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Strawn Master’s of Environmental Management Final Presentation

posted May 23, 2012, 9:34 AM by   [ updated Aug 18, 2012, 8:04 AM by Robert Scheller ]

MEM student Kathryn Strawn will be presenting her final project titled “Applying Habitat Suitability Modeling to Invasive Species Management: the Case of Yellowtuft in Southern Oregon”. The presentation will take place on Wednesday May 30th from 2-4 p.m. at Portland State University’s Distance Learning Center, Room 304. All are welcome to attend, or feel free to stream the presentation live by heading to the DLC website, and clicking ‘304 Live Stream’. The project abstract is below.


Invasive species are a critical concern for land management agencies, private industries, and private citizens who recognize the risk these species pose to wildlife habitat, ecosystem processes, and agricultural productivity. Nowhere is this risk more apparent than with the spread of Alyssum murale and Alyssum corsicum in Josephine County, Oregon. Federal, state, and local land management agencies, along with conservation organizations and concerned private citizens, are attempting to eradicate these two species. These groups are grappling with two unanswered questions: 1) What is the total extent of area invaded? and 2) which habitat types are most suitable for the Alyssum spp? One set of tools available to managers to address both questions are spatially explicit species distribution models (SDMs). I used the advanced statistical model, MaxEnt, to project the likely distribution and suitable habitat for the Alyssum plants across 1.8 million hectares of Southern Oregon and Northern California. To address dispersal patterns of Alyssum species, I analyzed the proximity of known infestations to roads and streams, and presence on serpentine soils. In total, 14 environmental characteristics representing topography, climate, and soil characteristics were used to project distribution across the study area. Current infestation were not found to exclusive reside along spread pathways - roads and streams – or require serpentine soils to establish. The resulting habitat suitability model identified high likelihood predominantly within the Illinois River Valley where the species was initially introduced. The single most important variable was soil depth, indicating higher suitable when the depth is between 140-200 cm. Climatic factors, and seasonal and annual temperature and precipitation variables, were of high importance to the distribution of both plants. The habitat suitability predictions were compared to the 2011 field surveys and the proposed 2012 aerial survey flight plan scheduled to illustrate how the model information can inform future surveillance activities. Species distribution models can be used in collaboration with local knowledge and experience to better identify areas of high concern, and redirect resources more efficiently.