Florissant Fossil Beds National Monument wetland ecological integrity: 2009?2019 synthesis report

Abstract

Wetlands at Florissant Fossil Beds National Monument (FLFO) are important because they are biodiversity hotspots and support iconic wildlife. They also provide valuable ?ecosystem services? such as attenuating floods, storing water, recharging aquifers, stabilizing and sequestering sediment, storing carbon, enhancing water quality, and cycling nutrients. This report summarizes 11 years (2009?2019) of wetland monitoring in three sentinel wetland complexes in FLFO. Monitoring included annual samples of 10 wet meadow and fen wetland sites in these complexes. We partition the data into a baseline period encompassing the first three years of our work for which we estimate conditions using a variety of indicators, or vital signs. We then estimate trend across the whole period of record. Results are compared to assessment points that allow us to interpret results in a management relevant context. We collected data on vascular plant species composition, woody species stand structure and damage and mortality of woody stems, soil chemistry, groundwater chemistry, and depth to water at shallow groundwater wells in each complex. We also documented human disturbance in and around each wetland complex. Projections suggest that climate change will likely reduce the number and extent of wetlands in the park and cause declines in the condition of associated flora and fauna and critical ecological functions, such as carbon and water storage. Human use can cause disturbance to wetlands across multiple scales and has well documented relationships with wetland condition. Wetlands at FLFO were impacted by over a century of cattle ranching and other human uses that increased soil erosion, altered hydrology, and made the area more susceptible to invasion by exotic plant species. Disturbance indicators at both a landscape and smaller scale generally showed an intermediate level of disturbance in and around our sentinel sites. Across all sites and indicators, we generally saw lower groundwater levels in response to drought conditions in 2010?2013 and in 2017?2018. However, groundwater at the Hornbek complex responded differently, potentially benefiting from a restoration project that filled incised channels in late summer 2012. Vegetation indicators showed relatively stable and healthy conditions in the park, except for native species cover, which was in intermediate condition.