The North – the 20 states bounded by Maine, Maryland, Missouri, and Minnesota—have a greater forest cover (42 percent of land area) and population density (194 people per square mile) than other large regions of the nation.
Five short- and long-term factors will be highly influential in the future of Northern forests regardless of the nature and magnitude of the effects of climate change.
Northern forests lack age-class diversity and will uniformly grow old without management interventions or natural disturbances. Nearly 60 percent of northern forest land is clustered in age classes spanning 40 to 80 years; young forests (age 20 years or less) are only 8 percent of all forests in the region; and forests older than 100 years are 5 percent of forests. Lack of age-class diversity results in forests being less diverse or resilient than they could be.
The area of forest land in the North will decrease as a consequence of expanding urban areas. Cities in the 20-state region are expected to gain another 27 million people in the next 40 years and subsume about 12 million acres of forest land. It is a relatively small loss (about 7 percent) of the total forest land area, but where it occurs it can have a huge local impact.
Invasive species will alter forest density, diversity, and function. Invasives are costly and difficult to control, if they can be controlled at all. The U.S. North has the dubious distinction of having the greatest number of invasive forest insects and plants per county due to nearly three centuries of active commerce, diverse tree species that provide suitable habitats, and the means for invasive species to spread. Invasive species reduce forest health, diversity, and value.
Management intensity for timber is low in Northern forests and likely to remain so. A low propensity or low capacity for forest management reduces options for addressing perceived problems such as low forest diversity, invasive species, and other insects or disease problems.
Management for non-timber objectives will gain relevance but will be challenging to implement. In the past, timber sales generated income that subsidized forest management costs for nontimber values such as improving wildlife habitat, increasing forest diversity, reducing hazardous fuels, or improving recreation opportunities. An unintended consequence of reduced timber harvesting may be reduced capacity to subsidize other management objectives.