The Use of Simulation in the Management of Privately Owned Forests in Britain

The use of simulation as a tool in planning, predicting output,and as part of a system of forest management is discussed andillustrated by an example based on thirty-seven privately ownedforest estates in the Dee valley in north-east Scotland. The simulation model is described and the results of a low anda high level of felling and afforestation are compared. Thepredicted outputs from the simulation runs are compared withthe records of actual output from 1970 to 1972. The estimated increment and output were: Annual increment of crops 20 years and older 52,000 m³ Annual output at the ‘high’ level .4,000 m³ Annual output at the ‘low’ level 27,000 m³ Average actual annual output 1970–2 18,000 m³ The conclusions drawn from the results of the management studyin the forests of the Dee valley are:

1. In the past, owners haveaccepted low rates of return from theirforest enterprise, theirprimary object being to re-create andmaintain a forest resourcesimilar to that which existed inthe past.
2. Objective reappraisalsof the forest enterprise are exceptionaland management is constrainedoften by arbitrary, rigid, andsevere decisions that imposeunforeseen consequences on activitiesin both the forest andother parts of the estate.
3. The current situation of the forestis very different from thatof the past and is continually changing.For example, the demandsof modern marketing and harvestingpractices are quite differentfrom those imposed even ten yearsago, and the proposed Wealthand Capital Transfer Taxes mayalter the relative importanceto the owners of forest incomeand capital.

Many forest owners in Britain now require a more objective approachto forest management with continuous reappraisal to ensure thattheir plans continue to serve their needs. As the financialresults of the forest enterprise are especially sensitive tothe felling and afforestation programmes, studies to answerthe following questions may be needed urgently:

1. Can a higheroutput than that harvested at present be sustainedin the future?
2. Should the rate of replacement of mature woods be altered?
3. Does the current rate of afforestation best serve the objectsof management in the light of altered tax commitments and cashliquidity requirements?

Computer simulation can be a useful aid in planning providedthat reliable information on costs, prices, and growth ratesis available. Forest managers must be encouraged to collectthe necessary data.