and Tape, K. 2001. Increasing shrub abundance in the Arctic. Nature 411: 546-547.
Tape, K., Sturm, M. and Racine, C. 2006. The evidence for shrub expansion in Northern Alaska and the Pan-Arctic. Global Change Biology 12: 686-702.
Tremblay, B. 2010. Augmentation recente du couvert ligneux erige dans les environs de Kangiqsualujjuaq (Nunavik, Quebec). Master Thesis, Universite du Quebec a Trois-Rivieres, Quebec, Canada.
Verbyla, D. 2008. The greening and browning of Alaska based on 1982-2003 satellite data. Global Ecology and Biogeography 17: 547-555.