CHANGE IN SPATIAL CHARACTERISTICS OF FOREST OPENINGS IN THE KLAMATH MOUNTAINS OF NORTHWESTERN CALIFORNIA, USA

Change in the spatial characteristics of forest openings was investiga ted in three forested watersheds in northwestern Siskiyou County, Cali fornia totalling approximately 24,600 hectares. Watersheds with minima l human disturbance were chosen for study. However, fire suppression h as been pervasive throughout. Characteristics of forest openings (area , perimeter, distance between neighboring openings) were measured on a erial photographs taken 41 years apart. An index of regional form was determined for the landscape. Shape complexity for each opening was ca lculated using two indices based upon fractals. Significant difference s were found using the Kolmogorov-Smirnov two-sample test between the perimeters, areas, distance from sample point to nearest opening, and distance between neighboring openings. The perimeters and areas became smaller, and the distances from the sample point to the nearest openi ng and between neighboring openings became greater over the 41 years b etween aerial photo sets. The estimated area occupied by openings decr eased from 25.8% to 15.6% of the study area. No significant difference was found in the shape of the openings except as the shape indices we re influenced by changes in size of the openings.