Miguel F.Acevedo
ABSTRACTS
TRANSITION AND GAP MODELS OF FOREST DYNAMICS
Ecological
Applications. 5(4):1040-1055. 1995
M.F. Acevedo 1, D.L. Urban 2 and M. Ablan 1
1 Institute of Applied Sciences and Department of Geography University
of North Texas, Denton, Texas 76203. 2 Department of Forest Sciences,
Colorado
State University, Fort Collins, Colorado 80523.
Abstract
We describe and apply a correspondence between two major modeling
approaches
to forest dynamics: transition markovian models and gap models or
JABOWA-FORET
type simulators. A transition model can be derived from a gap model by
defining states on the basis of species, functional roles, vertical
structure
or other convenient cover types. A gap-size plot can be assigned to one
state according to dominance of one of these cover types. A semi-markov
framework is used for the transition model by considering not only the
transition probabilities among the states, but also the holding times
in
each transition. The holding times are considered to be a combination
of
distributed and fixed time delays. Extensions in spatial are possible
by
considering collections of gap-size plots and the proportions of these
plots occupied by each state. The advantages of this approach include:
reducing simulation time, analytical guidance to the simulations,
direct
analytical exploration of hypothesis and the possibility of fast
computation
from closed-form solutions and formulae. These advantages can be useful
in the simulation of landscape dynamics and of species-rich forests, as
well as in designing management strategies. A preliminary application
to
the H.J.Andrews forest in the Oregon Cascades is presented for
demonstration.
Key words: forest dynamics, modeling, succession, gap, markov,
semi-markov,
transition, delay, simulation, ZELIG, shade-tolerant, shade-intolerant,
functional roles, H.J. Andrews, landscape, GIS, mosaic.
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