Experimental warming : how temperature affects germination and survival of Minnesota tree species

Seed germination and survival were assessed for ten Minnesota tree species and Rhamnus cathartica, a Minnesota invasive, grown under three temperature treatments (ambient, +1.8 °C, +3.6 °C) and two canopy types (open, understory) at two study sites near the ecotonal boundary between southern boreal and northern temperate forest biomes. Initial germinant establishment, overall establishment, and survivorship were analyzed in response to temperature and canopy type. When it had an effect, elevated temperature negatively influenced all three life-history phases, but the effects were more prevalent for overall establishment and survivorship. Abies balsamea, P. glauca, P. banksiana, B. papyrifera, and A. rubrum all showed considerable negative effects to heating, while P. strobus and P. tremuloides showed moderately negative effects. Meanwhile, both Quercus species and R. cathartica appear relatively unaffected by heating. Thus, even moderate climate warming will likely influence the germination and survival of Minnesota boreal and temperate tree species.