Pacific Southwest Region

Western Core Tables

Area Definitions and References

The WCT Volume tables are 01-11 and 25-29

Administrative National Forest:

Federal lands under the administration of the Forest Service, which have been designated by Executive Order or statute as National Forests or purchase units, or other acquired lands, including Experimental Forest and Rangelands, and Grassland areas. Area estimates are developed from the most currently available administrative forest 1:24,000 scale GIS layer from the National Forest Automated Lands Program. The Lake Tahoe Management Area is treated as its own Administrative Unit for planning and reporting. Only those lands administered by the Pacific Southwest Region are included in the reports.

Calveg Vegetation Type:

The Calveg vegetation classification system is used though the Pacific Southwest Region and California for mapping existing vegetation type attributes. Area estimates are determined from the Existing Vegetation GIS layer.

Census Water:

Lakes, reservoirs and ponds, and double line streams, slough, estuaries and canals from the 1:24,000 GIS layer, Region 5 Water Bodies derived from the National Forest Cartographic Feature Files. This mapping is consistent with the USGS National Hydrological Dataset and the US Census Bureau Tiger Files.

Forest Land:

Land at least 10 percent covered by trees of any size or species, including land that formerly had such tree cover and that will be naturally or artificially regenerated. Also included are pinyon-juniper, woodland and chaparral areas. The minimum area of forest land is 1 acre or as mapped on the latest Existing Vegetation GIS layer available at the time of reporting.

Full Harvest:

Productive available forest land that has been determined to be suitable for sustained yields in the National Forest Land and Management Resource Plan, and has been scheduled for full timber harvest production, usually involving short rotation, even age management prescription. This is referenced as Regulation Class I timber lands.

Land:

The area of dry land and land temporarily or partly covered by water, such as marshes, swamps, and river flood plains. Single line streams, sloughs, estuaries, and canals as mapped on 1:24,000 GIS layer, National Forest Cartographic Feature Files, are also included as land.

Non-Forest Land:

Land that has never supported forests and lands formerly forested where land is now development. This includes improved roads, powerlines, railroad clearings, building sites, and compounds. The minimum area of forest land is 1 acre or as mapped on the latest Existing Vegetation GIS layer available at the time of reporting.

Non Productive Forest Land:

Forest land incapable of yielding crops of industrial wood because of adverse site conditions. This land may also be referred to as noncommercial forest land. Area estimates are developed from Existing vegetation GIS layer, of both forest and shrub cover types and Calveg associated alliances. The tree and shrub species listed in the alliance descriptions are used to identify which vegetation types do not have industrial tree species, or do not meet the 20 cubic feet per acre per year productivity requirements.

Non-Stocked Forest Land:

Productive Available Forest Land where tree cover is less than 10 percent. Area estimates are developed from a Strata GIS layer derived from the Existing Vegetation layer which contains a mapped attribute of tree cover from above and reforestation status from agency records. When the mapped tree cover class is less than 10 percent, and no record of tree planting or natural regeneration has occurred, the area is considered non-stocked.

Not suitable / Not appropriate:

Tentatively suitable forest land where non-timber resource prescriptions have been assigned to meet National Forest Land and Resource Management Plan objectives. Sustained timber yields are not scheduled by these prescriptions, nor is the Allowable Sale Quantity calculated from these lands. These lands are referenced as Unregulated.

Proclaimed National Forest:

A Proclaimed National Forest is a Unit of Federal Lands permanently designated for National Forest purposes by Executive Order or statute. A Proclaimed National Forest is often managed by more than one Administrative National Forest or Unit. Area estimates are developed from the most currently available proclaimed forest boundary 1:24,000 scale GIS layer from the National Forest Automated Lands Program. Only those lands designated as a Proclaimed National Forest administered by the Pacific Southwest Region are included in the reports.

Productive Available Forest Land:

Available productive forest land is productive forest land that is not in reserved status through removal of the area from timber utilization by statue, ordinance, or administrative order, or pending reserved in the current National Forest Land and Resource Management Plan.

Productive Forest Land:

Forest land capable of growing 20 cubic feet per acre per year of industrial wood. A localized list defines which tree species are included as growing stock, and stocking potential of these industrial tree species, is used to define productive forest land. Area estimates are developed from Existing vegetation GIS layer, of both forest and shrub cover types and Calveg associated alliances. The tree and shrub species listed in the alliance descriptions are used to identify which vegetation types meet the productivity requirements.

Productive Pending Reserved Forest Land:

Land that is being considered for permanent reserved status in the most recent National Forest Land and Management Resource Plan. Although this land has not been removed from timber utilization by statute, ordinance, or administrative order, it is not being actively managed for timber production. Area estimates are developed from 1:24,000 scale GIS layers, Recommended Wilderness and Recommended Wild and Scenic Rivers.

Productive Reserved Forest Land:

Productive forest land that has been removed from timber utilization by statue, ordinance, or administrative order. For reporting purposes, designated Wilderness and Wild portions of Wild and Scenic Rivers are defined as reserved. Area estimates are developed from the most currently available administrative forest 1:24,000 scale GIS layer from the National Forest Automated Lands Program.

Reduced Harvest:

Productive available forest land that has been determined to be suitable, and has been scheduled for timber harvest production, but at a reduced harvest rates and longer rotations prescriptions to accommodate other resource objectives in the National Forest Land and Management Resource Plan. These lands are referenced as; Regulation Class II for long rotations both even and uneven aged management, and Regulation Class III for marginal timber yield prescriptions.

Site Class:

Site productivity, a classification of forestland in terms of inherent capability to grow crops of industrial wood. The class identifies the potential growth in cubic feet/acre/year and is based on the culmination of mean annual increment of fully-stocked natural stands. 1: 225+; 2:165-224; 3:120-164; 4:85-119; 5:50-84; 6:20-49. Area estimates are developed from a Strata GIS layer, the average Dunning Site Class of FIA (Forest Inventory and Analysis) sample plots within a unique mapped stratum, the associated regional forest type for the stratum, and the estimated productivity from published yield tables by regional forest type.

Stand Size:

Stand Size Classes are classification of forest land based on the predominant size of trees present; that is, sawtimber, poletimber, or sapling and seedling. Area estimates are developed from a Strata GIS layer derived from the Existing Vegetation layer which contains a mapped attribute of overstory tree size; the average visible crown diameter as seen from above, and its relationship to average tree diameter.

Stratum:

A 6-character code consisting of the forest number, planning unit, regional forest type, tree size class and tree density. For non-forest strata, the Calveg vegetation code is used instead of tree size and tree density. Area estimates are developed from a Strata GIS layer. The Strata layer is derived from a complete coverage of the latest Existing Vegetation layer for an Administrative National Forest, containing standardized mapped attributes. The mapping attributes are grouped into unique inventory stratum using pre-defined logic routines in order to develop population estimates for tree volume, growth and mortality of all mapped strata. Per acre average values of the associated FIA (Forest Inventory and Analysis) sample plots within each mapped each stratum, a used in the estimation process.

Suitable Forest Land:

Productive available forest land were stocking can be assured within 5 years, if harvested no irreversible damage is likely to occur, adequate information is available for the management of forested area, and scheduled harvest prescriptions for sustained yields of timber at some level has been assigned in the National Forest Land and Resource Management Plan. Allowable Sale Quantity is calculated from these lands.

Tentatively Suitable Forest Land:

Productive available forest land were stocking can be assured within 5 years, if harvested no irreversible damage is likely to occur, and adequate information is available for the management of forested area.

Unsuitable Forest Land:

Productive available forest land were stocking can not be assured within 5 years, or if harvested irreversible damage is likely to occur, or adequate information is not available for the management of forested area.

Western Forest Type:

The Society of American Foresters (SAF) Western Forest Cover Type classification. See the Crosswalk Table for a description of the types and the crosswalk from the more detailed Calveg vegetation classification system. This crosswalk logic is used to aggregate appropriate Calveg types into SAF cover types for determining area from the Existing Vegetation GIS layer.

USDA Forest Service - Pacific Southwest Region
Last Modified: Friday, 13 April 2012 at 12:05:55 EDT