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Conservation of
Norway spruce gene resources in Finland
Veikko
Koski
The Finnish Forest Research Institute, FIN-01301 Vantaa, Finland Norway spruce (Picea abies L. Karst.) is a relatively new tree species in most parts of the country. After the latest glaciation spruce returned later than birch and pine. Probably spruce occurred sporadically earlier, but no more than 5500 years ago it began to spread from the east. It took some 3000 years to reach the western and northern parts of Finland. It is also worthwhile to mention that a large proportion of the present land area has risen from the sea rather recently. Later on, some 100 to 200 years ago, human impact on forests, especially pine and spruce forests, used to be exploitive. Shifting agriculture with prescribed burning, deliberately ignited forest fires, tar burning, grazing of cattle, and merciless cuttings resulted in treeless areas, which primarily turned to broadleaved forests. Owing to early legislation, education and silviculture, forests recovered and are now a dominating component of the Finnish landscape. The total area of forest land of Finland is 20 million hectares, which is 66% of the total land area. Norway spruce is the second in abundance, after Scots pine (Table 1). In terms of growing stock the proportions of tree species in 1983-1993 were as follows (Yearbook of Forest Statistics 1994):
Picea abies 36.8% Betula spp. 14.5% Other broadleaved 3.1%
The earlier land use, mentioned above, had favoured broadleaved species. More recently spruce has reoccupied fertile sites, and even penetrated to rather poor `pine sites'. For the time being nothing seems to threaten Norway spruce and its genetic resources. However, gene conservation is a matter for the unforeseeable future. Our tree populations are close to the northern margin C the tree line of many species goes across Finland. Thus, in respect to climatic adaptability the populations must represent extreme variants of the species in question. On the other hand, a wide genetic variation has been revealed within populations. The goal of gene conservation is to ascertain that this kind of natural resource is neither accidentally nor deliberately lost. The global change of environment is a potential threat to genetic resources. Cultivated forests with foreign seed sources and genetically improved material will gradually alter gene frequencies, if there are no counteractions. The need for gene conservation was recognized by forest geneticists as early as the 1970s. Consequently, the number of trees subject to breeding has been large since the beginning. The establishment of gene reserve populations did not get started until the Strasbourg Ministerial Conference and UNCED had an impetus.As the first step, establishment of a network of in situ gene reserve forests was started in 1992. By March 1995 we have registered six spruce forest areas, the total area being 886 ha (Fig. 1). The distribution and coverage of the gene reserves is not satisfactory yet. The target is to find and establish some 10 more gene reserve forests, especially in the southwestern part of the country. There are also gene reserve forests of Pinus sylvestris, Betula pendula + B. pubescens, and even of Tilia cordata. The total number over all species is 29, and their area 5188 ha (March 1995). Besides gene reserve forests, genetic diversity has been stored in clonal archives. There are altogether close to 1600 clones, both plus trees and special forms in the clonal archives.
Table 1. Proportions of species according to their dominance in forests (Yearbook of Forest Statistics 1994)
Fig. 1. Gene reserve forests of Norway spruce (nos. 1-6 refer to breeding zones, see Table 2)
Table 2. Gene reserve forests of Norway spruce in Finland, registered by 1 January 1995
A national long-term tree breeding program of 1989 suggests establishment of long- term breeding populations for all main species by breeding zones. For P. abies six breeding zones have been delineated in Finland. The basic material of these breeding zones would be phenotypically selected plus trees. The designing of the factual populations is still underway. Finland is in the fortunate position that the genetic resources of the main forest trees, P. sylvestris, P. abies and B. pendula + B. pubescens, are not subject to direct threat. The challenge of gene conservation is how to justify necessary actions now in order to maintain the wealth even in the far future. Biodiversity and gene conservation are favourite issues, as long as your own money is requested. After a few years people may have new topics in their minds and selling the idea of gene conservation may be much harder than it is today. The main stream of gene conservation is by means of gene reserve forests. Based on the conditions of efficient pollination and the need of parcels of various age classes the minimum area of one unit ought to be 100 ha, i.e. 1 km2. Finding this large area of naturally originated forest in public ownership is not always easy. In the southern part of Finland forests are mainly privately owned and consist of rather small holdings. Plantings with transferred, and even unknown, origins interfere with the natural population structure. The frequency of nonindigenous provenances and genetically improved stock will gradually increase in the future. Rather than giving up the purity requirement and the target area of 100 ha, we could start with smaller `kernels' and then later on enlarge the population with plantings. Seed must, of course, originate from the nucleus. Extra costs of artificial enlargement may cause difficulties, and it requires sincere effort to carry through this kind of action. The advantage of gene reserve forests is that they are managed and merchantable timber may be harvested, as well as seed. For the time being we do not see urgent research needs in our spruce gene reserves. I consider the project a practical operation, where we must not waste any more time. Selection and documentation of the missing samples is the main goal. Characterization of populations by means of genetic markers would be desirable, but is out of the question because of economic restrictions. On the other hand, gene reserves provide excellent reference and study material for genetic studies. Public concern on nature protection and biodiversity has been efficiently promoted by the mass media. An emotional attitude readily leads to an all-or-nothing approach to conservation. The need for gene conservation is certainly well accepted and understood. Some contradiction occurs as regards the methods of conservation. Old forests and strict nature reserves appeal to laymen, whereas forest geneticists prefer actively managed genebanks. We have to keep on saying that conservation of forest genetic resources is the duty of the present generation. We still have large areas of native (spruce) forests in our country. As the first step a covering network of in situ gene reserve forests should be established. A guidebook for the handling of gene reserve forests is anticipated. The establishment of ex situ long-term breeding populations is still on the planning desk. Breeding zones have been delineated, and there are sufficient numbers of phenotypically selected plus trees in each zone. Every breeding zone will have a breeding population of its own. As the composition and the physical location of the breeding populations determine the mode of action into the far future, the planning has been thorough and time consuming. The choice between closed or open systems, large entities or substructures, basic population versus nuclei, are under discussion. Information on possible experiences on Small Multiple Population Breeding Systems or other advanced models of breeding/conservation would be useful. To my mind, gene conservation proper and effectively functioning breeding populations do not necessarily cover each other. After a few generations of selection a broad variation in breeding populations may become a `genetic load' instead of a `hidden treasure'. My final statement is: Let us start with simple and inexpensive measures, such as gene reserve forests, now. If we wait for a perfect universal method, it may be developed too late.
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