Effects of headwater wetland restoration on the demography and ecology of the federally threatened White Fringeless Orchid (Platanthera integrilabia) in the Cumberland Plateau of Kentucky, USA

Wetlands are critical biodiversity hotspots that support numerous rare species, including orchids. Over half of North America's terrestrial orchids depend on wetlands, and more than a quarter are threatened with extinction (G1-G3), with global rarity concentrated in the southeastern U.S. Despite this, effective restoration strategies for wetland orchids remain poorly understood. The white fringeless orchid (Platanthera integrilabia), a federally threatened species, is restricted to Appalachian wetlands and has suffered widespread declines due to habitat destruction and hydrologic alterations. In Kentucky, populations remain predominately vegetative with few flowers, with most populations persisting in shaded, closed-canopy conditions. This 11-year study evaluated the effects of canopy and shrub reduction and debris dam installation on P. integrilabia and its associated plant communities in a Kentucky nature preserve. Long-term monitoring revealed increased inundation rates, soil saturation, orchid viability, and enhanced floristic diversity. Flowering increased by over 1000% two to four years post-manipulation, along with an increase in fruit production, indicating increased reproductive potential. While white-tailed deer (Odocoileus virginianus) browsing increased post-management, the percentage of aborted flowers declined. Despite browsing pressure (~ 50% of orchids browsed), the substantial increase in flowering plants still resulted in higher fruit and seed production at restored sites. Our results highlight the importance of active management, including reduction of woody encroachment and hydrological restoration through debris dam construction, for conserving P. integrilabia and improving overall wetland biodiversity. This research expands our knowledge of rare wetland orchids in the region and contributes to broader efforts to restore imperiled orchids and their associated habitats.