Cooperative Stand Assessment (CSA) Codes and Terminology

Background

Cooperative Stand Assessment (CSA) is the forest stand mapping and information system used by the Minnesota Department of Natural Resources to inventory the approximately 5 million acres (7800 sq. mi.) owned and administered by the state.

At its origin in 1952, CSA was based on pencil-drawn land use maps and a computer-punchcard database. The system has matured into an Arc/Info geographic information system (GIS) database accessible online by DNR forest managers.

A key concept in forest management is the forest stand, which is a group of trees uniform enough in composition to be managed as a unit. CSA maps the boundaries and tabulates the contents of all forest stands 5 acres and larger on state-owned land. Stand boundaries are drawn by interpretation of aerial photographs. All other stand data are collected in the field on plots established within each stand; boundaries may be redrawn at the time of field data collection.

Whenever a cultural treatment such as cutting, thinning, planting or seeding is carried out in a stand, the stand's attributes are altered to reflect what has happened. Local forest managers submit their alterations to the CSA database on a regular schedule so that the entire database remains current.

Stand maps and databases are periodically reviewed to assess the need for comprehensive remapping and new data collection.


Terminology

Like all applied sciences, forestry has its own jargon to encapsulate complex concepts. Below are definitions of some key terms used in CSA stand descriptions.

Stand ID: A unique identifier for a stand in the statewide CSA database, consisting of:

For example, a stand in township 135, range 31 west, on state ownership (code 1), in section 16, with a type number of 32, would be represented as:

"t"+135+31+"w"+1+16+0032 = t13531w1160032

DBH: Diameter at Breast Height. A conventional measure of tree stem diameter, taken outside the bark at a point approximately 4.5 feet above ground.

Average Diameter Class: This is an average size expression for the trees populating a stand. The measurement is the average of diameter at breast height (DBH) for trees throughout the stand. Values for average diameter classes can range anywhere from under one inch for young saplings, to over 25 inches for large, mature trees.

Density: This figure expresses the stocking level of the stand. How it is translated depends on the stand's Average Diameter Class (see above). Density for stands with an average diameter class under 5" DBH is expressed as stems per acre, with values ranging from fewer than 250 to over 4000 stems per acre. For stands with a 5" to 14.9" average diameter class, density is given in cords, with values ranging from less than three to over 40 cords per acre. Finally, for stands with an average diameter class over 15" DBH, density is expressed as board feet, with values ranging from less than 250 to over 20,000 board feet per acre. Cords and board feet are defined under volume below.

Basal Area Per Acre: Another measure of how well a stand is stocked (see Density, above), basal area equals the sum of the cross-sectional area of all trees (or some designated subpopulation) measured at the conventional breast height of 4.5 feet above ground and averaged across the acreage of the stand.

Volume: Cords and board feet are conventional units of wood volume. A cord is a stack of logs measuring 4 feet wide by 4 feet high by 8 feet long; a board foot is a volume of sawn lumber equivalent to a piece 1 foot wide by 1 foot long by 1 inch thick. For rough comparison purposes, a cord approximates 500 board feet. Volume of trees between 5" and 14.9" in diameter is expressed in cords, that of trees 15" and larger in board feet.

Rotation Age: The age at which a stand would normally be harvested to capture maximum productivity from the site it is growing on.

Cover Type: These are general descriptive terms for the overall contents of stands, not to be confused with species designations, which refer to individual trees. The terms "offsite" and "stagnant" as used in cover type names signify low production. The cover type designations used in CSA are listed below.

Tree Species: The following is a listing of particular Minnesota tree species, as opposed to generalized stand cover types. Note that many of the species listed here do not appear in the cover type list; such species are generally never the predominant species in a given forest stand.

Condition Class: This expresses the situation of the stand with respect to the rotation age of its cover type. Condition classes used in the CSA inventory program are listed below.

Management Status: This expresses how the stand will be handled with respect to normal timber management. Management status classes used in CSA are listed below.

Physiographic Class: This term expresses the situation of the stand with respect to water drainage through the soil, which has a strong effect on species suitability, productivity, and management choices. Physiographic classes used in CSA are listed below.

Site Index: This is a conventional forestry measure of the timber-growing quality of a site for the primary species occupying it. It represents the average height attained by a tree of that species at 50 years of age.