South San Francisco Bay Eco Forecasting

Invasive perennial pepperweed (Lepidium latifolium) has spread rapidly throughout the western United States in the past fifteen years.
Pepperweed outcompetes many native species for water and nutrients, disturbing sensitive ecosystems. The purpose of this study is
to map the contemporary distribution of pepperweed throughout the wetland ecosystem of the restored South San Francisco Bay Salt
Ponds and create a habitat suitability model to predict future spread. Pepperweed reflectance data were collected in-situ with the GER
1500 spectroradiometer along with presence and absence pepperweed GPS data points. A Spectral Angle Mapper (SAM)
classification algorithm (Method A) was used to distinguish pepperweed spectra and map its distribution on an EO-1 Hyperion image
of the study area. Similarly, a supervised classification was run on an ASTER image of the study area. A GIS multivariate habitat
suitability model was created to predict areas most susceptible to pepperweed colonization. Variables incorporated into the model
were tidal extent, propensity for disturbance, pond salinity, proximity to levees and channels, and terrain curvature. A Generalized
Additive Model (GAM) was also used to generate a suitability map (Method B) and investigate the statistical probability that each
variable contributed to predict pepperweed spread. Results from the GAM revealed distance to channels, distance to disturbance
factors, extreme pond salinity and curvature as statistically significant in determining the locations of suitable pepperweed habitats