Unseeded territory
Written by Bethany Bradley, edited by Eve Beaury
Summary
Climate change is creating local conditions that plants might not be adapted to, potentially leading to poor performance and population declines. Restoration projects that use seeds sourced from warmer populations (termed ‘climate-adjusted provenancing’; Prober et al. 2016) could result in populations better-adapted to future conditions. However, experimental tests of plant performance under climate change are lacking, making it unclear whether warm-adapted seeds are likely to improve climate adaptation. Bucharova et al. (2016) used a common garden experiment to compare the aboveground biomass and flowering of plants grown from locally-sourced seeds versus warm-adapted seeds for six native perennial plants in Germany (Arrhenatherum elatius, Centaurea jacea, Daucus carota, Galium album, Hypochaeris radicata, Lychnis flos-cuculi). Warm-adapted seeds were sourced from other parts of Germany at distances of 100-450 km and a difference in mean annual temperature of 1.2-2.4 C. Locally-adapted seeds were sourced from within the same geographic region as the garden site - all seeds were bought from commercial vendors. In 2013, plant seedlings were exposed to a summer heat wave of ~1.5 C above the historical average. Plants were harvested at the end of the growing season to measure aboveground biomass and total number of flowers.
Four of the six plant species showed no significant difference between locally-sourced and warm-adapted provenance. Two of six plant species showed significantly poorer performance for one response metric in the warm-adapted plants (Hypochaeris radicata had 16% fewer inflorescences; Lychnis flos-cuculi had 17% lower biomass). While this experiment represents only a single growing season for perennial forbs, the results suggest that warm-adapted seed provenancing does not provide a short-term benefit for plant growth and may create a disadvantage in some cases.
Take home points
Most species and response metrics showed no significant differences between locally-adapted and warm-adapted seed provenance.
More and longer-term experiments of this sort are needed to better understand how plant provenance affects performance.
Management implications
Climate-adjusted provenancing may create some short-term disadvantages in plant growth relative to locally-adapted provenancing.
Ecological theory suggests that Climate-adjusted provenancing should lead to better performance long-term, but long-term experimental data are lacking.
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Keywords: Climate-smart restoration, assisted migration, assisted gene flow, climate adjusted provenancing, forest, managed relocation, plants, restoration