W. VIVANI and L. ROTAW. VIVANI and L. ROTA, of the Istituto Nazionale per Piante da Legno "G. Piccarolo," Turin, Italy, prepared this paper for the 13th session of the International Poplar Commission, held at Montreal, 23-28 September 1968.
Poplar cultivation in Italy and particularly in the Po valley, which is the example referred to for poplar cultivation in many other countries, is going through an economic and technical crisis as regards management planning and methods of cultivation, a crisis which may affect considerably its present structure.
The reasons for this crisis and its persistence are numerous, concomitant and interdependent. In the economic sector lies the unfavourable poplar market which, after a sharp drop in prices in recent years, especially for certain types of utilization, settled at a very low level. It has proved difficult to start an upward trend.
The following factors have contributed to this: the existence of many poplar plantations damaged by wood borers, the felling of immature plantations planted on agricultural land turned over again to crops due to the recent price increases in farm products, some not very fortunate legislative regulations,1 and the introduction onto the national market of exotic woods which have replaced poplar, particularly for the more remunerative uses such as plywood.
1 This refers to recent regulations governing the distribution of the produce from row plantations between the owner and the tenant. As the distribution of costs was not decided at the same time, the owners have been induced to anticipate felling.
Close cooperation among poplar growers through some kind of association could make for planned fellings, afford commercial protection to the product and thus stabilize prices, but lack of inclination toward cooperation among poplar growers hinders its establishment.
There are also other factors, each of which is partially responsible for the present situation of poplar growing in Italy.
The wide occurrence of various parasites which may be called traditional, particularly for example Cryptorrhynchus lapathi and Saperda carcharias among insects, and Dothicgiza populea among diseases, and above all the virulence shown in recent years by Marssonina brunnea, have inflicted a blow to poplar production, making necessary on the one hand more expensive cultivation and antiparasitic intervention and, on the other, causing deterioration in the quality and quantity of the timber produced.
In addition, the appearance in 1960-62 of a considerable number of unqualified entrepreneurs, who were confident of having found a new and advantageous field for capital investment, has given rise to unsound poplar cultivation, lacking in the necessary care and phytosanitary protection.
The first downward variations in price rapidly destroyed illusions and dampened enthusiasm, and finally plantations have been abandoned and sold at any price, and immature plantations uprooted; these events led to a further drop in prices. To this was added the ever-increasing shortage of agricultural manpower and the corresponding rise in wages. Faced with the present situation it should be considered what remedies exist, from a technical point of view, which could give a positive impulse to the market and serve as a guide to the bewildered poplar grower.
First of all, there is the possibility of reducing growing costs, by setting up appropriate organizations or by introducing new and improved mechanical equipment. As regards the latter, in recent years a steady tendency toward mechanization of all phases of poplar cultivation from planting to felling has been observed; specific problems caused by increasing technical difficulties are being solved, or experiments are being carried out.
This applies to pruning, which it is important to do well and in due time if assortments of value are desired; various machines particularly efficient for rapid and high standard work have been made. It is worth mentioning in this connexion that the existing equipment ranges from the more complex (such as pneumatic pruners or those which can climb up the tree and prune it at predetermined heights) to simpler manual pruners easy and efficient in use, so that it is possible to choose the most appropriate method according to the specific characteristics of the poplar farm (size, organization, availability of manpower, etc.).
Mechanical equipment has also been designed for felling, preliminary conversion and loading. These range from chain saws to fork-lift loaders installed in front of tractors for loading logs and gathering up branches; from mechanical chippers used for destroying discarded wood after preliminary conversion to mobile field barking machines.
In recent years considerable progress has been made toward solving the problem of stump removal, when felling has been carried out at ground level without any other work to facilitate stumping. A first step is the invention of stump removers with a circular crown, manoeuvred by a tractor of adequate power, which penetrates into the ground and then emerges carrying with it the so-called "carrot" formed by the tap root of the plant. However, the problem of disposing of the stumps remains an expensive task, to which should be added the problem of finding a place where they can be deposited.
For this reason poplar growers have welcomed new machines which can penetrate like a gimlet into the still rooted stump, chipping it up completely into small fragments. Afterward the land can be ploughed in the normal way by tractors, after removing any large roots which may have come to the surface. The soil is thus in good order while the fragments of stump, mixed with earth, undergo rapid decomposition. Such stump-chipping equipment has been made by skilled craftsmen and has not yet been produced on an industrial scale but, nonetheless, is used more and more frequently.
Another plan is to establish associations among poplar growers to carry out antiparasitic treatments considered indispensable for remunerative poplar cultivation.2
2 The importance of this argument has been stressed on more than one occasion by Dr. Federico Boccalari, President of the Italian Poplar Association.
Where these associations have functioned, they have proved to be particularly efficient, both in the amount of work and the reduction in costs they have obtained. A strong association would facilitate collaboration among producers, industrial users and consumers, which is indispensable for an effective improvement of the situation.
It now remains to consider management planning, which is the root cause of the bewilderment among poplar growers and which is at present under discussion. The subject is complex in that the factors and problems mentioned above are involved, together with more general ones which concern the future prospects of demand for timber as a raw material, and the organization and equipment of the wood-using industries.
Until today, the trend in the Po valley has tended toward establishing plantations for poplar cultivation of medium density (270 to 300 plants per hectare), with relatively short rotations (around 9 to 12 years). This was done to obtain young, medium-sized assortments capable of realizing more remunerative prices since the plywood industry was interested in these characteristics. As a result, other wood-using industries have followed this trend, installing equipment destined specifically for the manipulation and utilization of medium-sized poplar roundwood which was in good supply on the market.
This tendency is continuing, but there is some fear for the future in that, because of the various negative factors already outlined, poplar cultivation may diminish and so not be in a position to supply the ever-increasing industrial demand for timber recorded in the latest statistics. It would therefore be interesting to experiment with new management planning for poplar cultivation in order to determine the possibility of producing, at the lowest possible cost, the greatest quantity of wood per hectare.
In the first place it is necessary to recall that, by comparing yield data obtained from the felling Or two uniform plantations of 10 and 15 years respectively, Piccarolo, founder of the Istituto Nazionale per Piante da Legno at Turin, observed that, between the 10th and the 15th years, the volume of wood doubled.
Data given by an FAO study3 confirm this argument. It gives the growth of a poplar plantation in the different years of rotation, and it is apparent that total growth in the 15th year is more than double that in the 10th year, in the case of rather thinly spaced poplar plantations (250 plants per hectare).
3 FAO, 1958. Poplars in forestry and land use, FAO Forestry and Forest Products Studies, No. 12, Rome. See particularly Table 4.
For a more recent study by Prevosto4 on the growth and yield of clone I-214 (the most widely used poplar in the Po valley), as affected by spacing and length of rotation, even more precise and detailed information is given.
4 Michele PREVOSTO. L'accrescimento del pioppo euroamericano I-214 nei diversi ambienti della pianura lombardopiemontese in relazione alla spaziatura ed al turno. Ente Nazionale per Carte e Cellulosa, Rome, 1965.
The data which follow have been taken from various tables given in this study.
FIGURE I. - Line plantation of Populus nigra var. italica growing near Turin.
CASTELLANI
INCREMENT PER HECTARE OF POPLAR PLANTATION AT DIFFERENT YEARS FROM PLANTING AND AT DIFFERENT SPACING (CLONE I-214)
|
Spacing |
Years from planting |
Site class |
|||
|
1st |
2nd |
3rd |
4th |
||
|
Plants per hectare |
Cubic metres |
||||
|
Close (455-1111) |
5 |
165 |
144 |
116 |
78 |
|
10 |
445 |
388 |
296 |
213 |
|
|
15 |
554 |
464 |
363 |
259 |
|
|
Medium (278-435) |
5 |
112 |
92 |
70 |
50 |
|
10 |
404 |
343 |
255 |
174 |
|
|
15 |
616 |
503 |
371 |
230 |
|
|
Wide (200-270) |
5 |
88 |
71 |
53 |
41 |
|
10 |
319 |
269 |
221 |
158 |
|
|
15 |
572 |
486 |
402 |
272 |
|
It appears from these data that, especially in the medium and widely spaced plantations, to lengthen the rotation from 10 to 15 years results, in the last 5 years, in additional increment sufficient to make the poplar growers reflect seriously on the validity of the shorter rotations at present in practice.
Objections will be raised at this point on the effect of compound interest on planting and tending costs if rotations are lengthened. On the other hand, in recent years certain conditions have been observed which can lessen the force of such objections.
The appreciable increase in price of certain traditional farm products (cereals, legumes, etc.) makes it possible to reconsider the advantage of growing farm crops in poplar plantations during the first years of the rotation, that is, as long as the poplar foliage development permits the successful growing of crops between the rows. This form of double cropping in the early years brings in an annual revenue which can compensate the poplar grower for establishment and tending expenses, and considerably lessens the incidence of compound interest even in the case of a longer rotation.
FIGURE 2.- 4-year-old Populus X euramericana near Rome.
ENTE NAZIONALE PER CARTE E CELLULOSA
Italian legislation, thanks to the active interest of the Direzione Generale per l'Economia Montana e per le Foreste, now provides for state contributions toward the establishment of poplar plantations in the areas particularly suited to this cultivation (land along watercourses subjected to temporary flooding). These contributions, which may amount to 50 percent of the total establishment costs, thus reduce the initial investment and lessen the burden of lengthening the rotation. It is highly desirable that such provisions become even more widely applied so that Italian poplar cultivation may aim at greater timber production.
FIGURE 3. - 4-year-old Populus X euramericana near Bergamo.
CASTELLANI
In view of these varied related factors it would be useful to experiment with new management planning based on plantations with wide spacing, especially between rows, on the lengthening of present rotations; and on the association of tree growing with traditional farm crops, at least for as long as it proves to be economic and technically possible.
In this way it should be possible to achieve a greater timber production to meet the increasing demand for raw material, as well as a reduction in costs (reduced planting expenses due to wider spacing, possibility of obtaining an initial contribution from the State, revenue obtainable from associated farm crops). The overall balance sheet from poplar growing could thus be greatly improved.
It is obvious that such management planning will imply some changes in the ratios of the various assortments to be obtained, to the advantage of those destined to meet an ever-increasing demand, in particular for paper and particle board.5
5 As indicated by G. Giordano at the Turin meeting on poplar cultivation problems, April 1968.
There may be an initial disadvantage caused by the larger dimensions of the logs which Italian industries are not at present equipped to process. It will be up to them to adapt to the new conditions, taking into account that the disadvantage will be compensated for by a greater availability of timber.
