Was the Grass Always Greener? Mapping the Historical Extent of Grassland Ecosystems on the San Juan Islands

Abstract:

 Although western Washington conjures images of dense, lush forests, the San Juan Islands (located in the central Salish Sea) were once the home of open, sunny grasslands and prairies.  In an effort to preserve the unique biodiversity of these ecosystems, organizations such as the National Park Service are interested in enacting programs to restore and conserve native grasslands on the islands.  I aim to support these initiatives by mapping the historical extent of grasslands on the San Juan Islands over the past 150 years.  This spatial information will improve understanding of historical ecological trends and help develop a historical baseline for conservation initiatives, which in turn will be useful in the development of conservation and restoration practices.

  I am working to create a map series showing the extent of grasslands at multiple points in time over the past 150 years.  This process is being completed over the course of two years.  The first phase of the project, Data Acquisition and Digitization, includes downloading historical and contemporary land cover imagery in the form of hand drawn maps (T-Sheets), field notes, and remotely sensed satellite imagery.  This imagery has been digitized and classified using a combination of manual methods and remote sensing software such as ENVI.  This process also includes site visits to validate aerial imagery classification and refine the accuracy of the land cover classification process.   I have begun toconduct preliminary data analysis, will includes quantifying changes in total grassland area and the rate of change over the established time frame.  

Keywords: Historical, biogeography, grasslands, Salish Sea, ecology, GIS

Authors: