In order to effectively respond to the growing public concern, and to begin to understand the relationships of 
wildlife populations to their habitats on a landscape level, TAC began the Wildlife Habitat Study (WHS). The core 
of WHS is a GIS data base aimed at examining the expected distribution and quantity of various types of wildlife 
habitats resulting from current or proposed land management direction on California’s public and private forested 
lands. This paper describes the issues and methodologies employed concerning design, automation, analysis, 
product production and maintenance of that GIS data base. 
CONCEPTUAL DESIGN 
The primary area of interest for this study are the lands considered to be the commercial forests of California, an 
area of approximately 38 million acres (15 million hectares), including the North Coast, Mendocino, Klamath, 
Siskiyou, Cascade, and Sierra Nevada regions of the state. In order to evaluate wildlife habitats relative to forest 
management practices, it was determined that three base data layers would be needed: 
1) Vegetation 
2) Land Ownership 
3) Management Prescriptions 
From these, Expected Management Intensity, a data layer derived from each of the above three, could be used to 
examine the quantity and distribution of various types of habitats available throughout the state’s forested lands. 
DATA SOURCES 
Vegetation 
This data layer consists of the major vegetation types for forested areas for the state of California. It was 
developed from the CALVEG Plant Communities Study completed in the early 1980’s using Landsat MSS satellite 
imagery. This data layer was acquired in digital format from the California Department of Forestry and Fire 
Protection, Forest and Rangeland Renewable Resources Assessment Program’s ARC/INFO data base. 
The minimum identified type in CALVEG is 400 acres (160 hectares). While not sufficiently detailed for site- 
specific analysis, it is a sound foundation for analysis at the landscape level. 
Ownership 
The core of the ownership data layer was provided by four private forest products firms in digital format. These 
were imported into ARC/INFO format, or converted into ARC/INFO format from COMARC COMPIS format and 
Intergraph IGDS format. The original data capture scale for this data was either 1:12,000 or 1:24,000, with 
excellent ground control. Therefore, all other data sources were matched to these existing sources. 
Data for other private land owners was captured from a variety of paper maps at various scales and extents, with 
little or no geographic reference appearing on the manuscripts. Techniques employed for deriving geographic 
control for these data sources are discussed later. 
There were two primary data sources for public lands within the study area: the US Forest Service (USFS) 
Secondary Base Series at 1:126,720 scale (Forest Visitor Maps), and the US Bureau of Land Management (BLM) 
Surface Management Maps derived from the US Geological Survey 1:100,000 series base. These data sources were 
sometimes in conflict in terms of public ownership, so the most recent of the USFS or BLM sources was assumed 
to be most correct. 
Management Prescription 
Each National Forest within the USFS has prepared (or is preparing) a Land Management Plan as per the National 
Forest Management Act. These plans delineate the forest into various categories of management such as 
wilderness, wild and scenic rivers, recreation, or general forest. Either a final plan or a preferred alternative 
from draft plans were available for all but two of 17 forests or special management units (ie. Lake Tahoe Basin 
Management Unit) within the study area. The plans for those two forests are being re-compiled due to significant 
portions of those forests being damaged by wildfire in 1987.