Running up that hill (with plants)
Written by Grace Gutierrez, edited by Bethany Bradley
Summary
With rapidly changing climate conditions, researchers worry that locally adapted native plants will be particularly vulnerable to climate change, potentially causing local extinctions. One recommended strategy to increase climate resilience is to use seeds sourced from warmer locales in conservation or restoration planting (termed ‘climate-adjusted provenancing; Prober et al. 2016). However this approach has few empirical tests to support the strategy. Anderson and Wadgymar (2020) examined the fitness of the perennial forb Boechera stricta in five different common gardens along a 1000 m (from 2533 to 3600 m) elevation gradient in Colorado. In order to test local adaptation, seeds were gathered from source populations at 5 different elevations (2533, 2710, 2890, 3133, and 3340 m). Plants were then planted in garden plots at the same elevation where they were sourced (local provenancing) or at different elevations from where they were sourced. In order to simulate future climate conditions researchers also removed snow from a portion of all 5 garden plots. Plants that underwent snow removal (simulating future climate conditions) had lower seed germination and plant survival rates than control plots, suggesting that Boechera stricta is generally better adapted to current versus future (warmer) climate across all elevations. The highest elevation populations (i.e. those at the cold range margin) consistently showed the poorest performance across all gardens, suggesting that these populations are locally maladapted to climate and unlikely to be resilient to climate change. This latter finding is consistent with Hampe & Petit (2005)’s hypothesis that populations near the ‘leading edge’ will have genes characterized by founder effects (where the leading edge population was derived from a small subset of the larger population) and might therefore have lower diversity and lower resilience to climate change.
Take home points
Plants sourced from the ‘leading edge’ of the population had the worst overall performance at all sites, suggesting that strict local provenancing could result in maladaptation of these populations to climate change (see definition in Prober et al. 2016)
Plants sourced from trailing edge and middle of the population performed similarly across the elevation gradient, suggesting that admixture provenancing, predictive provenancing, or climate-adjusted provenancing would lead to comparable climate resilience for this species (see definitions in Prober et al. 2016)
Management implications
Except for the seeds sourced from the highest elevation, which showed local maladaptation to climate, most seeds performed similarly well across the elevation gradient. For this species, mixing seed provenances across the elevation gradient leads to similar plant performance.
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Keywords: Climate-smart restoration, assisted migration, assisted gene flow, climate adjusted provenancing, forest, managed relocation, plants, restoration