forest stand simulation models

Mike Sonntag MICHAEL at
Wed Jul 6 04:07:38 EST 1994


I am currently involved in the task of developing a model of mixed
species, mixed ages, distance dependent, process based tree growth
model mainly for use for planted forests under not to dry and not to
cold conditions. Basis will be a modified single species, single age,
distance independent, process based stand growth model (TREEDYN,
develped by Prof. Bossel and co-workers, University of Kassel,

We want to get answers to questions like: is yield of mixed forests
(e.g. beech and spruce) higher as in mono cultures under different
climatic and soil conditions? what kind of cutting strategy is
working best? and especially: with climate change what will be the
results to forests concerning yield and sustainability and the like
(EC sponsored project LTEEF: long term effects of CO2 and climate
change  to european forests)? in short: we want a generic model only
with parameters that have biological meaning and are easily derived
for different plant species and site and meteorological conditions.

As this will be the greater part of my Ph.D. thesis (in physics) I am
wondering why there seems to be no model of this generic type to be
on the "market" (so I was told. If you know of such a model please
feel free to correct me.). There has to be a reason for this and I
don't want to bear a dead child:
- is this task to formidable, are there to many processes involved on
to many levels to get any meaningful simulation results?
- are there no data to validate such a mixed species model?
- do researchers feel that processes like photosynthesis, allocation
and soil processes are to poorly understood to make a model based on
assumptions about these processes scientiffically justifiable?
- are there other types of models (e.g. gap models or whole stand
models) that can answer questions of impact of environmental
conditions more easily than a process based single tree model?
- is there any experience with this kind of model that suggest that
there is some fundamental error to believe an endeveour of the kind I
want to undertake to be not fruitfull?

I would be greatful for any first hand hints and suggestions
concerning my task.

Michael Sonntag
Environmental Systems Research Center
University of Kassel
Moenchebergstr. 11
34109 Kassel
Tel.: 0561 804 3175
Fax : 0561 804 3176
Mail: michael at

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