Sustainable use and management of non native trees in the alpine region

Activity A.T1.1Comprehensive database on NNT distribution, threats, benefits, policies and appropriate risk management measure

D.T1.1.1 ALPTREES Report on Database with Inventory

This study in Working Package WPT-1 aimed to perform an inventory of non-native tree species growing in Alpine Space forests and cities, analyzing their diversity, distribution, and geographic origin.
Our results show that at least 526 NNT are currently growing in forests and urban areas in the Alpine Space. The number of NNT growing in urban areas (352) is much higher compared to woodlands (13), yet a considerable large number were reported for both urban areas and forests (161). These figures clearly show that a large proportion (67%) of reported NNT are currently being cultivated exclusively in cities in the Alpine Space. Of these, the most common NNT are Aesculus hippocastanum (horse chestnut), Robinia pseudoacacia (black locust), and Gleditsia triacanthos (honey locust).
Most of the reported NNT (90%) have their natural distribution range outside of the European geographical area. The largest number of these species were introduced from Asia (248) followed by North America (180).
About 5% of reported NNT have been considered (potentially) invasive in one or several regions of the Alpine Space. Most of them have their native distribution range in North America.
NNT are widely used in the Alpine region for landscaping and horticultural purposes (35%). Other frequently mentioned benefits include their use as an ornamental tree or their potential to sequester carbon.


D.T1.1.2 Report on Expert survey

In total, 101 experts were interviewed on 50 non-native tree species (Table 1). The experts come from different fields, e.g., dendrologists, employees of a tree nursery or a forestry institute, practitioners, nature conservationists, forest owners, or researchers working at universities across the Alpine space.


D.T1.1.3 Manual for data collection on non-native species in urban, peri-urban and rural areas

Every institution that is considering a preparation of a data collection on non-native tree species - whether it is a local community, an expert institution, or a research institute - deals with the following questions:

  • why should we do this work - the purpose of preparations,
  • in what way will the work be carried out - the course of preparations,
  • on which areas will the work be done and what data do we need to achieve the purpose – methodology,
  • what results can be expected and
  • what will be their practical value?
  • The manual tries to explain the above-mentioned processes on an example of the local community, specifically the Municipality of Gorenjska Region


Activity A.T1.2 Field survey of NNT in high conservation value areas

D.T1.2.1 Report on field survey

The status of semi-natural oak-hornbeam forests (European Union habitat type 9160) is classified as unfavorable in several regions across the Alpine Space (AS). This habitat type is considered threatened by invasive non-native species including several non-native tree species (NNT). In the lowlands of AS in south-west Germany, dispersal of the NNT red oak (Quercus rubra L.) has been reported in several protected forest habitats, located in the habitat type 9160 (FFH9160).


Activity A.T1.3 Mapping of ecosystem services provided by native and non-native tree species

D.T1.3.1 Map of ecosystem services provided by native & non-native trees

Mapping and calculating the forest ecosystem indicators and services that stem from native and non-native trees on the territory of the Alpine Space. Different indicators are defined, measured and estimated in order to assess and gain insight on  the economic value and the impact they have in the Alpine forest area.


D.T1.3.2 Assessment report of outcomes and knowledge transfer

Assessment of ecosystem services provided by forests under the influence of the climate changes. The main goal of this report is to identify hotspots of forest ecosystem services to better protect the forest areas that are affected by the climate change. The report should serve as a tool for the stakeholders, which they could use to make decisions and policy measures for the forest areas in the Alpine space.


Activity A.T1.5 Development of the inclusive approach for site-specific risk assessments

D.T1.5.1 Testing report on the trial of site-specific risk assessment

This testing report on the trial of site-specific risk assessment is based on the methodology developed in the framework of the ongoing ALPTREES project. The pilot area for testing the sitespecific risk assessment for non-native tree species is Gorenjska region, which is situated in the north-west of Slovenia.


DT1.5.2 Manual for Site Specific risk assessment

Non-native tree species (NNT) are used in forestry across the Alpine Space for their growth performance, valuable timber, and resistance to drought and pest or pathogen damage. Yet, cultivating NNT may pose risks to biodiversity and associated ecosystem services, and several NNT are evaluated as invasive in some regions in the Alpine Space. Such conclusions typically follow the results of a risk assessment, which do not adequately consider site-specific variations in impacts and the extent of the affected area. Here, we present a new methodological framework to mitigate risks associated with NNT while taking advantage of the ecosystem services that certain tree species can provide. The framework is based on a stratified assessment of risks posed by NNT that distinguishes between different ecosystem types or sites and considers the effectiveness of available management strategies to mitigate negative effects.