Age Class: An interval into which the age range of trees or forest stands is divided for classification or use (e.g., 0–10 years, 10–20 years).

Age Class Distribution: The proportion of various age classes of a forest or forest cover type within a defined geographic area (e.g., ECS subsection).

Annual Stand Examination List: List of stands to be considered for treatment in a particular year, selected from the seven-year stand examination list. Treatment may include harvest, thinning, regeneration, prescribed burning, re-inventory, etc.

Assessment: A compilation of information about the trends and conditions related to natural and socio-economic resources and factors. For the initial round of SFRMPs, the focus is primarily on trends and conditions of forest resources. Standard core assessment information sources and products have been defined.

Basal Area: The cross-sectional area of a tree measured at 4.5 feet above the ground. Basal area is often used to measure and describe density of trees using an estimate of the sum of the basal area of all trees within a geographic area (e.g., basal area per acre).

Cover Type: The tree species having the greatest presence in a forest stand (in terms of volume for older stands or number of trees for younger stands).

Desired Future Forest Composition (DFFC): The ultimate desired condition of forest lands in the subsection. DFFC goals could include the amount of various forest types within the subsection, age-class distribution of forest types, the geographic distribution of forest types and age classes across the subsection, and the related level of management for even-aged forest, extended rotation forest, etc. Within landscapes that are predominantly forested, the DFFC considers and reflects all forest lands in the subsection (DNR and non-DNR). However,the DFFC should also identify the role of DNR lands in achieving the broader subsection goals. In subsections where forest land is highly fragmented and DNR forest lands are major islands within developed/agricultural areas, the DFFC focuses primarily on DNR lands. DNR subsection teams establish seven-year forest management objectives for moving toward the DFFC goals. Subsection teams may also establish other interim (e.g., 25-, 50-year) forest composition benchmarks to help track progress toward the DFFC.

Dominant Trees: Trees in the upper layer of the forest canopy; larger than the average trees in the stand.

Ecological Classification System (ECS): A method to identify, describe, and map units of land with different capabilities to support natural resources. This is done by integrating climatic, geologic, hydrologic, topographic, soil, and vegetation data.

Extended Rotation Forests (ERF): Forest stands for which the harvest age is increased beyond the optimum economic harvest age to provide larger trees, wildlife habitat, and other nontimber values. Management of ERF on DNR-administered lands is described in DNR Extended Rotation Forest Guidelines (1994).

Even Aged: A forest stand composed of trees of primarily the same age or age class. A stand is considered even aged if the difference in age between the youngest and oldest trees does not exceed 20 percent of the rotation age (e.g., for a stand with a rotation age of 50 years, the difference in age between the youngest and oldest trees should be 10 years or less).

Forest Stand: A group of trees occupying a given area and sufficiently uniform in species composition, age, structure, site quality, and condition so as to be distinguishable from the forest on adjoining areas.

Old Growth Forests: Forests defined by age, structural characteristics, and relative lack of human disturbance. These forests are essentially free from catastrophic disturbances, contain old trees (generally more than 120 years old), large snags, and downed trees. Management of old growth forests on DNR-administered lands is described in Old Growth Guidelines (1994).

Prescribed Burning: Deliberate burning of wildlands (e.g., forests, prairie, or savanna); in either their natural or their modified state and under specified conditions within a predetermined area to meet management objectives for the site.

Prescription: A written statement that specifies the practices to be implemented in a forest stand to meet management objectives. These specifications reflect the desired future condition at the site and landscape level and incorporate knowledge of the special attributes of the site.

Regeneration: The act of renewing tree cover by establishing young trees naturally (e.g., stump sprouts, root suckers, natural seeding) or artificially (e.g., tree planting, seeding).

Riparian Areas: The area of land and water forming a transition from aquatic to terrestrial ecosystems along streams, lakes, and open-water wetlands.

Rotation Age: The period of years between when a forest stand (primarily even aged) is established and when it receives its final harvest. This period is an administrative decision based on economics, site condition, growth rates, and other factors.

Silviculture: The theory and practice of controlling the establishment, composition, growth, and quality of forest stands to achieve certain desired conditions or management objectives.

Section: A level within the Ecological Classification System. From largest to smallest in terms of geographic area, the ECS is composed of the following levels: Province > Section > Subsection > Land Type Association > Land Type > Land Type Phase. Sections in Minnesota range from approximately 220,000 acres in the Southern Superior Uplands (which has only a small area in Minnesota) up to over 12.1 million acres in the North Central Glaciated Plains, with the average being 5.4 million acres.

Site Index: A species-specific measure of actual or potential forest productivity or site quality, expressed in terms of the average height of dominant trees at specific key ages, usually 50 or 100 years.

Stand Examination List: DNR forest stands to be considered for treatment (e.g., harvest, thinning, regeneration, prescribed burning, reinventory) over the planning period based on established criteria (e.g., rotation age, site index, basal area, desired future cover type composition). These stands are assigned preliminary prescriptions and most receive the prescribed treatment. However, based on field appraisal visit, prescriptions may change for some stands because of new information on the stand or its condition.

Stand Selection Criteria: Criteria used to help identify stands to be treated as determined by the subsection team. Criteria include rotation ages, site index, basal area, cover type composition, understory composition, and location. Factors considered in developing stand selection criteria include desired forest composition goals, timber growth and harvesting, old growth forests, extended and normal rotation forests, riparian areas, wildlife habitat, age and cover type distributions, regeneration, and thinning and prescribed burning needs.

Subsection: A level within the Ecological Classification System. From largest to smallest in terms of geographic area, the ECS is composed of the following levels: Province > Section > Subsection > Land Type Association > Land Type > Land Type Phase. Subsections are generally 1–4 million acres in Minnesota, with the average being 2.25 million acres.

Section Forest Resource Management Plans (SFRMP): A DNR plan for vegetation management on forest lands administered by DNR Forestry and Wildlife that uses ECS subsections as the basic unit of delineation. Initial focus is to identify forest stands and road access needs for the duration of the seven-year plan. There is potential to be more comprehensive in the future.

Thinning: A silvicultural treatment made to reduce the density of trees within a forest stand primarily to improve growth, enhance forest health, or recover potential mortality (e.g., selective thinning, row thinning).