Capstone project

Understanding the Relationship between Substrate Cover and Seedling Abundance of the Santa Rosa Torrey Pine (Pinus torreyana var insularis)

The Santa Rosa Island Torrey pine (Pinus torreyana var insularis) is the rarest endemic pine species on the North American continent (Hall and Brinkman 2013). These pines exists within four stands on Santa Rosa Island (North, Cogan, Main, and Box), which is located 42 km off the coast of southern California. Over the past 150 years, much of the native vegetation on Santa Rosa Island (SRI) was heavily degraded by non-native grazing ungulates. These grazers were eradicated in 2011, prompting a unique opportunity to document vegetation regrowth patterns in the SRI Torrey Pine stands. My research was conducted jointly with the 2018/19 SRI Torrey Pines Demography Survey. Following the first survey in 2014, this survey is completed every 4 years to monitor regrowth within the groves. In order to better understand the reproductive health of SRI Torrey Pines, I compared seedling abundance within the groves from 2014 to 2018. Because the first demography survey documented substrate and soil, My research serves to establish baseline datasets for seedling height and substrate categorized by ranks. I hypothesized that if a grove is composed mainly of leaf litter and woody canopy, then it will support the highest abundance of seedlings.

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