Difference between revisions of "AVVIRK-2000"

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General System description

System name: AVVIRK-2000

Brief overview

AVVIRK-2000 is a Norwegian DSS developed in order to answer large-scale strategic forest management planning needs.

Scope of the system

AVVIRK-2000 is a deterministic simulation model, with no elements of optimization or stochasticity built in. The simulation system comprises two phases:

1. Simulations are made for each individual stand.
2. The potential harvest at the forest level (i.e. the union of all stands) is calculated.

In this second phase, in case of existence of harvest constraints an iterative tool operating heuristics should be used, in order to achieve a few, but satisfactory solutions. Harvest constraints allowed are:

1. a non-declining harvest path or net income path for the period of 100 years,
2. a user-given harvest level or net income level for any number of 10-year periods up to 10,
3. a harvest path according to user-given final harvest ages for all stands, or
4. a harvest path according to removal of stands with relative annual value increment lower than a user-given percentage.

Until here, the model has only taken into account timber production considerations. Since environmentally orientated practices have become more important, the model also provides means for alternative regimes, although the areas that are going to be managed under these regimes have to be manually selected by the user:

1. An ‘’ecologically orientated regime’’ where no treatments are allowed until the forest reaches a user-defined maturity. From this stage onwards the forest state is assumed stable and a harvest corresponding to 70% of the current increment at 10-year intervals is performed;
2. A ‘’scenically orientated regime’’ where no harvest in old growth forest is allowed until adjacent areas have been regenerated and reached a height of 2 m;
3. A ‘’preservative regime’’ where specified areas are excluded from the production, harvest and value computations.

System origin

• AVVIRK-2000 development had as starting point two models which were used for long-term forest management planning in Norway in the 80’s and 90’s: AVVIRK3^[1] and the previous model developed by Hobbelstad^[2].
• The AVVIRK-2000 model was tested and evaluated with respect to its applicability in management planning by Eid^[3].

Support for specific issues

Harvest planning, according to some other issues like sustained revenue, user harvesting goals, forest maturity, landscape protection, or biodiversity conservation.

Data and data models

Typical spatial extent of application

Although analyses for large forest areas and environmentally orientated practices is possible, AVVIRK-2000 probably has a larger potential for use in practical planning at the private farm property level, where the decisions are focused on timber production.

Forest data input

The spatial unit of the input data used by the programme is the stand. The standard inventory data required are: variables (diameter, height…) describing the average tree, the number of stems per ha, ordinary state description variables such as volume per ha, age, and site quality. The tree species allowed are Norway spruce (Picea abies (L.) Karst), Scots pine (Pinus sylvestris L.) and birch (Betula pubescens).

Type of information input from user (via GUI)

User has to define some forest and stand level treatment conditions, regeneration methods and the discount rate used for the economic predictions.

Models

Forest models

This DSS uses the AVVIRK-2000 deterministic simulation model, previously described. Area-based empirical models for growth, recruitment/regenation and mortality is applied. Cost calculations are based on production models for harvesters and forwarders, and incomes are based on functions reflecting timber prices for spruce, pine and birch.

Decision Support

Definition of management interventions

Economic evaluation is made by means of the net present value (NVP). The NPV of a silvicultural regime is determined by the cash flow originating from the calculated timber values and harvest costs, and from the costs for silviculture, assuming all treatments take place in the middle of the 10-year periods. Fixed costs (administration, planning, etc.) may be included in the NPV too. The NVP takes into account the soil expectation value and the NPV at year 100, i.e. the state of all stands is projected from yr 100 to the assumed final harvest age, which depends on the stand age in year 100.

Typical temporal scale of application

The time scope of the system is the strategic planning. Projections are made for a period of 100 years, divided into 10 periods of 10 years. Within these periods, in the middle of each 10 years, all treatments take place. However, the model may, together with a GIS tool, may serve as a powerful tool for decision analyses on a tactical and an operational level

Decision-making processes and models

AVVIRK-2000 uses a deterministic simulation model with no elements of optimization or stochasticity built in.

References

Cited references

1. ↑ HOBBELSTAD, K. (1988): Planleggingsprogrammet AVVIRK3. Dept of Forest Mensuration, Agric. Univ. of Norway, As, Melding 42, 38 pp. (In Norwegian.)
2. ↑ HOBBELSTAD, K. (1979): Edb-program for beregning av balansekvantum. In Bruaset, A. (ed.). Landbrukets arbok, pp. 190-198. Tanum-Norli, Oslo. (In Norwegian.)
3. ↑ EID, T. (2004): Testing a large-scale forestry scenario model by means of successive inventories on a forest property. Silva Fennica, 38(3): 305–317.

External resources

• EID, T. et K. HOBBELSTAD (2000): AVVIRK-2000: A Large-scale Forestry Scenario Model for Long-term Investment, Income and Harvest Analyses. ‘’Scand. J. For. Res.’’ 15: 472-482.