Five Anthropogenic Factors That Will Radically Alter Northern Forests in 50 Years
A new study by U.S. Forest Service scientists and partners identifies five factors that are expected to change northern forests in the next 50 years. The study, “Five anthropogenic factors that will radically alter forest conditions and management needs in the Northern United States,” was recently published in the journal Forest Science.
The study’s lead author is Stephen Shifley, a research forester with the Forest Service’s Northern Research Station in Columbia, Mo.
Photo by Joe O'Brien, USDA Forest Service, bugwood.org.
The study stems from the Northern Research Station’s Northern Forest Futures Project, which is an effort to forecast forest conditions over the next 50 years in the 20-state region extending from Maine to Minnesota and from Missouri to Maryland.
One of the factors that Shifley believes will radically alter northern forests is a lack of age-class diversity in forests.
Forest inventories show that there is an imbalance in forest age classes in the North, Shifley said. Due to historical patterns of forest disturbance, the vast majority of forests are middle-aged, which for trees is between 40 and 80 years old. Young forests and very old forests are comparatively rare.
This results in a lack of forest diversity, which limits important types of wildlife habitat and makes forest landscapes less resilient to future disturbances caused by forces such as invasive species, insects, diseases, violent weather, or climate change.
Urban expansion is another factor that will influence forests in the next 50 years. The area of forest land in the North will decrease as urban areas expand. Cities in the 20-state region are expected to gain another 27 million people in the next 50 years and grow by about 5 million hectares.
Invasive insects and plants will alter forest density, diversity, and function. The U.S. North has the dubious distinction of having the greatest number of invasive 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.
Timber management will also influence forests. The study found that management intensity for timber is low in Northern forests and likely to remain so, resulting in fewer 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. An unintended consequence of reduced timber harvesting may be reduced capacity to subsidize other restoration activities – either through revenue from timber sales or through manipulation of vegetation and woody fuels during logging.