Wind-Driven Dispersal of Seeds and Pollen

With the help of real-world micrometeorological data measured during the vegetative growth period (May-September) of ten consecutive years (1998-2007) in a boreal forest of southern Finland, the authors investigated the effects of a warming-induced increase in local convective turbulence (caused by a postulated 3°C increase in local temperature) on the long-distance dispersal (LDD) of seeds and pollen based on mechanistic models of wind dispersal (Kuparinen et al., 2007) and population spread (Clark et al., 2001).

For light-seeded herbs, Kuparinen et al. report that spread rates increased by 35-42 m/yr (6.3-9.2%), while for heavy-seeded herbs the increase was 0.01-0.06 m/yr (1.9-6.7%). Somewhat analogously, light-seeded trees increased their spread rates by 27-39 m/yr (3.5-6.2%), while for heavy-seeded trees the increase was 0.2-0.5 m/yr (4.0-8.5%). In addition, they note that "climate change driven advancements of flowering and fruiting phenology can increase spread rates of plant populations because wind conditions in spring tend to produce higher spread rates than wind conditions later in the year."

As for the significance of their findings, the four researchers, hailing from France, Germany, Israel and the United States, write that -- in addition to the obvious benefits of greater LLD (being better able to move towards a more hospitable part of the planet) -- the increased wind dispersal of seeds and pollen may "promote geneflow between populations, thus increasing their genetic diversity and decreasing the risk of inbreeding depression," citing the work of Ellstrand (1992) and Aguilar et al. (2008), while further noting that "increased gene flow between neighboring populations can accelerate adaptation to environmental change," citing the work of Davis and Shaw (2001) and Savolainen et al. (2007), which phenomena are all very positive developments. In fact, they report that the "dispersal and spread of populations are widely viewed as a means by which species can buffer negative effects of climate change [italics added]." Hence, this is another example of global warming itself providing an impetus for plants to better deal with the challenges it may pose for them.

Additional References
Aguilar, R., Quesada, M., Ashworth, L., Herrerias-Diego, Y. and Lobo, J. 2008. Genetic consequences of habitat fragmentation in plant populations: susceptible signals in plant traits and methodological approaches. Molecular Ecology 17: 5177-5188.

Clark, J.S., Lewis, M. and Hovarth, L. 2001. Invasion by extremes; population spread with variation in dispersal and reproduction. American Naturalist 157: 537-544.

Davis, M.B. and Shaw, R.G. 2001. Range shifts and adaptive responses to quaternary climate change. Science 292: 673-679.

Ellstrand, N.C. 1992. Gene flow by pollen: Implications for plant conservation genetics. Oikos 63: 77-86.

Savolainen, O., Pyhajarvi, T. and Knurr, T. 2007. Gene flow and local adaptation in trees. Annual Review of Ecology, Evolution and Systematics 38: 595-619.