Carex seedling emergence in restored and natural prairie wetlands

Carex species, common dominants of wet meadows and widespread in ecosystems in the northern hemisphere, seldom naturally recolonize drained wetlands following hydrologic restoration. We conducted a seedling emergence experiment with five Carex species in restored and natural prairie wetlands to determine if recolonization is limited by the suitability of conditions for seed germination and seedling emergence. Seeds were sown unstratified in the fall or spring, or stratified in the spring, and seedling emergence was monitored for two field seasons. Seedling emergence was 3-360 times higher in restored compared with natural wetlands, regardless of seed treatments. In restored wetlands, a seed dormancy breaking treatment, whether in the field (fall, unstratified seeding) or in the lab (spring, stratified seeding), was important for seedling emergence. In both restored and natural wetlands, the majority of seedlings emerged within year one compared with year two of the study, indicating the importance of initial steps to optimize seedling emergence. Restored wetlands were drier than natural wetlands but seedling emergence was generally not related to soil moisture conditions.Our findings indicate that a recolonization lag can be overcome through direct seeding of these Carex species with an emphasis on appropriate seed pretreatment and timing of sowing.