Centre de Recherches Forestières ONF, INRA Orléans, Ardon, France

In France, Norway spruce covers 6% of the total forest area (730 000 ha) and produces an average of 6 million m³ per year (Fig. 1). Overall productivity is 5.7 m³ ha^-1 year^-1 and can reach 15 m³ in the best sites. The main advantages of growing Norway spruce are: its biological plasticity especially with regard to soil nutrients, high yield and white wood production (used for paper pulp). Handicaps are the low level of wood mechanical properties, its sensibility to late spring frosts, drought, Fomes and bark beetles (Scolytus).

Just after World War II, a strong effort was put into establishing Norway spruce plantations in order to constitute a resource for construction and paper. In this time, plantations were done at high density (up to 10 000 trees/ha) and concentrated in low elevations. Norway spruce now reaches a top position among tree species with 40 million plants produced and 10 000 ha planted per year. The decrease has many causes such as the increasing planting of broadleaves (from 3000 to 11 000 ha) and the competition from a diversity of coniferous species (mainly Douglas fir). At the same time, thinnings were delayed in order to use the timber and thus make the first thinning more profitable. As a consequence, some stands were destroyed by storms or pests, and some others produced low-quality wood, reducing profits.

Today, 14 million plants are produced annually (including Christmas trees) and 1300 ha are afforested. Silviculture practices are changing with a better soil preparation, reduced plantation spacing (1300 trees/ha) and a more intensive thinning practice.

Stands disappearing in natural conditions. This concerns the populations with scattered distribution or present in small areas. Stands can be transformed when the natural regeneration is too low or insufficient during logging operations. Stands located near an expanded economic area are also threatened (industries, communication ways, ski resorts, etc.). Lastly, human mistakes such as clear-cutting of a valuable stand without any care for its substitution must not be forgotten.

Genetic pollution. Firstly, exotic material can be planted in the area with autochthonous or natural Norway spruce forests. The second aspect is less easy to consider. It appears in natural stands when seed collection is made on a very small number of trees (one tree easy to climb or near the roadside). The loss of genetic variability is great but unknown.

Industrial emissions. This phenomenon is the most spectacular insofar as areas are wide (Vosges mountains in France). So, many very valuable stands have disappeared. Some exist only in field experiments such as the IUFRO provenances tests.

Climatic change. Consequences of this phenomenon are unknown but cannot be neglected. Indeed, this small change can weaken stands which will be more sensible to stress or industrial pollution.

In a distant future, foresters can be confronted with two risks. The first one is a change of selection aims for desired characters: pest resistance, branch structure, wood quality. The second one is related to climatic change, mainly global warming. Gene conservation can be a tool which will be used to find the material adapted to the conditions of this distant future.

Three approaches are needed: preservation of our own resources, identification and fulfilment of our own needs for future breeding programmes, and participation to the international Network. According to the situation, some propositions will be made to react in emergency conditions or to prepare a planned approach.

Studies on the structure of the natural area were carried out by INRA for the IUFRO experiment 1964/68 in the eastern part of France. Studied traits were: adaptation, phenology, growth and wood quality. All these traits exhibit huge significant effects at provenance, region, country or area levels. Significant relationships with

geographical information were observed with altitude which presents a negative effect with growth and an optimal range between 200 and 1000 m for the Alps and the Carpathians.

A multivariate approach was performed by principal components analysis with provenance means for mortality rates before and after the first thinning (age 13 and 20), terminal bud flushing (age 5), total height (age 13), girth (age 20) and Pilodyn measurement (age 20). The main part of variability (63%) is described by axis one for regions and countries and by axis three for country. Some countries exhibit a huge heterogeneity for their principal components values. This heterogeneity can be explained by the heterogeneity of geographical conditions (area and elevation; e.g. in the former USSR), the mixture of native and non-native material (south of Sweden) and typical refuge areas during the last glaciation (Bulgaria, Greece, southern Yugoslavia).

Detailed research results are to be found elsewhere. On the basis of the traits measured in field tests on a sample of the whole natural resource, it is possible to gather provenances in regions, countries or main areas. Generally, the closer the regions or countries in Europe, the closer their parameters. Nevertheless, with better-defined material, such as progenies or clones originating from a region, information suggests a mosaic structure.

In France, natural Norway spruce populations are located in the eastern part of the country (Jura, Vosges and Alps) and belong to the margin of the Alpine area of the species' distribution range. In our conditions, natural origins exhibit weak phenotypic performance compared with exotic ones. Yet, they seem to have relatively good wood quality and, sometimes, a small branch diameter.

Up to now, selection criteria used in France have been related to adaptation, and include phenology, growth and wood quality. This latter trait is not well understood as so far. Firstly, it is highly negatively linked with growth, and secondly, genetic changes are not well understood. For these traits, the best provenances originate from the Carpathian area (south of Poland, Czechoslovakia, Romania) and the southern part of the Nordic area (north of Poland). The centre of Poland (disseminated stands) appears to be very interesting too.

As in other countries, the available information depends on the type of material used. On the one hand, a part of stands is registered by CEMAGREF (Centre national du machinisme agricole, du génie rural, des eaux et des forêts) which is in charge of collecting information (at the stand level) and deciding if the seed crop can be used for reforestation. The main part of the resource is covered, but the information is estimated (morphological traits, growth) and its accuracy is small (phenotypic estimation). On the other hand, a few stands are investigated in field tests by research institutes (INRA or AFOCEL). The accuracy is good but these tests are young (less 40 years) and the observed traits (adaptation, juvenile growth, wood quality) cannot be easily compared with the previous ones.

As shown in Table 1, Vosges (a very small natural area) and Jura (geographical conditions relatively homogeneous) seem to be well represented. Conversely, the Alps, which present a wide range of natural conditions (river, soil, exposures and elevation) are under-represented. In addition, the surface of stands and the seed collections are smaller.

Up to now, the provenance tests show that the natural variability is so large that it is difficult to describe and create a region of provenance. So it is possible to imagine a strategy with two terms (Table 2). Short-term action can be undertaken with a small number of stands which are well known or used as standards, or which present a risk of disappearing rapidly. The second, long-term action can be carried out on a larger number of stands which are representative of the whole resource.

The choice will be done rapidly (Option 1) or could require more information (Option 2) and take more time.

The objective of these rules is to maintain the natural structure and composition of a stand before doing anything. The main rules should be: delayed logging operations, collecting seeds with great care and representative sampling, storage of seeds in appropriate conditions (temperatures below 0ºC), silvicultural measures (low intensity of silviculture, natural regeneration or plantation with native seeds). Some of these rules could be followed by the Forest Service or with its assistance. Nevertheless, the constraints associated with these rules can be opposed to the profitability of the forest and should be compensated by financial help.

For Option 1, the study of genetic diversity could use information from evaluations of the existing field tests as well as biochemical analyses. For the second option, information provided from stand regulation and registration system (CEMAGREF) should be updated in the forest (in tests if these exist) or in early nursery tests which should be planned. The addition of information from biochemical analyses should give a good idea of the natural variability and of the sampling to be done.

After the gene conservation stands have been selected, the discarded stands are free from the temporary protection rules. The candidate stands are registered within the national network.

The area of the designated stands will be divided into two parts: core area surrounded by a buffer zone (area). The temporary rules applied become permanent and are completed by further specific rules for genetic resources conservation. The main difference between them could be the intensity and methods of silviculture. In the core area, silviculture could be done with a low level, in order to increase competition and thus support the specific character of a stand. For the buffer area, silviculture should be more intensive but planting, if needed, should always be done with seeds collected in the core area of the same stand.

The most important difficulty seems to be the agreement which could be found somewhere between a 'gentlemen's agreement' and a strong administrative rule. On the other hand, rules are accepted more easily if financial compensations are available. Another, also financial, consideration could be the use of seeds for reforestation purposes. The second difficulty is the control of the agreed rules and the related assignment of responsibilities. The third difficulty is the time and the cost. In the beginning of a such project, a lot of money can be spent, and a lot of people can act.

Three types of actors are involved in the gene conservation activities in France. Forest Administration (Ministry) is required to define rules and to suggest the financial means. Research institutes (INRA, AFOCEL, universities) can carry out studies and analyses, while development institutes (ONF, CEMAGREF) are essential for practical forest works such as identification of the gene conservation stands, silviculture and measurements.

The relevant French forestry organizations are listed below:

• AFOCEL: Association of Forest and Cellulose (private research)

• CEMAGREF: (Centre national du machinisme agricole, du génie rural, des eaux et des forêts) (state development)

• INRA: National Institute for Agronomic Research (state research)

• ONF: Office national des forêts (state forest management)

Two objectives are suggested for the activities of the international Network: identification and fulfilment of the national needs for breeding programmes and active involvement and contribution to the international networking activities. Our participation in the international Network may include:

• exchange of information

• joint collection of material

• exchange of material

• ex situ gene conservation (from global conservation to controlled conservation and breeding).

Studies on the natural variability have shown that material originating from Germany, Poland, Romania and Czechoslovakia is interesting and performs well in our conditions. As indicated in Table 3, material from Germany seems to be sufficient, and could be easily increased if needed. For Romania, the genetic basis we have is relatively small, but the natural variability is also comparatively small.

From Poland, a great number of genotypes is present in our field experiments and in the existing two seed orchards. As the original stands partly disappeared, owing to the industrial emissions, the material available in our tests could be used for reforestation in Poland. Such material will have a characterized genetic basis. Material from Czechoslovakia is of high interest but is not represented in our experiments except in the IUFRO provenance experiment. As parts of the country are also under the risk of genetic losses by industrial emissions, an effort should be made to collect the natural diversity. This material could be conserved in our conditions and then be returned. At the same time, it can be used in our own national breeding programme. A part of the field tests in France can thus be considered as important ex situ gene conservation units of international importance insofar as the number of genotypes is high enough.

Conclusions

Up to now, gene conservation of Norway spruce in France was at the beginning phase. Some ideas are settled for our own material, and some actions have been started, such as investigations of the structures of genetic diversity or genetic characterization of Norway spruce material originating from a small area of natural occurrence of the species in France. From now on, the main part of the work will need to be further developed.

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