Weeds and climate change

On the subject of weeds and biological invasions, touched on in this week’s “Practical Evolution” essay, the NY Times ran a long piece last week about the relationship of weeds and climate change. The story, by Tom Christopher, covers the work of Lewis Ziska, who grows weed plants in different carbon dioxide concentrations. One of the messages is that weeds are poised to take advantage of changes in the environment because of their genetic diversity, while we have bred diversity out of crop plants.

I enjoyed the discussion of cheatgrass (common in Western Kansas) and this passage about the work of Andrew MacDougall, of the University of Guelph, on an oak savanna in British Columbia:

MacDougall concluded that rather than serving as drivers of change, the foreign grasses were functioning more in the role of passengers, merely filling in as the natives disappeared. In fact, the foreigners seemed to be serving a stabilizing role. By blocking light from reaching the soil, they inhibited the germination of tree and shrub seeds. Keeping the brush at bay in this fashion preserved the open character of the savanna habitat so that the remnants of the original savanna wildflowers, grasses and wildlife could at least survive. In light of these findings, MacDougall says, he came to believe that the primary cause of the native floras decline was human intervention. Before European settlement, fire periodically cleansed the soil surface of dead plant material. Suppression of fire since settlement had allowed a thick layer of litter to accumulate, and the foreign grasses cope better with this than do the natives.

The end of the story mentions the prospect of kudzu-derived ethanol, as well as introgression of wild plant genes into crops. What more could you ask for?