For several years the Nature Conservancy has been developing a modeling tool to examine the consequences of changing land-use and land-cover at Eglin Air Force base. The model allows people to conduct 'thought experiments' that test how well different pieces of ecological knowledge fit together in the Eglin landscape. It allows people to vary landscape properties such as the spatial distribution of forest types, along with the rules that govern the ecological functioning of this simulated landscape.
Our main concern has been understanding how historical land-use practices have interacted with fire to shape the current Eglin landscape, and what type of future landscapes are possible with different types of management intervention. The modeling framework aids this goal by providing an organized way of synthesizing ecological knowledge. This process of synthesis allows researchers to identify how consistent these pieces of knowledge are with one another, while building an awareness of where important gaps in understanding exist.
In consultation with Eglin Air Force Base and Nature Conservancy staff we have developed a model that includes a rough approximation of the climate and topography of Eglin. In the model a landscape will be composed of a set of vegetation states, dynamically changes due to successional and disturbance processes. This page contains movies of forest vegetation change from three simple model scenarios: wild, fire supression, and road fragmentation.
|Each of scenario movies plays shows the vegetation of Eglin
Air Force base changing at five year intervals. The forest landscape is
represented by eight vegetation types that are classified based upon a
sites dominant vegetation: longleaf pine (LL), longleaf pine with some
sand pine (LLSP), longleaf pine with some hardwoods (LLHW), sand pine with
some longleaf pine (SPLL), hardwoods with some longleaf pine (HWLL), sand
pine (SP), mixed hardwood and sand pine (HWSP), hardwood (HW), wetlands
(WET), and wetlands with some sand pine (SP).
The colors used to represent these vegetation types in the movie maps are shown in the legend.
|Wild Fire Scenario (baseline):In this model scenario
the estimated historical fire regime was allowed to continue unimpeded.
This scenario provided some support for the model's accuracy, by maintaining
the presumed historical vegetation in a similar state. This case provides
a baseline to compare against the other two scenarios.
|Fire Supression Scenario: In this scenario, the fire
initiation rate is decreased 10 times, to 1 initiation/100 km2/yr. This
is meant to simulate the effects of fire suppression, by greatly reducing
the number of fires that are fire to spread, but not eliminating them entirely.
While large fires continue to occur, it does not occur frequently enough
to maintain longleaf pine and these areas are invaded by hardwood and sand
pine. Sand pine invasions spread from along the riverine marshes, while
in other areas hardwood grows up from beneath the long leaf. Areas of long
leaf persist for over a hundred years, but after two hundred years there
are no remaining areas dominated by long leaf.
|Road Fragmentation Scenario: In this scenario, the landscape has been cut into pieces by a number of roads. These roads halt the spread of fires. While the same number of fires are initiated as in the base case, the presence of roads reduces their impact on some areas of the landscape. The smaller fragments are unable to support large fires, and consequently the sites within these areas do not burn frequently enough to prevent hardwood and sandpine from invading. This process occurs gradually, since fires do continue to occur, but gradually the more fragmented areas, for example those areas already fragmented by rivers, loose their longleaf pine.|
|Comparison of Scenarios: This image is a summary comparison of the landscape change that occurs between the model scenarios. Click on the image for a larger version.|