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Situation of the conservation of Norway spruce in Belgium Alphonse NansonStation de Recherches
Forestières, B-5030 Gembloux, Belgium Norway spruce stands in Belgium cover around 200 000 ha, about one-third of the total forest area of Belgium. Production averages 12 m3 ha-1 yr-1, making it the most valuable and profitable forest tree species in Belgium. The conservation of Norway spruce as a species is in no way endangered but some concern can appear at the level of populations. As a matter of fact, some outstanding ones have already disappeared. An important but indirect genetic conservation has taken place in breeding programmes. More than 20 provenance experiments (20 ha, 600 provenances), 29 seed stands (230 ha), 1224 plus trees or clones, 2 seed orchards (10.2 ha, 189 clones), 20 progeny and clone tests (25 ha, 300 genetic elements), 4 clone parks (878 clones) and 1 scientific seed collection (295 scientific seedlots, 21.4 kg) are maintained in situ or ex situ. However, no consistent and comprehensive active long-term management of forest genetic resources has yet been implemented. To develop such long-term management of forest genetic resources, it will be necessary to construct and manage databases and fill them with updated genetic resources, to implement trace keeping in forest management of the provenance or variety used in new plantations, and to develop a management programme using accepted principles and apply them at the level of practical implementation.
Introduction The purpose of this paper is to present a short account of the present situation of the conservation of Norway spruce (Picea abies) in Belgium. It has to be recalled that Norway spruce is not indigenous in Belgium and that it was introduced around the middle of the last century from central Europe (Austria, Germany and possibly Poland). The precise origin of every stand is, however, almost never known. Norway spruce is planted almost exclusively in Wallonia, the southern and most forested region of Belgium (80% of total forest area), mainly in the Belgian Ardennes. This last subregion is a `Region of Provenance' in the sense of OECD/EEC regulations. It is characterized by an elevation ranging generally from 300 to 700 m (mean around 450 m), a rather harsh climate (mean temp. -7EC; annual rainfall from 1000 to 1400 mm) and acid soils (pH -4.5). The total area of Norway spruce stands amounts to around 200 000 ha, about one-third of the total forest area of Belgium (-620 000 ha). The mean annual increment amounts in average to 12 m3 ha-1 yr-1 with extremes lying from under 9 m3 ha-1 yr-1 on the high boggy plateaux up to around 20 m3 ha-1 yr-1 on the best sites. From the economic point of view, Norway spruce is the most profitable forest tree species because it is easy to plant in the open and to manage in evenly aged stands. Moreover, all products find easily a profitable output (small roundwoodsCpoles, excellent paper; medium woodsCpoles; large woodsCvaluable timber for sawmills and possibly veneer). It is criticized by `Ecologists' mainly because it is not indigenous and it forms dark homogeneous stands that may degrade the soil. This last point has never been proved in spite of many studies; the `darkness' and homogeneity of the stands are being solved by heavier thinnings than in the past.
Present situation of conservation So far, no pure conservation has been practised. Genetic conservation has only been done in the frame of the present breeding programme for which it is a sort of by-product. Therefore, the classical scheme of presentation used in forest tree breeding will be followed hereafter. Provenance experiments Provenance experiments are indirectly a means to conserve many provenances outside of their range. In a number of cases, the original stands from which seed was collected have disappeared or their trace has been lost. When these provenances are outstanding, a way to try to restore the original population is to collect material from provenance experiments. For example, this has been done for the Polish provenance Zwierzyniec Lub., the original stand of which having been cut down, cuttings and grafts were sent from Belgium to Polish colleagues. For Norway spruce in Belgium, there are more than 20 provenance experiments covering more than 20 ha (Table 1) and comparing more than 600 provenances from the whole European range (a certain amount of these provenances is common to different experiments). The first experiment was planted in 1931. Among them are the three International Provenance Experiments in Norway spruce (Promoters: First: Schmidt, 1938; Second: Langlet-Krutzsch, 1964; Third: Tyszkiewicz-Kociecki, 1972). Some of them have been assessed in detail in Belgium (nE1: Delevoy 1949; Gathy 1960; Nanson 1964c, 1965a; Verstraete 1993). The transformation of some of these old provenance tests into Provenance Seedling Seed Orchards (Nanson 1972) through severe selective thinnings, leaving only the best trees of the best adapted provenances, is contemplated. This could be envisaged for replicates of experiment nE2 that have a one-tree plot structure. Table 1. Present situation of the genetic conservation of Norway spruce in Belgium*
* Minimum numbers. H A genetic element is the genetic unit considered, e.g. a provenance, a progeny, a clone, a clonal mixture, etc. Some elements can be common to different items.I N.B.- 21.4 kg x 10 ha/kg = 214 ha.Seed stands According to definitions (e.g, OECD/EEC regulations), a `seed stand' is a stand that is phenotypically superior for most forest characteristics and that has been officially selected and included in an official Register of Basic Materials. In Belgium, Galoux and Reginster (1953) first began this selection around 1950; Gathy continued up to around 1960 and Nanson after that. At present in Belgium, 29 seed stands of Norway spruce covering a total area of 230 ha are officially registered. So far, these seed stands are not really protected against normal felling (around 60-90 years in usual practice). This should be envisaged in the future. Difficulties are, however, present due to the kind of ownership (private seed stands are almost outside any measure) and to the limited longevity of Norway spruce in Belgium (practically not more than 100-120 years). Active ex situ
conservation in `conservation plantations' is then a good
opportunity but needs some supplemental financial means and human
resources as well as a long-term follow-up organization. Plus trees So far, 198 plus trees (`mature clones': phenotypically selected at forest stage after sexual maturity: more than 30 years), 148 `juvenile clones' (selected in early forest stage: between 5 and 30 years) and 878 `infantile clones' (selected in nursery), so a total of 1224 clones, have been selected. Mature and juvenile clones are conserved in situ but not over the normal forest exploitation term (60-90 years). The best of them are conserved ex situ in seed orchards (see below). Infantile clones are conserved in four propagation clone parks, either of ortets, or of ramets, or both. These propagation clone parks have, however, a limited lifespan (10-15 years) and should be then re-propagated.
Seed orchards Two grafted clonal seed orchards of respectively 1.50 ha (in Halle) and 8.7 ha (in Fenffe) are settled; they now contain respectively 54 and 135 clones, so 189 clones in total. The last one is an `evolving seed orchard' that, besides its functions of seed production and a source of `clonal mixtures', is also a conservatory of one of the best clones (Nanson 1986; Nanson et al. 1992). The lifespan of such seed orchards is expected to be between 50 and 100 years. The conservation of these seed orchards and thus of component clones is dependent on their performances and their economic justification.
Progeny and clone tests So far, at least 20 comparative experiments are planted; they are composed mainly of genetic materials from the Ardenne Region of Provenance. They contain at least 300 genetic elements (progenies, clones, standards) and cover at least 25 ha in total. This represents a considerable source of genetic diversity of high value. The lifespan of these tests is again some 60-90 years. Their further conservation depends on the general breeding strategy but has not yet been truly envisaged from the pure conservation standpoint. A precise updated inventory of this resource would be a first step.
Clone parks Classical clone parks: Classical clone parks are pure collections of clones represented by 2 or 3 ramets of every clone planted at rather large spacing (4 x 4 m at least). In Belgium, there are no such parks because they are too expensive to create and maintain. They are replaced partly by evolving seed orchards which merge the functions of clone park and seed production on the same site. Note that these evolving seed orchards are conserving only the best clones. The number of these clones is a compromise between the importance of the genetic gains requested and the need of genetic diversity within the synthetic variety produced by the evolving seed orchard.
Propagation clone parks: Propagation clone parks are made of ortets or ramets of infantile clones, with the main purpose of producing cuttings en masse for the vegetative propagation of clonal mixtures. At present, two propagation clone parks of ortets and two propagation clone parks of ramets are planted and hedged to produce cuttings: 878 infantile clones are thus conserved. With a present spacing of 1 x 1 m (a bit too low), they cover about 0.30 ha. The lifespan of such propagation clone parks is expected not to exceed some 15 years. Therefore, a conservation policy and actions will be soon necessary. However, this needs time, money and labour.
Seed banks In our Research Station, 295 scientific seed lots (provenances, progenies) with a total weight of 21.4 kg are stored in refrigerators (at +2 or !17EC). In our conditions, 1 kg of seed of Norway spruce can create around 10 to 15 ha of plantation at the standard spacing of 2 x 2 m. Therefore, this seed amount represents at least 214 ha of plantations.
Pollen banks No pollen has yet been stored.
In vitro conservation Because of the present failure of the in vitro propagation of Norway spruce, no such conservation is envisaged.
Usual forest plantations Usual forest plantations can be a source of genetic diversity within the species because every plantation can be from a different provenance (population). In Wallonia, the Forest Service is using in principle `Recommendable Provenances' from Belgium and from some other countries (Nanson 1978). This should bring a genetic gain in total production of around 20% compared with a random use of provenances. So far, however, the identity of the provenance has not been frequently registered in the Forest Management Plan. It is hoped that this measure will be generalized by the Wallonian Forest Service and it should be the rule within a few years (see Trace keeping in forest management, below). After inputting this information to an adequate database, these data can be the basis for long-term management of Wallonian genetic resources, making the balance between genetic gains and genetic diversity.
Natural regeneration In the Belgian Ardennes, many Norway spruce stands can be regenerated by natural seeding. However, foresters are finding it simpler to use plantations. Natural regeneration can be worthwhile when the mother trees have a good phenotype and a genetic base sufficiently large to prevent further inbreeding. For more detailed aspects of natural regeneration from the genetic standpoint, see Nanson et al. (1991). Natural regeneration can be very useful to conserve exceptional seed stands, for example. However, conservation plantations with the reproductive material collected in these seed stands are another more flexible opportunity.
Threats and awareness of genetic conservation In Belgium, Norway spruce as a forest species is not threatened thanks to its profitability. However, the trace and identity of many very good seed stands (e.g., OECD/EEC blue labels or equivalent) have been lost because of the lack of active conservation measures. In fact, much seed has been collected on these `elite seed stands' and later commercialized and this has led to numerous plantations. But we do not know where these plantations are situated. From the conservation point of view it is as if they were lost! In this way, some very good populations have been lost after the severe windfalls of January 1990! The public and even foresters are not aware of this situation. Forest Geneticists are a bit concerned but, up to now, their means were so restricted that they were directed almost exclusively toward Forest Tree Breeding in the short term. Let us hope that the evolution of ideas on gene conservation will bring them some additional means in order to preserve the future!
Prospects for further conservation This matter needs further consideration, deep reflection, extended exchange of ideas and a deeper literature survey (e.g., Arbez et al. 1987; Kleinschmit et al. 1989; Martin 1986; Namkoong et al. 1980; Nanson 1993, 1994; Palmberg 1987; Steinmetz 1991). However, it seems that the following tentative guidelines could be open to discussion.
Construction and management of databases One of the first steps to consider is surely to do a survey and an updating of present known genetic resources and to include them in an adequate database. In this respect it should be noted that the embryo of such a database does exist. Through the FOREST EEC Research Project, Belgium, France and Germany agreed on a European common database structure for seed stands and conservation plantations with the example of Douglas-fir (Riboux 1993; Servais 1993; Servais and Riboux 1993). This database, with a decentralized structure and needing only personal computers, was tested and partly fulfilled: it is thus operational and maintained at our Station de Recherches Forestières in Gembloux. It can be extended easily to Norway spruce. Projects are to extend this database to other objects such as plus trees, seed orchards, clone parks, family mixtures, clonal mixtures, seed and pollen collections, etc. and to other species.
Trace keeping in forest management As mentioned earlier, the provenance (or variety) of every usual plantation in public forests will be identified and reported in the Forest Management Plan. Three levels of reliability are to be distinguished in ascending order:
Long-term management of forest genetic resources Once reported in the Forest Management Plan, with their own level of reliability, these data can be transferred to the conservation database, at least for the most outstanding or typical provenances. There they could join data coming from breeding programmes (plus trees, seed orchards, etc.). This will be the raw material for the development of long-range management of forest genetic resources. This last should optimize the balance between genetic diversity against genetic gains in long-term plantation programmes. For example, a sufficient amount of diverse outstanding provenances and varieties for productivity, quality, resistance-adaptation, could be favoured without excluding special provenances or varieties to maintain a sufficient genetic diversity between stands. Of course, this management should ensure the long-term preservation of the chosen materials through adequate special actions programmed over a century at least. For example, present seed stands and seed orchards should be conserved through several conservation plantations (1 to 4 ha each) perfectly registered, controlled (thinnings, etc.) and renewed in due time. In Wallonia, the Forest Tree Seed Centre named `Comptoir Wallon des Matériels Forestiers de Reproduction' will be soon established in the centre of the region, in Marche. Besides its main mission of providing Walloon nurseries with the best genetic materials, it can also play a major role by collecting adequately such basic materials and distributing them to state nurseries for conservation. All these actions should be set up with definition of priorities in a general Long-term Management of Forest Genetic Resources programme under the control of the Forest Service and prepared by forest tree breeders with the collaboration of relevant tree seed centres.
Conclusion In Belgium, Norway spruce is one of the most valuable and profitable forest tree species. The conservation of Norway spruce as a species is in no way endangered but some concern can appear at the level of populations. As a matter of fact, some outstanding ones have already disappeared. A very important but indirect genetic conservation has taken place in breeding programmes. Many provenance experiments, seed stands, plus trees, seed orchards, progeny and clone tests, clone parks, scientific seed collections are maintained in situ or ex situ. But because of lack of means that, of necessity, are allocated by priority to genetic improvement, no consistent and comprehensive active long-term management of forest genetic resources has been implemented yet. In order to develop such long-term management, it seems that construction and management of databases and filling them with updated genetic resources represents a prerequisite. Trace keeping in forest management of the provenance or variety used in plantations is a second one. Then should follow the development of a programme for long-term management of forest genetic resources, using accepted principles and at the level of practical implementation. At this stage, long-term management of forest genetic resources and long-term strategy of forest tree breeding should probably merge into a unified philosophy. References Arbez, M. et al. 1987. Les ressources génétiques forestières en France. Tome 1. Les conifères INRA and BRG, 236 p. Delevoy, G. 1949. Note préliminaire relative à l'essai international 1937 sur l'influence de l'origine des graines d'épicéa. Com. Stat. Rech. Groenendaal, Sér. B, nE4, 17 p. Galoux, A. and P. Reginster. 1953. L'inventaire des peuplements à graines de Belgique. Trav. Sta. Rech. Eaux et Forêts, Groenendaal, Sér. B, nE15, 31 p. Gathy, P. 1960. L'expérience internationale sur l'origine des graines d'épicéa (Picea abies Karst.). Résultats en Belgique. Trav. Sta. Rech. Eaux et Forêts, Groenendaal, Sér. B, nE24, 32 p. Kleinschmit, J. et al. 1989. Konzept zur Erhaltung forstlicher Genressourcen in der Bundesrepuplik Deutschland. Forst u. Holz. 44(15):379-404. Martin, B. 1986. Conservation et gestion des ressources génétiques. Rev. Fr. Franç., nE spécial 1986:240-245. Namkoong, G., R.D. Barnes and J. Burley. 1980. A philosophy of breeding strategy for tropical forest trees. C.F.I. Oxford, Trop. For. pap. nE 16, 67 p. Nanson, A. 1964. Données complémentaires au sujet de l'expérience internationale sur l'origine des graines d'épicéa en Belgique. Trav. Sta. Rech. Eaux et Forêts Groenendaal, Sér. B, nE28, 40 p. Nanson, A. 1965. Contribution à l'étude de la valeur des tests précoces. I.- Expérience internationale sur l'origine des graines d épicéa (1938). Trav. Sta. Rech. Eaux et Forêts Groenendaal, Sér. E, nE1, 60 p. Nanson, A. 1972. The provenance seedling seed orchard. Silvae Genetica 21(6):243-249. Nanson, A. 1978. Provenances recommandables pour la sylviculture. Liste 2. Bull. Soc. Roy. Forest. Belgique:217-246. Nanson, A. 1986. The evolving seed orchard: a new type. Proceed IUFRO Meet., Williamsburgh, Oct. 1986:554-566. Nanson, A. 1993. Gestion des ressources génétiques forestières. Annales Gembloux 99:13-36. Nanson, A. 1994. Managing genetic resources: a task for tree seed centres. Invited paper, Workshop of African Tree Seed Centres, Foulpointe-Antananarivo (Madagascar), Nov. 1994 (Vaneberg, ed.), Silo National des Graines Forestières, BP 5091, Antananarivo, Madagascar, 11 p. Nanson, A., D. Jacques and A. Servais. 1991. La régénération naturelle du point de vue génétique. Forêt Wallonne 12:19-21. Nanson, A., D. Jacques and A. Servais. 1992. Les vergers à graines à Fenffe. Silvae Belgica 99(2/92):31-36. Palmberg, C. 1987. Conservation of genetic resources of woody species. Symp. Silv. Mejor. Genetic., CIEF, Buenos Aires, Oct. 1987, 16 p. Riboux, A. 1993. EEC Gene Pool Management: Development of a Douglas fir compatible database. Version 1.0, Progr. MS DOS compatible. EEC Project 91/93 nE MA2B-CT90-0010(DTE). Sta. Rech. Forest. Gembloux, Prog. 375 Kbytes; Listing 125 p; User's guide, 26 p. Servais, A. 1993. Conservation of Genetic Resources: Development of a Compatible Data Base. EEC Project 91/93 nE MA2B-CT90-0010(DTE). Sta. Rech. Forest. Gembloux, 9 p. + Ann. Servais, A. and A. Riboux. 1993. EEC Gene Pool Management: Catalogue of field genetic resources. Data from a compatible database between Belgium, France and Germany. EEC Project 91/93 nE MA2B-CT90-0010(DTE). Sta. Rech. Forest. Gembloux, 43 p. Steinmetz, G. 1991. Les ressources génétiques forestières et leur protection. Rev. Forest. Franç. nE spéc. 43:28-31. Verstraete, P. 1993. L'expérience internationale de 1938 sur l'origine des graines d'épicéa (Picea abies Karst) en Belgique. Résultats en 1992/93. Trav. Fin d'Etud., Fac. Sci. Agron. Gembloux, 93 p.
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