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 sediment integrity as the land was 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 that are common to the island. This experiment sought to quantify the volume of sediment that has been lost on a south facing slope in the middle of the island that contains a sparse grove of Q. tomentella. The slope was divided into three terraces based on the slope’s profile. 170 slope locations were selected to measure staple exposure from a 2007 restoration attempt which acted as an approximation for the amount of erosion that has occurred since the restoration. A penetrometer measured hardness of the surrounding substrate. In total, over 58 cubic meters of sediment has been lost from this slope since 2007, with steeper slopes with softer substrates experiencing higher erosional rates. This data informs future restoration attempts in their decision for placement of sediment retention devices. Future studies could focus on areas of the slope that would benefit most from fog collecting devices, as lack of water on the slope is a factor that currently prevents the colonization of many plant species.


Biodiversity | Evolution | Other Ecology and Evolutionary Biology | Population Biology


Kathryn McEachern

Lab site

California State University, Channel Islands (CSUCI)

Funding Acknowledgement




URL: https://digitalcommons.calpoly.edu/star/318


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