Gap Analysis: The vegetation of Northwestern California

TitleGap Analysis: The vegetation of Northwestern California
Publication TypeThesis
Year of Publication1997
AuthorsThorne, JH
Thesis TypephdMasters thesis

This thesis is a report on the mapping and results of the Gap Analysis Project (GAP) for the northwest floristic province of California. GAP is part of a national program to develop conservation profiles for species and natural vegetation communities at a regional level. Conservation profiles were determined by ranking 82 natural vegetation communities and 100 woody species according to their spatial extent on 54,249 km² of land broken into 4 management classes. Forty four communities appear to be at risk because of their low presence on protected lands. Thirty six communities are located mostly on private lands. Twenty three communities fell below the spatial resolution of the study. The 15 oak woodlands and forests were found to be the largest taxonomic classification at risk with a total of 561 km² out of 16368 km², or 3.4% currently located on lands managed for conservation. As was found for the southwest region to the state, the majority of communities at low elevation have poor representation on lands allocated to conservation. The procedures used in creating the GIS database used for the analysis are described. Conservation profiles derived using the GAP technique were compared with the California Dept. of Fish and Game's nonspatial rankings of natural vegetation communities. The comparisons and the structure of database are discussed to present to regional planners and resource managers a better understanding of how to evaluate GAP findings in light of their own process.