Agro-forestry evaluation: using goal programming: a case study in the Canterbury foothills

Abstract

The assessment of multiple land uses is a challenging area in applied policy-related research. The question of which land use combinations best meet the needs of society is complicated by the fact that various use options are not directly comparable. Goal programming is a method by which multiple land use can be assessed, without the need to convert levels of output to a common measurement unit. By specification of priorities and levels of achievement the optimal mix of uses can chosen to meet the goals of the users.

This study is an introduction to practical Goal programming with the use of agro-forestry versus pure pastoral farming and pure forestry as an example of conflicting land use. Although not a complicated example, the study demonstrates the key attributes of Goal programming, including multiple measurement units for outputs, the use of priority weightings, the setting of achievement levels and sensitivity analysis of results. The role of the program analyst is not to make the choice, but to present the results so that the decision-maker can clearly understand the implications of making a final decision.

In this study a major issue was that of tree density for agro-forestry. Agro-forestry has an economic advantage over conventional pastoral farming on the lower producing foothills where diversification into other less conventional forms of pastoral farming is not practical. A major limitation to the establishment of agro-forestry is the high initial capital requirement and the length of time before any substantial benefits can be gained. The results suggest that the tree density of 100 stems per hectare is the most profitable but this tree density is still expensive, showing negative returns in most years and only in year 30 does any substantial benefit accrue.