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With continually increasing summer temperatures and intense heat waves, it can be easy to neglect the ecological effects of winter climate change. However, shifts in the climate during winter can have profound consequences for eco-evolutionary dynamics in extratropical latitudes and high-elevation locales. Climate change has increased winter temperatures, disrupted snowpack, and reduced ice cover (Rixen et al., 2022). Extreme losses of snowpack are projected for many regions by the end of the century (Talsma et al., 2022). Patterns of climate change are complex and region dependent, but winters are becoming less reliable overall, with elevated temperatures and altered snow dynamics. In ecosystems with cold winters, many plant species require exposure to low, but not necessarily freezing, temperatures for a prolonged period to break dormancy in the spring; this chilling requirement prevents leaf emergence, flowering, or germination from occurring in the middle of winter (Chuine et al., 2016). Warming winters have advanced the onset of spring and could result in insufficient overwinter chilling. In addition, spring and fall frosts that occur after plants become physiologically active can perturb phenology and reduce fitness. Finally, novel winter climates could disrupt biotic interactions among plants, their mutualists, and antagonists. Here, I discuss emerging research frontiers in these domains.
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Thermal Forcing Versus Chilling? Misspecification of Temperature Controls in Spring Phenology Models
Climate‐change‐induced shifts in the timing of leaf emergence during spring have been widely documented and have important ecological consequences. However, mechanistic knowledge regarding what controls the timing of spring leaf emergence is incomplete. Field‐based studies under natural conditions suggest that climate‐warming‐induced decreases in cold temperature accumulation (chilling) have expanded the dormancy duration or reduced the sensitivity of plants to warming temperatures (thermal forcing) during spring, thereby slowing the rate at which the timing of leaf emergence is shifting earlier in response to ongoing climate change. However, recent studies have argued that the apparent reductions in temperature sensitivity may arise from artefacts in the way that temperature sensitivity is calculated, while other studies based on statistical and mechanistic models specifically designed to quantify the role of chilling have shown conflicting results. We analysed four commonly used combinations of phenology and temperature datasets obtained from remote sensing and ground observations to elucidate whether current model‐based approaches robustly quantify how chilling, in concert with thermal forcing, controls the timing of leaf emergence during spring under current climate conditions. We show that widely used modeling approaches that are calibrated using field‐based observations misspecify the role of chilling under current climate conditions as a result of statistical artefacts inherent to the way that chilling is parameterised. Our results highlight the limitations of existing modelling approaches and observational data in quantifying how chilling affects the timing of spring leaf emergence and suggest that decreasing chilling arising from climate warming may not constrain near‐future shifts towards earlier leaf emergence in extra‐tropical ecosystems worldwide.
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- PAR ID:
- 10570462
- Editor(s):
- Bjorkman, Anne
- Publisher / Repository:
- Wiley Online Library
- Date Published:
- Journal Name:
- Global Ecology and Biogeography
- Volume:
- 33
- Issue:
- 12
- ISSN:
- 1466-822X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1111/geb.13932
