Modeling forest stands: PipeTree simulator and Gibbs canopy model
meeting: Phenotypic plasticity in response to environmental changes:
Scaling from the molecular to ecosystem levels.
(Nikko, Japan, October 2008)
In this paper, I will demonstrate how modeling and simulation
can contribute to scaling up from foliage to small forest stand.
The first topic is the development of a functional-structural
PipeTree (1), which is designed to reconstruct
Abies veitchii stand by the interactions of unit modules within
tree and the light competition among trees.
Without using any constraints such as allometric rules at individual level,
PipeTree generated a dynamics which is similar
to the time change of the relationship between tree diameter and height
appeared in field observation.
In the second topic on Gibbs canopy model (2), I introduce a statistical
method to reconstruct canopy structure (foliage configuration) based on a
three-dimensional data of light measurements.
The Markov chain Monte Carlo (MCMC) method defined by the model allows us
to ``sample'' foliage configurations from the Gibbs distribution which is a
set of configurations weighted by the likelihood under observation.
Based on the posterior distribution of foliage configuration, we can evaluate
the estimates of canopy production and evapotranspiration.
This method is a kind of Bayesian approach which is recently recognized as a
useful tool for the data analysis in the field of plant ecology (e.g. 3).