Landscape-scale vegetation change following fire in point Reyes, California, USA

Abstract

Fire is an important factor in determining plant community composition and distribution. This study quantifies landscape-scale vegetation change following a large fire at Point Reyes National Seashore, California, USA. Vegetation in the Point Reyes region is characterized by a complex mosaic of grassland, shrub, and forest plant communities, and by high levels of plant diversity. Although large fires are relatively rare on the coast of California north of San Francisco Bay, they are important in determining the distributions of plant communities at the landscape scale. We mapped vegetation communities throughout the study area using aerial imagery and analyzed how vegetation shifted following fire. We found substantial areas had transitioned from coastal scrub to ceanothus scrub (Ceanothus thyrsiflorus Eschsch.) or Bishop pine (Pinus muricata D. Don) forest following fire. Transitions from shrub to tree vegetation following fire have rarely been documented in this region. Logistic regression analysis was used to examine the factors influencing the post-fire distribution of Bishop pine and ceanothus scrub. Proximity to pre-fire Bishop pine stands and pre-fire vegetation type were the most important predictors of post-fire Bishop pine regeneration. Pre-fire vegetation type, burn severity, and topography were the most important predictors of post-fire ceanothus scrub distribution. This study demonstrates the capacity of these ecosystems for substantial change over short time periods in response to fire, and identifies some of the factors driving this change.