Kang Xiong Thesis Defense
A Remote Sensing Analysis of Pitch Canker Severity in Bishop Pines at Point Reyes National Seashore
Pitch canker is a fungal disease that threatens the health of Bishop pine (Pinus muricata) trees at Point Reyes National Seashore (PRNS). Using 2 m spatial resolution WorldView-2 imagery and 0.05 m spatial resolution imagery acquired from an unmanned aircraft system (UAS), we classified three images (from 2013, 2017 and 2018) with object-based image analysis (OBIA), and employed GIS to quantify changes in pitch canker severity from 2013 to 2017. Overall accuracies of 63.8% and 81% were achieved for the 2017 and 2018 classified images, respectively. The red-edge (RE) band was found to be a poor predictor of pitch canker severity; however, the addition of multiple variables increased the coefficient of determination value (R2) for the 2013 and 2018 multiple regression models (i.e., 0.2755 and 0.3562, respectively). An estimated 32 ha of overlapping Bishop pine forest in the 2013 and 2017 images increased in pitch canker severity from healthy-low to medium-high. An additional 55 ha of Bishop pine forest was identified in the 2017 classified image as having shown increase in pitch canker severity. This study presents methods for the detection and classification of pitch canker severity.