Climate change experiment suggests assisted migration may be necessary to save range-restricted plant species

Paul Reed

Publication Date:

Climate change poses an existential threat to plant species with restricted geographic ranges. However, climatically favorable habitat may exist at higher latitudes if species can reach such locales. Thus, successful restoration projects should consider how climate change impacts species ranges in the future. In a climate manipulation experiment conducted between 2016-2018, we monitored populations of 14 range-restricted native species in three prairies across a 520 km latitudinal Mediterranean climate gradient in the Pacific Northwest, USA. At each site, 20 plots were divided evenly into controls and three climate treatments: drought, warming, and warming+precipitation. Each year, we measured rates of survival, growth, and reproduction to calculate population growth rates (λ). We found that for many species λ was greatest at the northern site and ≥1 (growing or stable), with climate treatments being neutral or beneficial relative to control. At the central site, warming often negatively impacted λ relative to the control, with several species exhibiting λ<1 (decline) under warming but λ>1 in the control. Lastly, λ was <<1 for most species at the southern site under all treatments. These results suggest that conditions are already detrimental towards the southern end of this gradient, and that climate change may make matters worse within some parts of these species’ ranges but be neutral/favorable towards the northern edge of/beyond their ranges. Thus, these species may need to migrate northward to cope with climate change. If they are unable to do so alone, assisted migration may be the only option for their persistence.

Resource Type:
Audio/Video, Conference Presentation, SER2019

Society for Ecological Restoration