Lemly, Joanna M., authorLaughlin, Lauren, authorSmith, Gabrielle A., authorNational Park Service (Fort Collins, Colo.), publisher2025-12-042025-12-042025-06Lemly, J. M., L. Laughlin, and G. A. Smith. 2025. Inventory of fens and rare fen-indicator plant occurrences at Grand Teton National Park and John D. Rockefeller, Jr. Memorial Parkway. Science Report NPS/SR 2025/325. National Park Service, Fort Collins, Colorado. https://doi.org/10.36967/2313526https://hdl.handle.net/10217/242366NPS 136/197330, 642/197330, June 2025.Fens are groundwater-fed, peat-accumulating wetlands that form where the accumulation of organic material exceeds decomposition. While fens are common at northern latitudes, fens in the Rocky Mountains are relatively rare, small features that support numerous rare plant species. Little is known about fens in Grand Teton National Park (GRTE) and John D. Rockefeller, Jr. Memorial Parkway (JODR). While GRTE and JODR are managed for natural resource preservation and recreation, the parks have a history of other land uses and have seen increasing visitors in recent years. To better manage fen resources in GRTE and JODR, the National Park Service funded the Colorado Natural Heritage Program to create a map of potential fens within GRTE and JODR, visit potential fen polygons to verify their status as fens, and survey for rare fen-indicator plant species. The initial map of fens created in the winter of 2022-23 contained 906 potential fens covering 5,208 acres. Field sampling in the summer of 2023 verified 41 fens and 28 peat-accumulating wetlands. The revised map contained 1,016 acres of confirmed or highly likely fens, which were concentrated at elevations below 2,100 m in specific areas of the parks, including Lower Jackson Lake watershed and most of JODR. One hundred and twenty-seven populations of 23 rare fen-indicator plant species were observed either within or near confirmed fens. Rapid vegetation surveys were conducted in 38 confirmed fens. Most were basin fens, several of which contained floating mats, and seven sites were sloping fens. Vegetation composition was overwhelmingly native and indicative of excellent condition. Most sites were dominated by graminoids, specifically sedge (Carex) species, and some sites also contained willows (Salix spp.) and other low shrubs. Quantitative vegetation sampling was carried out in five sites for more precise estimates of species cover. Water chemistry measurements of pH and specific conductance were collected in the field at most sites, and water chemistry samples were collected at five sites for more detailed lab analysis. Water pH ranged from 4.86-8.65 and specific conductance ranged from 1 1105 μS/cm. Most fens were characterized as rich fens, with some considered poor fens and no sites meeting the water chemistry and vegetation classification of extreme rich fen. GRTE and JODR fens are exceptional resources that support numerous rare species. Management plans for the park units should protect and avoid impacting these special habitats and their species so they remain intact into the future.born digitalreportsengCopyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.Fens -- Wyoming -- Grand Teton National ParkFens -- --John D. Rockefeller, Jr. Memorial ParkwayWetland mappingText