Ecology and Management of Weeds in a Changing Climate

Abstract

Weeds cost hundreds of billions of dollars annually through crop losses, management costs, and many other types of deleterious economic impacts. Many of these impacts are rapidly increasing due to the spread of invasive plants into new regions. That such changes in weed distributions could be exacerbated by climate change is fairly obvious, and distributional changes due to climate change have already been observed in many regions of the world. In particular, actual and potential range expansion in concert with warming patterns has been evaluated for many species in some of the world’s major temperate regions: North America, Europe, and Oceania. In each case, potential poleward expansion is forecasted, along with negative consequences, although if climate change is extreme enough, contraction of weed ranges is also predicted. Other regions such as Asia and Africa may experience new weed management challenges due to anticipated changes in seasonal rainfall patterns. Responses of weeds to climate change are complex, involving at least four important components: responses to increased CO2 levels, increased temperatures in temperate and boreal regions, increased climate variability, and evolutionary responses. Invasion of many plant species will progress farther and faster if assisted by climate change, and this change is likely to accelerate evolutionary adaptation of weeds to climate extremes. However, steady progress is being made in our understanding of these dynamics, thus making the prospects for tracking and mitigating anticipated impacts encouraging, provided sufficient resources are available for continued research and management.