Final Environmental Impact Statement - Appendices 

Wasatch-Cache National Forest B8 - 1 

APPENDIX B – 8 

Vegetation Cover Type Map 

Introduction 

GIS personnel from the Intermountain Region of the USDA Forest Service, Regional Office 

(RO) developed the original map of the plant communities of the Wasatch-Cache National Forest 

in 1995. The Forest was divided into 11 zones, based on geologic features, vegetation, and 

elevation ranges. These zones closely match the ecological subsections that were later developed 

for this portion of the Intermountain Region of the Forest Service. These included: 

1. Cache Front 

2. Ant Flats 

3. Monte Cristo/Curtis Creek/Sinks 

4. Causey Conglomerates 

5. North Wasatch Front 

6. South Wasatch Front 

7. Wasatch Hinterlands 

8. Chalk/Weber 

9. West Flank (Uinta Mountains) 

10. North Slope Outwash (Uinta Mountains) 

11. North Slope Glaciation (Uinta Mountains) 

Originally there were 75 spectral classes, derived from satellite data using the Terra Mar Image 

Analysis System. These types were then grouped into similar vegetation classes using satellite 

imagery and knowledge of existing vegegetation by RO personnel, by ocular comparisons. The 

RO ten step process for the vegetation classification process is described below (see RO 

PROCESS: DESCRIPTION OF WASATCH-CACHE VEGETATION ATTRIBUTES). The 

classification included both forest and non-forest vegetation types. The forested type size class 

information was determined by overlaying stand examination data over the forested vegetation 

types provided from the satellite classification. The size class was then added to these polygons 

with the use of GIS technology, to produce maps of the existing vegetation on the forest. 

A classification of the plant communities was done using satellite imagery and knowledge of 

Regional Office personnel of the existing conditions on the ground. Forest Inventory maps from 

1974 of available/capable timberlands were used to populate data associated with timber stands 

(size class and canopy closure). Very little other site data was used in this classification. District 

personnel involved with forest or rangeland vegetation as part of their job began evaluating and 

making modifications to this map. The forest ecologists then began an evaluation of these 

vegetation maps in 1999 and using, field observations, knowledge of the forest, and digital 

orthophotos, made some additional adjustments to the vegetation map. 
Final Environmental Impact Statement - Appendices 

Wasatch-Cache National Forest B8 - 2 

Along the Wasatch Mountains, it was found that the original vegetation cover type map often 

failed to distinguish Gambel oak communities from aspen communities. In the Stansbury 

Mountains it did a poor job of delineating mahogany stands, over estimated the occurrence of tall 

shrub communities, and under estimated the occurrence of spruce-fir and limber pine stands. In 

the Uinta Mountains, riparian communities (including willow, wet meadow, and bottomland 

hardwood communities) were under estimated, and all conifer-dominated communities were 

originally delineated as lodgepole or spruce-fir. No mixed conifer communities were classified. 

Forest-wide, no differences were noted in sagebrush dominance. The forest has significant acres 

of mountain big sagebrush, spiked big sagebrush, low sagebrush, with moderate amounts of 

Vasey big sagebrush (primarily occurring in the Bear River Range near the Idaho border), silver 

sagebrush (uncommon except in some portions of the Uinta Moutains adjacent to and in riparian 

areas and as a minor component in the North Sinks area in the Bear River Range). Sagebrush as 

well as grassland communities were originally mapped, but these were later combined into as 

single sagebrush cover type because there were no real similarities between the mapped 

distribution and actual occurrences of these types on the ground. Originally, tall forb 

communities were not classified. This type was later mapped using knowledge of where these 

communities are known to occur. 

Some problems still occur with the existing vegetation map of the forest. Additional work needs 

to be done on all the noted deficiencies with the existing vegetation map. 

RO Process - Description of Wasatch-Cache Vegetation Attributes 

This document describes the vegetation classification attribute process of Wasatch-Cache 

National Forest vegetation data done by the Intermountain Region Forest Service, Regional 

Office. 

Processing Steps from Terra Mar to ARC/Info: 

Step One: GEO-Reference Landsat image using ERDAS image processor 

 and create ARC/Info GRID (rastar model) format. 

Step Two: Reclassify original 75 class GRID into the new classes 

Identified by District Forester during work on Terra Mar 

Step Three: Use GRID processing capabilities to take data from 30 meter 

 resolution to 5 acres (a combination of regiongroup, select 

 and nibble commands from the GRID module). 

Step Four: Produce polygons from the GRID data. 

Step Five: Produce hard copy maps at 1:24,000 of Conifer stands with 

unique identifiers for reclassification to specific conifer type 

based on Wasatch-Cache timber RAM maps. 
Final Environmental Impact Statement - Appendices 

Wasatch-Cache National Forest B8 - 3 

Step Six: Data files with the unique identifier and the new type for the 

conifer files was then transfered to the TYPE attribute in the 

ARC/Info polygon file via an AML written in the Region 4 GIS Lab. 

Tracking procedures were written into the AML to allow checking 

of the data submitted for correctness. Errors were 

identified during the data transfer process and corrected by 

GIS personnel and District Forester. 

Step Seven: Ponderosa Pine stands and regeneration cuts were identified 

through a union with stand polygons obtained by the Regional 

GIS personnel from the W-C supervisors office GIS personnel. 

Step Eight: Quad size 1:24,000 hard copy maps were produced with all 

types for review by forest personnel 

Step Nine: Areas of confusion of Oak/maple types and Aspen types along the 

Wasatch front were identified and a simple rule base applied to 

correct oak/maple types to Aspen and Conifer/Shrub types to Aspen 

The following steps were used in ARC/Info to identify oak/maple 

and conifer/shrub types to be changed to Aspen type: 

1. General Aspect and Elevation rules were identified by District 

Forester. 

2. Aspect and elevation polygons were created in ARC/Info's 

GRID module and vectorized. 

3. Aspect and elevation polygons were unioned together and then 

unioned with the vegetation layer. 

4. Arc/Info queries were performed in INFO for the rulesand 

selected polygons were retyped to ASPEN. 

GENERAL RULES USED: 

In TYPES originally designated OAK/MAPLE

Northeastern Slopes above 8,000 feet changed to ASPEN 

All other slopes above 8,500 feet changed to ASPEN 

In TYPES originally designated CONIFER/ASPEN

Northereastern Slopes above 7,500 changed to ASPEN. 

All other slopes above 8,500 changed to ASPEN. 

Step Ten: Supervisors office GIS Personnel split coverages into quads.