How does rising atmospheric CO2 affect marine organisms?

Click to locate material archived on our website by topic

Shrub Proliferation Throughout Low Arctic Ecosystems
Lantz, T.C., Marsh, P. and Kokelj, S.V. 2013. Recent shrub proliferation in the Mackenzie Delta Uplands and microclimatic implications. Ecosystems 16: 47-59.

The authors write that "local observations, repeat photos, and broad-scale remote sensing suggest that tall shrubs are becoming an increasingly dominant component of Low Arctic ecosystems," but they say that "to date there have been few quantitative estimates of the rate of tall shrub expansion."

What was done
To help fill this data void, Lantz et al. "used soft copy stereo visualization of air photos to map fine-scale changes in tall shrub tundra and green alder density in the upland tundra north of Inuvik, Northwest Territories, between 1972 and 2004," while also using 2004 photos "to map tall shrub tundra in areas affected by fires that occurred between 1960 and 1968."

What was learned
The three Canadian researchers report that "the vegetation in the upland tundra east of the Mackenzie Delta has changed dramatically in the last three decades with relative increases in tall shrub cover and alder density of 68.1 and 35%, respectively," while noting that "fine-scale anecdotal observations and broad-scale investigations using NDVI [Normalized Difference Vegetation Index] suggest that changes in vegetation have been widespread (Bhatt et al., 2010; Mackay and Burn, 2011)."

What it means
"Based on these results," in the words of Lantz et al., they suggest that "predicted increases in the size and frequency of tundra fire are likely to drive rapid shrub proliferation in the Low Arctic." Indeed, they report that local observations in other regions, combined with broad-scale remote sensing studies, suggest that similar changes have taken place across the Low Arctic portion of the entire Northern Hemisphere, citing Silapaswan et al. (2001), Thorpe et al. (2002), Jia et al. (2003), Stow et al. (2004), Forbes et al. (2010), Beck and Goetz (2011) and Fraser et al. (2011). And they say that "in the Northwest Territories and Alaska, anecdotal observations and population age structure data suggest that the proliferation of the nitrogen fixing species green alder has contributed significantly to the observed vegetation changes," citing Tape et al. (2006) and Lantz et al. (2010). And that is one of the many different places and ways in which the greening of planet earth continues.

Beck, P.S.A. and Goetz, S.J. 2011. Satellite observations of high northern latitude vegetation productivity changes between 1982 and 2008: ecological variability and regional differences. Environmental Research Letters 6: 10.1088/1748-9326/6/4/045501.

Bhatt, U.S., Walker, D.A., Raynolds, M.K., Comiso, J.C., Epstein, H.E., Jia, S.G., Gens, R., Pinzon, J.E., Tucker, C.J., Tweedie, C.E. and Webber, P.J. 2010. Circumpolar Arctic tundra vegetation change is linked to sea ice decline. Earth Interactions 14: 1-20.

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.

Fraser, R.H., Olthof, I., Carriere, M., Deschamps, A. and Pouliot, D. 2011. Detecting long-term changes to vegetation in northern Canada using the Landsat satellite image archive. Environmental Research Letters 6: 10.1088/1748-9326/6/4/045502.

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.

Lantz, T.C., Gergel, S.E. and Henry, G.H.R. 2010. Response of green alder (Alnus viridis subsp fruticosa) patch dynamics and plant community composition to fire and regional temperature in north-western Canada. Journal of Biogeography 37: 1597-1610.

Mackay, J. and Burn, C. 2011. A century (1910-2008) of change in a collapsing pingo, Parry Peninsula, Western Arctic Coast, Canada. Permafrost and Periglacial Processes 22: 10.1002/ppp.723.

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.

Stow, D.A., Hope, A., McGuire, D., Verbyla, D., Gamon, J., Huemmrich, F., Houston, S., Racine, C., Sturm, M., Tape, K., Hinzman, L., Yoshikawa, K., Tweedie, C., Noyle, B., Silapaswan, C., Douglas, D., Griffith, B., Jia, G., Epstein, H., Walker, D., Daeschner, S., Petersen, A., Zhou, L., and Myneni, R. 2004. Remote sensing of vegetation and land-cover change in Arctic tundra ecosystems. Remote Sensing of Environment 89: 281-308.

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.

Thorpe, N., Eyegetok, S., Hakongak, N. and Elders, K. 2002. Nowadays it is not the same: Inuit Quajimajatuqangit, climate caribou in the Kitikmeot region of Nunavut, Canada. In: Krupnik, I. and Jolly, D. (Eds.), The Earth is Faster Now: Indigenous Observations of Arctic Environmental Change. Arctic Research Consortium of the United States/Smithsonian Institution, Fairbanks/Washington, DC., pp. 198-239.

Reviewed 3 July 2013