Ryan Summers & Dr. Brett Hartman Environmental Science & Resource Management, California State University Channel Islands Introduction Human use of Santa Rosa Island dates back 13,000 years, starting with the Island Chumash before ranching was introduced in Non-native ungulate populations (sheep, cattle, feral pigs, deer, and elk) reached their peak in the mid 1900’s at 120,000 head. Intensive grazing led to replacement of native woodland, chaparral, and scrub vegetation with European annual grassland, increased vegetation patchiness, and induced erosion on bare areas on the ridgelines. Following creation of Channel Islands National Park in 1986, all non-native grazers were targeted for removal to restore native vegetation on the island. Feral pigs were removed by 1992, cattle were removed by 1998, and introduced deer and elk were removed by The resulting changes in native vegetation have been dramatic, and this provides a valuable test of efficacy of ungulate removal for restoration. We classified multiple Landsat image years to describe long term vegetation change and compare the magnitude of change across different landforms that influence accessibility and different aspects that influence water stress resulting from solar insolation and prevailing winds. Methodology LandSat LT1 TM5 & 7 image years (1991,1993,1998,2003, 2010, 2015) Pixel extent 30 m resolution. Dark Object subtraction from all years using ENVI. The Maximum Likelihood Classification tool was used to select training samples and create vegetation signatures from Landsat bands. Training samples were selected by known vegetation covers and modified based on field observation, aerial photos, elevation (Aster DEM 30 m), and Google Earth. Six veg classes (Island Chaparral, Mixed Woodland, Grasses, Scrub, Sand, Bare) were created from training samples & each image year was classified. Accuracy assessment was conducted with ground truth points (n=223) collected in 2015 and Results Map Accuracy assessment was taken w/ n=223 giving a 85.6%. Native vegetation (Scrub (Baccharis, Lupine, Chamise)) have increased since Non-native grassland has been decreasing. Convex landforms on average had less change, where as concave landforms had a dramatic increase in vegetation. Vegetation change was more significant on North facing slopes, whereas vegetation change was less significant on northwest facing slopes affected by prevailing winds. Acknowledgements Thank you to Dr.’s Sean Anderson, Cause Hanna, Linda O’Hirok, Kiki Patsch, Robyn Shea, and the pervious work done by Sean Clark & Colten Schmidt. Thank you to the capstone class of ESRM Program Figure 1: Vegetation Signatures based off light band frequencies, then extrapolated to island as a whole. Conclusion 25 Years of Vegetation Change on Santa Rosa Island Hypotheses: (A) Vegetation change will be greater in areas that were more accessible to non-native grazers (accessibility indicated by slope). (B) Hill orientation will affect vegetation change due to stressors. Importance This study will help further restoration management practices on SRI by identifying bare and other areas that are not recovering. Monitoring vegetation recovery following non-native grazer removal is a robust test of passive restoration theories. This study will also further our understanding of how different abiotic stressors affect vegetation recovery on SRI. Mixed Woodland Fencing & Hill Accessibility Coastal Scrub Bare Ground Vegetation change on SRI has been significant in the last two decades. A decrease in bare ground as well as grassland shows management that the island has been in a positive flux since the removal of non-native ungulates Figure 2: Different Vegetation classes from SRI Ground truth 1991 & 2015 SRI vegetation map based off Landsat imagery Scrub Bare Sand Chaparral Grasses Hectares 25 Years of Vegetation Change by Slope Veg Cover Scrub Mixed Woodland Grasses Island Chaparral SandBare Ground ACCY % 76%77%95%82%100%84% Figure 4: Native vegetation (scrub) has drastically increased while bare ground and grassland has been decreasing Woodland Slope Figure 3: Accuracy percent by veg class was taken by GPS field points Chap Grass Woodland Vegetation Change by Convex and Concave Landforms Hectare s Vegetation change on convex and concave landforms from shows woodland & chaparral increasing on concave landforms.