NATURE ORIENTED SILVICULTURE IN THE SOUTH-EASTERN ALPS

Selvinat Socrates
schema nuovo 28.7.01

Pietro Piussi

Dipartimento di Scienze e Tecniche ambientali forestali
Università degli Studi Firenze (Italy)

1. Definition

During the second half of the XX century foresters working in the South- Eastern Alps regions in Italy became more and more interested in the concepts of nature oriented (or near to nature), silviculture (from now on NOS) and started to implement them..

With NOS we define an approach to silviculture aimed at carrying out economic, protective, aesthetic goals adopting criteria consistent with the spontaneous dynamic of the forest stand, that is trying to use as much as possible natural factors and mimic natural structures and processes.

According to some critics NOS is a nonsense since forestry is always connected to a "non natural" withdrawal of matter from the ecosystem, consequently to artificial changes in structure and dynamics. In fact NOS represents a general approach to forest management and therefore, only as a consequence, a silvicultural system (one or more) and a utilisation method.

The origins of NOS can be tracked back to the concept of silviculture proposed by Gayer (1886) who was against the clear cut system and in favour of a long regeneration period, mixed stands, and irregular texture of forests. More recently the association Pro Silva supports the ideas of NOS since in such a way it is possible to achieve a better functionality of the forest system and to satisfy the protective role, the request of primary production and the maintenance of cultural and aesthetic values.

2. Geographical distribution

NOS developed in the South-Eastern Alps (Regions of Friuli-Venezia Giulia, Veneto, Trentino-Alto Adige) where the main vegetation types, in an altitudinal sequence, are mixed oak stands usually managed as coppices; chestnut coppices or groves, black pine plantations, beech (coppices or high forests) forests, pure or mixed stands of beech, silver fir and Norway spruce, Scots pine stands, mixed conifers forests, subalpine norway spruce forests, subalpine forests with Swiss stone pine, Norway spruce and larch forests variously combined ore pure.

All these are mountain forests which must be managed for multiple use since they are usually placed on medium to steep slopes, where soils are usually thin, rocky outcrops, and landslides and erosion phenomena are widespread. Many woods belong to the Municipalities, mainly at the intermediate and high altitudes, whereas at low altitudes (Prealpine area) most of forests land belongs to small private owners. Quite small is the forest area belonging to the State or to the Regions. The distribution of many of these forests, especially at high altitudes, coincides with that of tourist development areas (settlements, ski resorts, trekking itineraries).

Obviously NOS cannot be practised in coppices, nor in chestnut groves and its leading criteria can be implemented only gradually and partially in stands whose structure is far from that which represents the target: for instance spruce or black pine plantations.

3. The departure situation

It is necessary to recall the situation of forests and forestry during the years following World War II. (1940-45). Because of the intense and prolonged exploitations due to the poverty of mountain populations, the exceptional cuts and damages caused by WWI (1915-1918) which was fought in many forest areas of the Eastern Alps, and WWII, the limited technical and scientific knowledge, the administrative and political problems, forests were frequently degraded. The main characteristics were:

A. low biomass and impoverished tree composition
B. low productivity (soil degradation caused by erosion, litter collection etc.)
C. widespread grazing in the forest
D. wide areas covered by plantations done, using only one tree species, on areas previously occupied by woods destroyed during the war or by meadows and pastures not utilised any more
E. large use of the clearcut system followed by artificial regeneration
F. wide distribution of oaks, chestnut, beech, hophornbeam etc. coppices (for the production of charcoal)
Essentially the majority of these forests provided fuelwood, timber, forage, litter which were extremely important for the economy of mountain territories, so that the role of soil and water conservation were matters of secondary importance (had a second rank position).
We must also remember that in some areas of Friuli and Veneto the traditional selection cut system, more economically than ecologically oriented, was still practised.

4. Development of NOS in Italy

Since the Fifties in the Region Trentino-Alto Adige, and later in the other Regions of the North West of Italy, foresters became aware that this situation was totally unsatisfactory from the productive and the protective point of view. Gradually a new model of forest management was defined to satisfy the following targets: better mechanical and biological stability of forest stands, better productivity, higher protection of soil and water. The principles and objectives of multiple use principle were revised with the addition of the recreational use of forest land. Forestry operations were supposed to run with a higher efficiency (in terms of labour sue, safety, losses of timber, damages to the forest). At the same time the problems of fauna were taken into account, especially those of game, sometimes a damaging factor (red and roe deer, chamois) sometimes an endangered species (capercaille, brown bear). More recently it has been appreciated the importance of dead wood (standing snags and logs lying on the grounds) for biodiversity, regeneration and soil characteristics.
When pioneer stands were involved (f.i. pine or larch woods) the guiding line became those of favouring the spontaneous succession.
Silvicultural models are shaped according to stand structures of unevenaged forests of Cadore (Veneto) and Swiss forests managed in accordance with the Femelschalg (modified uniform system) and Plenterung (selection cut system). In such a way timber marking criteria were defined dealing with both individual trees and whole stands. Some targets were: biodiversity in the tree layer, more complex vertical and horizontal structure, standards for an optimal total standing volume and its distribution in size classes.
Coppices belonging to Municipalities were usually prepared to conversion to high forests through a series of thinnings.
Silvicultural management is supported by other activities aimed at providing a general frame for forestry activities improving living conditions of forests workers.
Silvicultural practices cannot be discussed or implemented independently from a spatial and temporal frame; therefore management plans for all public properties are prepared and periodically revised. NOS finds an extremely useful support in the management method named "control method" which has been adopted in many forests. According to this method the allowable cut (and its distribution in various diameter classes) is established in compliance of the results of periodical detailed inventories: it is thus possible to know the growth of the stand and its reaction to previously done cuts or to damages caused by weather or parasites with a high degree of precision.
Watershed management has been developed through the construction of small dams in torrents, plantations aimed at reducing erosion, avalanche control structures.
Working conditions have been improved through the construction of forest roads (paying attention to soil stability and to the visual impact) and the development of logging methods and technologies.
Timber prices have been steadily declining during the last decades whereas environmental safety has been increasingly appreciated and the recreational value of rural area became a strong point of the tourist economy. Forest economy so as land use choices are strictly linked to the general problems of the territory; forestry was therefore integrated in provincial or regional planning.

5. Silvicultural techniques

More specific silvicultural criteria are shaped for the various forest types and, within each type, in compliance of fertility, structure and standing volume. Basic characteristics are dominant height, standing volume, its distribution in diameter classes and annual increment.

The targets of NOS are:

Targets of NOS can be reached by high forests in which the silvicultural methods applied can be the selection system of the Swiss Femeschlag system (that is a uniform system in which cuts are done on patches and strips according to site and stand conditions and the regeneration period is not previously defined and is rather long) Clear cut is banned, except on small areas or for sanitary purposes, since it changes abruptly energy fixation and mineral cycling, and wildlife is heavily disturbed. The traditional classification of intermediate and final cuts disappears and is replaced by the concept of cultural cuts which combine both thinnings and regeneration cuts.

NOS does not suggest a new silvicultural system, different from, and opposed to, the traditional ones, but a new way of implement already known systems. It is neither in favour of a specific spatial structure even if a multilayered structure is preferred. The implementation of cutting systems becomes less tied to standard pattern and is aimed to obtain locally specific objectives of composition, spatial structure, stability and yield. The last objective consists both in quantity and wood quality.

Cuts are done with a 10-20 years periodicity, depending on site productivity, stand conditions (growth, health, regeneration etc.) and general economic constraints. The concept of rotation age has no relevance any more.

The evaluation of economic aspects of NOS are quite complex (and they will not be treated in detail). The forest road system, the technological improvement (cable, tractors, etc.) and the improvement of labourer's skills can balance the technical difficulties of logging unevenaged stands and small areas. On the positive side there are also the use of natural regeneration which takes places under the cover of the old stand, and the absence of early interventions (weeding, early thinnings, etc.).