After analyzing the available literature, the authors compiled several key findings about the role climate plays in the evolution of weeds:

• Evidence suggests elevated CO2 may contribute to weeds becoming more competitive and developing resistance to herbicides.
• The adaptive evolution of weeds is likely due to two factors: the strong selective pressures exerted by changes in climate and the unique characteristics of weeds, including short lifecycles, strong dispersal abilities and ample genetic variation.
• Weeds evolve in response to both the direct effects of climate change and the indirect effects – such as new fire patterns and new crop introductions.
• Growth rates and other weed traits have been found to vary predictably with variations in climate. In addition, drought and elevated CO2 have been observed to cause genetic and phenotypic changes within individual weed populations.

The authors say there are several important knowledge gaps that remain to be explored – from the differential impact of climate change on herbicide resistance to climate-induced shifts in weed distribution, demography and fitness. Clearly it is time for further research.

Read the WSSA press release here.