|
Contact
Journal is suspended
Managing Editor
- Ruth Landolt, Eidg. Forschungsanstalt WSL, CH-8903
Birmensdorf, Schweiz
Publisher
Index and Abstracts
- PDF download see Contents
Volume 77, Issue 1/2:
(2002)
Schönenberger, W.; Fischer, A.; Innes, J.L. (eds) 2002:
Vivian's Legacy in Switzerland - impact of windthrow on forest dynamics.
For. Snow Landsc. Res.
77,
1/2:
1-224.
Schönenberger, W., 2002:
Windthrow research after the 1990 storm Vivian in Switzerland: objectives, study sites, and projects.
For. Snow Landsc. Res.
77,
1/2:
9-16.
Abstract
In this special issue we publish a series of articles which summarise the results of ten years research on four study sites in mountain forests in the Swiss Alps. The study sites were set up after the 1990 blow-down caused by the storm Vivian. Each site was divided into the following three treatments: (1) uncleared with natural regeneration, (2) cleared with natural regeneration, and (3) planted (cleared with natural and planted regeneration). Special projects studied and compared the soils, the dynamics of the ground vegetation, the natural and artificial forest regeneration, the mycorrhiza, the impact of ungulates, the diversity of insects, the spread of bark beetles, the formation of avalanches, the surface erosion, and the timber decay in the different treatments. This paper summarises the common objectives of the projects and the characteristics of the four study sites.
Keywords
disturbance, blow-down, vegetation succession, forest regeneration, natural hazards, insects, mountain forest, Switzerland
Wohlgemuth, T.; Kull, P.; Wüthrich, H., 2002:
Disturbance of microsites and early tree regeneration after windthrow in Swiss mountain forests due to the winter storm Vivian 1990.
For. Snow Landsc. Res.
77,
1/2:
17-47.
Abstract
In 1990, the catastrophic storm Vivian created extensive windthrows, particularly in some mountain forests of the Swiss Alps. We have since been observing the vegetation succession and the tree regeneration in uncleared and cleared windthrown stands on four study sites in mountain forests at altitudes of 900 to 1600 m a.s.l. On the study sites, microsites were mapped and, subsequently, 236 permanent quadrats were installed. At two-year intervals, data were collected on plant and moss species between 1992 and 2000. Vegetation dynamics were analysed with respect to the succession of microsites, disturbance types, treatments and years of tree seed germination. Vegetation cover increased in all quadrats observed independent of microsites and types of disturbance. On most of the microsites, Rubus idaeus increased in frequency and in cover during the first 10 years after the windthrow. Grasses such as Calamagrostis villosa, Agrostis capillaris and Avenella flexuosa also increased. The most abundant regenerating tr
Keywords
windthrow, storm, disturbance, advance and post-windthrow regeneration, tall herb communities, Picea abies, Rubus idaeus, mountain forest, Switzerland
Lüscher, P., 2002:
Humus dynamics and changes in rooting patterns in windthrow areas.
For. Snow Landsc. Res.
77,
1/2:
49-59.
Abstract
Abrupt changes in site conditions due to windthrow initiate altered dynamics in humus formation, which affect germination, seedling growth and rooting patterns and thus also reforestation. This study examines changes in the upper soil horizons of four long-term observation sites with regard to morphology (humus form), porosity and rooting patterns. The new tall vegetation produces a different type and amount of litter, and the microclimate near the soil surface changes. Biological activity, organic matter turnover and mixing with the mineral fraction are accelerated. Where clearing operations damaged the soil, increased soil density and clogging of pores in the rooting zone impair drainage and aeration, which hinders rooting patterns and retards resettlement by trees, so that reforestation is greatly delayed. Clearing operations should cause as little damage as possible and new stock should be appropriate to the site type.
Keywords
humus dynamics, windthrow, humus form index, bulk density, porosity, rooting patterns, Switzerland
Schönenberger, W., 2002:
Post windthrow stand regeneration in Swiss mountain forests: the first ten years after the 1990 storm Vivian.
For. Snow Landsc. Res.
77,
1/2:
61-80.
Abstract
Sapling density and height were monitored for ten years after the 1990 storm Vivian on four windthrow study sites in four different regions of the Swiss Alps. Each study site was divided into three different treatments: (1) uncleared, (2) cleared, and (3) planted after clearing. In each treatment the number, height and condition of natural and planted saplings higher than 20 cm were assessed in 25 sample plots of 50 m2. In 2000, ten years after the storm, a mean of 1700 saplings ha-1 was counted. 14 species were found, of which Acer pseudoplatanus, Picea abies, Sorbus aucuparia, and Salix spp. were the most frequent. In two out of three study sites sapling density was significantly lower in the uncleared treatment than in both cleared treatments. Hardly any regeneration stock stemmed from the previous stand and survived the storm, so that almost all regeneration established by germination. The natural increase in the density of saplings was rather slow. In treatment "cleared and planted" 2000-2600 saplings p
Keywords
windthrow, blowdown, storm, disturbance, planting, regeneration, mountain forest, Switzerland
Egli, S.; Peter, M.; Falcato, S., 2002:
Dynamics of ectomycorrhizal fungi after windthrow.
For. Snow Landsc. Res.
77,
1/2:
81-88.
Abstract
Ectomycorrhizal fungi are dependent on the carbohydrates produced by higher plants. Their main energy source is lost immediately if the higher plant is eliminated, e.g. as the result of windthrow. In this study we investigated how long ectomycorrhizal fungi can survive in the soil and still be capable of colonizing naturally regenerating seedlings on an uncleared windthrow site. A biotest was used for measuring the mycorrhizal inoculum potential of the soil and morphological and molecular techniques for identifying the ectomycorrhizas. Ten years after the windthrow event, the number of infective ectomycorrhizal fungi in the soil of the windthrow plot was significantly smaller than in the adjacent forest. The remaining species, including Tylospora asterophora, Telephora terrestris and Cenococcum geophilum were still able to fully mycorrhize the new seedlings. The results are discussed with respect to possible implications for forestry practice.
Keywords
windthrow, ectomycorrhizal fungi, inoculum potential, regeneration
Frey, W.; Thee, P., 2002:
Avalanche protection of windthrow areas: A ten year comparison of cleared and uncleared starting zones.
For. Snow Landsc. Res.
77,
1/2:
89-107.
Abstract
In 1990 storm Vivian destroyed large montane and subalpine protection forests in potential avalanche starting zones. In the first decade after the storm, uncleared areas prevented avalanche release, whereas severe avalanche activity in cleared areas was observed. Down slope movement of lying stems during the first two years was considerable due to branches breaking under snow loads, but later in the first decade the subsequent movement towards the ground surface was relatively small. An experimental application of the calculated maximum snow load with a statistical return period of 30 years on lying stems showed that after 10 years the stems are stable, and are even quite resistant to further movement for up to 30 years. The increasing loss of wood strength after a decade decreases the protection capacity of uncleared parts. This capacity loss must be compensated for by the protective function of upcoming regeneration. If necessary, the partially weakened protection capacity in uncleared areas can be reinfor
Keywords
windthrow areas, avalanche starting zones, managing storm damage, protection function, Switzerland
Gerber, W.; Rickli, C.; Graf, F., 2002:
Surface erosion in cleared and uncleared mountain windthrow sites.
For. Snow Landsc. Res.
77,
1/2:
109-116.
Abstract
This study focused on the erosion processes in scars inflicted by storm Vivian. The windthrow study sites of Pfäfers, Schwanden and Disentis were investigated in relation to the soil characteristics and the plot treatments "uncleared", "cleared", "planted" (Schönenberger this issue). Thirty-five erosion scars (ES) were selected in 1992, and erosion activity was assessed by measuring the changes in their surface areas between 1992 and 2000. Furthermore, soil samples were taken to establish the grain size distribution. From a geotechnical point of view, the erodibility of the soil material increases between that in Disentis and Schwanden and that in Pfäfers. Nevertheless, on the "cleared" as well as the "planted" treatments at Pfäfers, the soil material proved better for vegetation re-establishment than on the same treatments in Schwanden and Disentis. During the investigation period (1992-2000) eight new ES developed, indicating that the soil stability of the study sites had entered the delicate phase whe
Keywords
windthrow, erosion, grain size distribution, vegetation re-establishment, slope inclination, Switzerland
Duelli, P.; Obrist, M.K.; Wermelinger, B., 2002:
Windthrow-induced changes in faunistic biodiversity in alpine spruce forests.
For. Snow Landsc. Res.
77,
1/2:
117-131.
Abstract
After the severe windthrow caused by the storm Vivian in 1990 in the Alps, political conflicts arose over the question whether clearing of the resulting gaps in the forest should be promoted and publicly subsidised. One argument against clearing was that uncleared windthrow areas would be better for the enhancement and conservation of biodiversity. In three regions in the Eastern Swiss Alps, the fauna was assessed for up to ten years after the storm in pairwise comparisons between cleared and uncleared windthrow areas and an intact managed forest control plot.
A total of 1856 species of invertebrates, reptiles, and small mammals were collected and identified. Windthrow areas yielded 35-69% more animal species than the intact forest plot. Neither the number of arthropod species collected in flight and pitfall traps, nor the number of red-listed species showed any significant differences between cleared or uncleared plots. However, extrapolation of rarefaction functions to estimate total species numbers per p
Keywords
biodiversity, fauna, storm, windthrow, succession, conservation, ecological resilience, Switzerland
Wermelinger, B.; Duelli, P.; Obrist, M.K., 2002:
Dynamics of saproxylic beetles (Coleoptera) in windthrow areas in alpine spruce forests.
For. Snow Landsc. Res.
77,
1/2:
133-148.
Abstract
Storms are important disturbance factors in the development of forest ecosystems. They trigger definite changes in vegetation composition and hence also in the associated insect fauna. Three windthrow areas created by the storm Vivian in 1990 in alpine spruce forests were each subdivided into a cleared and an uncleared treatment. The abundance of the three most frequent beetle families (Scolytidae, Cerambycidae, and Buprestidae) was monitored with two different trap types during six summer periods within the first 10 years after the windthrow. The large supply of breeding substrate triggered a distinct increase in insect abundance and in the species richness of this guild (except for the number of buprestid species) over a period of approximately five years. The first group reaching peak numbers were the Scolytidae (in 1992), followed by the Buprestidae (1994) and then by the Cerambycidae (1996). Ips typographus, the most important bark beetle, peaked in the third season after the storm (1992). The maximum n
Keywords
Buprestidae, Cerambycidae, Scolytidae, biodiversity, dead wood, succession, Ips typographus, Switzerland
Kupferschmid, A.D.; Schönenberger, W.; Wasem, U., 2002:
Tree regeneration in a Norway spruce snag stand after die-back caused by Ips typographus.
For. Snow Landsc. Res.
77,
1/2:
149-160.
Abstract
In a managed Picea abies mountain forest on Gandberg (northern Swiss Pre-Alps), almost all trees were killed by a European spruce bark beetle outbreak in 1993 and left unharvested. As we assumed the large amount of bark litter would have a negative effect on tree regeneration, we investigated natural tree regeneration in 12 permanent plots after bark removal and in 12 control plots with a bark cover of 50%. In half of the plots, 200 Picea abies seeds were sown per plot in 1995.
No advance tree regeneration was present. Three Picea abies seedlings m-2 germinated naturally in 1994. 3.8% of the 2400 sown Picea seeds germinated in 1995, resulting in 7.5 seedlings m-2, with equal numbers in plots with and without bark litter. We assume pieces of bark to have no effect on Picea germination. The mortality of naturally germinated Picea was 25% each year, regardless the age of the saplings (1-7 year). Acer pseudoplatanus saplings were almost as numerous as Picea (0.58 m-2) in 2001, but pioneer trees such as Betula pe
Keywords
Forest regeneration, snags, Picea abies, experimental sowing, seed source, Switzerland
Senn, J.; Wasem, U.; Odermatt, O., 2002:
Impact of browsing ungulates on plant cover and tree regeneration in windthrow areas.
For. Snow Landsc. Res.
77,
1/2:
161-170.
Abstract
Wild ungulates are often considered a threat to natural forest regeneration in windthrow areas. We studied their impact on developing vegetation in windthrow clearings on the northern side of the Swiss Alps. Fifty pairs of exclosure and control plots were established seven years after the windthrow and the composition and percentage of vegetation cover recorded. At that time, vegetation cover, including regeneration of woody species, did not differ on the two types of plots. Three years later, total cover had increased by about 40% in both types of plots. Thus, browsing ungulates did not slow down the growth of plant cover. The ungulates had only mild effects on the development of some plant groups: tall forbs, such as Epilobium angustifolium, which ungulates prefer, were fewer in the unfenced control plots than in exclosures, although the frequency of the other favourite species like Vaccinium myrtillus were not influenced by ungulates. The numbers of seedlings and saplings of woody species had increased fo
Keywords
windthrow, forest regeneration, ungulates, browsing, Switzerland
Mocalov, S.A.; Lässig, R., 2002:
Development of two boreal forests after large-scale windthrow in the Central Urals.
For. Snow Landsc. Res.
77,
1/2:
171-186.
Abstract
The processes of natural regeneration after windthrow were investigated in two permanent study areas located in the southern and middle taiga of the Central Urals. The forest types were dominated by Pinus silvestris and Larix sibirica in the north (Pinetum vacciniosum) and by Abies sibirica and Picea obovata in the south (Piceetum oxalidosum).The number of trees in the two study areas sharply increased over the seven years following the windthrow, mainly due to an increase in the number of broadleaved trees, with Betula pendula and Populus tremula predominating. Regeneration was most abundant on sites where the windfall debris was cleared, and was least on those that remained uncleared. The regeneration established after the windthrow was dominated by broadleaved species, while advance regeneration before the storm was dominated by conifers. Advance regeneration of conifers mostly survived in areas where the windfall debris was not cleared, but the rate of coniferous regeneration was higher in the cleared pa
Keywords
windthrow, regeneration, forest development, natural forest, boreal forest, Ural mountains, Russia
Dobbertin, M., 2002:
Influence of stand structure and site factors on wind damage comparing the storms Vivian and Lothar.
For. Snow Landsc. Res.
77,
1/2:
187-205.
Abstract
The influence of site factors and stand structure on wind damage to forests by the storms Vivian in 1990 and Lothar in 1999 was examined using classification tree methodology. More than 400 systematically located inventory plots within the area affected by both storms, covering approximately two thirds of the forest area in Switzerland, were used in the analysis.
Within the area 17% of the plots showed signs of damage by Vivian and 37% by Lothar. Classification tree methodology was used to recursively partition the data set into damaged and undamaged sites. Using ten-fold cross-validation, overall classification accuracy was around 80% for the Vivian storm and 65% for the Lothar storm.
For both storms the probability of damage increased with stand height, development stage, percentage of conifers, soil-water logging and soil depth. Damage was higher on hilltops, on plains or on gentle slopes, while irregularly structured stands had lower probabilities of storm damage. For the Lothar storm, forests with pri
Keywords
forest storm damage, windthrow, soil condition, stand factors, classification trees, Switzerland
Bründl, M.; Rickli, C., 2002:
The storm Lothar 1999 in Switzerland - an incident analysis.
For. Snow Landsc. Res.
77,
1/2:
207-217.
Abstract
On 26 December 1999 the storm Lothar hit Switzerland, followed by the storm Martin during the night from 27 to 28 December. High wind speeds and heavy gusts were characteristic of both storms, which caused great damage to forests, buildings and infrastructures. More than 12 million m3 of timber were damaged and the total cost amounted to 1.7 billion CHF. In this paper an overview of the meteorological conditions, the damage and the measures taken to deal with it is presented. It can be concluded that the consequences of the storm were well managed by most involved. However, improvements are possible for example, in the areas of the meteorological warning and communication of warnings and of communication between the different groups responsible for crisis management and recovery. Rapid decision-making according to clear criteria and the clear communication of a structured plan for coping with the damage in the forest could accelerate the recovery and lead to more satisfactory results.
Keywords
windthrow, storm, Lothar, atmosphere, risk management, natural hazards, Switzerland
Angst, C.; Volz, R., 2002:
A decision-support tool for managing storm-damaged forests.
For. Snow Landsc. Res.
77,
1/2:
217-224.
Abstract
Based on the results of research and on the experience gained after the storm Vivian, the Swiss Forest Agency has developed a decision-support tool for managing windthrow in mountain forests. It helps to reach a transparent, replicable decision as to whether, on a specific windthrow area, the fallen timber should be harvested or left. Our present knowledge of the relevant criteria, such as hazardous natural events, forest damage, forest management, nature conservation, social aspects, costs and profitability, is compiled. For each criterion, a list of possible arguments supporting either harvesting or leaving the fallen timber on the ground is given. All the issues relevant to the specific windthrow area are recorded and evaluated in a checklist, which provides a visual impression of the pros and cons of the final decision.
Keywords
windthrow, storm damage, forest management, forest policy, decision-support tool, Switzerland
|
|
