A transnational cooperation for sustainable use and management of non-native trees in urban, peri-urban and forest ecosystems in the Alpine region (ALPTREES)

The expected benefits and potential risks of non-native tree species (NNT) to European geographic regions have polarized the opinions of experts and citizens. Benefits include climate change (CC) mitigation and adaptation, contributions to bioeconomy, urban and peri-urban green infrastructure and mitigation of natural hazards. However, NNT may become invasive and thus may pose risks to native biodiversity, ecosystem functioning or ‡ § | ¶ #

socio-economy. In critical and vulnerable ecosystems such as the Alpine Space (AS), such risks and benefits must be carefully considered before management decisions are made. Experiences in the management of NNT in urban areas, peri-urban, rural territories and forests are often region-or city-specific and rarely shared. Given the challenges in NNT management with respect to both benefits and risks, an European transnational approach is needed to qualify the role of NNT in future AS ecosystems. The objective is to provide a transnational strategy for a responsible use and sustainable management of NNT in the AS with the help of an integrated Decision Support System. The project fits within the context of national and regional site-derived policy aiming at protecting and enhancing biodiversity to ensure ecological connectivity and cultural resources while maintaining a high level of resilience and ecosystem services across the AS. Implementation activities of the ALPTREES project include 1.
developing a comprehensive database on NNT, 2.
projecting the current and potential distribution of NNT in the AS under CC scenarios 3.
determining their invasive potential and 4.
analyzing the different ecosystem services provided by NNT to assess the tradeoffs between risks and benefits.
ALPTREES will formulate management recommendations for NNT under different climate and economic scenarios based on experience from sample plots combined with model projections, citizen science, and multiple stakeholder meetings. With the help of policy briefs, a handbook of lessons learned, transnational pilot actions for best management practices, and an inter-active online Decision Support System a close stakeholder interaction and -benefit will be ensured Another innovative output of the project is the Open ALPTREES Knowledge Hub, that will support the transnational and interdisciplinary knowledge transfer.
presentare la distribuzione attuale e quella prevista degli NNT in AS in diversi scenari di CC; 3.

Français (French)
Les avantages attendus et les risques potentiels des arbres non natifs (NNT) pour les régions géographiques européennes ont polarisé les opinions des experts et des citoyens.  (Walther et al. 2002) and thus changing growing conditions. The potential and rate of spread into higher elevations is expected to further increase in the future (Becker et al. 2005, Dainese et al. 2013, Petitpierre et al. 2016. Petitpierre et al. 2016 predicted the optimal suitability for NNT to shift from lowland to the montane or even subalpine zone. Human influence on the spread of NNT includes anthropogenic disturbances, like direct land-use changes that create niches for NNT, human population density, increasing mobility and development in mountainous areas (Dainese et al. 2013, McDougall et al. 2010). These will further enhance the colonization, persistence and invasion by increasing propagule pressure (Chytrý et al. 2008). The results of further studies confirmed the importance of the human impact (Marini et al. 2011) on the increase of NNT. Therefore, adaptation efforts are required to respond to the challenges of the invasive potential of the NNT on the Alpine environment, economy & society.
Native tree species are increasingly affected by pests, diseases, drought, and increased temperatures (Allen et al. 2010), and many of them are now considered threatened in Europe (Rivers 2019 Nevertheless, Urban, Peri-Urban and Forest Ecosystems provide crucial goods and services such as attractions for tourism and recreation as well as climate and biodiversity conservation. NNT can support the adaptation of European forests and urban areas to CC, but simultaneously entail risks for biodiversity and ecosystem functions. Walter et al. 2005 defined changes in species composition, in succession patterns and in nutrient cycling as the most important environmental effects of NNT propagation. It is important to address the patterns and impacts of NNT dispersal in the AS in order to provide a useful set of guidelines for managers, as for example forest management has a regulatory effect on the distribution of NNT (Martin andMarks 2006, Matlack andSchaub 2013).

Tackling territorial challanges
Efforts have already been undertaken to responsibly manage NNT and forestry has experiences with responses of potential invasive tree species to their local management (Sitzia et al. 2015). However, neither European, national nor regional strategies for the management of NNT in the AS consider the challenges of CC yet. Moreover, the lack of a consistent methodology to assess the invasiveness of NNT in Europe hampers the comparison of risks across regions and national jurisdictions (Bindewald et al. 2019). This has led to an incoherent patchwork of local strategies for NNT in the AS. Under a prudent estimation, currently, ca. 4% of the European forest area (8.5mio ha) is covered with over 150 different NNT species (Brus et al. 2019). Furthermore, a yet not well-known number of NNT are cultivated as ornamentals in (peri-) urban areas. In order to formulate sciencebased policies for biodiversity conservation while balancing the trade-offs between forest health and ecosystem services, it is important to not only quantify the range of benefits but also the risks linked to biodiversity. The common territorial aim is therefore to identify current and future benefits as well as detrimental impacts of NNT in the AS (Fig. 1).
Map of the Alpine Space region (AS) showing the target territory for the application of the strategy of NNT to be developed in the ALPTREES project. The presence of non-native species in local ecosystems is becoming more common and more challenging to manage, yet NNT management methods and related regulations are often country-specific and not shared regionally/transnational, especially in the Alpine space region.

Target groups
Stakeholders and residents of the Alpine Space and their future generations will benefit from the sustainable action for CC adaptation, mitigation, and a system change for ensuring ecosystem services. Regional, national and local policymakers, landowners, public authorities, urban planners, regional agencies, and NGOs will benefit from a comprehensive strategy providing valid input for their governance strategies. Conservation managers, forest businesses and alpine communities will be provided with a handbook helping them to optimize their management of NNT in a sustainable and cost-efficient manner. The objectives and nature of activities of ALPTREES follow strategic policy developments in the policy cycle involving analytical assessments aiming at elaborating a transnational strategy for NNT in the AS (Table 1).

Target groups
Please further specify the target groups local public authority Municipalities in the AS regional public authority Regional public authorities will benefit from comprehensive strategy that provides valid input for their governance strategies.
national public authority National authorities are representative of national ministries and benefits from comprehensive strategy that provides valid input for their governance strategies. sectoral agency Regional agency dealing with forestry, ecology and sustainable development, can gain from comprehensive strategy for valid governance strategies.
infrastructure and (public) service provider Provision of CC and NNT risk management tools for environmental service provider and urban service provider (e.g. tree safety and tree health in cities)

interest groups including NGOs
Various NGOs (nature conservation, education,forest protection, rural development)will be invited to participan on pilot actions. International organisation under national law Constribution to international policies; Observer include international organisation International organisation under inter-national law Transnational cooperation strategies will provide technical guidance to International organisation under inter-national law; certification bodies e.g. PEFC and FSC General public Citizens of AS, aim is to increase the awareness and knowledge of NNT

Project objectives and outputs
The overall objective of ALPTREES is to improve knowledge-based decision-making on the responsible use and management of NNT in the AS by developing a transnational strategy. This strategy will evaluate the tradeoffs between promoting CC adaptation through planting adapted NNT while preserving and enhancing biodiversity, ecosystem services and cultural resources of natural forests. Based on scientific analysis, also with the help of a Citizen Science approach, ALPTREES' strategy of sharing knowledge on challenges and best practices as well as the establishment of a transnational network to learn from each other and take advantage of synergies will significantly contribute to the Table 1.
Target groups of the ALPTREES project.
protection, conservation and connectivity of Alpine Space ecosystems. The specific objectives are: 1.
Increasing knowledge on the current and prospective status of NNT in the AS: transnational inventories of policies, NNT distributions, threats, management measures and ecosystem services.

2.
Development and implementation of a unified homogeneous and science-based solution strategy for NNT in the AS. 3.
Increasing public awareness and capacity building on the responsible use of NNT through dialogues between science, administration, and citizens.

Contribution to regional strategies and policies
NNT are being discussed as an alternative to adapt European forests to climate change, in the likelihood of a drastic reduction in the distribution range of native tree species in climate change (Dyderski et al. 2017). The growing importance of NNT for European CC adaptation measures is increasingly reflected in policy frameworks. At the same time, invasive NNT can seriously affect nature conservation goals, economic activities, livelihoods, food security, and human health and well-being, and thus bear the risk of undermining progress towards sustainable development as also impeding achieving the United Nations, (2015-2030) Sustainable Development Goals (SDGs). Utilizing the true potential of NNT in the Alpine space while safeguarding the native ecosystems from potential threats of the NNT is thus crucial. A wide range of policy instruments and framework exists which can guide science-based management of NNT in the Alpine space (Table 2).

Policy framework Potential role
Convention on Biological Diversity provision of guidance for safeguarding native biodiversity In addition, ALPTREES will help to strengthen the sustainable use of natural resources under CC (Action Group 6 of EUSALP) by addressing potential conflicts between Table 2.
Some examples of Policy frameworks and their potential role in the management of NNT in the Alpine space.
stakeholders such as forestry, nature conservation and environmental protection. Outputs for site-specific evaluation of NNT risk/benefit, trade-offs will support the Action Group 8 of EUSALP to improve risk management; the results will provide solutions for protecting against natural and man-made disasters and improving CC management. The project will also target the ecological connectivity of urban, peri-urban and rural areas Action Group 7 of EUSALP.

Project structure
The Alptrees consortium consists of 12 project partners (PP) from seven countries in the AS. Additionally, a network of 32 observers outside the PPs is invited to actively advising on the project development. The project activities are structured in thematic work packages (WP), which includes management (WPM) and a communication work package (WPC). Technical WPT1 aims to analyze the spatial extent for potential or existing invasive NNT in the AS. This information is essential for risk/benefit and trade-off analysis and therefore for underpinning decision-making including prioritization of sensitive areas of high conservation value. Under WPT2 Risk maps will be developed based on CC projection models, with special emphasis on the forest area, urban forests, the peri-urban interface, and urban trees. These products are essential to support tools for CC adapted decision making in the public and private space. WPT3 will focus on the transfer of knowledge generated in the project to end-users at different levels. Preliminary project results will be shared first with observers, stakeholders and experts from the AS in 2 Transnational Stakeholder Seminars and various separate stakeholder workshops in each AS country during which the Open ALPTREES Knowledge Hub will be furnished with contents. The objective of WPT4 is to provide a transnational strategy for knowledge-based decisionmaking on responsible use and management of NNT in the AS. Stakeholder commitment will be widely encouraged to integrate diverse knowledge and perspectives into the management of invasive species and to deal with potential conflicts of interest.

Communication strategy
Communication improves the understanding of the responsible use of NNT for CC adaptation of European forests and urban areas. Yet, a communication strategy requires cross-sectoral and transnational cooperation to secure the biodiversity, ecosystem services and cultural resources of native forests against the invasion risks that could be represented by NNT. The knowledge gained in the ALPTREES project through transnational cooperation of experts in the ALPTREES PP consortium will be shared through formal and non-formal education tools. In a series of public events both at the national and international levels, like movies/documentaries, scientific conferences, public talking, school activities, forest and horticulture professionals, the PPs will educate stakeholders to engage with science and administration for sustainable development of the biodiversity in the AS. All the communication activities will follow the bottom-up approach "listenobserve -inspire". The activities will target local policymakers, stakeholders from the forestry industry and urban/rural planning, along with the general public (Table 1).

Acknowledgment
This proposal was selected to be funded by the Alpine Space Programme on 01.10.2019, which is financed through the European Regional Development Fund (ERDF) as well as through national public and private co-funding of the Partner States (Total eligible costs: 2.348.664; EURERDF grant:1.996.364 EUR). The authors thank the respondents who participated in this work.

Funding program
Funded by the Interreg Alpine Space Programme, financed through the European Regional Development Fund (ERDF) as well as through national public and private co-funding of the Partner States. (Total eligible costs:2.348.664; EURERDF grant:1.996.364 EUR).

Grant title
A Transnational Cooperation for Sustainable Use and Management of Non-Native Trees in Urban, Peri-Urban and Forest Ecosystems in the Alpine Region.

Hosting institution
Austrian Research Centre for Forests (BFW), Vienna, Austria

Ethics and security
The idea in this proposal is the property of the ALPTREES project and it partners. Further circulation of this proposal is welcome with reference to the ALPTREES project.

Author contributions
Lead project partner, BFW, Vienna developed the idea of the proposal and the other project partners from Austria, Germany, France, Slovenia and Italy contributed by editing and providing inputs.

Conflicts of interest
The authors and contributors declare no conflict of interest.