A Case Study of Forest Ecosystem Pest Management

Holling, C.S., Dantzig, G.B., Baskerville, C., Jones, D.D., & Clark, W.C. (1975). A Case Study of Forest Ecosystem Pest Management. IIASA Working Paper. IIASA, Laxenburg, Austria: WP-75-060

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Abstract

The boreal forests of North America have, for centuries, experienced periodic outbreaks of a defoliating insect called the Spruce Budworm. In anyone outbreak cycle a major proportion of the mature softwood forest in effected areas can die, with major consequences to the economy and employment of regions like New Brunswick, which are highly dependent on the forest industry. An extensive insecticide spraying programme initiated in New Brunswick in 1951 has succeeded in minimizing tree mortality, but at the price of maintaining incipient outbreak conditions over an area considerably more extensive than in the past. The present management approach is, therefore, particularly sensitive to unexpected shifts in economic, social and regulatory constraints, and to unanticipated behavior of the forest ecosystem.

Most major environmental problems in the world today are characterized by similar basic ingredients: high variability in space and time, large scale, and a troubled management history. Because of their enormous complexity there has been little concerted effort to apply systems analysis techniques to the coordinated development of effective descriptions of, and prescriptions for, such problems. The Budworm-forest system seemed to present an admirable focus for a case study with two objectives. The first, of course, was to attempt to develop sets of alternate policies appropriate for the specific problem. But the more significant purpose was to see just how far we could stretch the state of the art capabilities in ecology, modeling, optimization, policy design and evaluation to apply them to complex ecosystem management problems.

Three principal issues in any resource environmental problem challenge existing techniques. The resources that provide the food, fibre and recreational opportunities for society are integral parts of ecosystems characterized by complex interrelationships of many species among each other and with the land, water and climate in which they live. The interactions of these systems are highly non-linear and have a significant spatial component. Events in anyone point in space, just as at any moment of time, can affect events at other points in space and time. The resulting high order of dimensionality becomes all the more significant as these ecological systems couple with complex social and economic ones.

The second prime challenge is that we have only partial knowledge of the variables and relationships governing the systems. A large body of theoretical and experimental analysis and data has led to an identification of the general form and kind of functional relations existing between organisms. nut only occasionally is there a rich body of data specific to anyone situation. To develop an analysis which implicitly or explicitly presumes sufficient knowledge is therefore to guarantee management policies that become more the source of the problem than the source of the solution. In a particularly challenging way present ecological management situations require concepts and techniques which cope creatively with the uncertainties and unknowns that in fact pervade most of our major social, economic and environmental problems.

The third and final challenge reflects the previous two: How can we design policies that achieve specific social objectives and yet are still "robust"? Policies which, once set in play, produce intelligently linked ecological, social and economic systems that can absorb the unexpected events and unknowns that will inevitably appear. These "unexpecteds" might be the one in a thousand year drought that perversely occurs this year; the appearance or disappearance of key species, the emergence of new economic and regulatory constrains or the shift of societal objectives. We must learn to design in a way which shifts our emphasis away from minimizing the probability of failure, towards minimizing the cost of those failures which will inevitably occur.

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