Langau – Close-to-nature management, reflections based on 20 years of

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How to balance forestry and biodiversity conservation – A view across Europe

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Langau – Close-to-nature management, reflections based on 20 years of

experience

J. Doppler

Forstverwaltung Langau, Gaming, Austria

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< Fig. C 22.1. Mixed mountain forest – the optimal stand (Photo: Johannes Doppler).

Context, legal frame, and ownership structure

The private forests of the former ‘Rothschild’sche Forstverwaltung Langau’ are located in southern Lower Austria on the border to Styria. The com-

plete forest enterprise has very recently changed ownership in 2018/2019. It is now owned by the Prinzhorn Holding. The information presented in this case example refers to the developments taking place under the ownership of the ‘Roth- schild’sche Forstverwaltung Langau’.

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Austria

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Table C 22.1. General information on the Langau forest.

Total forest area 8431 ha

Organisational structure four forest districts managed by four foresters; one head forest manager Main management types No clearcutting since 1994; selective felling at varying intensities

Total standing volume 2 600 000 m³

Annual growth 5 m³/ha

Annual cut 42 000 m³

Deadwood (standing and lying) 50 m³/ha (estimated)

Altitude 1050 m a.s.l.

Ownership Rothschild’sche Forstverwaltung Langau (owners of the trust were the members of the Rothschild family); since 2018/2019 the forest is owned by Prinzhorn Holding

Climate Typical climate of the alpine foothills with high precipitation; seasonal extremes in late winter falling mainly as snow; often rainy periods in June/July; low annual average temperature (~5.7 °C)

Soil Shallow dolomite rendzina soils; limestone brown loam; gravel in floodplain areas

Geology Northeastern limestone Alps: limestone, dolomite with occasional occurrence of sandstone

Protected areas 1159 ha of wilderness area (‘Wildnisgebiet Dürrenstein’); 216 ha of strict forest reserves (‘Hinterer Oiswald’) 11 ha of old-growth islands/patches Natural forest community Submontane and montane Norway spruce–fir–beech forests (Picea

abies–Abies alba–Fagus sylvatica) with sycamore (Acer pseudoplatanus), ash (Fraxinus excelsior), mountain elm (Ulmus glabra); subalpine Norway spruce forest, beech forests, floodplain forests, ravine forests with sycamore and mountain elm

Statement

“The key to the success of close-to-nature management is to ensure continuity.”

Because of the supposedly difficult local conditions, forest management in limestone-dominated mountain ranges has traditionally been equated with stand-wise tree removals. This often resulted in ecologically and structurally unstable coniferous forests. Ecological knowledge and experience as

well as technical developments, however, have led to a significant improvement of framework conditions. This case study argues that the management of mixed mountain forests that build on the princi- ples of continuous cover forestry is possible despite adverse conditions.

Timber/Biomass

Non-timber products

Erosion

Protection

Biodiversity Recreation

Landscape Climate Groundwater

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Forest history and cultural heritage

For many centuries, the forests of Langau – owned by the Carthusian Monastery Gaming since the fourteenth century – were not used for the extrac- tion of wood as a raw material. They served as pas- tures for livestock, primarily for ‘clarified butter’

production. Only extremely rocky areas were excluded from grazing. In some parts, cattle grazing was practised until the 1960s. It was only in the second half of the eighteenth century, that exploitation of the forest began: primeval forests were cleared on a large scale, with the main aim of supplying firewood (‘energy wood’) for the cities of Vienna and Bratislava. Beech timber was charred on site as it could not be transported by water because of its weight. Firewood was also used as the main source of energy for the regional iron industry. The first use of timber for construction only started in the second half of the nineteenth century. In retrospect, the introduction of brown and hard coal saved the Langau old-growth forests from being completely exploited.

These plundered natural forests, however, gave rise to the highly valued old Norway spruce–silver fir–beech stands of today. We also know that the historical large clearcutting operations were not

‘clearcuts’ in a strict sense, as mature beech (Fagus sylvatica) and silver fir (Abies alba), which were of low value, were not cut and remained as seed trees.

The ‘academic’ age-class forest with final clearcutting was then introduced from 1870 onwards under the influence of the theory of the highest net revenue. For over a century, 60 % Nor- way spruce (Picea abies) and 40 % European larch (Larix decidua) was considered as the ideal growing stock target. The suppression of the vital beech was the consequence of the ‘modern’ forestry goals, achieved by clearcutting, cattle grazing, and the deterioration of humus layers by burning the cleared areas.

The abandonment of clearcutting did not take place until 1980. A strict and consistent ban on clearcutting was introduced in 1994. Since that time open, unstocked areas originated only after calamities such as windthrow, bark beetle infestations, or avalanches.

Close-to-nature management in the forests of Langau

Soil protection

Ultimately, the soil is at the centre of management considerations. All interventions are measured to determine their influence on soil development;

under no circumstances should fertility be impaired.

On degraded soils, be it through historical second- ary uses or through inappropriate stocking (e.g.

pure conifer stands), a reversal of the trend is sought through various measures. These include building up the humus layer through the ban on clearcutting, and minimising the loss of biomass through wood harvesting as far as possible. Branch material remains in the stand and no energy wood assortments such as wood chips are removed. The removal of the whole tree in the course of cable logging is not applied. Further emphasis is put on converting raw humus into mould or mull (i.e. well decomposed leaf organic matter) humus with the exception of subalpine Norway spruce forests.

Under the given circumstances this is achieved by promoting broadleaved tree species and silver fir.

Increasing the diversity of herbaceous plants can make a considerable contribution to the recovery of the topsoil. This can be supported by irregular thinning of dense forest stands.

Multi-functionality

Silvicultural practices in Langau can be character- ised as integrative and sustainable. There is no maximisation of timber production in disregard of the demands of nature conservation, forest aes- thetics, wildlife habitats, recreational space, and protective function (fig. C 22.2). Despite the consid- eration of diverse objectives, forestry continues to remain subject to the principle of economic effi- ciency. This means that the growing stock should be maintained or increased as a minimum requirement. Surpluses for the owners must be generated in the medium term. Reinvestment in the forest (e.g. for the construction of roads, stand mainte- nance, thinning operations) need to be financed in any case. This has been achieved in Langau forest during the last 20 years, despite low average roundwood prices, by minimising administrative costs, improving operating procedures, and exploring opportunities for additional income through diver- sification.

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Economic considerations

Ecologically oriented forest management does not imply losing sight of economic aims; actually, the contrary is true. In the long term, ecologically oriented silviculture may prove to be more economically attractive than age-class forest management.

However, this requires sound knowledge of yield-related inter-relationships between individual trees and stand dynamics. The economic aim in the forest enterprise is to produce large-dimension, high-quality timber (fig. C 22.3) for the following reasons:

– ‘Wood only grows on wood’, an annual diameter increment increase of 5 mm for trees with a diameter of 40 cm yields about twice the area of wood growth as compared to that of a tree with a diameter of 20 cm.

– The proportion of valuable wood assortments increases with larger tree diameters.

– The costs of harvesting wood decreases with increasing tree diameter. This is particularly true in mountain regions, as options for mechanisa- tion are comparatively limited and the proportion of manual work is substantial.

– In close-to-nature forestry, it is primarily the individual tree that is assessed and not the stand. The growth and value development potential of the tree, its quality, health status, and its relationship to neighbouring trees are of main concern.

– There is no need to determine the rotation period as the individual maturity of the tree is considered.

Example: a Norway spruce of good quality with a diameter of 500 mm at breast height is not removed as its economic value may continue to increase. A tree with a smaller diameter, trunk damage (wood rot) and/or poor quality could very well be removed in view of roundwood production. The question of ‘letting a tree mature’ is an essential principle of close-to-nature forestry – the actual age of a tree is actually of minor importance.

The responsiveness of individual trees of different species to different silvicultural measures is taken into account. The increase in diameter can be stim- ulated by providing more space to individual trees.

This ‘thinning effect’ was underestimated in the past, especially for older trees, ultimately leading to rotation periods of 100–120 years for the main Fig. C 22.2. Combining ecological and economic aims on

the same forest area (Photo: Johannes Doppler).

Fig. C 22.3. High-quality timber production in Langau forest (Photo: Johannes Doppler).

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tree species in Langau. Experience shows that even 200-year-old trees still react with additional growth to the removal of ‘competitors’, for example by increasing the surface area of the tree crown and thus the active assimilation area. At the stand level, this means that even when the number of trees is reduced, the overall stand growth does not neces- sarily decrease. This correlation is particularly strik- ing in the case of beech. The stocking rate can be reduced to 60 % without loss of total production – growth is ‘concentrated’ on a small number of trees.

Key silvicultural measures in Langau forest

Favouring natural regeneration

The opening of dense canopies has the positive side effect that more sunlight reaches the forest floor, thus enabling the development of vascular plants that require such conditions. In addition to a diver- sification of the herbaceous layer the probability of natural regeneration of a forest stand considerably improves. Natural regeneration is the first important step in ecological forest management – pro- vided that the parent stand is adapted to the loca- tion and consists, at least partially, of tree species of the potential natural forest community (fig. C 22.4).

Natural regeneration has a number of advan- tages as compared to artificial regeneration (sow- ing or planting). It is thus at the heart of forest management in Langau forest. It eliminates afforestation costs which are estimated at a minimum of 3000 €/ha. If the enterprise would implement stand-wise clearcutting, this would result in an annual afforestation area of approximately 30 ha.

The financial impact would amount to a minimum of € 90 000, whereby such an investment will only produce a return after many decades.

In the case of a stand which is well adapted to a particular site, natural regeneration will ensure propagation of a large variability of genetic material for the next generation stand. In close-to-nature forestry, regeneration of stands is a continuous process and not limited to a single ‘mast’ or exceptional seed year of the main tree species. The aim is to extend the regeneration period as much as possible and to use several seed years of particular tree species. The seed production of Norway

spruce and beech, for example, fluctuates greatly from year to year, but these species have numerous seed years per decade of varying intensity. The seed production of silver fir, sycamore (Acer pseudoplat- anus), and ash (Fraxinus excelsior) does not fluctu- ate as much. In contrast, the genetic variability of plants used in artificial reforestation is much nar- rower as they often originate from a few selected individual trees (with obviously good growth or timber characteristics). Natural regeneration takes advantage of nature producing an extensive sur- plus of new seedlings, and allows natural selection to determine which genotypes survive, and therefore the genetic variability of the populations of particular tree species. Increased focus is given by the enterprise also to activating latent genetic characteristics of trees with regards to changing environmental conditions (epigenetics). This is supported by allowing the establishment of seedlings from different seed years which further broadens the genetic basis of forest stands and adaptation potentials.

The roots of naturally regenerated seedlings can develop freely, adapted to the specific soil conditions. Depending on the planting method used in artificial regeneration, the roots of the plants are often injured and deformed and are usually subject to plant shock, and only recover after a number of years. Under the climatic conditions that prevail in Langau forest, artificial regeneration in spring is always a risk, especially owing to the timing of snowmelt. Seedlings which have already started to sprout are very susceptible to breakage or if that is to be avoided they may have to be preserved in cold storage until conditions for planting are suitable. ‘Föhn’ weather phases following planting have repeatedly led to high losses of seedlings and expensive replanting measures. Tree species susceptible to browsing such as silver fir and sycamore cannot be artificially regenerated at reasonable economic cost. They need to be available in suffi- cient numbers, as is the case in natural regeneration. Only then can it be ensured that they will form part of the next generation of silver fir trees.

Thinning with deliberation

The further development of young trees is accom- panied by a minimum of intervention. Mature stands provide young trees with canopy shelter and stability allowing management costs to be kept to a minimum. Other positive effects are the creation

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of ecological niches through uneven shading or radiation. Shade-bearing tree species can develop under dense canopies while light-demanding ones find suitable conditions in gaps or along stand edges. Marking trees for removal also allows control of the light conditions (fig. C 22.5). Cautious interventions will tend to promote ‘development.

is used again few lines down again shade tolerant tree species, which is called ‘pre-regeneration’. This is particularly important for silver fir, for which slow growth in early development stages is typical.

Depending on local conditions, opening the canopy too strongly may lead to development of dense grass cover, which then hinders the regeneration of tree species with shallow seedling roots, such as Norway spruce. As a simple rule, in Langau forest no more than 10 % of the mature trees are removed during the first intervention, so that stability of the stand is only slightly affected and that for a short time. Natural disturbance events such as lightning, bark beetle infestations, storms, or snow break also

initiate stand renewal. If such disturbances occur in the form of small gaps they can be incorporated as management measures with a view towards enterprise goals.

The next interventions aim at counteracting homogenisation by promoting tree species and structural diversity (vertical and horizontal structure) every 5–20 years, depending on site conditions. Initial successes have been achieved on better forest sites, especially where all tree species in the old stand were still represented. In the absence of beech and silver fir, repopulation tends to take longer. However, the dispersal potential of seeds from old beech and old silver fir in close vicinity to a thinned Norway spruce stand is surprisingly good and will ensure that these species will become part of the next stand. On less fertile soils, the effects of such interventions only showed after several decades.

Fig. C 22.4. Natural regeneration indicates forest site potential (Photo: Johannes Doppler).

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Game management is imperative

Besides the silvicultural treatment, it is necessary to control the game population to ensure successful regeneration (fig. C 22.6). If the aim is to manage forests more ecologically, a change of common hunting practices and culture is unavoidable. The

‘carrying capacity’ of game populations very much depends on actual site conditions; in comparison to nutrient-rich sites, those poor in nutrients can only support smaller ungulate populations. This is a problem particularly on poor dolomite rendzina sites, common in Langau forest. Close-to-nature forest management on the other hand also leads to a significant improvement of game habitat offer- ing ungulates a species-rich diet across the entire forest area.

The Rothschild Forest Administration thus iden- tified ‘site condition’ as most important when it comes to impact of game, mainly roe deer (Capreo- lus capreolus), red deer (Cervus elaphus), and cham- ois (Rupicapra rupicapra), on the forests and regen-

eration. Also keeping ungulate populations high for hunting purposes by feeding, was practiced and resulted in considerable browsing damages. Thus the formerly renowned hunting area Langau, required an adaptation of its hunting approach best serving the close-to-nature forest management concept. Besides an adequate hunting reform, a major challenge for the forest enterprise was to convince forest owners and employees alike that hunting (which had played a very important role for more than 100 years) should be subordinate to the objectives of forest management.

Essential changes made to Langau’s hunting approach:

– Recognition that in mountain forests no economic profits can be made by hunting – hence there is no lease of hunting grounds (which actually results in a loss of sovereignty on the part of the landowner). Therefore, the enterprise no longer collects any income from hunting.

Fig. C 22.5. Tree marking as a vital silvicultural tool for developing forest stands (Photo: Johannes Doppler).

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– The feeding of roe deer and chamois has been stopped: starting in 1980 the counterproductive feeding of chamois, and since 1991 the winter feeding of roe deer, was abandoned. The number of red deer feedings has also gradually been reduced.

– Intensification of hunting in order to reduce excessive game densities with focus on females to reduce the reproduction rate.

– Build on scientific knowledge for setting guide- lines as compared to traditional hunting customs and habits.

– The responsibility for the hunting areas was given to the forest managers.

Allowing for self-regulation

Further stand development should incorporate self-regulation as much as possible, thus avoiding labour-intensive intervention. The reduction of stem density will only take place in exceptional cases. Any following intervention is regarded as a

so-called ‘structural thinning’. Such thinnings aim at counteracting homogenisation in young stands.

The thinnings help maintain or improve stand structure and ensure the presence of the targeted tree species as well as the desired distribution of diameter classes and tree heights. If trees of the new generation ultimately grow into the canopy of the previous stand, only mature trees should be considered for removal thus allowing the younger trees to fully develop.

The sequence of interventions is also linked to the ability of a stand to react and follows the for- ester’s experience of intervening ‘early, moder- ately, and regularly’. Such an approach helps avoid destabilisation and lowers the vulnerability of stands to storms and snow break. Once a stand has reached its target volume (e.g. 400–500 m³), the next intervention will remove no more than the increment which accumulated since the last har- vest. In the Langau forest under average conditions and an annual increment of around 10 m³/ha, this would mean that approximately 50 m³ can be Fig. C 22.6. Hunting as a central instrument of forest conversion (Photo: Johannes Doppler).

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removed every seven years. The growing stock (in mature stands between 500 and 600 m³) will therefore only fluctuate slightly more than 10 %. From an economic perspective, this approach allows peri- odic generation of surpluses, unlike in even-aged forests. In even-aged forests, the high surpluses are only generated at the end of the rotation period (which used to be about 120 years in Langau forest). Selection cutting as performed in close-to-nature forest management thus represents an attractive alternative, especially for small forest holdings.

Well-trained staff and good forest access are essential

Felling is carried out carefully requiring good organisation and appropriate skills to avoid unnec- essary damage to the remaining trees. Therefore, the enterprise ensures professional training of its forest workers. This can take place either by visiting other forest enterprises which have extensive experience in close-to-nature forest management or under the guidance of one of the experienced forest workers. A further prerequisite for careful tree felling operations is the availability of a well-de- signed network of forest roads and skidding trails to avoid irreversible soil compaction by heavy machinery as far as possible. Small cable cranes are used in terrain with slopes of 60 % or more; such slopes are not uncommon in Langau forest. Cable logging has been shown to be economically viable even for small timber quantities, and to keep damage to soil and the stand to a minimum.

Nature conservation – an integral part of forest management

In addition to officially prescribed nature conservation measures, the Rothschild family saw nature conservation as a fundamental obligation as the former owner of Langau forest. We have to thank Albert Rothschild (born 1844; died 1911) for the last area of Norway spruce–silver fir–beech virgin forest in Central Europe. He was the one who, out of his own conviction, protected this area from any forest use already in 1875. This philosophy accom- panied the enterprise’s operations until its sale in 2019 being particularly evident in the development of forest management towards the greatest possible closeness to nature.

Next to the wilderness area ‘Dürrenstein’ with its 1159 ha (which includes the primeval forest

‘Rothwald’ as a core area), there is also the strict forest reserve ‘Hinterer Oiswald’ (216 ha) as well as six so-called ‘old –growth islands’ with a total area of 11 ha. About 400 veteran and cavity trees were designated by taking advantage of forest conservation support programmes. The entire forest enterprise is part of the landscape protection area

‘Ötscher Dürrenstein’ which has also been designated as a Natura 2000 area. Species under Annex II of the Habitat Directive in Ötscher-Dürrenstein are manifold and include: brown bear (Ursus arctos), lynx (Lynx lynx), greater mouse-eared bat (Myotis myotis), Alpine newt (Ichthyosaura alpestris), yel- low-bellied toad (Bombina variegata), Alpine long- horn beetle (Rosalia alpina), the scarce large blue

Fig. C 22.7. Alpine salamander (Salamandra atra) and Alpine longhorn beetle (Rosalia alpina) as two typical species of the Langau forest (Photos: Johannes Doppler (left) and Andreas Rigling (right)).

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(Phengaris teleius), Jersey tiger moth (Euplagia quadripunctaria), and the lady’s-slipper orchid (Cypripedium calceolus). Bird species under Annex I of the Birds Directive include: black stork (Ciconia nigra), golden eagle (Aquila chrysaetos), capercail- lie (Tetrao urogallus), eagle owl (Bubo bubo), grey- headed woodpecker (Picus canus), black wood- pecker (Dryocopus martius), red-breasted flycatcher (Ficedula parva), and rock ptarmigan (Lagopus muta).

Concluding reflections

The concept of close-to-nature forest management in Langau is nowadays applied in different variants, depending on the natural conditions (terrain, climate, soil) and the given stand composition. Stands range from easily accessible mixed forests with good soils to steep southern slopes on dolomite with pure Norway spruce reforestation and extreme stand damage by red deer. Such a diversity of conditions mean that the forest managers of Langau are confronted with a suite of challenges. The path towards the ideal of a ‘Plenter’ forest-type struc-

ture structure in mixed mountain forest stands can therefore be quite different, and in some cases may take considerable effort and a long time. The minimum requirement in Langau forest is to reverse existing site degradation. Such has already been achieved by increasing the amount of broadleaved trees in stands over large areas.

Nature conservation has always been anchored in Langau forest enterprise and is part of our daily work. The enterprise implements various aspects of nature conservation across the entire forest area.

Those include besides soil preservation, natural tree species mixtures, and ground vegetation, the preservation of old trees, the designation and protection of special biotopes, and the accumulation of deadwood to a certain extent in all forest districts (fig. C 22.8). Recognising the extraordinary functions of forest ecosystems in managed forests should never be underestimated, even if this is associated with supposedly economic compromises.

The key to the successful implementation of a new forest management concept is committed employees. In our forest districts a forest manager Fig. C 22.8. Deadwood as a means for improving species richness in managed forests (Johannes Doppler).

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has an annual felling target of approximately 10 000 m³ and is responsible for the shooting of around 100 ungulates. All trees to be removed (or retained) need to be consciously and carefully assessed both from a silvicultural and nature conservation perspective. Such work and decision-mak- ing requires highly skilled and qualified foresters whose achievements are very much appreciated at the enterprise. With a view to the future both the economic and legal framework of the enterprise will need to support the implementation of forest management in this sense, as ‘continuity is essential for successfully carrying on such a concept’ in Lan- gau forest.