Contract number

V4-1818

Department:

Department of Forestry and Renewable Forest Resources

Type of project

ARIS projects

Type of project

CRP projects

Role

Lead

Duration

01.11.2018 - 31.10.2021

Value of co-financing

€105,000.00

Total

€140,000.00

Project manager at BF

Brus Robert

ABSTRACT

In the coming years, large areas of affected or destroyed forests will have to be restored or rejuvenated in Slovenia. When selecting tree species that will be able to grow and perform well in the long run, site suitability and ecological acceptability, profitability, availability of forest reproductive material and costs of restoration and tending will have to be taken into account. Climate change and increasingly frequent natural disturbances will lead to the retreat of some tree species from certain habitats or even changes in their distribution range (e.g., Norway spruce), and there is also the possibility of the emergence of new, as yet unknown, diseases and pests that could affect our native tree species. In such cases, these species will need to be replaced by more resilient, preferably native, tree species and their provenances. However, there is no guarantee that the range of native tree species will be sufficient to meet the requirements necessary to achieve all objectives over the long term.

Therefore, when selecting the appropriate tree species, it is strategically wise to prepare backup or alternative solutions that could in some cases include non-native tree species (NNTS). In addition to the timber production potential and profitability of NNTS, their potential better adaptability to climate change or better resilience to biotic and abiotic factors could be important. In Slovenia, like elsewhere in Europe, NNTS began to be planted on a large scale in forests at the end of the 19th century. After black locust, species such as eastern white pine, Douglas fir and northern red oak account for the largest share of the wood stock of NNTS in Slovenian forests. In recent decades, the use of NNTS has declined markedly and has almost ceased today.

However, a gradual increase in the use of NNTS in order to replace even a small share of removed native species or to increase the profitability of forests is not without risk to the natural environment, as these species could cause undesirable effects on autochthonous vegetation, impair site conditions, overgrow domestic species or even become invasive. Another risk of future cultivation of these species may also be their poor adaptive capacity, which would make plantations or stands unsuccessful and unprofitable.

The gradual introduction or increase in growing intensity of NNTS must therefore be supported by the results of long-term and thorough testing. Unfortunately, in Slovenia there is little research or practical experience that would enable scientifically-based recommendations on the use and cultivation of NNTS. The number of NNTS that have been planted or tested so far is limited; the number of existing plantations and provenance tests allowing analysis is limited; and many of them are approaching the final cut period. Therefore, now is the last opportunity to analyze NNTS, evaluate their adaptability and economic performance, gather experience and determine which of them could be more intensively used in the future without serious threat to the natural environment. Some NNTS in Slovenia have already clearly shown good adaptability in difficult conditions (e.g., the resistance of Douglas fir to ice storms, drought and bark beetle attack in areas where Norway spruce has been severely affected). Moreover, they have not negatively impacted the environment and have great potential for fulfilling several functions, including profitability, which is an important priority of forest owners. Douglas fir is one of the few non-native tree species that has been cultivated in our country for a long enough period to enable a full evaluation of its potential and risks. In addition, in the future it will also be necessary to analyse in a comprehensive way some of the other most common non-native tree species.

In addition to the most widespread non-native tree species, it is necessary to begin experimenting as soon as possible with other as yet unused species, as decades of testing may be required to yield useful results. It is also necessary to review the rich experience and good practice examples on the use of NNTS in other European countries and to examine them appropriately in our country. Thus, it will be possible to formulate the foundations and guidelines that future forest management can use directly in the public forest service for current planning, silviculture, seed husbandry and nursery practice and for inclusion of NNTS in forest management plans.

When introducing NNTS, it is necessary to take into account existing legislation and regulations on NNTS in Slovenia, which are relatively restrictive due to the high priority placed on nature protection. The future use of NNTS will be of interest to the forest owner in the long term due to the economic effects, which are largely based on the quality and value of the timber products of the species used. In the future, there will likely be a great deal of demand for softwood timber. Little is known about the timber quality and market prices and possibilities of NNTS in Slovenia. It will be important to highlight this aspect within the project. For the increased use of certain species (e.g., Douglas fir, whose increased use has recently been foreseen by the Slovenia Forest Service), it will be necessary to provide forest reproductive material of required quality and provenance as well as to deliver clearly presented silviculture guidelines. When considering a possible increase in the extent of cultivation of NNTS, it will be important to take into account the public's attitude towards this sensitive issue. In general, public opinion is not against the use of NNTS unless their invasiveness is in question, but in the future, it will be necessary to educate the public and focus on public awareness as well. Forest owners, who are usually more in favour of traditional approaches to forest management, including the use of native tree species, are not well aware of the potential of NNTS. Therefore, various thematic workshops, presentations and seminars will be necessary to address forest owners as well.

The objectives of the project are as follows:

  • to analyze the success of past cultivation of Douglas fir and other non-native tree species (NNTS) such as eastern white pine, northern red oak, black walnut and black locust in Slovenia, to evaluate their potential with respect to economic attractiveness, legal bases and possible environmental constraints and to compare the situation with that of other countries of the Alpine region;
  • to develop concrete guidelines for provenance selection, silviculture methods of Douglas fir and other proposed species by appropriate sites and to transfer knowledge into practice through seminars, workshops and management plans;
  • to assess the protection risks in the use of Douglas fir and other NNTS in forestry and to develop forest protection measures;
  • to elaborate a set of other potentially suitable NNTS appropriate for the start of systematic long-term testing (e.g. Serbian spruce, Greek fir, grand fir, Caucasian fir, Sitka spruce, Lawson cypress) and, in cooperation with forestry practice and forest owners, to establish experimental plantations of selected species;
  • to analyze and expand the network of forest seed objects and to develop concrete useful protocols for seed husbandry and nursery practice that will enable the undisrupted supply of forest reproductive material;
  • to analyze the properties of the wood and NNTS timber market potential in Slovenia and propose concrete measures for its improvement; and
  • to educate and inform forest owners, forestry professionals, the wood processing industry and the general public about this important yet little known topic.

 

THE PHASES OF THE PROJECT AND REALIZATION

Program of work and the activity plan:

The project will be carried out in six work packages (DS) with formal participation of researchers from the Department of Forestry and Renewable Forest Resources (BFG) and the Department of Wood Technology (BFL) of the Biotechnical Faculty of the University of Ljubljana and researchers from the Forestry Institute of Slovenia (GIS). In addition, the project will include experts from the Slovenia Forest Service (ZGS), the Institute of the Republic of Slovenia for Nature Conservation (ZRSVN), Ministry of Agriculture, Forestry and Food (MKGP), Slovenian Union of Forest Owners (ZLGS), foreign experts from COST action NNEXT, representatives of forest seed traders and forest nurseries from Slovenia and, if necessary, external experts from neighboring countries. Each of the six work packages will be led by an expert from one of the participating research institutions, and in most work packages collaborators from other institutions will also participate.

The six work packages (DSs) are as follows:

  • DS1: Analysis of the success of Douglas Fir and other NNTS cultivation in Slovenia and recommendations for future use
    The leader of the work package is K. Jarni (BFG); other participating associates are R. Brus from BFG and L. Kutnar, A. Marinšek and other associates from GIS; co-workers of ZGS, ZRSVN and COST action NNEXT will also participate.
  • DS2: Silviculture and tending of Douglas fir and other NNTS in Slovenia
    The leader of the work package is J. Diaci (BFG); other participating associates are G. Fidej, D. Roženbergar, T. Nagel and R. Brus from BFG; M. Čater from GIS and colleagues from the ZGS are also involved.
  • DS 3: Risks of the introduction of non-native tree species
    The leader of the work package is N. Ogris (GIS); other collaborators are B. Piškur, M. de Groot, A. Kavčič and D. Jurc from GIS, as well as associates from BFG, including M. Jurc, T. Hauptman and R. Pavlin.
  • DS4: Non-native tree species in the restoration of forests through planting and sowing
    The leader of the work package is H. Kraigher; participating associates from GIS are M. Bajc, G. Božič, T. Grebenc, M. Hrenko, T. Mrak, N. Šibanc, B. Štupar, T. Unuk, M. Westergren and P. Železnik, with other participating associates from BFG, ZGS, seed traders and nurseries.
  • DS5: Evaluation of the relevant characteristics of selected non-native tree species in terms of the needs of the Slovenian wood processing industry
    The leader of the work package is M. Humar (BFL); participating associates from BFL are B. Lesar, D. Kržišnik, S. Grbec and K. Čufar.
  • DS6: Dissemination of results and project management
    The leader of  work package is R. Brus (BFG); participating associates are the leaders of the DSs and other experts from BFG (A. Rozman), GIS (P. Železnik, H. Kraigher) and BFL as well as associates of the ZGS, ZRSVN, MKGP, ZLGS and nurseries

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