The coordination of traits from individual organs to whole plants is under strong selection because of environmental constraints on resource acquisition and use. However, the tight coordination of traits may provide underlying mechanisms of how locally adapted plant populations can become maladapted because of climate change. To better understand local adaptation in intraspecific trait coordination, we studied trait variability in the widely distributed foundation tree species, Based on adaptive syndrome theory, we hypothesized that trait expression would be coordinated among and within trait spectra, reflecting local adaptation to either exposure to freeze‐thaw conditions in genotypes sourced from high‐elevation populations or exposure to extreme thermal stress in genotypes sourced from low‐elevation populations. High‐elevation genotypes expressed traits within the phenology and WES that limit frost exposure and tissue damage. Specifically, genotypes sourced from high elevations had later mean budburst, earlier mean budset, higher wood densities, higher bark fractions and smaller xylem vessels than their low‐elevation counterparts. Conversely, genotypes sourced from low elevations expressed traits within the LES that prioritized hydraulic efficiency and canopy thermal regulation to cope with extreme heat exposure, including 40% smaller leaf areas, 67% higher stomatal densities and 34% higher mean theoretical maximum stomatal conductance. Low‐elevation genotypes also expressed a lower stomatal control over leaf water potentials that subsequently dropped to pressures that could induce hydraulic failure.
Seed sourcing decisions affect short‐ and long‐term restoration outcomes. Seeds sourced closer to restoration sites are likely to be better adapted to local conditions and therefore may perform better than those sourced farther away, following assumptions of local adaptation. However, plants may not be adapted to future conditions under climate change; hence, managers are considering a predictive provenancing approach, where plant materials adapted to predicted conditions are used at a site. Currently, there is little empirical evidence available to inform this approach. To address this, we evaluate predictive provenancing using three species of forbs used in tallgrass prairie restorations (
- NSF-PAR ID:
- 10392602
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Restoration Ecology
- Volume:
- 31
- Issue:
- 1
- ISSN:
- 1061-2971
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract As climates change, species with locally adapted populations may be particularly vulnerable as specialization narrows the range of conditions under which populations can persist. Populations adapted to local climate as well as other site‐specific characteristics like soils present challenges for inferring how changing climates affect fitness, as climatic and nonclimatic variables that constitute local conditions decouple. We conducted two transplant experiments involving American ginseng to test how climatic conditions affect performance while controlling for effects of other site characteristics. We first out‐planted populations from differing elevations to gardens arrayed along an elevation/climate gradient. We also grew maternal plants under temperatures corresponding to home‐site and future conditions (16.4–22.4°C), transplanting resultant progeny to two home‐sites at different elevations (400 m, 800 m). Source populations responded idiosyncratically to elevation reflecting how nonclimatic site characteristics strongly affected plant fitness. Germination rates declined for seeds from maternal plants exposed to warmer temperatures, which compounded with diminished seed production of maternal plants, suggested that population growth may decline rapidly as warm years become hotter and more frequent. Controlling for maternal temperature effects provided evidence that plants are adapted to home‐site conditions, both climatic and nonclimatic, with population growth rates for out‐planted populations ranging from below population replacement levels (
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Abstract During the “decade on restoration,” we must understand how to reliably re‐establish native plant populations. When establishing populations through seed addition, practitioners often prioritize obtaining seed from locations geographically near the restoration site (i.e. “local seed sourcing”). They are assumed to be under similar environmental conditions to the restoration site and should establish more robust plant populations and preserve local biotic interactions better than seeds sourced from further away. However, this assumption remains virtually untested in realistic restoration settings and the importance of seed sourcing, relative to other factors such as seeding rate and management regimes, is unclear.
To determine if seed sourcing decision impacts plant establishment, abundance and phenology, we developed a partnership between university‐researchers and a native seed producer that kept records on where their seed was sourced from and where it was planted. At each site, we recorded the abundance and phenological stage of five commonly used tallgrass prairie restoration species seeded at 24 sites undergoing restoration across Michigan. We considered two measures of seed source locality: geographic distance (seeds were sourced from locations 6–750 km away from their respective restoration sites) and environmental distance. We also obtained data on the seeding rate and post‐seeding management at each site.
We found that no measure of seed source locality predicted the likelihood of plant establishment or abundance at restoration sites. However, sites sown with seed from further away, or from cooler and wetter climates, had a greater proportion of flowering individuals earlier in the season. Finally, sites with higher seeding rates had greater plant abundance, and post‐seeding management of the restoration site increased the likelihood a species would establish by 36%.
Overall, these results support that seed sourcing decisions did not impact plant establishment or abundance in our system. However, using less‐local seed sources may alter flowering phenology.
Our results suggest that tallgrass prairie restoration efforts should prioritize higher seeding rates, post‐seeding management, and might expand the region seed sources are considered “local”, though this may impact flowering phenology. Future research leveraging native seed producer records can help answer critical questions about restoration seed sourcing.
