Northern Rockies Ecological Conservation II: Determining the Distribution of Whitebark Pine in the Intermountain West Through Spectral Signature Classification to Assess Forest Health Within the Region

Whitebark pine (Pinus albicaulis; WBP) plays a critical ecological role in the Northern Rockies and was listed as a Federally Threatened species in 2023. WBP decline due to disease and insect infestations has been further exacerbated by climate change, requiring improved monitoring tools for natural resource managers. Previous models of WBP distribution lacked confidence, limiting their use in conservation planning. This project partnered with and received invaluable in-situ tree location data from the National Park Service, the United States Forest Service, the Bureau of Land Management, the U.S. Fish and Wildlife Service, the Whitebark Pine Ecosystem Foundation, and the Yellowstone Club in order to assess the feasibility of using earth observation data to classify and map WBP with high accuracy. Our team processed Landsat 8 Operational Land Imager, Landsat 9 Operational Land Imager-2, Sentinel-2 Multispectral Instrument, and digital elevation data to extract spectral signatures and classify tree species using a random forest model trained on our in-situ tree location data. The Sentinel-2 model was used to to classify WBP areas compared to limber pine (Pinus flexilis), other non-target tree species, and non-forested land. The WPB classification showed a low error of omission (3.93%) and commission of (4.69%), plus a high Kappa Index of Agreement of 0.93 for the WBP class compared with reference data. The final maps provide a tool to assess WBP distribution and identify areas for future data collection across the Intermountain West. Our team also produced an Esri Field Maps template for our partners for aiding their field surveys and WBP health monitoring efforts. Limitations included difficulty with classifying understory vegetation, leading to over-prediction of WBP in some areas. This feasibility study demonstrated that NASA Earth observations can support long-term WBP monitoring and distribution assessment across the Intermountain West, but more reference data is needed to further understand the results.