While the hiking paths were created as a space for recreational activities, the trails also serve as an important conservation corridor for plant and animal species [22]. The PCT connects seven national parks, the AT transverses six national parks, and the CDT intersects three national parks, including Rocky Mountain, Grand Teton, and Yellowstone. As the trails are located along mountain ridges, the corridors act as a climate refuge for numerous species due to the diversity of the habitat in mountainous terrain [10]. The extensive size of this complex trail system limits continuous ground-based vegetation monitoring and benefits from broad, comparative landscape-scale remote sensing analysis. Landsat and MODIS satellite imagery are crucial resources to study comprehensive vegetation health and assist in forest productivity assessment [39; 40]. Remote sensing is a powerful tool for understanding forest loss and has been applied along segments of the Triple Crown trail system through the use of satellite systems, aerial imagery, and LiDAR [19; 22; 26; 41]. Satellite imagery can also be used to estimate forest productivity, a critical metric for carbon cycling and forest health [42]. Wildfire regimes play a significant role in vegetation and have been examined in numerous locations along the PCT and CDT [43; 44; 45]. Wildfires are recognized as a natural landscape process in regions of the Triple Crown such as the mid-elevation xeric interior forests of the Rocky Mountains along the CDT and the Sierra Nevada Mountains of California along the PCT [8; 46; 47]. As these fires remove low-growing brush and rejuvenate the soil, tree species such as lodgepole pine (_Pinus contorta_) are fire-adapted for rapid recovery [8]. However, the intensity and frequency of wildfires have changed due to human influences such as anthropogenic climate change, drought, and intentional acts of arson [48]. In addition, in some locations, forest management practices suppressed fires, preventing low-intensity burns and causing an accumulation of underbrush [49; 50]. Wildfires have caused numerous closures of the trail system due to the dangerous conditions. These wildfire events pose a significant threat to the U.S. National Scenic Trail system as vegetation recovery after intense burns is often slow and hindered by prolonged drought conditions [8; 51]. Optical imagery such as Landsat Thematic Mapper/Operational Land Imager and Moderate Resolution Imaging Spectroradiometer (MODIS) are available to monitor the long-term change associated with wildfire events over several decades and compute spectral indices such as the normalized burn ratio (NBR) and normalized differenced vegetation index (NDVI) [52; 53]. The long-term impact following vegetation disturbance can also be monitored through analysis of various spectral indices and temporal segmentation to identify recovery rates [54]. Phenological patterns are shifting throughout the world as the onset of spring, peak summer vegetation growth, and fall senescence dates are altered by global climate change [55]. The altered annual temperature cycle may modify species ranges and pose a particular risk for endemic species dependent on environmental conditions in a specific location. Changes to the timing of vegetation processes also pose a threat due to the phenological mismatch between flowering plants and pollinators [56]. To collect ground-based phenology data, large citizen science efforts are being implemented at specific sites, such as the Walking with Wildflowers effort in Yosemite National Park on the PCT [57]. Citizen science phenology data are also collected in the Great Smoky Mountain National Park along the AT [58] and at Lily Lake in Rocky Mountain National Park on the CDT [59]. These ground-based observations are consolidated in databases such as iNaturalist. In addition, phenology data are collected through a network of PhenoCams, in situ digital cameras that collect imagery at a high temporal frequency [60].