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The conservation of Norway spruce gene resources in the Federal Republic of Germany Heino Wolf Forestry Research Institute of Saxony, D-01827 Graupa, Germany Summary In Germany, Norway spruce is the most important timber tree and covers about 35% of the forest area and about 60% of the total fellings in 1993. Beginning in the eastern part of Germany in the 1960s and continuing in the western part of Germany in the 1980s, severe damage of Norway spruce stands caused by air pollution and forest decline could be observed. Recording of these damages started in 1984. In 1994, Norway spruce had the largest area damaged of all tree species because of its big proportion of the total forest area. The heaviest damages could be observed in the higher altitudes of the mountainous regions and the Alps which are mainly part of the natural distribution area of Norway spruce. Stands over 60 years old showed the worst damages. In 1985, the working party Conservation of Forest Gene Resources was established to coordinate the efforts of federal and state institutions concerning the conservation of forest gene resources. Among other tree species, Norway spruce has the first priority. Based on the conservation work already done by different tree-breeding institutions, the working party developed a `Concept on the Conservation of Forest Gene Resources in the Federal Republic of Germany' in 1989. In the concept, several in situ and ex situ measures were planned which should be realized within the next decade. The conservation work done since 1989 was mainly concentrated on the in situ conservation of Norway spruce stands, the establishment of ex situ conservation stands, the collection and storage of seeds and the vegetative propagation of single trees. Finally, research needs and tasks were identified related to the conservation activities planned.
The origin, natural distribution and occurrence of Norway spruce forests
Origin of Norway spruce forests After the last ice age, Norway spruce most probably remigrated into the area of today's Germany from two refugial areas, the Balkan Peninsula and the Carpathian Mountains. One of the main migration streams led obviously from the Beskides over the Sudeten to the Ore Mountains which were reached about 6500 BC. The other mainstream started in the refugial area on the Balkan Peninsula, followed the edge of the eastern Alps, crossed the river Danube, went west and northwest and came over the Bohemian Forest to the Bavarian Forest in the southeast of Germany. Both migration streams may have met in the Fichtelgebirge, the Frankonian Forest and the Thuringian Forest. About 4000 BC, the Harz Mountains were reached. The southern part of Germany was remigrated by Norway spruce parallel to the northern edge of the Alps, coming from the eastern parts of the Alps and finally reached the Black Forest in 1500 BC (Fig. 1).
Natural distribution In Germany, Norway spruce occurs naturally in the mountainous and subalpine regions. Its natural distribution area covers the Alps, the higher altitudes of the Black Forest and of the Middle and East German Mountains. In the natural forest societies, pure Norway spruce stands can be found on extreme sites only, e.g. at the high mountainous and subalpine level of the northern edge of the Alps, on cold, wet sites of the Black Forest and the foothills of the Alps, and at the higher altitudes of the Bavarian, Middle and East German mountainous areas. Apart from these particular sites, Norway spruce normally contributes to mixed beech, fir or pine forest societies in different percentages. In total, Norway spruce is associated on about 25% of the natural forest areas. Fig. 1. Probable remigration streams of Norway spruce in the Herzynic-Carpathian and alpine distribution area (Proposal of F. Kral, 1976 in Schmidt-Vogt 1987) NOT AVAILABLE
Artificial distribution and occurrence In consequence of the thorough devastation of the forests until the end of the 18th C and the enormous timber demand in early industrial times, natural forests were changed to artificial forests. Because of its wide ecological range, fast growth rate and ability to cope with clear-cut conditions, pure Norway spruce stands were promoted by forestry apart from Scots pine. These led to an:
C extension of Norway spruce on sites which were not suitable for Norway spruce within the natural distribution area, and C extension on sites outside of the natural distribution area.
The promotion of Norway spruce by forestry for two centuries was accompanied by the transfer of reproductive material. In many cases, the origin of this material was not known or not suitable in the long term. These facts make it difficult to identify and delimit natural autochthonous Norway spruce forests from nearly natural or artificial formations of Norway spruce forests. Apart from these, Norway spruce showed good yield and quality performance on very different site conditions which favoured the planting of this species over a long period. In 1993, about 30% of the total land area of Germany was covered by forests, i.e. the forest area added up to 10.7 million ha, and 3.8 million ha of the forest area (35%) consisted of mainly pure Norway spruce stands. The proportion of Norway spruce in the total fellings was about 60%, i.e. 16.9 million m3. Today, Norway spruce is the most important timber species in Germany. Factors threatening Norway spruce gene resources In the past, the structures and the character of natural forests in Germany were heavily influenced by exploitation, deforestation, change of species composition, etc. Since industrialization, forest decline caused by air pollution influenced Norway spruce populations locally and regionally. In the eastern part of Germany, the damage of Norway spruce stands began in the 1960s and took dramatic dimensions, especially in the Ore Mountains. In many cases, the locally adapted populations disappeared within the shortest time. Since the beginning of the 1980s, the damages caused by forest decline also increased in western Germany. As opposed to the damages in eastern Germany, these damages could only be related in single cases to a certain emittent of air pollution. Since 1984, the damages to the forests have been ascertained and published in a yearly report in the western part of Germany and since 1990 in the whole of Germany. The results of visible damages of Norway spruce (loss of more than 25% of needles) show clear differences in the percentages and in the development of the damages in the northwest, east and south of Germany (Fig. 2). In 1994, the highest average damages could be observed in the eastern part of Germany. Norway spruce stands in the higher altitudes of the Thuringian Forests and the Ore Mountains were particularly damaged. Norway spruce stands with more than 30% of damaged trees could be found in the Alps, the Black Forest, the northwestern Hessian Mountains and the southwestern part of Schleswig-Holstein. The distribution of the damages on age classes showed a clear difference between stands over 60 years and under 60 years of age (Table 1). Mixed stands were damaged as well as pure stands. In summary, Norway spruce has the largest area damaged of all tree species because of its large proportion of the total forest area. The heaviest damages were observed in the higher altitudes of mountainous regions and the Alps, which are part of the natural distribution area of Norway spruce, where stands >60 years old had the worst damages. In future, climate changes caused by global warming could lead to a threat to Norway spruce populations. However, the consequences are very difficult to estimate. In particular, an increase in temperature connected with higher evaporation and lower precipitation could result in higher susceptibility to pests and diseases. Fig. 2. Development of visible damages (= loss of more than 25% of needles) on Norway spruce, 1984-1994
Table 1. Development of forest damages, 1984-1994, distributed on age classes
* No figures available; since 1990, beginning of a new time series including the newly established states after reunification.
Conservation aims and current state of activities
History and organizational structure of Norway spruce gene conservation Because of its importance for forestry, Norway spruce was one of the major species in tree-breeding programmes. Following the Norway spruce provenance trial of 1936/37 established by Rubner, Germany participated in the 2nd International IUFRO-Norway Spruce Provenance Trial of 1964/68 and in the International (IUFRO) Norway Spruce Provenance Trial of 1972. The conservation of populations and individuals of interest was already part of the breeding programmes in the different research institutions. Because of the heavy damages by air pollution in the German Democratic Republic, a special programme for the conservation of Norway spruce was established in 1985. In the Federal Republic of Germany, the working party `Conservation of Forest Gene Resources' was established in 1985 based on a resolution of the Bundesrat (upper house of the German parliament) and an agreement among the Federal Ministry of Agriculture, Food and Forestry and the different State Ministries responsible for Forestry. The working party is composed of appointed representatives of the Federal Government and of the different state governments. The task of the working party is the development of a concept for the conservation of forest genetic resources and the coordination of gene conservation activities. The implementation and realization of gene conservation activities is the responsibility of each state and its research institutions and forest services. After the reunification of Germany, the new estabilished states joined the working party.
Objectives and measures of Norway spruce gene conservation The general objective of forest gene conservation is to conserve and save the genetic variation of tree and shrub species in the following generations. In the medium term, in situ conservation of Norway spruce stands and their natural or artificial regeneration by sowing or planting will not be possible in many regions owing to the continuing air pollution. Consequently, ex situ measures will be of great importance, e.g. the establishment of seed orchards and clone collections, the storage of seeds or parts of plants, and vegetative propagation. The following remarks are based on the concept of the working party Conservation of Forest Gene Resources which was published in 1989 before the reunification of Germany in 1990. The figures mentioned below for the planned conservation measures were extrapolated to consider also the Norway spruce forests of the five newly established states of Germany. It is planned to cover about 1% of the Norway spruce area, i.e. about 38 000 ha, with conservation measures within the next decade beginning in 1989. From this area, 80%, i.e. 30 800 ha, will be conserved in situ. It is assumed that it will not be possible to conserve the remaining 20% in situ owing to the increase of forest decline. For these 7200 ha, ex situ measures will be used. To minimize the risk of loss, it is planned to take double ex situ measures for about 3100 ha of the in situ area. Norway spruce stands which should be conserved by sowing or planting, i.e. 15 200 ha, will also be conserved by storage of seeds.
In situ measures In total, 30 800 ha of Norway spruce stands will be conserved in situ. The soil of 75% of these stands should be improved by application of lime. The vitality of all in situ stands should be increased by regular stand maintenance, thinning and fertilizing. The change in vitality has to be monitored by regular analysis of the soil and the needles. The results of the analysis will be used as a decision-making aid for future management. On condition of the fructification being sufficient and the soil conditions still suitable, about 300 ha/year of Norway spruce stands have to be regenerated naturally, after having reached a suitable age. The natural regeneration is promoted by specific silvicultural management, e.g. by fertilizing. Additionally, about 300 ha/year should be regenerated artificially using material from stands worth conserving.
Ex situ measures About 10 300 ha of Norway spruce stands are to be conserved by ex situ measures; 3100 ha out of these are included in double measures. This area should be conserved representatively on an area of about 1000 ha. The establishment of seed orchards will be one priority of the ex situ conservation. Especially in the higher altitudes of the mountainous and subalpine regions, various Norway spruce populations have already disappeared. Some of these populations are part of different national and international provenance trials or conserved in clone collections established for breeding purposes. This material can be used to assemble clones in collections or seed orchards. In the first decade, about 6000 trees should be selected from the 7200 ha to be conserved ex situ. These 6000 trees have to be conserved representatively on an area of 600 ha. Additionally, clone collections should be established for the conservation of endangered relict populations and single trees which represent rare genotypes or material important for breeding. For this, 1000 clones can be estimated, thus requiring an additional area of 20 ha. It is planned to conserve about 13 200 ha of Norway spruce stands by sowing and planting in situ and ex situ. Together with the procurement of seeds for these measures, seeds for storage purposes have to be collected. In Germany, seed collection of Norway spruce is possible every 3 years on average. In the first decade, about 12 000 ha of Norway spruce stands should be collected with 4 kg seeds per stand. As an additional conservation measure, pollen of about 5000 selected breeding trees has to be collected and stored. In the first decade, the storage of plants or parts of plants is not planned for. It is much more effective to store seeds. If starting material is limited and cannot be propagated in a different way, macrovegetative propagation is used. For this purpose, about 6000 clones with an additional area of 10 ha will be needed. The microvegetative propagation using tissue culture is not developed yet. But this method is of special interest for the conservation of old trees which are difficult to propagate by cuttings or grafting. The current state of activities Among other species, the conservation of Norway spruce gene resources has the highest priority. Because of the different levels of damages, regional priorities have to be set. Generally, the conservation measures are mainly concentrated on Norway spruce stands which are approved according to the federal law on forest reproductive material. In 1993, 44 466.2 ha of Norway spruce stands were approved for the production of selected reproductive material. About 62% of these stands were the property of the states. The remaining stands were mainly distributed between private (19%) and corporate owners (18%). Only a marginal percentage belonged to the Federal Republic of Germany (1%). Additionally, several in situ and ex situ measures were taken to conserve Norway spruce gene information until the end of 1993. The emphasis was laid on in situ conservation of Norway spruce stands, the establishment of ex situ conservation stands, the collection and storage of seeds and the vegetative propagation of single trees by cuttings (Tables 2, 3 and 4). Activities in 1994 and ongoing activities in 1995 will be published in the next report of the working party Conservation of Forest Gene Resources at the end of 1995.
Table 2. Conservation activities in the field
Research activities and needs In the past, research activities in forestry were mainly concentrated on the growth and yield of forest stands, silvicultural measures and genetic characterization of populations by provenance and progeny trials. Because of the extent of the forest decline, research was started on forest ecosystems but focused mainly on biogeochemical and energy cycles. On the other hand, a certain lack of knowledge could be observed in the field of gene conservation. Normally, measures should be based on scientific results, but gene conservation measures had to be established immediately to avoid the loss of a significant amount of genetic information. In this case, research should accompany the measures of gene conservation. The research activities and needs can be divided into two categories, the research on practical gene conservation measures and the research on specific problems which are related to the necessary methods of gene conservation. Table 3. Collection and storage of conservation material
Table 4. Propagation for conservation
The latter includes research on the influence of air pollution on the genetic structure of populations and reproductive mechanism, methods to identify and evaluate genetic variation as well as mechanisms and parameters of resistance. The research about gene conservation measures related to Norway spruce covers all aspects of in situ and ex situ measures:
Facing the climatic change caused by global warming, investigations seem to be overdue on the relationship between the genetic diversity observed and the adaptability of populations, on the influence of silvicultural measures on the genetic structure of populations and on the mechanism generating the variability observed into phenotypic adaptive traits. Further reading
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