Effects of Invasive Species on Post-Fire Ceanothus spinosus Seedling Establishment

This study compared seedling establishment of the native chaparral species Ceanothus spinosus in two different burn sites at Pepperdine University following the Woolsey Fire of November 2018. One site was a low-density fuel site, and experienced a “cool burn,” and the other site was a high-density fuel site and experienced a “hot burn.” In the low-density fuel site, fire type-conversion had occurred, resulting in a dominance of exotic species. The high-density fuel site was populated by many native fire-following species and chaparral shrubs, exemplifying pristine post-fire conditions. Initially, I hypothesized that seedling success in the cool burn site would be hindered by competition from exotic species, resulting in lower physiological performance and resource availability compared to those at the hot burn site. However, indicators of plant health such as photosynthetic rates, root length, shoot length, and predawn water potential showed no significant differences. Due to the unseasonably late rainfall that coincided with the summer dormancy state of the exotics, resulting in high soil moisture, I concluded that the C. spinosus seedlings in the cool burn site did not face significant competition from exotics