Environmental Engineering Reference
In-Depth Information
Providing the Landscape Basis: ELM
The Everglades Landscape Model ELM (Fitz and Sklar 1999) is a regional-scaled,
grid-based model framework, that brings together different landscape layers, like
vegetation, hydrology and topology, and combines these layers to a GIS-like output
representation. The vegetation types used here derive originally from the Florida Gap
Analysis project (Pearlstine et al. 2002), providing a spatial resolution of 28
28 m,
which are aggregated in ELM into cells of the size 1,000
1,000 m. The ELMmodel
uses its own hydrologic modelling, but uses boundary conditions from the larger scale
South Florida Water Management Model (SFWMD). ELM also contains simple
modelling of the nutrient (e.g. phosphorus) fluxes of suspended material, and growth
and competition of major vegetation types. A key objective of ELM is to project the
movement of phosphorus from the agricultural areas into the Everglades.
Modelling Animal and Population Distributions: ATLSS
The Across Trophic Level System Simulation program, or ATLSS, is an integrated
set of computer simulation models representing the biotic community of the Ever-
glades/Big Cypress region and the abiotic factors that affect it (DeAngelis and
Gross 2001). The major objective of the ATLSS models is to estimate the effects of
hydrologic scenarios on key biota of the Everglades. The spatial extent of the
models is the entire Everglades/Big Cypress region and some surrounding areas,
and the spatial resolution is generally 500
500 m cells, though sometimes finer.
Relevant abiotic quantities, such as hydrology, fire, and major storms are modeled.
Hydrological scenarios from the SFWMD are used for this purpose.
The output of this model at the 2
2 mile grid scale,
is converted to a
500
500 m grid scale. The ATLSS models are spatially-explicit, using GIS map
layers of topography, soil, vegetation type, etc. The biotic community is represented
by a hierarchy of models, beginning with the process models of the biota constituting
the energy base, including vegetative biomass, lower trophic level invertebrates, and
decomposers (Fig.
21.5
). Models that contain some relevant details on size and age
structure simulate several important functional groups, such as fishes, macro-inverte-
brates, and small reptiles and amphibians, which utilize the production of the energy
base and provide food for some of the top consumers (for size/age structure models
see Chap. 9, for an example on local models and process models see Chap. 18).
Several individual species that are highly valued because they are unique or
threatened, or are regarded as indicators of the overall conditions of the ecosystem,
are modeled in much greater detail, using individual-based models (see Chap. 12).
These species include the American alligator, the American crocodile, several species
of wading birds, white-tailed deer, the Florida panther, the Cape Sable seaside
sparrow, and the snail kite. The objectives of the ATLSS program over the long
term are to aid in understanding how the biotic communities of South Florida are
