Hello Jeff and others

We have been gradually progressing our modelling of coarse woody debris in
Tasmanian wet eucalypt forest. Lee Stamm recently completed his honours
research here on "Measuring and modelling coarse woody debris in tall wet
eucalypt forests in southern Tasmania" ; see
http://www.warra.com/warra/docs/research_projects/docs/research_project_0409.htm

We are currently preparing papers for publication based on this work, but his
thesis abstract reads as follows:

"The objective of this study is to model the decay-class and diameter-class
distributions of coarse woody debris (CWD) in an unmanaged, even-aged tall
lowland Eucalyptus obliqua forest subject to cyclical stand-replacing wildfire
by both volume and mass. Modelling the dynamics of CWD is an important step
towards understanding how disturbance, both natural and anthropogenic, affect
this substrate as it supports many different types of organisms, performs
valuable ecosystem services and is a significant proportion of the biomass of
many forests.

The honours thesis arising from this work is presented in three sections.

The first section covers the CWD collected from lowland wet E.obliqua forest in
the Warra Long Term Ecological Research site in Southern Tasmania, and deals
with measurements of the proportions and densities of ‘rot types’ within the
five decay-classes of CWD. It demonstrates that, although there is some overlap,
the standard five-point decay classification system used by Forestry Tasmania
(FT) is a valid surrogate for ‘internal decay state’ and for relative wood
density. Comparisons of CWD sampled from different locations within Warra, and
logs of different diameters, show that the sites selected had little influence
on the internal decay state, but that log diameter did.

The second section employs the five-point decay-class system to construct a
stage-based decay model to simulate temporal change in CWD volume and mass. Key
parameters were populated with data describing the density of CWD in each
decay-class and diameter class obtained from the first part of the study. A
forest growth model and a stagfall model for even aged tall wet E. obliqua
forests, derived from models developed within FT, were then combined with the
decay model to enable modelling of stand-level CWD dynamics over single or
multiple cycles of wildfire and regrowth. Some of the important findings that
emerged from this section are:

It is possible to model CWD using a stage-based model in which the rates of
transition of CWD through stages of decay vary by decay-class and diameter-class
The mean volume of CWD decreases with decreasing wildfire return interval
CWD is more abundant in larger diameter-classes under longer wildfire return
intervals
Volume and mass of CWD follow different trajectories

The third section presents a synthesis of the previous two sections, and briefly
discusses the ways in which the CWD model could be applied in order to
facilitate a better understanding of the impacts of natural disturbance and
forest management on CWD dynamics within tall lowland wet eucalypt forests in
Tasmania."

For reference, the model was developed using the Simile visual modelling
environment, which we can recommend for this sort of work, especially for those
of us who prefer not to write pages and pages of computer code.

Regards

Simon Grove



`'*:-.,_,.-:*'``'*:-.,_,.-:*'``'*:-.,_,.-:*'``'*:-.,

Dr Simon J Grove, Conservation Biologist,
Biology and Conservation Branch,
Division of Forest Research and Development
Forestry Tasmania, GPO Box 207, Hobart, Tasmania 7001, Australia.
Tel. 61 3 6233 8141. Fax 61 3 6233 8292.
Email: simon.grove@....
Web addresses: http://www.forestrytas.com.au/
http://www.warra.com


>>> "Jeff Stone" <jeff.stone@...> 06/03/07 11:26 >>>
Hi

While I moderate this discussion list, I've not been involved with
dead tree research or modelling for a number of years.

I wouldn't mind hearing what people are doing in terms of modelling
dead tree dynamics, either standing or down.

Cheers

Jeff Stone
Southern Interior Forest Region
Ministry of Forests and Range
Kamloops British Columbia
jeff.stone@...


-----------------------------------------------------
This transmission is intended solely for the person or
organisation to whom it is addressed.
It is confidential and may contain legally privileged
information. If you have received this transmission in
error,you may not use, copy or distribute it.
Please advise us by return e-mail or by phoning 61 3 62338203
and immediately delete the transmission in its entirety.
We will meet your reasonable expenses of notifying us.
Despite our use of anti-virus software, Forestry Tasmania
cannot guarantee that this transmission is virus-free.
-----------------------------------------------------