Long-term trends in swamp tree growth across drought and salinity gradients in the northern Gulf Coast
This study will examine the potential effects of climate-change-induced sea level rise, drought and water extraction by examining tree growth patterns across the Gulf Coast, specifically targeting long-term research plots (North American Baldcypress Swamp Network (NABCSN) vs. Suwannee River: Middleton et al. 2015, Light et al. 2002).
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The objectives of this project are to predict climate change responses of freshwater species by tracking responses of tree growth to salinity and flow shifts. Managers can use the information to design water management strategies to maximize swamp forest health. The study will dovetail with an on-going groundwater salinity intrusion and production study with the University of Florida.
Freshwater species along rivers of the Gulf Coast lie along freshwater tidal to fresh riverine gradient, but tree production and growth are lower where salinity is higher (Middleton et al. 2015).
These studies will be conducted in long-term research sites along the Suwannee River NWR (Helen Light) and the Gulf Coast portion of the North American Bald Cypress Swamp Network (NABSCN). Suwannee plots were set up in 1996-9 (Light et al. 2002). NABSCN Gulf Coast plots were set up after 2006, and have replication at the landscape level, with five replicate swamps per geographical location. All sites are near USGS gages, which continuously record water discharge and salinity. The Light plots lie along flow and salinity gradients, and many were relocated in 2014 (Middleton and Anemaet, personal observation). Forest tree mensuration techniques (e.g., dbh and height) were deployed in the Light plots along the Suwannee River; these trees will be re-measured to determine shifts in growth and species composition in the last 15 years. Trees in NABSCN are outfitted with tree growth bands, and have measured annual tree growth in the last 5-10 years (Neches River TX, Mississippi River LA, and Sopchoppy/Aucilla River FL). NABSCN sites also have a suite of data on ecosystem function (production and regeneration) and environment (water level, sediment and salinity via recorders and Sediment Elevation Tables).
- IPCC (Intergovernmental Panel on Climate Change). 2014. Climate Change 2014: Impacts, adaptation, and vulnerability. Part A: global and sectoral aspects. Field, C.B. et al. (Eds.), Contribution of Working Group II, Fifth Assessment Report. Cambridge University Press, Cambridge, UK, pp. 1-33.
- Light, H.M., Darst, M.R., Lewis, L.J. 2002. Hydrology, vegetation and soils of riverine and tidal floodplain forests of the Lower Suwannee River, Florida, and potential impacts of flow reductions. U.S. Geological Survey Professional Paper 1656A, Denver, Colorado.
- Middleton, B.A., Johnson, D., Roberts, B. 2015. Hydrologic remediation for the Deepwater Horizon Incident drove ancillary primary production increase in coastal swamps: Ecohydrology v. 8, p. 838-850.