For those who wander looking for wildflowers during California’s springtime, I suspect this tree will be immediately familiar. It is the valley oak or roble that grows near the main parking lot to the exceptional North Table Mountain Ecological Reserve, photographed seven years ago in early morning light.
About 200km (120 miles) to the west of this tree, the current tallest oak in North America can be found. That particular valley oak is 47m (153 ft.) in height. Historically, white oaks (Quercus alba) in the old-growth forests of West Virginia, like the Mingo Oak, exceeded 60m (over 200 ft.).
Although widespread in distribution within California’s central valleys and foothills, Quercus lobata is listed as Near Threatened in a 2017 IUCN Red List Assessment. Habitat fragmentation and agricultural / urban expansion are listed as the main causes of its decline, but habitat shift and contraction due to climate change are also considered as part of the assessment process; it is conservatively predicted that there will be a 27% decrease in suitable habitat for valley oak by 2099.
One of the strategies to deal with declining populations is restoration. I am not a restoration ecologist, so others will correct me in the comments, but my understanding of the modern best practices for restoration is to bulk up local populations using seed sourced from those same local populations. The notion is that localized populations may have higher frequencies of genes (or expressions thereof) that foster local adaptations to the environment; the introduction of genetic material from non-local populations may actually work against future generations in that region.
Post-dating the IUCN assessment is this 2019 paper: Adaptational lag to temperature in valley oak (Quercus lobata) can be mitigated by genome-informed assisted gene flow (Browne et al. in Proc. Nat. Acad. Sci.). The authors state up front:
We show that an ecosystem-foundational species in California, valley oak (Quercus lobata), is already mismatched to current temperature and will likely experience further declines in growth rates as temperatures rise over the next century.
The authors propose another consideration for those involved in restoration: genome-informed assisted gene flow. To summarize: in order to mitigate climate change’s effects on a local population, it isn’t enough to bulk up numbers of plants using locally-sourced seeds; instead, informed introduction of genes from plants that are best-suited for warmer temperatures may have to become a standard conservation practice in restoration (at least in some instances).