St. Cloud State University theRepository at St. Cloud State Culminating Projects in Geography and Planning Department of Geography and Planning 5-2018 Mapping the Potential Distribution of Oak Wilt (Ceratocystis fagacearum) in East Central and Southeast Minnesota Using Maxent Melissa Gearman St. Cloud State University, [email protected] Follow this and additional works at: https://repository.stcloudstate.edu/gp_etds Recommended Citation Gearman, Melissa, "Mapping the Potential Distribution of Oak Wilt (Ceratocystis fagacearum) in East Central and Southeast Minnesota Using Maxent" (2018). Culminating Projects in Geography and Planning. 6. https://repository.stcloudstate.edu/gp_etds/6 This Thesis is brought to you for free and open access by the Department of Geography and Planning at theRepository at St. Cloud State. It has been accepted for inclusion in Culminating Projects in Geography and Planning by an authorized administrator of theRepository at St. Cloud State. For more information, please contact [email protected]. Mapping the Potential Distribution of Oak Wilt (Ceratocystis fagacearum) in East Central and Southeast Minnesota Using Maxent by Melissa B. Gearman A Thesis Submitted to the Graduate Faculty of St. Cloud State University in Partial Fulfillment of the Requirements for the Degree of Master of Science in Geography and Planning May, 2018 Thesis Committee: Mikhail Blinnikov, chairperson Jorge Arriagada Jeffrey Torguson 2 Abstract Forest diseases and pathogens can cause significant damage to an ecosystem. Understanding where they are going to occur and what variables are important in their distribution can stave off the detrimental effects they have on established and at risk ecosystems. With the advancement of spatial analysis and remote sensing technology, these diseases can now be managed through modeling. Modeling allows researchers to determine the extent of the disease, which variables lead to the increase in infection centers, and predict the distribution of the disease. This study used Maxent, a presence-only species distribution model (SDM), to map the potential probability distribution of the invasive forest pathogen oak wilt (Ceratocystis fagacearum) in eastern and southeastern Minnesota. The model related oak wilt occurrence data with environmental variables including climate, topography, land cover, soil, and population density. Results showed areas with the highest probability of oak wilt occur within and surrounding the Minneapolis/St. Paul metropolitan area. The jackknife test of variable importance indicated land cover and soil type as the most important variables contributing to the prediction of the distribution. Multiple methods of analysis showed the model performed better than random at predicting the occurrence of oak wilt. This study shows Maxent has the potential to be an accurate tool in the early detection and management of forest diseases. 3 Table of Contents Page List of Tables ........................................................................................................................ 5 List of Figures ........................................................................................................................ 6 Chapter 1. Introduction ........................................................................................................................ 7 Forest Pathogens ........................................................................................................ 8 Species Distribution Models ...................................................................................... 10 Oak Wilt ..................................................................................................................... 13 2. Methodology ...................................................................................................................... 16 Oak Wilt Occurrences ................................................................................................ 16 Environmental Variable Selection and Modification ................................................ 17 Climate Variables........................................................................................... 18 Topography .................................................................................................... 18 Land Cover..................................................................................................... 21 Soil Types ...................................................................................................... 21 Population Density ......................................................................................... 22 Variable Modification .................................................................................... 23 Bias File Creation ...................................................................................................... 25 Maxent Setup ............................................................................................................. 26 Model Evaluation ....................................................................................................... 27 3. Results ............................................................................................................................... 29 Potential Distribution ................................................................................................. 29 4 Chapter Page Variable Importance................................................................................................... 31 Model Evaluation ....................................................................................................... 34 4. Discussion ......................................................................................................................... 36 Spread of Oak Wilt .................................................................................................... 36 Land Cover and Oak Wilt .......................................................................................... 37 Soil Type and Oak Wilt ............................................................................................. 39 Population Density and Oak Wilt .............................................................................. 40 Conclusion ................................................................................................................. 41 Limitations and Future Research ............................................................................... 42 Works Cited ........................................................................................................................... 44 Appendix: Response Curves .................................................................................................. 51 5 List of Tables Table Page 3.1. Percent contribution of each environmental variable ..................................................... 32 6 List of Figures Figure Page 1.1. Study area........................................................................................................................ 8 1.2. Oak wilt infected tree ...................................................................................................... 14 2.1. Oak wilt occurrence locations ......................................................................................... 17 2.2. Elevation raster of study area .......................................................................................... 19 2.3. GAP-derived land cover of study area ............................................................................ 20 2.4. Suborder soil classification of study area ....................................................................... 22 2.5. Population density of study area ..................................................................................... 23 2.6. Variable modification model .......................................................................................... 25 3.1. Maxent picture output ..................................................................................................... 29 3.2. Reclassified Maxent output............................................................................................. 30 3.3. Oak wilt presence and absence locations ........................................................................ 31 3.4. Jackknife test of variable importance ............................................................................. 33 3.5. Receiver operating characteristic curve .......................................................................... 34 4.1. Location of soil suborders Psamments and Hemists....................................................... 40 7 Chapter 1: Introduction The health of many of the world’s forests is at risk due to humans’ unique ability among animals to significantly alter their environment (Millar and Stephenson 2015; Lindenmayer, Laurance, and Franklin 2012; Cushman and Meentemeyer 2008). An increase in forests pests and pathogens is just one consequence of increased human interaction with the natural world (Weed, Ayres, and Hicke 2013). The importance of forests cannot be overstated; they are sources of raw materials and food, they prevent soil erosion, purify the air and water, and provide habitat for countless species. An increase in forest pests or pathogens would be devastating (Anagnostakis 1987; Needham et al. 2016). With the advancement of spatial analysis and remote sensing technology, management of these pests and pathogens