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Can Plants Migrate Poleward Rapidly Enough to Avoid Extinction in the Face of "Unprecedented" Global Warming?
Reference
Alsos, I.G., Eidesen, P.B., Ehrich, D., Skrede, I., Westergaard, K., Jacobsen, G.H., Landvik, J.Y., Taberlet, P. and Brochmann, C. 2007. Frequent long-distance plant colonization in the changing Arctic. Science 316: 1606-1609.

What was done
Concentrating their efforts on the Svalbard Archipelago - the islands of which were almost entirely glaciated during the last glacial maximum of 20,000 years ago (which phenomenon excluded the glacial survival of "most, if not all, species," according to Alsos et al.) - the nine scientists analyzed DNA fingerprinting (amplified fragment-length polymorphism) of 4439 samples from most of the geographic ranges of nine plant species native to the Arctic, after which they used the genetic data thereby obtained to reconstruct past plant colonization patterns. More specifically, they say they "determined the frequency of effective long-distance dispersal events, identified the source areas, and assessed whether dispersal ability is more limiting than establishment in a new area."

What was learned
Alsos et al. discovered that long-distance colonization of the Svalbard Archipelago "has occurred repeatedly and from several source regions," with probable propagule dispersal vectors being "wind, drift wood and drifting sea ice, birds, and mammals." In addition, they found that "the genetic effect of restricted colonization was strongly correlated with the temperature requirements of the species, indicating that establishment limits distribution more than dispersal."

What it means
Given the likelihood that dispersal mechanisms in existence during the early and mid-Holocene (i.e., from 9500 to 4000 years Before Present, when Alsos et al. report that "the climate was 1 to 2C warmer [our italics] than today") are probably "still operating," as they describe it, the nine researchers conclude that "Arctic species seem to be able to track their potential niche and that unlimited dispersal models may be appropriate to estimate long-term range shifts for Arctic regions." In other words, getting viable plant propagules to Arctic lands made newly-suitable for plant growth by global warming - no matter how rapid it might have been - appears not to be a problem, which means that as soon as new Arctic lands are capable of supporting the growth and reproduction of various plants, they will do so.

Reviewed 19 September 2007