## 2 Methods
### Study Site  
The Triple Crown trail polyline vector data were acquired from the National Park Service, National Forest Service, Continental Divide Trail Coalition, and Pacific Crest Trail Association. ArcGIS Pro was utilized to buffer the polylines with a distance of 1 km on either side of the linear trail path to create a 2 km wide corridor (Figure 2). The 2 km corridor was selected based on prior research examining the ecological function of trail networks as linked conservation corridors [10]. In addition, the 2 km wide corridor allowed for analysis of broad landscape patterns across large protected areas using moderate spatial resolution imagery such as 500 m MODIS data products [72]. \begin{table}
\begin{tabular}{c c c c c c} \hline
**Data Source** & **Dates** & **Temporal Resolution** & **Spatial Resolution** & **Units** & **Data** ** **Accessed** \\ \hline PhenoCam v2.0 [65] & Variable & Daily & – & Green chromatic coordinate (GCC) & ORNL DAAC [[https://daac.ornl.gov/VEGETATION/guides/PhenoCam_v2.html](https://daac.ornl.gov/VEGETATION/guides/PhenoCam_v2.html)]([https://daac.ornl.gov/VEGETATION/guides/PhenoCam_v2.html](https://daac.ornl.gov/VEGETATION/guides/PhenoCam_v2.html)) (accessed on 24 January 2025) \\ \hline Hansen Global Forest Change v1.11 [66] & 2001–2023 & Annual & 30 m & Date (disturbance) & [[https://earthengine.google.com](https://earthengine.google.com)]([https://earthengine.google.com](https://earthengine.google.com)) (accessed on 11 January 2025) \\ \hline Monitoring Trends in Burn Severity (MTBS) [67] & 2001–2024 & Annual & 30 m & Thematic (low to high severity) & GEE [[https://earthengine.google.com](https://earthengine.google.com)]([https://earthengine.google.com](https://earthengine.google.com)) (accessed on 8 January 2025) \\ \hline MODIS MCD64A1 v6.1 Burned Area [68] & 2001–2023 & Daily & 500 m & Date (burn occurrence) & [[https://earthengine.google.com](https://earthengine.google.com)]([https://earthengine.google.com](https://earthengine.google.com)) (accessed on 8 January 2025) \\ \hline Climate Hazards Center InfraRed Precipitation with Station (CHIRPS) [69] & 2001–2023 & Pentad & 5566 m & mm/pentad & GEE [[https://earthengine.google.com](https://earthengine.google.com)]([https://earthengine.google.com](https://earthengine.google.com)) (accessed on 8 January 2025) \\ \hline LandTrendr Landsat 5/7/8 [62] & 1984–2024 & 16-day & 30 m & Digital number (DN) & [[https://earthengine.google.com](https://earthengine.google.com)]([https://earthengine.google.com](https://earthengine.google.com)) (accessed on 21 January 2025) \\ \hline National Agriculture Imagery Program (NAIP) & 22 June 2009 7 June 2010 & Variable & 1 m & Digital number (DN) & USGS Earth Explorer [[https://earthexplorer.usgs.gov](https://earthexplorer.usgs.gov)]([https://earthexplorer.usgs.gov](https://earthexplorer.usgs.gov)) (accessed on 22 January 2025) \\ \hline MODIS MOD9 GA v6.1 Surface Reflectance [70] & 2001–2024 & Daily & 500 m & Digital number (DN) & GEE [[https://earthengine.google.com](https://earthengine.google.com)]([https://earthengine.google.com](https://earthengine.google.com)) (accessed on 20 January 2025) \\ \hline MODIS MOD10A1 v6.1 Terra Snow Cover [71] & 2001–2023 & Daily & 500 m & \% snow cover & GEE [[https://earthengine.google.com](https://earthengine.google.com)]([https://earthengine.google.com](https://earthengine.google.com)) (accessed on 10 January 2025) \\ \hline \end{tabular}
\end{table} 
Table 1: _Cont._The 20,556 km\({}^{2}\) study area includes variable habitat with 24 different Level III ecoregions [73]. The ecoregions along the PCT transition from the arid Sonoran Desert in the south to more mountainous environments, including the Sierra Nevada, Klamath Moun  
Figure 2: Corridors of the (**a**) Pacific Crest, (**b**) Continental Divide, and (**c**) Appalachian National Scenic Trails with the locations of sites for LandTrendr recovery analysis and the distribution of PhenoCam sites for validation.