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To the editor

Unasylva welcomes letters from readers on any topic related to forestry and the environment. Letters should be reasonably short and legible. English, French or Spanish is preferred, but other languages will also be considered. Please address letters to: Editor, Unasylva, FAO Forestry Department, Via delle Terme di Caracalla, 00100 Rome, Italy.

Nothing sacred about sustained yield

Otto Eckmullner and Andras Madas have written a chapter called 'The production functions" in Forest policy: a contribution to resource development, the last book in Nijhoff and Junk's Forestry Sciences series, edited by F.C. Hummel (reviewed by Jack Westoby in Unasylva 37 [148] 55-57). In their discussion of sustained-yield forestry in this chapter, one would have expected a more scientific treatment when the authors are two experienced professors like Eckmullner and Madas. As the text is formulated, however, it is mainly a defence of the myth of sustained yield rather than a rational discussion of various options in felling policy. The authors start their section on the principle of sustained yield by stating the following:

"One of the most fundamental principles of forest policy must be that forests should be managed in a way which will maintain and where practicable, improve the productive capacity of the site and the forest."

I agree that this has been, de facto, one of the most fundamental principles of modern European forest policy, although it has not always been practiced. That is why it is necessary to discuss the subject. But why does sustained yield have to be a "fundamental principle"? Eckmullner and Madas do not give any justification for their statement. They merely assert that management "should seek to prevent too great fluctuations in the level of annual or periodic fellings;... the amount of wood removed in a, say, ten year period, should not surpass the allowable cut for that period" (emphasis added).

These are all normative statements, and the reasons behind them are never discussed. Their unconditional proposition that "the principle of sustained yield and an allowable or potential cut should, of course, be applied to a country's forestry as a whole also' is straightforwardly erroneous.

Sustained yield may be a reasonable policy for a firm, or forest owner, restricted to forest production and with little knowledge on alternative capital investments, but from a country's point of view many options for capital investments are open for consideration. The transfer of capital from forests to other sectors by high fellings surpassing the so-called (by whom?) allowable cut may be highly rational if more profitable investments are available and lack of funding is felt as a restriction. This is especially the case when the forests contain large proportions of old and slow-growing stands. The same argument may be used in the case of individual forest firms if they are ready to enter into other businesses.

And here we are at the centre of Pressler's theory of "money yield' as opposed to the earlier concept of "forest yield'. Pressler demands of forestry that it yield as much in money terms as any other economic activity. Most elegantly this is formulated in Faustmann's formula, which states that a forest stand should be felled when its marginal rate of return falls below the rate of discount, with the rate of discount being understood as the opportunity cost of capital. Faustmann's formula is obviously correct for one individual stand, but if it is practiced rigorously in a forest structured differently from the so-called "normal" forest, the volume of fellings and consequently the economic result will vary considerably over time if the rate of discount is maintained. This may not be correct if investment opportunities vary from one planning period to another. Therefore, an economically optimal time path of fellings may be rather complicated to calculate. K.S. Lyon and R. Sedjo have, however, shown how the long-term supply of timber from a forest region is likely to develop if the actors behave in an economically rational manner. Based on a chosen age structure of the forest, their example diverges greatly from the sustained-yield option.

From society's point of view. Faustmann's formula is obviously too simple. It takes the price of timber as given. When discussing a felling policy of a country, the volumes involved are so large that the price will be affected. Optimal time paths of fellings in a social context must therefore be determined in less elegant but more comprehensive ways. This has been attempted in Sweden, where nothing indicates that a non-decreasing volume of fellings, as advocated by Eckmullner and Madas, is necessarily the best option.

The economic cost and benefits of various paths of fellings are not discussed by Eckmullner and Madas. Rather, they make the principle of sustained yield a moral obligation. This is the same position as taken by N.A. Moiseev and S.G. Sinitsin at the seventeenth IUFRO World Congress in 1981. One would have thought that W.D. Klemperer's arguments at the same event would have had some influence on how sustained yield is discussed later. I do not demand from Eckmullner and Madas that they agree with Klemperer's economic arguments; only that they not totally overlook them. The question of whether their contribution to the book is to be seen as one policy statement as opposed to many others becomes quite justified. I would, for myself, have preferred a discussion of the many, equally rational, options available, rather than Eckmullner and Madas's own personal opinion. Nor can I imagine that they themselves wanted to formulate the felling policy of world forestry.

Ole Hofstad
Dept. of Forest Mensuration
and Management
Agricultural University
of Norway

Goals of the international undertaking on plant genetic resources

· To promote greater efforts in the exploration of plant genetic resources.

· To facilitate the adoption of appropriate legislative and other measures for the conservation and use of genetic material.

· To allow access to genetic materials and to permit their export when requested for research, breeding and conservation purposes.

· To strengthen international cooperation and to improve the capabilities of developing countries.

· To foster a coordinated network of base collections in national, regional and international gene banks under the auspices of FAO.

· To develop a global information system on available crop genetic species:

· To promote greater financial support and security for conservation work.

Adopted by the Twenty-second Session of the FAO Conference, Rome, November 1983

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