ALPEROS


Nummer: 10588
Akronym: ALPEROS
Titel (deutsch): Seed propagation of indigenous species and their use for restoration of eroded areas of the alps
Projektstart: 01.01.1998
Projektende: 27.12.2006
AuftragnehmerIn: Direktion Raumberg-Gumpenstein
Projektleitung: Dr. Bernhard KRAUTZER
Finanzierungsstellen: Bundesministerium für Land- und Forstwirtschaft, Umwelt und Wasserwirtschaft
Wissenschaftszweig:

Zielsetzung

- Entwicklung und Etablierung einer wirtschaftlichen Saatgutvermehrung standortgerechter Arten
- Entwicklung und Optimierung ökologischer Wiederbegrünungsverfahren in Hochlagen
- Erreichen eines nachhaltigen Erosionsschutzes.

Within the whole alpine area, thousands of hectares are machine graded or affected every year, e.g. by construction of ski runs, ski lifts, tourists infrastructure and roads. Restoration of damaged areas in high altitudes is much too often done with an inadequate combination of technical and biological measures. Cheap application techniques and cheap seed mixtures containing species that are not adapted for high altitudes are state of the art. The resulting ecological and economical damage is considerable: soil erosion, increased surface runoff, degradation of the vegetation, need for frequent reseeding and constant fertilising, flora falsification, expensive maintenance. Due to this situation, especially the economically important winter and summer tourism got a very negative image.
The research project ”Seed Propagation of Indigenous Species and their Use for Restoration of Eroded Areas in the Alps” supported by the EU, was carried out from 1999 to 2002. At 8 different locations at altitudes between 1.200 and 2.300 meters, trials were set up and assessed during the last four years. The necessary demands on application techniques in order to avoid erosion during the first two growing seasons as well as demands on seed mixtures in order to achieve the development of a dense, sustainable vegetation at different altitudes and under different site conditions were assessed. The specific climatic conditions with its limiting effects on growth and biomass production of plants, that are increasing with altitude, were observed. Different parameter were used to describe the ecological value of plant stands depending on the seed mixture used. To quantify the possible improvements, a comparison to standard techniques and mixtures was made. Recommendations for optimal time of restoration activities and top soil conservation are given for practical purposes. It was the aim of this project to create a new state of the art in ecological restoration of damaged areas at high altitudes of the Alps.
In order to get a basis for the practical use of indigenous seed mixtures, the demands of 14 indigenous grasses, leguminosae and herbs for a successful seed production were assessed for conventional and organic production systems. Different trials were carried out in order to optimise cultivation, weed control, fertilisation, harvesting methods and seed quality of the following species: Avenella flexuosa, Deschampsia cespitosa, Festuca pseudodura, Festuca supina, Phleum alpinum, Phleum hirsutum, Poa violacea, Trifolium nivale, Anthyllis vulneraria, Anthyllis alpestris and Leontodon hispidus, Sesleria albicans, Trifolium alpinum, Trifolium badium.
A commercial seed production of most species should be established during the project period.

Abschlussbericht


Kurzfassung (deutsch)

Wirtschaftliche Saatgutproduktionsverfahren konnten für die folgenden Arten erreicht werden: Avenella flexuosa, Deschampsia cespitosa, Festuca pseudodura, Festuca supina, Phleum alpinum, Phleum hirsutum, Poa violacea, Trifolium nivale, Anthyllis vulneraria, Anthyllis alpestris and Leontodon hispidus. Die Ergebnisse der Exaktversuche zeigten in Seehöhen zwischen 1.200m und 2.400m deutliche Vorteile bei Verwendung standortgerchten Saatgutes. Zur Erosionsvermeidung ist eine zusätzliche Abdeckung des Bodens mit Mulchmaterial notwendig. Die Applikationstechnik hat nur im ersten Jahr signifikanten Einfluss auf die Bodendeckung. Im Vergleich aller Standorte wurde eine signifikant bessere Bodendeckung bei Verwendung standortgerechter Mischungen ab dem dritten Vegetationsjahr erreicht. Auf den meisten Standorten wurden signifikant höhere Artenzahlen erhoben. In Höhenlagen über 1.700 m waren nur mehr standortgerechte Arten in der Lage, reifes Saatgut auszubilden. Der Biomasseertrag standortgerechter Mischungen war mit den Werten der Handelsmischungen vergleichbar, tendenziell wiesen die Handelsmischungen aber bessere Energiekonzentration auf. 1. Seed production The slow growing rate of the alpine grasses and forbs, their subsequently low competitive capacity and their susceptibility to fungal diseases make seed production difficult in context of organic farming. Application of herbicides and fungicides are indispensable for the seed production of alpine species. Therefore, seed propagation of alpine species according to the prescription of organic farming is very risky, expensive and not profitable at all. As a general result of our investigations, an economically meaningful seed production is possible for the following indigenous species: Avenella flexuosa, Deschampsia cespitosa, Festuca pseudodura, Festuca supina, Phleum alpinum, Phleum hirsutum, Poa violacea, Trifolium nivale, Anthyllis vulneraria, Anthyllis alpestris and Leontodon hispidus. However, seed production of such species needs very experienced farmers. The demands on maintenance and chemical weed control are high, fluctuation in yield can be extreme. But on average, yields and product quality were observed to increase hand in hand with experience through the years. Therefore, economic considerations made are only reflecting the current situation. For the three species Sesleria albicans, Trifolium alpinum, Trifolium badium, successful seed production is not yet possible or economically meaningful. Further research work has to be carried out. In Austria, a commercial seed production of most species was established during the last four years. Indigenous seed mixtures for different altitudes and site conditions are available on the market in the meantime. 2. High altitude restoration Alpine ecosystems are characterised by unfavourable climatic conditions with limiting effects on growth and bio-mass production of plants that are increasing with altitude. At an altitude of 2000 m, the number of growing days (average daily temperatures > 5°C) is reduced to 67 days. In alpine environments, vegetation has therefore a growing season of two to three months to establish. Because of the limited growing period, restoration activities at high altitudes should be carried out the first weeks after snow melt. During this period, most soils have a satisfying water content, also on exposed sites. The results of our investigations on climatic site conditions also indicate, that large scale interventions and thus restoration with seed mixtures generally should be avoided above altitudes of 2.400 m. The conservation of the topsoil as substrate is important for an enrichment in indigenous plants deriving from restoration, as their seed cannot be obtained on the market or it is very expensive. Our results indicate that even after a partial mixing of the topsoil with mineral layers, which are devoid of a seed bank, seed densities can be considerable. The conservation of the topsoil should therefore be regarded as a very important task planning restoration. Discarding the topsoil during the construction of a ski slope represent a waste of valuable autochthonous plant material, which is available in place for a site-specific, low-impact restoration. Results of several earlier assessments indicate that up to altitudes of 1.600 m, a minimum of 70 % vegetation cover is required to avoid erosion. Above timberline, more dense vegetation with a cover of about 80 % is recommended. Therefore, a sufficient combination of application technique and adapted seed mixture, reaching the minimum requirement of a sustainable vegetation with 70 to 80 % cover within the first two vegetation periods has to be the goal behind restoration in high altitudes. Our assessment on vegetation cover of the plots showed, that under average conditions of high altitudes the necessary minimum demand on cover can be achieved in the second vegetation period at the earliest. This requires application techniques with sufficient protection of top soil for the first two vegetation periods. The comparison of different application techniques during our assessments on erosion and surface runoff in the weeks after restoration showed clear results. Only an additional cover of top soil is able to reduce surface runoff and soil losses to an acceptable degree. A lot of different techniques are available that would guarantee a sufficient protection of top soil like straw mulching, hay mulching, different mats, nets, three-dimensional mats etc. The use of application techniques enabling a satisfying cover of top soil should be generally recommended for restoration of slopes at high altitudes. A comparison of three different application techniques at each site, assessed for the whole project period, showed comparable results for plain hydroseeding and techniques with covered top soil in terms of vegetation cover. Only the technique hydroseeding combined with mycorrhiza inoculum exhibited significant lower cover in the first two growing seasons. Taking into account the results of our erosion trials, the use of mycorrhiza combined with extensively minimised fertilisation would be an alternative to the commonly used chemical or organic fertilisers, provided that it is combined with an additional cover of top soil like on locations Zillertal and Bayrischzell. As the straw cover was the only difference between the two treatments where mycorrhiza was employed, the higher vegetation cover achieved where the straw cover was used provides evidence for the short-term beneficial effect on seedling establishment. Due to the better protection against surface runoff and soil erosion during the first two vegetation periods, only the techniques with additional cover of top soil can be recommended. An overall statistical assessment of all locations showed significant better cover of indigenous seed mixtures up from the third growing season. The results obtained give a clear answer to the necessity of using indigenous seed mixtures. Except for site Zillertal, indigenous seed mixtures were able to reach the minimum demands on vegetation cover with a single fertilisation. For practical use, these results should establish a new state of the art in restoration and maintenance expenditure, leading to a clear reduction of expenses. The widespread argument that fast growing components of commercial species and on principle steady fertilization for some years are needed to enable a fast protection against erosion, cannot be confirmed by the results obtained. The results also indicate the differences between sites and development of single species. For practical use, a stipulated composition of indigenous seed mixtures should be avoided. The more extreme the site conditions and the larger the restoration area, the more important is an according composition of the seed mixture, created by an expert. A classification of mixtures referring to the ecological value of the assessed species was used for this report. Summarizing the valuable groups with expected sustainability, indigenous seed mixtures reached the minimum requirement of 70 % cover. In comparison, the share of valuable groups from the commercial mixture remained below 45 %, containing about 10 % indigenous species immigrated from plots with indigenous seed mixtures. Furthermore, indigenous species were able to remain their original share. In the commercial mixture, the share of not adapted species decreased from 50 % to about 20 %, mainly at the expense of total cover. For practical use, the results clearly indicate that commercial seed mixtures containing a high percentage of species that are not adapted to site conditions would lead to a repeated seeding and fertilization to reach a vegetation cover securing sufficient protection against erosion. In a long term estimation, it can be assumed that the lack of sustainable indigenous species will cause steady efforts, especially in altitudes above 1.800 m. The assessment of fertility showed, that commercial lowland species with single exceptions are not able to get fertile in altitudes above 1.800m. Under average climatic conditions during the growing season, most indigenous species are able to produce ripe seeds up to altitudes around 2.300 m. This is a very important condition for an enrichment of the seed bank, supporting an independent regeneration of vegetation in case of damage. On most sites, a significant higher number of species was found on plots with indigenous vegetation, also reflecting a higher ecological value resulting from the use of indigenous seed mixtures. Grouping main species referring to their ecological value, it is also evident that the roots of indigenous and adapted species in general show higher tensile strength. Therefore, better resistance against mechanical damage caused by cattle, preparation of ski runs or tourists can be expected. In some parts of the Alps, the use of ski runs or other restored areas is of great importance for mountain grazing. Dry biomass yield from restored sites in high altitudes is comparable to alpine pastures, assuming that available humus was stored sufficiently and applicated again. In general, commercial and indigenous seed mixtures have comparable yield. Digestibility as one of the main characteristics of forage quality showed a decrease with altitude, while the content of fibre increased. In comparison to commercial mixtures, a significant reduction of digestibility is possible, reflecting the faster development of pre-alpine and alpine species. In view of an economic evaluation, the set up costs indicate that commercial seed mixtures would be much cheaper than seed mixtures including indigenous species. But when looking at the years following the set up the sites that use commercial seed mixtures have to calculate with follow up costs (reseeding and steady fertilisation). So in the long term in order to reach a sustainable restoration the use of indigenous species is meaningful not only from an ecological but also from an economical standpoint. Concerning the application technique, plain hydroseeding is the cheapest method even if there is a 60 % chance that the whole application has to be repeated because of heavy surface runoff and soil losses and as a consequence a bad vegetation coverage and unsatisfying restoration. Therefore from an ecological point of view strict rules to use application techniques that cover the top soil have to be adopted because enterprises always will try to use the economical cheapest technique which in that case could cause problems with erosion.

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