• Projected mid-century warming here is among the highest absolute values of any US-bordering ecoregion (~4-5 °C under SSP3-7.0); the northern hardwoods band is projected to shift roughly a full USDA zone north.
• Boreal species at their southern range edge (balsam fir, white spruce, paper birch) are contracting; southern hardwoods (oak, hickory, even tulip poplar at the southern margin) are advancing.
• Garden-relevant: tender perennials marginal in zone 4 today may be reliably hardy by mid-century, but cold-hardiness alone is not the gate — northern provenances of native species face heat-tolerance stress on their southern flank.