By Valiree Green
Minnesota DNR Forestry
As people use state forest land for recreation, they often wonder about the activities they see happening, sometimes very large changes they did not expect to see.
State forest lands have many purposes, ranging from recreation, watershed protection, wildlife habitat and forest management. When forest managers make plans in the forest, they must consider the natural and man-made changes over the longterm. They must consider how forest management activities will affect both the forest ecosystem as well as the public that uses the forest.
On most publically owned forest land, foresters seek to find socially acceptable practices that sustainably accommodate as many of the above purposes as possible.
As you might imagine, this can be a difficult balancing act, and none of this happens “willy-nilly.”
On lands administered by the Minnesota DNR, management starts with an over-arching planning effort called Subsection Forest Resource Management Planning (SFRMP). Subsection refers to the different ecoregions statewide. After all, goals and the means to reach those goals can differ significantly across the state; southeast Minnesota hardwood forests differ from northern aspen/birch, which differs from lowland conifer types, etc.
The SFRMP process is conducted with inputs from many people. Not only do other divisions in the DNR participate, but the general public is invited to review and comment periods as well. Other types of plans, such as off-highway vehicle, local zoning, county, national forest, all can impact the SFRMP.
The building blocks of the division’s plan include a long-term forest “inventory” system. Information on species, relative number, size and condition of the trees and other vegetation is determined and mapped out. From these, areas of work are scheduled.
Every 10 years forest stands to be examined (and possibly treated) are listed out, and foresters physically visit each one of them. This information is then the basis for making decisions in the SFRMP process. When stands meet certain criteria, they are selected out into a pool for possible management actions.
Possible actions include harvest, commercial thinning, timber stand improvement, supplemental planting, removal of invasive exotic plants and so forth. These man-made actions are designed to replicate natural processes as best as possible.
Within each of these actions there are a myriad of possible practices. For example, there are many types of harvesting systems such as single-tree selection, shelter wood, seed tree and clear cut. The choice of treatment is a continuum from very intense, which is often very noticeable, to “hands-off.”
The Division of Forestry manages over four million acres of state forest land across Minnesota. Some of it is reserved from harvest and active management of any kind. These forests are reserved as old growth areas and are allowed to grow naturally without interference from man.
Other areas, called Old Forest Reserve, are open to harvest but are scheduled out on a longer timeframe than their normal rotation age.
Many forests are managed on a rotation that fully uses the commercial value of wood as well as preventing losses from disease and insect issues. Those rotation ages vary by forest type and species. For instance, oak in southeastern Minnesota is often on a 100-year rotation, while aspen in the north may be on a 40-year rotation age.
The forest is a dynamic system, changing all the time. Some change is man-made and some is not. What we see at any one moment is but a snapshot in time. No human action is also action because doing nothing allows something else to happen. Watch your forests through the years and see how they progress.