Zur Entstehung der NaiS-Standorttypen In der traditionellen Pflanzensoziologie werden die Pflanzengesellschaften rein floristisch definiert. Insbesondere im naturnahen Waldbau genügen diese Definitionen nicht, da aus ihnen oft nicht genau auf den Standort und das Wuchsverhalten der Bäume in einem einzelnen Bestand geschlossen werden kann. Im Gegensatz dazu verwendet das im Rahmen der Vorarbeiten zu den NaiS-Projekten (NaiS für «Nachhaltigkeit im Schutzwald») entwickelte System der Standorttypen floristische, standörtliche und waldbauliche Merkmale. Ein Standorttyp entspricht dabei einem mehr oder weniger engen Bereich auf den verschiedenen Standortgradienten beziehungsweise in den herkömmlichen Ökogrammen mit den Dimensionen Bodenfeuchte und Bodenreaktion. Seine Beschreibung umfasst auch den Baumbestand mit Konkurrenzsituation, Mischungsgrad und -form, Oberhöhe und Prozessen der Naturverjüngung sowie ein gezeichnetes, idealisiertes Bestandesprofil. Diese Beschreibung soll die Zuordnung eines realen Bestandes zum Standorttyp ermöglichen. Ein zentraler Teil des NaiS-Standorttypensystems ist das Konzept von Höhenstufen, deren Grenzen nicht primär nach der Meereshöhe, sondern nach dem Verhalten der Baumarten festgesetzt wurden. Für die Typendefinition wurden ausserdem Standortregionen unterschieden, die hauptsächlich durch die klimatischen Verbreitungsgrenzen der Hauptbaumarten definiert sind. Die Ökogramme liegen für jede Höhenstufe und Standortregion einzeln vor. Die Benennung und die Nummerierung der Standorttypen stützen sich auf bestehende kantonale Kartierungen und gesamtschweizerische Übersichten. Mit dem System der NaiS-Standorttypen wurde ein in der ganzen Schweiz anwendbares, praxisorientiertes Hilfsmittel geschaffen, mit dem sich die vielfältigen Wälder des Landes standörtlich und waldbaubezogen beschreiben lassen. Das System kann und soll je nach Zielsetzung verfeinert und angepasst werden. Sur la création des types de station NaiS Dans la phytosociologie traditionnelle, les communautés végétales sont définies de manière purement floristique. En particulier dans la sylviculture proche de la nature, ces définitions ne sont pas suffisantes, car elles ne permettent souvent pas de tirer des conclusions précises sur la station et la croissance des arbres dans un peuplement. En revanche, le système de types de station développé lors des travaux préparatoires des projets NaiS (NaiS pour «Nachhaltigkeit im Schutzwald» ou «durabilité en forêt de protection») utilise des caractéristiques floristiques, de station et sylvicoles. Un type de station correspond à une fourchette plus ou moins étroite sur les différents gradients de station ou, plus particulièrement, dans les écogrammes classiques avec les dimensions humidité du sol et réaction du sol. Sa description comprend également le peuplement avec sa situation concurrentielle, le degré et la forme de mélange, la hauteur dominante et les processus de régénération naturelle ainsi qu’un profil de peuplement idéalisé dessiné. Cette description doit permettre d’attribuer un peuplement réel au type de station. Une partie centrale du système de types de station NaiS est le concept d’étage altitudinal, dont les limites ne sont pas principalement déterminées par rapport au niveau de la mer, mais par le comportement des essences. Pour la définition des types, une distinction a également été faite entre les régions des stations, qui sont principalement définies par les limites de la distribution climatique des principales essences. Les écogrammes sont disponibles individuellement pour chaque étage altitudinal et chaque région géographique. La dénomination et la numérotation des types de station sont basées sur la cartographie cantonale existante et sur des vues d’ensemble nationales. Avec le système de types de station NaiS, un outil pratique a été créé qui peut être utilisé dans toute la Suisse pour décrire les diverses forêts du pays en termes de station et de sylviculture. Le système peut et doit être affiné et adapté en fonction des objectifs. On the emergence of the NaiS site types system In traditional plant sociology, plant communities are defined purely by floristic criteria. However, these definitions are not sufficient, especially in close-to-nature silviculture, since they often do not make it possible to draw conclusions about the exact site conditions and growth behaviour of trees in a stand. In contrast, the system of site types which has been developed during the preparatory work for the NaiS projects (NaiS for “Nachhaltigkeit im Schutzwald”, in English “Sustainability in the Protection Forest”) uses floristic, site and silvicultural characteristics. A site type corresponds to a range on the different site gradients (which may be wide or narrow) or in the conventional ecograms whose axes are soil moisture and soil reaction. The site type description also includes the tree population with the competitive situation, degree and form of mixture, dominant tree height and processes of natural regeneration and describes an idealized stand profile. This description should enable the assignment of a real stand to a site type. A central part of the NaiS site type system is the concept of altitude levels, the limits of which are not primarily determined by height above sea level, but by the behaviour of the tree species. For the definition of the type, a distinction was also made between site regions, which are mainly defined by the climatic distribution limits of the main tree species. Ecograms are available individually for each altitude level and site region. The naming and numbering of the site types is based on existing cantonal mapping and nationwide overviews. With the system of NaiS site types, a practice-oriented tool has been created that can be used throughout Switzerland to describe the country’s diverse forests in terms of site conditions and silviculture. The system can and should be refined, taking account of the objectives fixed, and adapted as necessary.

Neue Waldstandort-Hinweiskarte Graubündens zur Ermittlung sensitiver Standorte und Bestände Kenntnisse der Waldstandorttypen sind grundlegend, um den heutigen Zustand und die künftige Entwick-lung des Waldes zu verstehen. Insbesondere in Schutzwäldern ist entscheidend, wie widerstands- und anpassungsfähig die heutigen Bestände sind. Die komplett überarbeitete, flächendeckende Waldstandort- Hinweiskarte für den Kanton Graubünden ist ein wichtiges Planungsinstrument: Sie dient als Grundlage für die Bestimmung von Standorten und Beständen, die empfindlich auf den Klimawandel reagieren könnten. Darüber hinaus ermöglicht sie es, flächendeckende Baumartenempfehlungen für die Zukunft zu erstellen. Nouvelle carte des sites forestiers des Grisons pour l'identification des sites et des peuplements sensibles La connaissance des types de stations forestières est fondamentale pour comprendre l’état actuel et le développement futur de la forêt. Dans les forêts de protection en particulier, la résilience et l’adaptabilité des peuplements actuels sont cruciales. La carte des stations forestières modélisée pour tout le canton des Grisons a été entièrement révisée. Elle constitue un outil de planification important qui sert de base pour déterminer les types de stations et de peuplements susceptibles de réagir de manière sensible au changement climatique. En même temps, la carte des stations forestières modélisée peut être utilisée pour établir des recommandations d’espèces d’arbres à l’échelle régionale pour l’avenir.

Modelling of the vegetation belts and the areas of beech and silver fir for Switzerland The vegetation belts and the distribution area of beech and silver fir in Switzerland are an essential basis for the classification of forest site types with ecograms and therefore for site-specific recommendations of tree species and for forestry. Their limits, which are to a large extend defined by climatic factors, were until now only defined on a qualitative basis. For the future usage of the ecograms for tree species recommendations the limits must be described quantitatively, so that they can be modelled for the future with climate scenarios. With maps in a high spatial resolution of the forest-relevant climate variables and with additional important site parameters, those parameters were selected, which were relevant for the actual limits of the vegetation belts as well as for the beech and silver fir areal. The altitudinal belts were modelled by means of a linear regression between the known position of a representative altitudinal limit and the respective climatic factors at that position. The areal limits were modelled with a fuzzy logic approach. The climatic variables for the time span 2070–2099 were calculated on the basis of the climate (emission) scenario A1B (regional models RegCM3 and CLM), so that the limits of the altitudinal belts and the areas could be modelled for the future. The results of the model approaches are ecologically plausible. This could be shown in a comparison with the forest site types on the sample points of the National Forest Inventory and in an expert evaluation. The developed vegetation and climate maps as well as the modelled projections of the altitudinal belts in the future are the basis for the inclusion of climate change in the recommendation of tree species. They serve as decision support for forest managers and authorities in the forestry planning which is confronted with many uncertainties.

Importance of marteloscopes for practice and teaching in Switzerland Marking is one of the core tasks of silvicultural activity. The decisions made are based on the application of the basic forestry methods, but always include a subjective component, as experience plays an important role. In this context, the “silvicultural God's gaze” in German “waldbaulicher Götterblick” is often spoken of. A possibility to discuss different silvicultural options and their consequences in a factual and comprehensible way is offered by the marteloscope. It is a didactic tool that makes it possible to carry out marking exercises based on quantitative data on site. Ideally, it consists of a real inventory and software that allows evaluation and discussion of the results, as well as a dynamic growth model. The marteloscope was developed in France in the 1990s. Today, there are many more than 40 marteloscopes in Switzerland that deal with a wide variety of silvicultural issues. Marteloscopes play a particularly important role in training and education: they allow the practice, questioning and improvement of one's own silvicultural actions based on quantitative principles. There is great potential for the further development of marteloscopes, in particular regarding the implementation of specific thematic and silvicultural issues, which, in addition to the usual stand characteristics such as tree species, diameter distribution, base area and volume, for example, allow statements to be made on ecology or on variables relevant to mountain silviculture such as local light availability. Several marteloscope software solutions have been developed in recent years. It would be important at least to simplify the data exchange between the solutions. It would also be desirable to close the gap that currently exists in the modelling of further stand development, to better estimate the consequences of different intervention variants.

The new NaiS target profile for rockfall Due to new findings on the protective function of forests against rockfall, the Federal Office for the Environment started in 2008 with a revision of the Swiss target profiles for rockfall protection forests. Until now, fall velocity of rocks, rock mass, as well as the forested slope length, were not considered for the determination of the target profile. In order to incorporate all of these important factors, an Internet-based form has been developed which calculates the target profile. This article firstly gives a short overview of the most important aspects of rockfall in protection forests and secondly presents the approach used for the calculation of the new target profile. Although the German word “Steinschlag” only refers to small rock particles, forests also have a protective effect against large blocks (e.g. >5 m 3 ), however, a long forested transit zone with a sufficient number of trees with larger stem diameters is required for a relevant energy and risk reduction. The new target profile offers possibilities to account for such situations as well.

Expansion and development of Green Alder stands in eastern Switzerland In many subalpine regions of Switzerland, the Green Alder (Alnus viridis) is expanding as summer pastures are abandoned. The Federal Office for the Environment has set up a research project to improve the understanding of the characteristics of Green Alder and the consequences of its expansion. This project is based on a literature search, interviews with experts and GIS-based analysis of the past and present occurrence of Green Alder in three areas of eastern Switzerland. The results show that Green Alder is present at all exposures in the research areas. It is not lime-intolerant, but is less present on well drained basic subsoils. It is much more widespread than hitherto believed. In the canton of Glarus as well as in the Surselva, the area of Green Alder stands has doubled in the past 75 years. Only a few have developed to high forest stands. Therefore Green Alder stands should be considered, at least in their optimum oceanic sites, as permanent association, and not pioneer forests. In many places a broad belt of Green Alder has developed at the upper treeline, which is preventing the establishment of other species (e.g. Spruce) which might be possible because of climate change. Without intervention, the Green Alder stands will in all likelihood continue to expand over the coming decades. The areas affected by this expansion should be identified as of now, and a decision taken as to whether or not to tolerate this expansion. It is important that planning measures (agriculture, forestry, regional development) be taken early enough.

Modelling the impact of ungulate browsing on the development of the protective forests of the Rigi-Nordlehne Forests on the northern slopes of the Rigi Mountain in central Switzerland (“Rigi-Nordlehne”) have a key protective function against rockfall, erosion, landslides, flooding and debris flows. Forest management endeavours to guarantee that these forests can maintain their role in the long term. Thus multi-story canopies are favored, being resistant and resilient to natural disturbances such as windthrow. In addition, the mixture of tree species should conform to the guidelines of the national project “Sustainability and success monitoring in protection forests” (NaiS). However, at the present time an imbalance in tree species is evident in the regeneration layer, due to the considerable impact of browsing by wild ungulate populations in these beech and fir forests. To predict future mixtures of tree species, the spatially explicit model of forest development Rigfor was developed and applied to simulate and compare two scenarios of forest dynamics. The scenario “current browsing” suggests that silver fir cannot regenerate and that regeneration of maple and beech is greatly hindered. In the scenario “reduced browsing”, however, a species mixture conforming to the national guidelines can be achieved in the regeneration layer. The simulations show that the amount of beech timber decreases whichever the scenario, while for the larger fir trees in diameter classes above 35 cm no changes are to be expected in the coming decades. However, from 2082 onwards a continuing high browsing rate would lead to the elimination of nearly all silver fir trees at the pole stage and in the long run silver fir may be completely eradicated from these stands. We conclude that under a dense canopy of old trees, silver fir and beech can be regenerated if ungulate browsing is considerably reduced. Spruce regeneration however requires more light and this is not often found on the northern slopes of the Rigi Mountain. Opening up the canopy to foster regeneration of the desired mixture of species is a key measure in order to maintain the long-term protective function of these forests. This will only be possible, however, if the current high browsing intensity can be reduced.

Economic consequences of browsing problems on Rigi-Nordlehne Stand regeneration with suitable tree species plays a key role in the management of protection forests. This is complicated in many regions in Switzerland due to browsing damage caused by game animals. In particular, the regeneration of the valuable Abies alba species is regionally heavily impaired. This can entail considerable expenses for the support of stand regeneration and compensation of lost protective effects. Using the Rigi-Nordlehne in Switzerland as test location, the following three questions were studied with the help of an analysis of cost-effectiveness and based on the Rigfor forest development model: 1) What costs are to be expected over the next 50 years for protection measures against browsing damage, 2) what would be the cost of a reduction of the game population size and 3) what measures are necessary for the replacement of the protective effects against avalanches and what are the respective costs? The study resulted in cost estimations for technical measures against browsing damage, game regulation and the combination of these two strategies. In addition, costs for the replacement of lost protective effects related to snow movements were estimated. The study shows, that the high pressure of browsing damage at the Rigi-Nordlehne causes forest management problems as well as economic disadvantages. Their amount is 3 million to 6.6 million Swiss francs within 50 years depending on the measures taken. Thus, the results obtained by the study at the Rigi-Nordlehne provide a new argument in the discussion of regeneration in protection forests, which in Switzerland for many years has mainly been lead based on silviculture and game ecology issues.

Adequate management practices to attain the profiles specified in the Swiss guidelines for the management of mountain protection forests are not always unequivocally clear. This applies among others for beech forests that have a protective function against rockfall. We defined two management scenarios, one of which aims at harvesting trees starting with a minimum diameter at breast height of 40 cm, whereas the other one is focused on the creation of small gaps (area of 500 m 2 ) over a maximum of 10% of the total stand area. These scenarios along with a control scenario characterized by no management were studied using the forest growth model BWINPro. In the control scenario, number of trees, basal area and standing volume were highest. The developments simulated under the two management scenarios were similar, when in scenario thinning harvesting levels corresponded to the growth over a 10-year period. In the other cases, number of trees, basal area and standing volume are lower under scenario gap because harvesting interventions occur more regularly. If the rocks have a volume exceeding 0.2 m 3 , the requirements of the profiles are attained more quickly under scenario gap , because in scenario thinning the larger trees are preferentially harvested. Because tree regeneration was not simulated, it is difficult to realistically predict the development of the number of trees. However, management interventions are needed in such forests, particularly if the profile for rocks with a volume below 0.2 m 3 is to be attained and maintained.

Over the past decades the framework conditions pertaining to the care of mountain forests have changed radically. Wood production has become less and less profitable whereas public demands placed on the forest have grown considerably, particularly with regard to its protective function. The paper gives an overview of the most important developments since the appointment of Jean-Philippe Schütz at ETH Zurich as professor of silviculture. We concentrate on the following issues; firstly the teaching of mountain silviculture, which has been carried out since 1980 by Professor Schütz. Secondly, implementation,which since 1984 has been fostered by the Swiss Mountain Silvicultural group and, thirdly, developments with regard to projects.

The article shows that knowledge of the site of a particular forest stand, together with research results and experience, can provide information that is important for the cultivation of mountain forests, including knowledge of the composition of the tree species and the structure and growth capacity of natural forest. Furthermore, certain sites can, thus, be characterized by factors that influence restocking, such as snow mould,lush ground vegetation or low temperature. The guidelines«minimale Pflegemassnahmen» – «Minimal tending of protection forests» (WASSER und FREHNER, 1996) are based on this principle. For individual sites, warnings about natural dangers such as rock fall or statements concerning nature conservation can be made (e.g., the occurrence of tree species, suitability as a biotope for Capercaille). In conclusion, two research projects on the relationship between site and natural dangers will be presented.

The development of planted Norway-spruce trees as well as the germination and self-seeding of natural regeneration were investigated on various forest locations on the north and south slopes between 1470 and 1800 m above sea level in the training forest of ETH Zurich in Sedrun, canton of Grisons, Switzerland.