Forested watershed
Many species in riparian and lowland forests can tolerate intermittent wet and dry conditions, and they can tolerate periodic floods and moisture stress. Extended droughts would cause significant damage to shallow-rooted species, but increased winter and spring precipitation could buffer summer droughts in low-lying areas on the landscape.
Under a high emissions scenario, researchers forecast more insect pest damage in northern forests due to increased metabolic activity in active periods and increased winter survival. Drought-stressed trees are also typically more vulnerable to insect pests and diseases. Emerald ash borer and Dutch elm disease are expected to continue to limit ash and elm species.
Invasive species are generally expected to benefit from changing conditions and increased stress, but it's hard to predict exactly how they may be affected by climate change.
Multiple forest impact models tend to agree that these species are likely to decline in suitable habitat and biomass across a range of climate scenarios by the end of the century. Many of these species are near their southern range limits in the Northwoods.
Multiple forest impact models tend to agree that these species are likely to increase in suitable habitat and biomass across a range of climate scenarios by the end of the century. These forests are relatively diverse with tree species occupying a variety of microsites, which reduces the risk of some species declining under future conditions. Many of these species are near their northern range limits in the Northwoods, so they may benefit from gene flow from southern populations.
Climate change has the potential to alter the hydrologic regimes in riparian systems and lowlands across the Upper Midwest. These hardwood forests are particularly adapted to annual and seasonal fluxes in water tables, and the regeneration requirements of several species within this forest type are linked to these cycles. Shifts in the timing or amount of precipitation could disrupt the function of these forests. Groundwater-fed systems may also have some additional resilience where cooler, wetter soil conditions are maintained over time.
Northern hardwoods usually contain many species and age cohorts, and they exist on a range of soil types and landforms. This diversity gives them many potential future pathways to respond to changing conditions. Sites dominated by a single species like sugar maple are more susceptible to future stressors, however, as are stands with reduced structural diversity.
Under a high emissions scenario, researchers forecast more insect pest damage in northern forests due to increased metabolic activity in active periods and increased winter survival. Drought-stressed trees are also typically more vulnerable to insect pests and diseases. Emerald ash borer and Dutch elm disease are expected to continue to limit ash and elm species. New pests such as Asian longhorn beetle present unknown risks.
Deep snow insulates tree roots in northern hardwood systems from fluctuating winter temperatures. Many northern hardwood species are susceptible to root frost damage, including sugar maple and yellow birch. As climate change continues to increase winter temperatures in the Upper Midwest, it is expected that the winter snowpack will be reduced and more variable, and that freeze-thaw events will become more common. The potential for more freeze-thaw events could exacerbate ongoing hardwood dieback in northern Michigan and northern Wisconsin.
These are northern species near their southern range limits in Michigan. Multiple forest impact models tend to agree that these species are more likely to decline in suitable habitat and biomass across a range of climate scenarios by the end of the century.
