Hubertus Prange1
1 Fachhochschule Weihenstephan, 85350 Freising, Germany.
Abstract
Starting with the historical forest exploitation in central Europe, this paper presents the change in forest management.
The fast development of the industrialized society (population, economy, science, environmental protection) after the second world war has introduced important new approaches to forestry. But it has also placed forestry into a situation where a precarious balance between ecology and economy, between nature-oriented and profit-oriented thinking has to be achieved.
Besides the classical function as a supplier of raw materials, new forest functions are recognized, i.e. the protective and the recreational functions. Mappings of the forest functions define their hierarchy and, if necessary, special silvicultural measures.
The failure of the exclusively profit-oriented classical forestry with large-scale pure stands of spruce and pine treated on the clear-cutting system, and the increase of scientific insights into the workings of the eco-system of the forest result in a change in the silvicultural approach. The features of the presently predominant forestry in harmony with nature are listed exemplarily.
Opening-up is necessary for any kind of forest use, but to achieve a natural way of managing forests it is absolutely indispensable: Forest tending means road construction (Leibundgut 1971).
After an overview of terminology, tasks and effects of forest opening the paper presents a short evaluation.
Planning new roads includes an inspection of the environmental effects and has to take into account the requirements of environmental protection and landscape tending.
In this way forestry in harmony with nature offers a good chance for the certification of the wood raw material.
Introduction
Virgin forests as well as managed forests (including man-made forests) cannot be put to use, established, tended or protected without a previous forest opening.
Since the early Middle Ages, the forests in central Europe have been subject to intensive use, with different effects on the state of the forests, which occasionally were even completely destroyed. These effects depended on factors such as the demand for wood or the accessibility of the forests. During the last century, however, extensive efforts have been undertaken to re-establish the original, natural state of the forests. This paper intends to present the dominant lines and the preconditions of this development as a basis for discussion.
Forest development and forest use from the beginnings until 1800
After the end of the last glacial period (about 12 000 years ago) vegetation, including trees and shrubs, reappeared all over Europe within a relatively short time. At the beginning of the Christian era (i.e. about 2000 years ago), most of central Europe, with the exception of bogs and the highest mountain areas, was covered with forests. The composition of tree species in these forests is called "natural" because it was at first practically untouched by human influence.
Depending on the habitat, mixed woods predominated on flat ground and on hilly areas, while. mixed stands of maple and ash grew in the valleys and ravines; the lower regions of the mountains were covered with deciduous forests (beech, maple, elm, ash), the medium regions with mixed mountain forests (beech, fir, spruce, maple, elm, ash), and the highest regions with coniferous forests (spruce, larch, stone pine).
For Germany, it is assumed that the original composition of tree species was 75 percent deciduous trees and 25 percent coniferous trees (Hausrath 1982). The present look of the forests in Central Europe is the result of 2000 years of intensive human influence on the natural development of the vegetation.
Ever since man started to live in permanent settlements (neolithic period, beginnings of agriculture), he influenced the state of the forests by his use: wood clearings for settlements, for arable land and grazing, the use of wood for construction purposes and as fuel.
The growing population and the ensuing inevitable wood clearings for new settlements, for more arable land and grazing, led to local overexploitation, which was furthered by bad road conditions and the extension of wood pasture. Documents from the eleventh century to the fourteenth century describe the decline of valuable beech-oak forests to unprofitable shrub. However, the core of large forested areas, especially in mountain areas, still consisted of virtually primeval forests where, due to the difficulties of transport, rarely any use was made of the wood.
The consequences of such irregular forestry were recognized at a very early stage. As a consequence, the methods and the amount of exploitation of the forests became regulated, a regeneration of the forests was decreed.
The coppice system was practised from the ninth century until the nineteenth century, locally even in the twentieth century. It met the local demand for fuel, fence posts and fascines.
From the Middle Ages until the middle of the twentieth century a composite forest system (coppice with standards) was also in use, which supplied fuelwood as well as timber.
The uncontrolled and, in areas of mixed coniferous forests, even a controlled femel method was practised locally as early as the fourteenth century.
Forest statutes and the development of a forest administration were meant to guarantee well-ordered forestry. Apart from the overexploitation caused by population growth, which sometimes led to the complete destruction of forests close to settlements, there was the huge demand for wood for the salt mines (in Hallstatt/Salzkammergut as early as 1000 AD), for glass works, charcoal production, mining and foundries, as well as for the developing timber trade (e.g. timber for shipbuilding in the Netherlands).
Until the nineteenth century, the opening of forests was primarily aimed at making them accessible to use, in other words to open transport routes for the wood to the consumer. If there were no natural or man-made waterways available, the wood was transported on wagons drawn by horses or oxen. When tracks were no longer usable, new parallel ones were laid across the stands. In mountainous regions, the wood was slid or "shot" (schießen) downhill, a method that caused permanent damages to the remaining trees, to the soil (starting points for erosion), and to the timber itself (high losses).
Less destructive transport methods for the soil and for the stands were skid and sledge trails and logging chutes made of wood or earth. These were built in Bavaria until the middle of the twentieth century. Logging chutes as well as rafting systems (mountain streams, rafting channels, rivers), however, had disastrous consequences for the adjoining forests. In order to profit as much as possible from these constructions, clear-cuttings were extended further and further until wide areas were denuded of trees (e.g. clear-cuttings in the central Black Forest in the surroundings of rafting systems approximately in 1765).
Only under optimum conditions such as fertile humus soil, survival of seed trees, top wood and branch layer, years of seed production, minimal grazing, a spontaneous natural reforestation could occur which was then supplemented by deliberate sowing and planting.
In order to achieve seeding from adjoining old growth, strip cutting, strip shelterwood cutting, patch cut system, which took into account dominant wind direction and transport directions, were recommended already in the eighteenth century.
It became obvious that in all those cases, where the clear-cuttings were more extensive and where wood pasture was practised more intensively, spontaneous, natural reforestation did not occur. In the mountainous areas, even karst developed locally, similar to the developments in the neighbouring Mediterranean countries in prehistoric times.
The conclusion is that, in spite of early forest statutes, administrative measures and silvicultural recommendations, the high demand for wood led to the practically complete destruction of accessible forests.
Forestry from 1800 to 1950
After the first starts towards the end of the Middle Ages, since the 18th century foresters have developed the principles of a planned and ordered forestry, where silviculture, first as an empirical branch of knowledge, later with a sound scientific foundation laid in this century, became increasingly important.
This section covers the most important points in this development.
1. Establishment of a forest inventory with periodic planning and control as the basis of sustained wood production, a principle which remains important for modern forestry.2. The systematic opening of the forests - combined with the forest inventory - by hauling roads, logging railroads and connections to the general railroad network.
3. The end of the coppice and the composite forest systems and the introduction of the high forest system with the appropriate methods of regeneration and exploitation which, however, still included clear-cutting.
4. Reforestation of the devastated sites and the conversion of unproductive stocks, mainly using pine on poor sites, and spruce on better sites, even if these sites were beyond the natural range of the species.
Since attempts to regenerate deciduous forests (beech, oak or other valuable broadleaved trees) on open spaces were unsuccessful due to the damages caused by late frost, devastated soil, poor seeding, wood pasture, browsing by game, there was an enormous increase in the plantation of coniferous forest since young trees of these species grow fast and there is a great height increment of standing timber even on poor sites. This increase was so extensive that it resulted in a change of the proportion of the tree species: according to Haurath, while in 1300 we find in Germany 75 percent broadleaved trees and 25 percent coniferous trees, in 1937 we have only 30 percent broadleaved trees compared to 70 percent coniferous trees.
This extensive plantation of a great number of pine and spruce in pure crops (often trees of inadequate provenance and planted on unsuitable sites) made the trees susceptible to biotic and abiotic damages.
5. The end of wood pasture supported the regeneration and the tending of crops.
The end of the right to collect litter, together with the input of atmospheric nitrogen, helped to improve the quality of woodland soils.
6. The development of the different scientific branches of forestry, such as soil science, silviculture and the introduction of systematic forestry instruction and training finally created the theoretical and practical conditions for an improvement in the management of the forests.
Natural forestry
The fast development of civilization (population, economy, science, environmental protection) after the second world war promoted forestry to a great extent. But it has also placed forestry into a situation where a precarious balance between ecology and economy must be reached.
The functions of the forest have expanded: originally it only supplied wood and was used for other minor functions. By now, we have to deal with new functions, besides the supply of raw materials, mainly the protective (environmental) and the recreational functions, which have already been included in forest legislation and are now recognized worldwide by the important documents produced by UNCED in Rio (1992).
Primary functions of the forests are defined and entail determined measures including restrictions on the use of sensitive areas (e.g. ban on the construction of roads and tracks).
The term "sustainability" - originally only applied to the supply, the use, the production and the yield of wood or timber - is extended to the sustained fulfilment of all functions of the forest and, in this context, conservation and improvement of the site and fertility of its soil are of primary importance.
We can observe a fundamental change in the silvicultural approach that affects silvicultural aims and intentions, i.e. the transition from the classical silviculture to a natural, ecologically oriented silviculture.
This change - taking its starting point in southern Germany, France and Switzerland - is connected with the names of K. Gayer, A. Engler, Ph. Guinier, H. Biolley, W. Ammon, W. Schädelin, H. Leibundgut, H. Mayer. It was, and still is, due to various factors:
· failure of classical forestry with its exclusive orientation towards economic success;· the problems caused by the extensive plantation of spruce and pine in pure stands (often on unsuitable sites), such as storm damage, snow breakage, insect attacks, degradation of the soil and the ensuing decline of the yield;
· management and cultivation on the basis of the clear-cutting system as an essential harvesting and regeneration method and the related problems in these partially unstable stocks of even-aged forests;
· the increase in scientific insights (e.g. into the ecosystem of the forests or cross effects of tree species and site).
Natural, ecologically oriented silviculture has become by now the predominant approach in central Europe. The functioning ecosystem of the forest as a natural mixture of tree species, and natural regeneration forest are regarded as the main conditions for low-risk, sustained, economic and healthy forest management and cultivation. The goal is the creation of varied, natural, mixed and stable forests. This does not exclude the existence of crops consisting mainly of fast-growing coniferous trees, but they must always be combined with deciduous trees, outside their natural range on stable sites.
Features of forestry based on natural conditions:
· sustained protection of the forest ecosystem;· sound knowledge of the site (site mapping);
· the use of tree species suitable to the site and of guaranteed provenance when establishing a stand;
· no clear-cuts;
· forest restoration by way of natural regeneration under the shelter of mature trees;
· in case of stock conversion sowing or planting under the shelter of the previous stand;
· femel system (selective cutting) as long-term treatment;
· long-term regeneration over long periods (mixed stands, trees of varied age classes, genetics);
· careful and gradual removal of the overstorey trees;
· maturing of sound old crop (heavy timber);
· forest tending with the aim of creating varied, natural, mixed and stable forests (tending of young growth, thinning, selective logging);
· thinning in 30 to 60 year old pure stands of coniferous trees which were often planted too densely in order to avoid loss of increment and to increase stability;
· no removal of dead wood;
· formation of forest borders (also along roads and tracks and rivers);
· operation of machinery and harvesters with little damage to soil and trees;
· forest opening as a precondition of this type of forest management.
This overview includes features that are based on historical and practical experiences as well as on scientific insights.
The application of the principles of a sustained, natural forest management, however, is not possible without the previous opening of the forests. Or, according to Leibundgut (1971): Silviculture means building roads.
Road development as a basis for natural forest management practices
1. Systematic presentation and terminology
From the point of view of natural forest management simple road construction is not sufficient. Forestry production always covers considerable areas; so according to Dietz, Knigge, and Löffler (1984) a proper forest opening always has to be developed in a sequence of stages.
Stage 1: connecting the forest to the public transport system (roads, railroads)
Stage 2: access to the different parts of the forest
Stage 3: access to the single compartments or units of the forest
In forestry publications as well as in practical work the following system is generally accepted: "basic transport system" with haul roads, "minor transport networks" with tractor or skidding roads. In other words, the basic transport system is supplemented by the minor transport system. The combination of both is called a "combined motor road and skidding road network". There are several solutions for the minor transport network. The choice depends on factors such as the character of the soil, rough ground, obstacles and inclination of the slopes:
· skidding tracks [3-4 m wide, spacing pattern: 20 or 30 (50) m\ in flat ten-am suitable for motorized harvesters:· tractor or skidding roads (low standard, sometimes consolidated tracks) on slopes;
· cable cranes on hill areas and especially in the Alps because of the high gradient of the terrain and the low road density (about 20 m/ha).
Mobile short distance (< 300 m) and medium distance (< 600 m) cable cranes with loads of 2-3 m3 and with a track width of 2-4 m have proved to be the best solution for normal uphill yarding.
2. Meaning
The opening-up of forests by roads with adequate planning and execution creates the necessary framework for any kind of forest management. For sustained, natural forest management, an adequate transport network is an indispensable condition.
(B = basic transport network
M = minor transport network):
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General |
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1. accessibility of the forests |
B, M |
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Planning |
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2. permanent structuring of the forest areas into compartments |
B, M |
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3. simplification of the planning, execution and control forest management work |
B, M |
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Forest tending |
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4. purposeful, adequate and well-measured tending appropriate to the respective type of stand and the stage of development |
B, M |
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5. starting and securing regeneration |
B, M |
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6. no removal of isolated groups of old crop and dead trees |
B, M |
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Harvesting (with the emphasis on methods that damage soil and stands) |
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7. use of environmentally acceptable technology (e.g. harvesters and processors) |
B, (M) |
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8. construction of landings |
B |
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9. wood transport |
B, M |
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Forest enterprises |
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10. motorized passenger transport (forest owners, foresters, forest workers, entrepreneurs, timber merchants, hunters) |
B |
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11. disposition of the work force (limited fields of activity, improved efficiency and quality of work, accident prevention, use of ergonomically designed work processes and machinery) |
B, M |
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12. freight transport, e.g. the transport of machines, tools, plants, fencing |
B, M |
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Forest protection |
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13. protective measures for the forest (execution and control, insect attacks, game, forest fires, clearance of waste wood and breakage) |
B |
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Activities connected with the public |
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14. guiding and controlling recreational activities, guided tours in the forest, actions connected with natural phenomena or in case of catastrophes |
B, (M) |
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Activities outside forestry |
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15. integrated forest opening not only for forest management, but also for the needs of agriculture, water conservancy administration, the ower industry and military forces |
B |
3. Silvicultural evaluation of the minor transport network
As shown in the above survey, the greatest value of the minor transport network is the creation and accessibility of limited fields of action. This has considerable beneficial effects on all planning tasks as well as on their execution, for example regeneration, tending, harvesting and protective measures.
Forestry according to natural principles aims at mixed, stable forests containing various age-groups of tree species well-suited to the locality. The opening of the forests, especially the development of a minor transport network, provides the indispensable preconditions for a purposeful regeneration of the forests with long-term prospects.
Regeneration cuts are executed along the central axis between the skidding tracks (or the cable cranes), and this is also the area where natural or artificial rejuvenation (sowing, planting) is started. From there, the mature trees are cut and hauled in the direction of the skidding tracks.
This procedure has already proved to work well in the regeneration of existing mixed stands (e.g. spruce/fir/beech) or in the conversion of pure spruce stands into mixed stands of spruce and beech or spruce, fir and beech.
Forestry based on natural principles also aims at the preservation of the soil and stands, which are, after all, the main production capital.
Careless harvesting can seriously damage both, as shown by historical and modern examples.
All harvesting and especially hauling methods whereby timber has to be moved on the ground (as opposed to helicopter logging, for example), inevitably cause a certain amount of damage to the soil (compaction) and to the standing crop (damages to the trunks and the roots, danger of rot). So it is an important aspect of process technology and working techniques to minimize these damages with the help of a minor transport network.
A special point should be mentioned in this context: it is important that heavy machinery (processors, forwarders, tractors) moves only on the skidding trail which should, depending on the circumstances, even be padded with brush.
The correct system of felling and short hauling distances also contribute to the protection of the soil and trees.
If this method is used, inevitable damages are mainly restricted to the borders of the hauling roads and skidding tracks, which means that the space in between is saved for healthy growth and high-class timber production.
4. Problems concerning the construction of forest roads
Plotting the opening of a forest depends on the type of forest management: the needs of an exploitation enterprise in a tropical forest differ considerably from those of a sustained-yield forest in harmony with nature practised in Central Europe. And even in the last case there may be differences according to the intensity of use and forest functions.
But this question, as well as the problems of technical planning and the economic aspects of forest opening, is not discussed in this paper. Some ecological aspects are, however, treated.
As mentioned above, one of the essential principles of forestry in harmony with nature is the inclusion of ecological concepts. However, during the last decade the number of people and groups (environmentalists) who were afraid that continued road construction would destroy the natural landscape and its recreational quality of regions like the Bavarian Alps became more vocal.
Crucial points are, for example, road width, clearing widths, slopes of loose stones, mud or rock slides, erosion, returning units made of steel or concrete, but also the loss of peace and tranquillity for man and animals brought about by increasing motor traffic, week-end traffic, and leisure activities (such as mountain biking). Fortunately, a basic transport network is already established in the public forests in southern Germany. Nowadays projected new constructions can no longer be executed without an inspection of the environmental consequences. That means that in addition to the points mentioned above - basic planning, technical planning and economic evaluation/cost-benefit analysis - environmental aspects have to be taken into account.
That means careful planning of the opening-up, optimum adaptation of the tracks to the topography, restricted road width, careful execution, no extension of the basic road network but rather use of the minor transport network of skidding tracks and cable logging systems.
Such carefully planned and constructed roads and tracks meet the requirements of environmental protection, landscape tending and recreational activities. Such roads are an essential part of cultivated land.
List of technical terms
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Sound forest management practice: |
This term may be defined as follows: the primary goal is an ecologically sensitive forest management in the sense of the Rio Declaration, e.g. |
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· reflects forest ecosystem and forest functions |
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· realizes nature conservation |
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· supports soil protection |
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· increases mixed forests (of mainly native tree species) |
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· uses nature-oriented treatments (natural regeneration) |
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· improves forest structure |
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Clear-cut system: |
Removing an entire stand of trees in a single harvesting operation |
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Patch cut system: |
Creating openings of a defined size depending on the site, system of regeneration and height of surrounding old trees. The openings are to be managed individually by planting, regeneration or direct seeding. |
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Coppice system: |
The main regeneration is vegetative sprouting of shoots or suckers; this regeneration method is limited to deciduous tree species. Rotation about 20-40 years. |
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Coppice with standards (= composite forest system): |
Coppice with individual trees, which are mostly established by seeding, remaining for more than two coppice rotations. |
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Seed tree system: |
Selected trees or tree groups are left standing after the initial harvest to provide seed for natural regeneration. |
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Shelterwood system: |
Mature trees are removed in three or more cut phases to achieve a new even-aged stand under the shelter of remaining trees. Variants are strip or group shelterwood systems to achieve uneven-aged mixed stands. |
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Selections systems: |
Harvesting single scattered individuals or small groups of trees to tend the stand to encourage natural regeneration and to maintain an uneven-aged mixed stand. |
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Sustained yield forest: |
Forest enterprise with sustained yield in wood production nowadays in wood production as well as in performance of the protective and recreational functions (forest benefits). |
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Ecosystem: |
An ecosystem comprises the entire, interrelated universe of objects and living organisms within limited space which is, nevertheless, open in all directions. This universe differs from its surroundings and is to a certain degree capable of self-regulating processes. The ecosystem of the forest consists of: |
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a) the living green plants (the producers), |
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b) the animals and plants which live on these plants (the consumers), |
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c) the animals and plants which live on dead organic materials (the decomposers), the soil, and the ubiquitous all-pervasive air. |
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Basic transport system: |
Haul roads connect the forests to the public transport system. |
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Minor transport networks: |
Allows access to the single compartments or units of the forest by skidding tracks, skidding roads or cable cranes. |
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