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Fred Johnson

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Climate Change Adaptation for Coastal National Wildlife Refuges
National Wildlife Refuges (NWRs) along the East Coast of the United States protect habitat for a host of wildlife species, while also offering storm surge protection, improving water quality, supporting nurseries for commercially important fish and shellfish, and providing recreation opportunities for coastal communities. Yet in the last century, coastal ecosystems in the eastern U.S. have been severely altered by human development activities as well as sea-level rise and more frequent extreme events related to climate change. These influences threaten the ability of NWRs to protect our nation’s natural resources and to sustain their many beneficial services. Through this project, researchers are collaborating with...
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Informing the Identification of High-Priority Lands for the Everglades Headwaters National Wildlife Refuge Considering Future Climate and Urbanization
Reserve design is a process that must address many ecological, social, and political factors to successfully identify parcels of land in need of protection to sustain wildlife populations and other natural resources. Making land acquisition choices for a large, terrestrial protected area is difficult because it occurs over a long timeframe and may involve consideration of future conditions such as climate and urbanization changes. Decision makers need to consider factors including: order of parcel purchasing given budget constraints, future uncertainty, potential future landscape-scale changes from urbanization, and climate. In central Florida, two new refuges and the expansion of a third refuge are in various stages...
The study area shows the boundary (black line) of Everglades Headwaters National Wildlife Refuge acquisition area. Existing protected areas are shown in green. The areas considered in refuge design is a more detailed map of study area showing boundary (black line) of Everglades Headwaters National Wildlife Refuge acquisition area, Conservation Focal Area or fee zone (blue), protected areas (green), and areas excluded from consideration for the reserve design (brown). Map reproduced from U.S. Fish and Wildlife Service (2012).
Coastal ecosystems in the Eastern U.S. have been severely altered by processes associated with human development, including drainage of wetlands, changes in hydrology, land clearing, agricultural and forestry activity, and the construction of structures that "harden" the coast. Sea-level rise and the changing frequency of extreme events associated with climate change are now further degrading the capacity of those ecological and social systems to remain resilient. As custodians of ecological goods and services valued by society, coastal National Wildlife Refuges (NWRs) have an especially important role to play in helping socio-ecological systems adapt to global-change processes. To help refuges address this challenge,...
Abstract (from Ecological Modelling): Self-organization is a process of establishing and reinforcing local structures through feedbacks between internal population dynamics and external factors. In reef-building systems, substrate is collectively engineered by individuals that also occupy it and compete for space. Reefs are constrained spatially by the physical environment, and by mortality, which reduces production but exposes substrate for recruits. Reef self-organization therefore depends on efficient balancing of production and occupancy of substrate. To examine this, we develop a three-dimensional individual-based model (IBM) of oyster reef mechanics. Shell substrate is grown by individuals as valves, accumulates...
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