2 Federal Forestry Research Centre, Institute of Silviculture, A-1140 Vienna, Austria

In Austria, Norway spruce is a naturally occurring forest tree species that is of outstanding ecological and economic importance. In total, 1 870 000 ha or 56.1% of the production forest area is covered by spruce. Genetic resources of this species are not at stake in general. However, owing to uncontrolled forestry in former times the natural geographical pattern of genetic variation has been strongly modified. This complicates the study of natural genetic differentiation and the identification of gene resources. Anthropogenic activities have often blurred effects of local selection regimes and postglacial immigration.

The preservation of the adaptive potential of Norway spruce is done within the frame of a federal conservation programme that was launched in the 1980s. This predominantly pragmatic programme focuses on the declaration of gene reserves, i.e. in situ stands that represent ecologically important forest communities. In total, 3073 ha of large-scaled Norway spruce gene reserves (42 stands) and an additional 1069 ha of small-scale conservation units (82 stands) have been declared as genetic resources. As a backup, 318 kg of Austrian Norway spruce seeds are currently stored in the federal seed bank.

In the long term, identification of valuable spruce genetic resources should be based on a synoptic assessment of ecological (predominantly forest communities) and genetic parameters (results derived from field trials and genetic inventories).

Introduction

In view of an uncertain climatic future, the preservation of genetic adaptability of tree populations is crucial for the long-term stability of forest ecosystems (Committee on Managing Global Genetic Resources 1991). Global conservation efforts have to lay emphasis on those forest tree species that are close to extinction.

In Austria, no forest tree species is threatened to such an extent. It is not the whole species that is being driven to extinction, but diminishing local races or ecotypes are the main concerns. This also holds true for Norway spruce (Picea abies).

Austria is a mountainous country influenced by different climatic regions and manifold geological conditions. Thus, because of the various environmental factors, different ecotypes can be expected within a forest tree species. However, besides these natural environmental conditions, postglacial immigration and, beginning in the early Middle Ages, indiscriminate extensive cuttings for ore and salt mines, have long-lasting effects (population fragmentation, seed transfer, species shift) on the genetic composition of today's forest tree populations. These peculiarities have to be borne in mind if the existence of certain forest tree populations is at stake and means of conservation is discussed.

Austria's total wooded area amounts to 3.88 million hectares, i.e., 46.2% of the land area is covered by forests. Therefore, Austria is rich in forest resources compared with other European countries. However, governmental implementation of conservation activities is intricate. Only 30% of the forest is publically owned and a high proportion (69%) of private owners operates nonindustrial forest enterprises or owns small woodlots (< 200 hectares) (Anonymous 1993).

A meticulous depiction of the native range of Norway spruce was published by Tschermak in 1949. Here the range is only briefly described. In Austria, Norway spruce is widely distributed. The Alps, mountains of the Bohemian massif [Mühlviertel (Upper Austria) and Waldviertel (Lower Austria)], and higher elevations of the alpine foreland (Hausruck, Kobernauerwald) are naturally covered by Norway spruce. The Danube basin separates the Austrian range into the alpine and the range on the Bohemian massif with a sparsely covered link in the Strudengau between the cities of Grein and Ybbs. The eastern natural limits are indicated by a connection line starting from the cities of St. Pölten over Wiener Neustadt to Graz and then south along the eastern slope of the Koralpe. Some natural stands are also found in the mountainous region called Bucklige Welt.

Pure spruce stands are found in the Piceetum subalpinum. In this forest community the range varies in the Central Alps between 1400 and 2100 m and between 1100 and 1400 m in the Bohemian massif. In the northern alpine transitional zone, an elevational range of this forest community is typical at 1400-1900 m, and in the southern alpine transitional zone at 1500-2100 m. In the Piceetum montanum, Norway spruce is also the prime tree species. Elevational zones vary strongly from ecoregion to ecoregion (Central Alps 650-1700 m, northern transitional zone 500-1700 m, southern transitional zone 500-1800 m, Northern Limestone Alps 700-1600 m, Southern Limestone Alps 1000-1700 m).

Together with common beech and silver fir, P. abies is found in the (Abieti)-Fagetum with varying proportion between 600 and 1700 m along the northern and southern edge of the Alps and between 600 and 1300 m in the Bohemian massif. A detailed description of the natural forest communities is found in Kilian et al. (1994). Figure 1 shows the actual and the natural distribution of Norway spruce in Austria.

By the end of the Middle Ages high timber demand for ore and salt mining caused extensive clear cuts in the Limestone and Central Alps. Uncontrolled natural regeneration often turned out to be extremely difficult. If regeneration did not fail, larch and spruce were favoured and caused a reduction of the natural distribution area of broadleaved species.

The first, more extensive artificial sowing of Norway spruce was reported at the end of the 18th C in Upper Austria. Later, significant regenerations by planting were carried out in forestry. During the 19th C, extensive pure spruce forests were artificially established, especially in mountainous regions, e.g. south of the city of Steyr. Later, these spruce stands were devastated by heavy storms and bark beetles.

After World War I, Austrian forests were intensively utilized (Tschermak 1934). Restocking of these areas and smoothing out damage due to World War II, in total an afforestation area of 384 000 ha, favoured the artificial distribution of spruce. Today it is extremely difficult to differentiate between autochthonous and nonindigenous spruce stands. Even within the native range of this conifer, cutting and uncontrolled restocking have covered over the natural geographic differentiation. This especially holds true for lower and middle elevational ranges. In Austria, approximately 29% of the natural forest communities are pure coniferous forests. However, the actual proportion amounts to 69% of which pure spruce stands have a great share (45% of all coniferous stands) (Kilian 1985).

[figure and caption] not available

As the Austrian spruce forests are found from lower to subalpine regions, appropriate adaptedness of spruce populations is highly desirable for practical use. By the end of the 19th C some Norway spruce field trials had been launched. One of the more comprehensive common garden experiments comprised 80 Austrian Norway spruce populations originating from different elevations and forest communities (Cieslar 1907).

Today elevational adaptedness in forest tree species is taken as a self-evident truth, but at the turn of the century, Cieslar's conclusions were striking in forest science. Later, early tests to identify spruce populations by different growth rhythms in phytotrons were developed (Holzer 1975). Like other spruce provenances originating from the alpine range, Austrian populations are not characterized by outstanding field performance in field trials established outside the natural range (e.g. Krutzsch 1974). This is in accordance with biochemical investigations in Norway spruce (Lagercrantz and Ryman 1990). Consistently, alpine populations are genetically highly adapted compared with other native populations and result in poor performance if planted outside the alpine range.

Austrian provenances originating from lower elevations of the Bohemian massif (Waldviertel, Mühlviertel) have a yield performance which is typical of provenances of the Hercynic-Carparthian region (Guenzl 1979).

Severe forest decline in Austria made conservation efforts inevitable. In 1986, a programme for the preservation of forest genetic resources was launched at the Federal Forestry Research Centre, Vienna (Nather 1990; Litschauer 1994). Owing to Austrian peculiarities (see above), the ultimate goal was the conservation of genetic resources and in doing so restricting forestry as little as possible. For principal forest tree species, such as Norway spruce or silver fir, emphasis was laid on in situ conservation.

In situ conservation of Norway spruce

In Austria, forests aiming at the preservation of gene resources of Norway spruce are classified as (1) gene reserves and (2) small-scale conservation units. At least 5% of the wooded area is intended for in situ conservation. Relic populations and stands close to the timber line are over-represented in the conservation programme. As these stands are declared as conservation stands on a voluntary basis, a harmonious relationship between the Federal Research Centre and the owners is mandatory. There are no official means to declare and protect gene resources without the approval of the owner. Logging in these stands is the rule rather than the exception. However, there might be certain management restrictions. For instance, it can be agreed on that exclusively natural regeneration is permitted, cutting of undesired forest tree species will be necessary, and among other restrictions, a supplemental planting with forest reproductive material originating from the in situ population is mandatory if artificial regeneration is a must. The fulfilment of these agreements and the status quo of the in situ stands is periodically revised every 5-10 years. From an owner's perspective it is not obvious at first glance that a declaration might be advantageous for his forest enterprise. However, in declaring a resource there will inevitably be close links to silvicultural experts who contribute their expertise and a declaration may open the way to applying for federal funds.

Austrian gene reserves are forests that comprise an area of at least 30 ha. As pollen contamination from outside sources is unwanted, the core area should be framed by a 300-500 m wide buffering zone. The identification and declaration of Norway spruce gene reserves have been completed in the province of Carinthia. In the provinces of Lower Austria, Salzburg, and Tyrolia declaration has commenced (Table 1). Up to now (as of early 1995), more than 3000 ha of Norway spruce gene reserves have been declared.

Small-scale conservation units

Exceptionally, single stands (< 30 ha) were selected to preserve special populations. Approximately 1100 ha of small-scale conservation units are identified (Table 1).

In Austria, ex situ measures to preserve gene resources of Norway spruce have mainly been restricted to the storage of seeds originating from different ecoregions. Seed storage is a static conservation means and does not allow a change in the genetic composition of the resource in the course of environmental changes. This means does not significantly contribute to the ultimate goal to preserve the genetic adaptability in Norway spruce. Therefore, seed storage has to be assessed as a back-up measure. However, if this measure is a supplemental part of the conservation programme, for instance to bridge periods of lacking or insufficient seed crops, it is an important means. As the conservation of high elevated spruce stands (Piceetum subalpinum) requires special attention, those seed sources are especially maintained (Table 2).

Up to now, no seedling or clonal conservation orchards have been established. However, two clonal Norway spruce orchards are in preparation. One orchard will represent populations of the ecoregion `Northern Limestone Alps' (elevational range: 1350-1750 m); 107 clones have been propagated. Norway spruce of the subalpine region of Central Alps (elevational range: 1680-2050 m) will be represented by a second conservation orchards, for which 99 clones are selected. Besides the preservation of high-elevation Norway spruce populations, the seeds originating from these orchards are intended for additional seed supply for high-elevation afforestation (avalanche and torrent control). However, it must be considered that progenies of high-altitude parents do not completely retain the annual growth rhythm of their parents when parental trees have been grown at a low-altitude site (Johnsen 1989; Skröppa 1994).

An important but indirect means to preserve the adaptability of Norway spruce is the fact that meanwhile many spruce forests are regenerated naturally. For a long time restocking was predominantly performed after small clear-cuts by artificial planting. Today, approximately 53% of the final cut area is naturally regenerated. Since natural regeneration offers many genetic advantages over artificial reforestation (Geburek and Thurner 1993; Müller 1993) naturally regenerated forests are a prime choice for genetic resources. Even without identification and declaration, many naturally regenerated forests are potentially valuable gene resources.

According to the Austrian Forestry Act of 1975, spruce seeds have to be harvested in selected stands. In 1995, an area of 33 038 ha of spruce stands has been selected and declared as seed stands. It is clearly mentioned that these stands have been selected under criteria to improve forestry yield. Therefore, it is self-evident that the selection criteria to identify gene resources are not necessarily identical with those applicable to genetic conservation.

To get a better insight into the geographical genetic variation of Norway spruce, biochemical investigations have been started. Up to now, 22 presumably autochthonous populations (100 trees per individual population) have been sampled and genetically analyzed in part. Preliminary results of the federal genetic inventory indicate that the Austrian Norway spruce populations exhibit moderate genetic variation (for instance, mean of observed heterozygosity Ho = 0.15) with very low among-population differentiation (FST = 0.01) (for more details see Geburek 1994). This genetic inventory lays emphasis on native populations; however, nonautochthonous spruce stands also will be studied in the coming years.

In the long term, declaration of gene resources should be based on ecological criteria, biochemical variation (isozymes, molecular markers), and the results of stress experiments. Then a meaningful identification of populations of high adaptability could be performed, as already performed by the USDA-Forest Service (Miller and Westfall 1992).

Public awareness of the necessity of forest genetic resources

It is extremely difficult to assess the public awareness of the necessity of forest genetic resources. In Austria, no opinion polls have been held on this issue. If the recent number of reports in public media (newspaper, TV, radio) is considered to indicate the public awareness of genetic diversity in forests, Austria is probably above the European average. This might be connected with the fact that in an alpine country the protection of forests has always been important because of erosion, torrents, avalanches, etc. Most of the forest owners are aware of the urgent need to conserve gene resources and contribute on a voluntary basis to the federal conservation programme. Also indirectly, the public awareness of the importance of genetic diversity can be concluded from the following:

In the draft bill of the Austrian Forest Reproductive Material Act, besides the standard EU-categories (selected and tested reproductive material), the hallmark `high genetic diversity' is introduced.

Anonymous. 1993. Österreichischer Waldbericht - Jahresbericht über die Forstwirtschaft und Bericht des Bundesministers für Land- und Forstwirtschaft an den Nationalrat gemäß 16 Abs. 6 Forstgesetz 1975 i.d.g.F., 103 p. and annex.

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