A Process Model of Cambial Activity and Ring Structure in Conifers Using
Daily Climatic Data
by
Alexander V. Shashkin, Institute of Forestry, 660036 Krasnoyarsk, Russia,
Harold C. Fritts
and
Geoffrey M. Downes, CSIRO Division of Forest Products, Private Bag 10,
Rosebank, MDC, Clayton, Victoria, AU
TREERING 3.0 is a process model with:
- Calculations of:
- water balance, photosynthesis, carbon storage, crown growth, and cambial
activity calculated at daily time steps.
-
Inputs of:
- daily maximum and minimum temperatures, daily precipitation, and constants
(coefficients) for equations governing biophysical processes.
- Outputs of:
- daily values of growth regulating processes with crown growth, number
of cells dividing, enlarging, and maturing along with the resulting ring
structure.
- Capablility of Iteration:
- to optimize values of parameters or constants with uncertain values.
Four Modules Define the Growth Dynamics:
- Crown Growth:
- a function of bud primordia, changing leaf mass and limiting conditions
of temperature, water stress, available carbon.
- Cell Division:
- a function of 3 linear relationships controlled by crown activity,
limiting conditions and number of dividing cells.
- Cell Enlargement:
- a function of 2 linear relationships controlled by crown activity,
limiting conditions, and prior day's enlargement rate.
- Wall Thickening:
- a function of 2 linear relationships controlled by crown activity,
limiting conditions, and prior day's thickening rate.
Daily Rates and States are saved and Plotted
Model Limitations:
- Is only a beginning of modeling cambial activity, development
of wood structure and ring growth.
- Is limited by current knowledge and experience in constructing
mathematical equations that are adequate to describe the real processes
governing growth.
- Approximates many parameters and processes that have yet to be
validated with field measurements and controlled experiments.
- Applies primarily to dendrochronologically dated tree rings that
have been limited by variations in climate.
Plans for the Future:
- Refinement and revision of equations, model structure, and dynamics
of the relationships.
- Inclusion of 1) bud development, 2) phloem growth,
3) yearly changes of leaf and root areas, and 4) circumferential
and height growth.
- Applications to different sites and species.
- Possible integration with larger and more sophisticated models
of forest ecosystem development and tree growth.
To Download Files of the New TreeRing Model 2000 enter "http://tree.ltrr.arizona.edu/webhome/hal/treering/".
To Download Files of the older Modeling Program.
Please Send me Comments, Questions,
or Suggestions.
Return to Hal's Home Page.
Prepared by Harold C. Fritts hfritts@LTRR.arizona.edu --
Last updatedMarch 17, 2000