RARE PLANT CONSERVATION: A GIS-BASED APPROACH TO ASSESSING SUITABLE HABITAT WITHIN THE CALIFORNIA STATE PARKS, SANTA CRUZ DISTRICT

Abstract

Conservation practitioners face complex decisions when considering species conservation planning, particularly with rare species and landscape-level habitat management. The California State Parks, Santa Cruz District manages 72,290 acres within 44 parks in Santa Cruz and San Mateo Counties. Rare plant species pose specific conservation challenges in these areas, and a broad and comprehensive baseline approach to their conservation has not been conducted. This study focused on five rare species: San Francisco collinsia (Collinsia multicolor), Mash microseris (Microseris paludosa), San Francisco popcorn flower (Plagiobothrys diffusus), Santa Cruz microseris (Stebbinsoseris decipiens), and Pacific grove clover (Trifolium polyodon). Using the habitat suitability modeling tool in ArcGIS Pro, I developed five unique habitat suitability models tailored to each species ecological niche. These models integrated criteria including digital elevation models, detailed vegetation data, soil descriptions, and known population distributions. Within each criteria, categories were ranked using a suitability score from 1 (low) to 10 (high). Suitability scores from each criteria were then added, resulting in a final suitability score. These scores were then exported to a raster and symbolized based on those high to low suitability scores. Preliminary findings provide general insights for California State Parks staff, particularly when assessing wide scale management techniques. These models offer predictions of unknown populations within Parks sites and identify suitable habitat for targeted restoration efforts. Each species model predicted suitable habitat within State Parks boundaries, including areas without current occurrence records. Known occurrence records were used to adjust each model to reflect optimal habitat for current populations. This research underscores the importance of integrating advanced spatial analysis techniques with field data to support conservation and biodiversity management practices. Finally, these findings can inform broader conservation goals and guide future management practices within the Santa Cruz District of California State Parks system and beyond.