GIS in the Green Mountain National Forest Personnel: Charles Ferree, David Capen Cooperator: Bruce Reid, Green Mountain National Forest

In April of 1993 the School of Natural Resources entered into an agreement with the Forest Service to develop a digital spatial database for the Green Mountain National Forest. Elements of the database that have been completed to date include coverages of ecological land types and management areas, and the digitization of historic resource sites within the Forest is under way. The most important (and most time-consuming) components of the database are the stand and compartment coverages for each of the three ranger districts. Work on the Middlebury and Rochester districts has been completed, and is in progress for the Manchester district in the southwestern part of the state. Click on image for enlarged view (10k) ASQ Modeling The stand coverages and the extensive attribute data that the Forest Service maintains for them have found their broadest application in Allowable Sales Quantity (ASQ) modeling. This timber harvest model is currently being applied to the completed stand database for the north half of the National Forest; when completed it will give the Forest Service a powerful tool that will help to guide its forest management policies and procedures in the coming years.

	The first stage of the model applies forest-wide regulatory and ecological criteria to remove lands within the proclamation boundary from consideration for harvest. These constraints include the Forest Service's own Management Area designations (no harvesting may take place, for example, within wilderness areas), land suitability class, terrain steepness, and proximity to streams, to sensitive wildlife habitat, or to archaeological sites.	Click on image for enlarged view (10k)
	A more refined, project-level analysis based on silvicultural constraints starts by dividing the available land base into even- and uneven-aged management groups. It then weighs stand-specific data to identify further removals from the harvest base and lands that will be available for harvest in the near future. Stands under an even-aged management regime, for example, are eliminated if they are younger than 50 years; if they are within 500 feet of a stand regenerated less than 15 years ago; if they have been thinned within the last 15 years; or if they are under a current contract to be cut.	Click on image for enlarged view (64k) or on inset for zoom-in (72k)

Elements that will be incorporated into the model as it develops include threatened and endangered species locations, visual quality issues, and problems of stand access. Results to date indicate that forest-wide harvest constraints remove 53% of the land in the Rochester and Middlebury Ranger Districts from the available land base, and that another 20% of the total land base is withdrawn in the stand-level analysis.

Updated: 10 July 2000