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Impacts of Warming on Reproductive Output of a Forest Herb
De Frenne, P., Graae, J.J., Kolb, A., Brunet, J., Chabrerie, O., Cousins, S.A.O., Decocq, G., Dhondt, R., Diekmann, M., Eriksson, O., Heinken, T., Hermy, M., Jogar, U., Saguez, R., Shevtsova, A., Stanton, S., Zindel, R., Zobel, M. and Verheyen, K. 2010. Significant effects of temperature on the reproductive output of the forest herb Anemone nemorosa L. Forest Ecology and Management 259: 809-817.

What was done
The authors collected seeds of Anemone nemorosa L. -- a model species for slow-colonizing herbaceous forest plants -- found in populations growing along a 2400-km latitudinal gradient stretching from northern France to northern Sweden during three separate growing seasons (2005, 2006 and 2008), after which they conducted sowing trials in incubators, a greenhouse, and under field conditions in a forest, where they measured the effects of different temperature treatments (Growing Degree Hours or GDH) on various seed and seedling traits.

What was learned
De Frenne et al. report that "seed mass, germination percentage, germinable seed output and seedling mass all showed a positive response to increased GDH experienced by the parent plant," noting that seed and seedling mass increased by 9.7% and 10.4%, respectively, for every 1000 C-hours increase in GDH, which they say is equivalent to a 1C increase in temperature over a 42-day period.

What it means
The nineteen researchers -- hailing from Belgium, Estonia, France, Germany and Sweden -- concluded that "if climate warms, this will have a pronounced positive impact on the reproduction of A. nemorosa, especially in terms of seed mass, germination percentage and seedling mass," because "if more seeds germinate and resulting seedlings show higher fitness, more individuals may be recruited to the adult stage." In addition, they say that since "rhizome growth also is likely to benefit from higher winter temperatures (Philipp and Petersen, 2007), it can be hypothesized that the migration potential of A. nemorosa may increase as the climate in NW-Europe becomes warmer in the coming decades." And increasing migration potential implies decreasing extinction potential.

Philipp, M. and Petersen, P.M. 2007. Long-term study of dry matter allocation and rhizome growth in Anemone nemorosa. Plant Species Biology 22: 23-31.

Reviewed 17 March 2010