FAO STAFF 1
1 A paper prepared for the Sixth Session of FAO's Mediterranean Forestry Subcommission, Madrid, April 1958.
As a result of ecological and human action, the forests of the Mediterranean area are composed of stands of low density and slow growth. The timber produced is hard, heavy and crooked, more suitable for fuelwood than for industrial use.
These characteristics are aggravated by the facility of vegetative propagation, and a heavy undergrowth often limits the production of timber in quantity and quality, even though coppices yielding relatively large amounts of fuelwood often have a productivity superior to that of high forests. On the other hand, the climatic conditions favor all products such as cork, resins, tannins and essences, which are connected with the anatomic and reproductive processes of the trees rather than with their vegetative capacity. ²
² A. PAVARI, "Bases écologiques et techniques de la sylviculture dans les pays méditerranéens," Monti e Boschi, No. 10, 1954.
It is one of the most serious aspects of Mediterranean forestry that while general demand for sawn timber and pulp, which are the typical products of temperate forests, has been rising - at times at rather spectacular rates - the markets for the products of Mediterranean forests have been closing one after another. It is true that new techniques are beginning to make possible the utilization of wood of small dimensions, but the fact always remains that the Mediterranean forest has a substantially low productivity. This has led to consideration as to whether a change in silvicultural methods might not be able to reverse the present difficult situation of Mediterranean forestry, mainly as regards the production of industrial timber.
The need for a change is less urgently felt in the forests located in the zones of transition towards temperate and humid climates. Here, the establishment of forests similar to those growing in Central Europe does not encounter too many difficulties, and hence the transformation of stands with a view to increasing the output of structural timber and pulpwood appears feasible. The conversion of coppice into high forests, the artificial introduction of coniferous species, etc., are examples of this transformation already under way in many parts of the region. Any discussion on the applicability to the Mediterranean forests of silvicultural systems (for example, uniform systems versus selection systems) derived from Central European practices, would probably be more useful if restricted at first to the transitional temperate zones.
As regards forests situated in the Mediterranean zones proper, or those with climates of transition towards aridity, a more profound change in present silvicultural methods is probably necessary. In fact, the special conditions of his environment has long since led Mediterranean man to transform the original forests into park type forests or into tree plantations yielding mainly resins and bark, etc. These latter types of forest present forms quite different from those of the temperate-humid forest, where classical silviculture was born. The full utilization of this typical Mediterranean stand frequently calls for labor and techniques borrowed from agriculture, and thus a new, highly intensive silviculture is formed, fairly dependent on agricultural methods. In fact, forestry techniques in the Mediterranean zone are enlarging their scope far beyond the old limits of classical silviculture.
The time is ripe for discussing: first, to what extent, if any, the methods of classical silviculture are still valid for the Mediterranean area; secondly, the main lines of a new silviculture; and thirdly, how to apply these new methods to the Mediterranean forests in order to obtain from them products of high value.
A shift in emphasis of silviculture towards more intensive treatment yielding an output of higher value is neither new nor limited strictly to this particular zone. Throughout European countries there is a growing realization that the classic type of forest does not entirely satisfy the needs of a growing economy. ³ Statements that the classic forest is a slow-growing formation mainly aimed at enriching the soil; that natural regeneration is often capricious; that total production is relatively low and shows little variety, etc., are beginning to appear in the most influential forestry periodicals.
³ YVES CLAUDEL, "Nos besoins en bois de papeterie nécessitent des techniques de production rapide", Revue Forestière Française, November 1957.
The general trends in silviculture in Europe have been as follows.
The main characteristics are: pure, even-aged stands, in some cases of artificial origin; clear fellings; preference for low thinning; supremacy given to questions of economics, and therefore a tendency to neglect certain types of natural forests; drawing-up of rigid working plans; well-defined concepts of age and rotation; definite notion of "normal forest". In this type of silviculture, the stand is the main preoccupation of the silviculturist and trees are regarded mainly only in so far as they are the elements making up the stand. It could even be said that mathematics is the basic line of thought in this concept (order should reign in the forest) and that dendrometry is the applied science at the basis of silviculture.
This concept of silviculture may be described as classical, since it can be traced to as far back as the beginning of the nineteenth century. The birth of silviculture as a science was made under the auspices of this concept, which is closely connected with the names of Hartig and Cotta. The methods established by these two foresters gained the upper hand during the last century, and it was not until the twentieth century that strong objections to these methods began to arise. The numerous disadvantages which result from their systematic employment were stressed: impoverishment and degradation of the soil, loss of production, difficulties of regeneration, invasion of insects, etc. As a result, silviculture shifted its attention towards biology and a new trend was thus delineated.
Nothing symbolizes this trend better than the slogan "Back to Nature". It was encouraged by the big developments taking place in the fields of phytosociology and pedology in the first decades of this century. The biological sciences now take the place formerly occupied by mathematics. The study of ecology, phytosociology and pedology becomes the foundation of silviculture. The forest is no longer composed merely of an assembly of trees placed on the same area, but of a complex of biological associations in an equilibrium, in which all factors, even those which formerly appeared unimportant, are of importance for the well-being of the whole. Therefore, the tree as an individual comes to the fore and becomes the protagonist of silviculture. In fact, as Guinier has said, "To understand the forest is to understand the tree".
This modern silviculture is distinguished above all by a return to the precepts of the "natural forest" (from which derives a certain caution with regard to exotic species), complete freedom from theoretical plans or schemes, more intensive treatment, very short cutting cycles, careful and precise fellings, frequent and repeated cultural operations, etc. 4 It has been said that the modern silviculturist truly "fashions" his stands, devoting particular attention to every tree. This is made possible by the relative absence of administrative restrictions; much freedom is given to the "man on the spot".
4 P. FOURCHY, "Quelques aspects de la sylviculture contemporaire", Revue Forestière Française, May 1962.
This new fashion spread rapidly in Europe. It encountered a favorable reception in France, where foresters had been brought up with Parades' celebrated phrase: "To imitate nature, to hasten its work, this is the basic maxim of silviculture". But even in the country of Cotta, the evolution was initiated as early as the beginning of the century, mainly by Mayr through his book, Waldbau auf Naturgesetzlicher (Silviculture in Conformity with Nature). The trend has rapidly dominated European silviculture, which has become enriched with several important developments such as "jardinage", ii selective improvement", "management by control", etc., in which the spirit of modern thinking has been crystallized.
As already said, this evolution has been encouraged by the development of the biological sciences. Development is still in progress, and it is to be expected that silvicultural evolution will also continue. In fact, a third type of silviculture seems to be emerging, whose development may be decisive in particular for the future of Mediterranean forestry.
The new silviculture
The new silviculture is, to no small extent, a result of increased needs for forest products, and of the development of vegetative selection. On poor soils natural evolution leads to stands yielding a very low output. In addition, the original natural forests are either disappearing almost everywhere as a result of human action or else their products are no longer required. In many cases, therefore, the return to a natural "climax", particularly by natural means, is hardly to be desired.
The progress made in vegetative selection and tree hybridization has given fresh hope for a better utilization of soils by trees. The use of selected clones and hybrids in modern poplar cultivation, accompanied by very intensive treatment of the stands, has permitted yields never attained by the classic forest - in fact, ten or twelve times the yields of the latter. Similarly, the introduction of selected types of willow, although still in its experimental stages, would seem to promise unexpected, almost fantastic, yields per unit.
Obviously, these selected clones or hybrids are expensive and can only be used with the maximum benefit on very well prepared soils and through intensive tending. It seems as if silviculture now aims at suiting the environment to the tree; and this would, indeed, be the final stage in an evolution which has passed roughly through the following stages: neglect of the environment, subjection to the environment, adaptation of the environment. There is, in fact, a growing realization that modern silviculture cannot consist of a simple return to nature, and that foresters should not refrain from establishing stands which are entirely different from the natural ones, nor reject any means of increasing yields: fertilizers, irrigation, working of the soil. 5
5 H. FRANZ, "Naturgemässe oder standortsgemässe Waldwirtschaft", Allgemeine Forstzeitung, Hochschule für Bodenkultur, Vienna, No. 68, November 1967.
A new, intensive type of silviculture is therefore envisaged, in which the ecotype, the clone or the hybrid is the protagonist (the stand thus being composed of repetitions of "the same tree") and in which there is almost constant human intervention. On such a basis, the characteristics of the new silviculture inevitably become: even-aged stands of artificial origin, mainly through planting; intensive working of the soil, use of fertilizers, pruning, etc.; clear felling to reap the products.
An illustration of the new trend is provided by the action taken by some paper companies. For instance, the Spruce Falls Company at Kapuskasing, Ontario, whose annual output is 300,000 tons of paper for the New York Times, has begun an important afforestation project aimed at covering its wood requirements. The project is to be carried out in natural forests of Picea mariana, owned by the company and where the yields no longer satisfy the needs of the mill. More striking is the example of Japan. Although natural forests cover 61.8 percent of the land area, the new five-year forestry plan aims to raise forest productivity by artificial reforestation, stressing intensive systems of forest management and the development of forest tree breeding projects.
Studies recently carried out by Paterson and Weck 6 on the correlation between natural environment and potential productivity of the forest cannot but favor this new evolution. The findings of these two distinguished scientists, taken in conjunction with the fact, recently established by research, that productivity is practically independent of methods of thinning, 7 enables us to begin to discover the production ceiling of natural silviculture. Paterson, for instance, considers that the productivity of natural forests under the very favorable natural conditions of equatorial stations with high rainfall, does not surpass the figure of 17 cubic meters per hectare, inclusive of non-utilizable wood, roots, etc. Under these circumstances, it seems clear that supplementary energy must be afforded to the complex climate-soil, if higher outputs are to be expected.
6 S. S. PATERSON, The Forest Area of the World and its Potential Productivity, Department of Geography, Royal University of Göteborg, Sweden, 1956.
J. WECK, "Climate and potential productivity of forests" Forstarchiv No. 11. Hannover, November 1957.
7 R. SCHOBER, "Deutung und Aussage der Durchforstungsversuche: II. Die Buchen-Durchforstungversuche", Allgemeine Forstzeitschrift, Munich, No. 33-34, 21 August 1967.
FIGURE 1. - Artificial plantations with fast-growing species (poplars at Santa Fé, Granada, Spain).
FlGURE 2. - Mediterranean park-forest managed mainly for grazing and fruit production (oak stands in Turkey).
It will now be asked what has become of the former apprehensions about the disease potential and the impoverishment of the soil in pure stands As regards the former, pathologist, T. R. Peace, 8 writes.
"The author has no desire to deny that, in general, the disease potential of a pure stand is higher than that of a mixed one containing the same species. Though it may be desirable to remember that the most devastating tree disease so far encountered, chestnut blight (Endothia parasitica), destroyed chestnut in America mainly in mixed stands. It can be said that almost all agricultural crops are more liable to disease than their wild counterparts, nevertheless, the yield of usable material is invariably higher under managed cultivation. It is often suggested that this is due to the use of modern chemical disease-control methods, most of which are not applicable in forestry outside the nursery. But surely it is unnecessary to resign ourselves to the belief that we cannot elaborate methods of control lying between these inapplicable chemical methods on the one hand, and a slavish faith in the mixed "natural" forest on the other. In any case, there is little evidence in Great Britain that pure planting has, as yet, led to any major disasters. Nor, in the author's opinion, are any such disasters immediately imminent."
8 T. R. PEACE, "Approach and Perspective in Forest Pathology", Forestry, Vol. XXX, No. 1, 1957.
FIGURE 3. - Mediterranean natural pine forests (Pinus laricio) in Cyprus.
As to the impoverishment of the soil, the well-known pedologist, Duchaufour, 9 may be quoted:
"The forester therefore disposes of two methods of action for exerting a favorable influence on soil evolution: a natural, long-term method, by the maintenance of a biologically balanced stand, which itself ensures the conservation of its fertility; this is the method employed by traditional silviculture, and though extremely slow, it is usually sure An artificial method, more immediately effective, through the combined use of working of the soil and of fertilizers or ameliorators: this method is more rapid, but also more violent, and therefore more dangerous; it should be put into practice only with the necessary scientific guarantees, hence after a complete study of the environment."
9 PH. DUCHAUFOUR, "L'action des divers types d'humus sur les processus d'entraînement dans le sol forestier", Revue forestière française, December 1957.
It must be admitted that silviculture as here described should more accurately be defined as tree farming. This does not imply that the new forestry techniques must be exactly the same as those used in agriculture. It means that forestry, like agriculture, should be improved through the use of techniques based on the knowledge accumulated about artificial tree crops, until a new stage is reached in which the trees grown and crops produced are superior to those resulting from natural stands. In most countries, admittedly, forestry is largely based on the use of existing, more or less natural forests, just as agriculture, in some very backward places, is based on the use of existing, more or less natural herbage. But if wood is to continue to occupy an important place in the economy, it would probably be advisable to keep in mind the idea of improvement beyond the limits set by nature.
Foresters may therefore now have to face two different tasks, one dealing with the natural forest and the other more with wood crops. It will be up to the forester to ensure the best management of natural stands, from which the maximum range of benefits must be drawn. But a new method - tree farming - seems to be open for producing wood of the quantity, quality and price required by an expanding economy. For this, many new techniques will still have to be elaborated.
The aim of present-day forest management, by various methods of cutting, is to allow the annual leaf fall, branches, barks, fruits and detritus from cutting, to remain in the forest. It is the decomposition of this residue which supplies the soil with those elements which render possible a sustained yield.
In Mediterranean forestry, on the other hand, seeds, branches, bark, etc., which contain the greater proportion of mineral nutrients, are in most cases removed from the forest. In fact, it is the production of fruits, fodder, extracts, etc., which makes high demands on the soil, that gives to Mediterranean forestry its distinctive character.
This feature has necessitated treatments very different from those used in forestry proper, a situation that has long been understood both by foresters and forest owners of the region. Foresters have often warned about the impoverishment of forest soils owing to the removal of foliage and fruits. That forest owners are aware of the special Mediterranean conditions is clearly shown in the present intensive treatments carried out in most encinares and montados in the Iberian peninsula, in the best chestnut stands in Italy and in those of Valonia oak in Turkey. The survival of the chestnut as an important element in Mediterranean forestry is due, to a large extent, to a change from methods based on pure silviculture to an intensive forestry based on tree farming.
It seems, therefore, that an increase in the specialized production of Mediterranean forests is mainly dependent on the improvement of straight tree farming methods. Genetical selection and breeding of types, for instance, has frequently been pointed out as one of the most promising techniques to be adopted. Vieira Natividade 10 has indicated the importance of selecting clones and of intensifying research into vegetative reproduction as regards the cork oak. A better knowledge of the techniques of pruning and of the working of the soil in conjunction with fertilization and disease control is also urgent, in order to increase the production of fruits in the encinares. 11 The case would not appear to be very different for the production of resins.
10 V. NATIVIDADE, La Suberaie méditerranéenne - Situation et perspectives d'avenir, Lisbon, 1966.
11 M. M. BOLAÑOS, Consideraciones sobre los encinares da España, Instituto Forestal de Investigaciones, Madrid, 1943.
But increasing the production of so-called accessory products is not the main challenge to be met by Mediterranean forestry. To obtain sawnwood and pulp of the required quality, and above all in the required quantity, is an urgent need. In meeting the demand, the experience already gained by Mediterranean foresters in tree cultivation could be very valuable. The work already undertaken in Italy for the simultaneous production of better timber and better fruits in the same chestnut stands, by means of tree cultivation, would seem to show clearly the future direction to be followed by Mediterranean forestry.
Future of the natural Mediterranean forest
There still remains the problem of what policy to follow as regards the existing natural forests. In general the policy will depend on the physical, economic and social roles which the forests in question are still playing. Their economic role is considerably diminished. There remains their protective role and, to a lesser extent, closely dependent on local conditions, the social role. Are the roles played by these forests sufficiently important to justify keeping them under their present form of management?
If it is thought that the answer is affirmative, then it is essential that forest research should evolve methods of evaluating in terms as concrete as possible the physical and social benefits rendered by these forests, so that their claims can be asserted against the advantages of other competitive uses of the land. This has a very close bearing on the solutions to be decided for the present problems of the mountain areas of the Mediterranean. The possible solutions here range between maintaining mountains and hills as forest reserve, with light complementary forest industries, while agriculture and grazing continue at a subsistence level for a small population, and the retaining of the present populations on the land by every means possible.
If, on the contrary, it is thought that the answer is negative, then the only alternative is to render the forests economic, without forfeiting the social and physical benefits they may still afford. This can, in fact, be achieved by purely silvicultural methods, such as the introduction of conifers, the transformation of coppice into high forests, etc. The applicability of these courses is mostly confined to the more humid zones, and the conversion of unproductive hardwood areas into the desired forest types can be more expensive than the establishment of plantations. 12 Under these circumstances, it may be wondered whether the straightforward adoption of tree plantations should not be the central theme of every Mediterranean country. It is probable that artificial plantations will alone be capable of easily supplying those ample quantities of wood that, no matter what the technological qualities, will always constitute the essential basis of forest industries for the area.
12 "Stand conversion costs varied from $43.57 to $80.92 per acre, depending on the hardwood control method employed. Such costs are considered far in excess of those feasible for plantation establishment. These costs should be borne in mind by foresters acquiring land for planting with pulpwood or sawtimber production as the objective. Recently abandoned fields where brush has not yet completely occupied the site can be planted at a more reasonable cost and will present fewer forest management problems". Bulletin 403, West Virginia University Agricultural Experiment Station, October 1957.
Unfortunately, in the Mediterranean region, the establishment of tree plantations can be seriously hampered by the hunger for agricultural land resulting from the pressure of population. Here then is a dilemma to be resolved so far as the future of Mediterranean forestry is concerned.