Plant Community Dynamics in a Mangrove-to-Marsh Transition Zone


Description
This project focuses on the marsh-to-mangrove transition zone, or ecotone, in the Ten Thousand Island region of south Florida. Permanent vegetation transects were established in 2007 at Ten Thousand Islands National Wildlife Refuge, near Naples, Florida. Data on herbaceous plant species composition and cover collected at these transects over time will document vegetation shifts on the refuge. Ecological stressors that may influence vegetation in this area are increased winter temperature, altered precipitation patterns, and accelerated sea-level rise rates. The refuge is also within the impact area of a large hydrologic restoration project, the Picayune Strand Restoration Project, which has the goal of eventually restoring freshwater overland flow to areas south of the project site.
Objectives
  • Document the plant community dynamics in mangrove-to-marsh ecotone.
  • Use data obtained as a baseline to determine the long-term effects of the Picayune Strand Restoration Project on vegetation communities of Ten Thousand Islands National Wildlife Refuge.
Background
The subtropical region of the northern Gulf of Mexico contains a diverse array of marsh and forest habitats. Because of their position in the landscape, these habitats are extremely vulnerable to impacts from ecological stressors. Mangroves commonly occur in subtropical intertidal wetlands, where they compete with salt marsh plants in transitional areas. Recent studies have documented the expansion of mangrove forests into marsh habitats in the region. This expansion has been attributed to various factors, including major development projects that have drastically altered hydrology by decreasing freshwater overland sheet flow, increased salt-water intrusion from rising sea levels, and the absence of winter freezes that can cause mangrove mortality. In areas where infrastructure such as highways and housing developments prevents migration of marshes landward, the ecosystem may be displaced toward primarily forested habitat. Resource managers are therefore concerned about the long-term sustainability of wildlife habitats and marsh-dependent birds in areas where mangrove expansion is occurring.
Methods
Permanent vegetation transects were established in 2007 at Ten Thousand Islands National Wildlife Refuge (TTI NWR). Data on herbaceous plant species composition and cover is being collected at these transects. To document the rate of mangrove expansion at TTI NWR, the number and height of mangrove seedlings identified along each transect is also being recorded. A network of surface elevation tables and accretion plots is being used to monitor soil surface elevation changes and sedimentation rates.
Data Synthesis
  • Evaluate percent cover change for herbaceous and woody plant species.
  • Document mangrove encroachment into marsh habitat though stem density data.
  • Characterize sedimentation and soil surface elevation change over time.
References
  • Howard, R.J., Krauss, K.W., Cormier, N., Day, R.H., Biagas, J., and Allain, L., 2015, Plant-plant interactions in a subtropical mangrove-to-marsh transition zone: Journal of Vegetation Science, v. 26, p. 1198-1211.
  • Howard, R.J., Day, R.H., Krauss, K.W., From, A.S., Allain, L., Cormier, N., 2017, Hydrologic restoration in a dynamic subtropical mangrove-to-marsh ecotone: Restoration Ecology, v. 24, p. 471-482.
  • Krauss, K.W., From, A.S., Doyle, T.W., Doyle, T.J., and Barry, M.J., 2011, Sea-level rise and landscape change influence mangrove encroachment onto salt marsh in the Ten Thousand Islands region of Florida, USA: Journal of Coastal Conservation, v. 15, p. 629-638.
  • Ross, M.E., Meeder, J.F., Sah, J.P., Ruiz, P.L., and Telesnicki, G.J., 2000, The southeast saline Everglades revisited: 50 years of coastal vegetation change: Journal of Vegetation Science, v. 11, p. 101-112.

Project Information

Begin Date:
  • 01/01/2007
End Date:
  • 09/30/2020
Project Url:
  • n/a
Mission Areas:
  • Ecosystems
Capacities:
  • Ecological Stressors
USGS PIs (listed alphabetically):