Governments regularly spend public funds to purchase environmental amenities. They might purchase land to add to the public estate, pay to fence stock out of endangered native forest, or offer stewardship payments as incentives to conservation. Governments also regularly introduce policies to achieve environmental goals, even though these policies impose costs on firms, households or farms. The basic decision rule, to maximise environmental benefits from a given budget, in all these cases is received wisdom within the economics profession. In the case of purchase of land to add to the public estate:
Maximise environmental benefits by purchasing land in descending order of the ratio of benefit to cost until the budget is exhausted.
More generally, funds should be allocated to individual activities within a programme in order of the decreasing ratio of benefits to costs until the budget is exhausted. This rule can be applied when benefits can be measured in any monetary or non-monetary quantitative index. In the case of conservation of vegetation, it can be applied relatively simply in the field when vegetation types and land values can be mapped jointly through GIS techniques.
This simple decision rule is not always followed by government agencies that manage environmental programmes. Consider the protection of native vegetation, which is defined to include native forest, native woodland and native grassland. To meet international obligations to protect this kind of environment, most countries must involve private landholders in conservation because there are insufficient government reserves to meet the international commitments. Indeed, most countries have already introduced many policies to encourage private landholders to protect native vegetation on their forests and farms.
The New South Wales state government, in Australia, has introduced the Native Vegetation Conservation Act (1998) to ensure that private landholders protect vegetation. The Act constrains farmers to retain all the native forest, native woodland, and native grassland, on their land irrespective of the costs to them. Farmers can then apply for consent to clear and crop this land, but consent is rarely granted in full and often not at all. The Act is consistent with a decision rule of “maximise-benefits-only” - protect all vegetation irrespective of the costs to those who have to conserve it.
Constraints of this kind will inevitably lead to a loss of income and land value when they restrict the farm enterprises, and so will impose opportunity costs on the farmer. There is already ample published evidence on the sizes of these costs - from publications of the relevant state agency itself, consultants' reports, farmer submissions and independent research. For example, in a large region in the northwest of New South Wales, where land could be cropped very productively:
- some farmers bear only small losses (a quarter lose less than five per cent of their potential income),
- some farmers bear very large losses (another quarter lose more than half of their potential income),
- the overall losses of income per farm are high (an average loss of almost 30 per cent of potential income across the region), and
- the losses are highest for those who have already conserved most woodland.
Consider now the problem of reducing these costs by applying the benefit-cost rule as opposed to the maximise-benefits-only rule that has led to this position. There are three economic decision rules that might be used to rank projects or activities.
The benefit-cost rule: Impose the constraint on the farm with the highest ratio of environmental benefit per dollar of opportunity cost first, then on the farm with the next highest ratio, etc., until the environmental goal is met. And so maximise the ratio of benefits to opportunity costs.
The benefit-only rule: Impose the constraint on the farm with the highest environmental benefits first, then on the farm with the next highest benefits, etc., until the environmental goal is met. And so maximise benefits.
The cost-only rule: Impose the constraint on the farm with the lowest opportunity costs first, then the next lowest cost, etc, until the environmental goal is met. And so minimise opportunity costs.
But do these rules normally lead to different outcomes? If the “budget” or willingness to impose opportunity costs were large enough, all three would lead to the same outcome because constraints would be imposed on all suitable land. Otherwise the outcomes differ - that is the different rules lead to different levels of environmental benefit from the imposition of a given level of opportunity cost (or from the expenditure of a given budget).
Both the benefit-only and cost-only rules lead to inefficiencies (see Babcock et al (1997) and Wu et al (2000) for a discussion of the associated statistical issues). Benefit-only targeting leads to the retirement of highly-productive land from agricultural uses - which is a major reason why opportunity costs are often high when native vegetation is conserved under the Act in New South Wales. The cost-only rule can lead to the reservation or purchase of land with few environmental benefits, even though expenditure or opportunity cost is minimised.
A comparison of the benefit-cost rule and the benefit-only rule in the northwest of New South Wales illustrates the problem. The region is potentially highly-productive crop land but large areas of it are presently covered by native forest and woodland which cannot now be cleared. Much of this vegetation is under various degrees of threat even though it is not rare or endangered. The farm is the unit of assessment under the Act, so is used in the example. Benefits are measured as the percentages of species that are saved on each farm when its vegetation is protected rather than cleared to crops. The total benefit is the aggregate of percentage species saved across the farms - again following the present administration of the Act. The opportunity costs are measured as the losses in land value because land cannot now be cleared due to the Act.
The comparison of the two rules indicates substantial savings with the benefit-cost rule. For example, 90 per cent of the total benefits can be obtained by imposing 93 per cent of the total opportunity costs with the benefit-only rule, and by imposing only 54 per cent of the total opportunity costs with the benefit-cost rule. The benefit-cost rule saves 39 per cent of the total costs at this level of benefits. Again, 80 cent of the total benefits can be obtained by imposing 86 per cent of the total opportunity costs with the benefit-only rule, but by imposing only 46 per cent of the total opportunity costs with the benefit-cost rule. The benefit-cost rule saves 40 per cent of costs at this level of benefits.
While such results can only be indicative of the magnitudes, they do serve to highlight the inefficiencies of decision rules used by government agencies. In New South Wales, the Native Vegetation Conservation Act imposes high opportunity costs on farmers, partly because it is implemented through a high-cost decision rule. Now that suitable GIS technology, vegetation maps, and spatial land value data, are becoming available, these costs can be lowered with a more rational decision rule to guide choices in the field.
The environmental goal is not at issue, but the cost of achieving it is. We can identify who bears the opportunity costs of environmental conservation, and often value the magnitude of these costs. Now we can also reduce the levels of these costs with the use of the benefit-cost decision rule.
Agricultural and Resource Economics
University of New England
Armidale, New South Wales
Babcock Bruce A, Lackshminarayan PG, Wu JunJie and Silberman D (1997) “Targeting Tools for the Purchase of Environmental Amenities”, Land Economics, 73, 325-339.
Wu JunJie, Adams Richard M., Zilberman David, and Bruce Babcock (2000) “Targeting Resource Conservation Expenditures”, Choices, Second Quarter, 2000, 3-8.