October 1, 2017.
Ranching began on Santa Rosa Island in the 1840’s, consequently introducing nonnative megafauna that put novel selective grazing pressures on endemic plant species. Their movement patterns also altered substrate integrity as the land became denuded of any stabilizing vegetation. Dense groves of island oak (Q. tomentella) are known to aid in sediment deposition and retention. The groves also function to collect water during periods of intense fog common to the island. This experiment sought to determine whether sediment is being lost or deposited on a ridge in the middle of the island containing a grove of Q. tomentella. The slope was divided into three sections based on vegetation, severity of slope, and substrate type. Three transects were installed in each section. Each of the nine transects where 60 meters long and composed of nails that were a uniform 15 cm above the surface, installed in January 2016. The results show all three sites experienced soil deposition, but the three sites were not significantly different from one another. Three transect lines intersected with erosion control structures. In those locations, nails were additionally installed upslope and downslope of the structure to determine if there were differences between the two locations relative to the erosion control structure. The results show areas upslope of these structures experience more soil deposition than areas downslope. This data informs future restoration attempts in their decision for placement of erosion control structures. Future studies could focus on areas of the slope would benefit most from fog collecting devices, as lack of water on the slope is a factor currently preventing the colonization of many plant species.
California State University, Channel Islands (CSUCI)
The 2017 STEM Teacher and Researcher Program and this project have been made possible through support from Chevron (www.chevron.com), the National Marine Sanctuary Foundation (www.marinesanctuary.org), the California State University Office of the Chancellor, and California Polytechnic State University, in partnership with California Polytechnic State University, Channel Islands.