Forest [FAR1]

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. The possibility exists for interactions among multiple stressors to lead to more severe climate change impacts.

Quaking aspen and bigtooth aspen can tolerate a wide range of soil types and moisture conditions and aspen is a management priority for many landowners. These species may do well with a moderate amount of future warming, and the Tree Atlas and LANDIS models project either no change or slight increases for quaking aspen and bigtooth aspen by the end of the century under the mildest future climate scenario. Both models indicate that these species will fare much worse under hotter, drier climate scenarios.

Quaking aspen, balsam poplar, and paper birch are boreal 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. These species exist on a wide range of soils and landforms, and this forest type is a management priority for many landowners.

Aspen and paper birch are pioneer species evolved to thrive with regular disturbance. Wildfire and blowdown events could become more common under climate change, and continued management could benefit this forest type, but it is unknown whether aspen-birch forests would continue to persist if stand-replacing disturbances become much more frequent.

If climate change results in increased moisture stress during the growing season, drier sites will be exposed to greater drought stress and mortality. Warmer growing-season temperatures might encourage more suckering after disturbance, but projected temperatures in the assessment area may be beyond the physiological limits of aspen and birch species.

Lowland conifer forests are not expected to expand to new territory or outcompete other forest types, but acid or alkaline soil conditions may make them less suitable for invasive species or competing forest types.

These are boreal 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. These forests may not maintain their identity if dominant species decline and water tables change.

Sphagnum moss, the primary source of peat in these systems, may be susceptible to warmer conditions. Warmer growing seasons may increase evapotranspiration rates and reduce the rate of peat accumulation in these forests, and peat layers may begin to erode as decomposition rates increase.

Lowland conifer forests function in a relatively narrow window of water table conditions. Climate change has the potential to alter the precipitation patterns and soil moisture regimes in low-lying areas across the Upper Midwest. Roads and other watershed modifications are already harming lowland conifer forests in some areas. Water table impacts may be intensified as the hydrologic cycle becomes more episodic. Larger lowlands may be able to withstand a wider range of conditions than small, isolated depressions.

Low species diversity gives these forests few alternatives if conditions shift beyond tolerable limits, and low genetic diversity is a concern for red pine in particular.