Modeling ecological patterns and processes using agent-based
simulations and GIS
James H. Brown
Abstract:
I will talk about two collaborations in which colleagues and I have used
simulation to investigate the structure and dynamics of complex, spatially
explicit ecological systems. The first studies complement empirical studies
that
use ARCINFO GIS and the large data base of the North American Breeding Bird
Survey (a standardized census that has been conducted annually since the
mid-1960's and now includes about 2,000 locations across the US and
Canada) to
analyze spatial and temporal variation in the abundance of bird populations.
The
abundance of common species varies over several orders of magnitude and shows
interesting patterns with respect to location within the geographic
range. We
are asking whether we can mimic and therefore begin to understand these
patterns
with computer simulation models of the niche combinations of environmental
variables that limit abundance and distribution of each species. Using
GIS and
other data bases on weather, topography, soils, vegetation, etc., we can
simulate the abundance and distribution of imaginary species with specified
requirements.
The other studies are computer-based experiments to understand the complex
structures and dynamics produced by John Holland's artificial ecology
ECHO. In
this system agents ("individuals" of asexual "species") compete for
resources,
interact with other agents through "combat" (predation) and "trade"
(mutualism),
and reproduce with possible genetic change according to simple rules. The
outcome of running ECHO for many generations is the evolution of an
"ecological
community" containing multiple species with divergent characteristics. By
conducting controlled, replicated experiments in which we manipulate the
environment (e.g., rate of resource supply) and/or the rules of agent
behavior
(eg., the kind, number, and strength of interactions), we can investigate the
processes that affect "species diversity" and "community
dynamics."
Contact: James Brown
Department of Biology
University of New Mexico
Albequerque, NM
dept: 505-277-9337
lab: 505-277-6437
email: jbrown@bootes.unm.edu
(Alternate contact: Sarah - 505-277-9337, mornings only)