POTENTIAL EFFECTS OF CLIMATE CHANGE ON SPRING FENS AND THEIR ENDANGERED FLORAL SPECIES

Spring fens form wherever heterogeneities in the subsurface focus the discharge of calcareous groundwater. These wetlands are noted for diverse floral assemblages including rare and endangered species. The water tables under spring-fen peat mounds defines discharge mounds, rather than the normative recharge mound typical of raised peat bogs. Some spring fens (e.g. Cowles Bog , Indiana), form where clear breaches in low permeability sediment allow confined groundwater to discharge upwards. Others (e.g. Lost River spring fen, Minnesota), form at the distal ends of buried sand and gravel deposits located within less permeable units. The continual groundwater discharge from intermediate scale flow systems allows spring fens to flourish. If the hydraulic head in the recharge areas providing the ground water that sustains spring fens decreases with climate change, invasion of non-calcareous tolerant species will occur. We suggest that periodic monitoring of species assemblages be done at spring fens, unique ecological assemblages that might serve as sentinels for future climate change.