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Antarctic Plants Thrive in Warmer Temperatures
Reference
Xiong, F.S., Meuller, E.C. and Day, T.A. 2000. Photosynthetic and respiratory acclimation and growth response of Antarctic vascular plants to contrasting temperature regimes. American Journal of Botany 87: 700-710.

Background
Although the vast bulk of Antarctica is either maintaining a near-constant mean annual near-surface air temperature or slightly cooling (see our Climate Review: Recent Trends in Antarctic Surface Temperatures), the west coast of the Antarctic Peninsula has warmed substantially over the past several decades. Hence, it is only natural to wonder what impact this warming is having on the two species that make up the totality of the continent's vascular plants: Colobanthus quitensis (a cushion-forming member of the Caryophyllaceae) and Deschampsia antarctica (a prostrate tussock grass). Xiong et al. report that increases in the size and number of populations of these species have recently been observed along the Peninsula; and they present the results of their study of the growth responses of the plants to increasing temperature.

What was done
Young plants were collected from the west coast of the Antarctic Pennisula, transported in chilled boxes to Arizona State University, and propagated in growth chambers at a 12C/12C (day/night) temperature regime. After 14 months, seeds were collected from the C. quitensis plants and new plants started, while young tillers of D. antarctica were used to start new plants of that species. The new plants were grown for 90 days in growth chambers maintained at day/night temperature combinations of 7C/7C, 12C/7C and 20C/7C. At the conclusion of these treatments, various measures of plant growth were recorded.

What was learned
In the words of the authors, "plants of both species grown at a daytime temperature of 20C had greater relative growth rates and produced 2.2 - 3.3 times as much total biomass as plants grown at daytime temperatures of 12 or 7C." They additionally noted that plants grown at 20C also produced 2.0 - 4.1 times as many leaves and 3.4 - 5.5 times as much total leaf area.

What it means
As is characteristic of the biosphere in general, the results of this study demonstrate that vegetative productivity typically increases with rising temperatures. As for the future welfare of these indigenous plants, therefore, the authors note that "continued warming along the Peninsula will lead to improved vegetative growth of these species." It almost makes one hope that the isolated west coast warming would continue, so that these special plants could increase their tenuous grip on the edge of the continent from a toe-hold to a foot-hold. Do they deserve any less?


Reviewed 1 July 2000