A Defensible Approach Toward Landscape and Environmental Planning

摘要：ABSTRACT
The methodology of landscape and environmental planning have been severely challenged when classical concepts and models such as economic optimum, ecological fitness, safe minimum standard, carrying capacity and even sustainability have been questioned. It is observed that (i) It is extremely difficulty to have planning either aimed at ecological optimum or economic maximum, i.e. planning is not determined nor absolute in terms of environmental and economic criteria, it is defensible. (ii) Environment may impose some "ultimate" or "absolute" constraints on development, which planning has to come to terms with, but such limits and constraints are hardly definable nor acceptable, and therefore, have limited usefulness in planning, i.e. planning is in need of some defensible strategies to rationalize the planning process.
A defensible approach to landscape and environmental planning is, therefor, proposed. It is argued that planning is a defensible process and defending using some strategic frontiers at security levels (spatially security patterns) may be more reasonable and effective. Using a case study, it is further demonstrated that security levels and patterns are definable based on the disproportionate and irregularity quality of the dynamics of the ecological processes.

关键词：Landscape planning, spatial analysis, ecological planning, planning methodology

(This paper is reprinted from: Proceedings, Athens International Conference , Urban Regional Environmental Planning and Informatics to Planning in An Era of Transition (T. Sellis and D. Georgoulis eds.). National Technical University of Athens, Faculty of Architecture Dept. of Urban and Regional Planning, PP453-463, 1997)

1 INTRODUCTION: FROM MAXIMUM TO MINIMAX
Approaches toward sustainability in planning can be discussed in two categories, the maximization-optimization approaches and minimax-constraint approaches. Each category is further differentiated according to economic criteria and ecological criteria, resulting in a 2 X 2 matrix (Table 1)

Table 1 Major approaches to the sustainability of environment and development
Maximization-optimization approaches Minimax-constraint approaches
Economic criteria Economic efficiency, maximum difference between total social benefits and total social costs, based on cost-benefits analysis. Avoiding very high social costs, including: Safe minimum standards (SMS), Sustainable constraints (CS), Precautionary principles (PP),Development threshold costs, etc.
Ecological criteria Ecological fitness, optimum relationship, based on suitability analysis Avoiding ecological irreversibility, including:Carrying capacity, ultimate environmental threshold (UET), etc.

Both economic-maximization and ecological-optimization approaches follow the model of rationality, which depends on full information to make the best choice and a belief that knowledge can lead to the best action. The common rationale behind the minimax-constraint approaches is not to seek the best solution but to avoid the worst case.

1.1 Economic Maximization Approaches
In the economic maximization approaches, projected monetary benefits and costs are used to allocate environmental and man-made capital. The basic criterion is cost efficiency, and cost-benefits models are used to search for the maximum net social benefits of using or preserving environmental assets. By means of monetary terms, depleted environmental assets can be substituted by trade-offs. The reliability of these approaches in conservation and sustainable use of the environment is, however, doubtful (Foy 1990; Pearce 1994).

1.2 Ecological Optimization Approaches
The ecological-optimization approaches are based on suitability and capability analysis of the land according to physical attributes such as geology, hydrology, soil, vegetation and so on. The goal of planning is to search for the fittest environment for individual land use and activities. The ecological-optimization approaches are well known through McHarg's Design With Nature (McHarg 1969), which can be summarized as "all systems aspire to survive and succeed. This state can be described as syntropic--fitness--health. Its antithesis is entropic--misfitness--morbidity. To achieve the first state requires systems to find the fittest environment , adapt it and themselves" (McHarg 1981). The objective of landscape planning is thus the fittest plan, where individual uses of landscape match the intrinsic values of the landscape. Though widely used, ecological-optimization approach has been criticized for being physically deterministic and technocratic (Litton and Kieiger 1971).
The common feature between ecological-optimization approaches and economic-maximization approaches is their technocracy, or rationality and deterministic. They are based on the assumption that there is a best solution at which planning should be aimed, and which can be revealed through complete information and full knowledge through systematic analysis. It was argued, however, that all human knowledge is fallible and uncertain, knowledge simply does not show us what we must do ( Davidoff 1965; Faludi 1987). No real decision-making process can meet the demands of rationality: complete information and the simultaneous consideration of all possible alternatives. Man does not optimize, he "satisfices", that is he looks for a course of action that is "good enough" or "satisficing" (Simon 1957, 1976). Furthermore, the economic-maximum approaches and ecological-optimum approaches are, incompatible (Pearce 1973). This recognition leads to the advancement of putting constraints on the maximization process of development as discussed in the next sections.

1.3 Economic Principle of Minimax-constraint Approaches
(a) Safe Minimum Standards (SMS)
Among various development constraints proposed by the economists, the concept of Safe Minimum Standard (SMS), first developed by Ciriacy-Wantrup and further developed by others (Ciriacy-Wantrup 1968; Bishop 1978), is one of the most widely discussed. It aims at minimizing the potential of the worst case such as the extinction of a species, which is irreversible and whose social cost is uncertain.
The SMS principle was to deal with the problem of endangered species. It is argued that species are renewable resources within limits but have a threshold or critical zone. Once that critical zone is reached, further depletion is irreversible. This reduces the reservoir of potential resources for humanity. The long-run implications of permitting the reservoir to be reduced are unpredictable because of both social and natural uncertainties. A solution to prevent this potential catastrophe or the worst case from happening is the adoption of a safe minimum standard at which enough habitat is preserved to avoid such a catastrophe. The SMS is an application of the minimax principle rooted in game theory (von Neumann and Morgenstern 1947; Luce and Raiffa 1957).
In addition to the minimax principle and SMS, several other similar and closely related concepts have been proposed by economists, such as "sustainable constraints" (CS), the "precautionary principle" (PP) and "reserved rationality" which implies the commitment of resources now available to safeguard against the potential adverse future outcomes of some decisions (Foy 1990; Perrings 1991; Pearce 1994).
In all cases there is a presumption to conserve the environmental assets unless the social cost of conservation is "very high." This argument is further based on the assumption that environmental degradation beyond certain limits causes "the worst case" of large social loss for its uncertainty and irreversibility. Two questions arise:
The first question is about the "worst case." The "worst case" for decision making purposes in the minimax approach is identified as being based on incomplete information, it can not be the most extreme of a known range of outcomes, since the range of outcomes is not known, nor can it be the worst imaginable case. It is thus always possible, as is argued by some scholars (Perrings 1991), to construct an excuse for any policy, in which the worst case environmental costs are infinite, but such a construction would not only paralyze all activity, it would fail utterly to discriminate between different policies