Urban Tree Guard – Safeguarding European Urban Trees and Forests Through Improved Biosecurity (UB3Guard) COST ACTION CA20132

Full title: Urban Tree Guard – Safeguarding European Urban Trees and Forests through Improved Biosecurity
Action number: COST Action CA20132
Programme: European Cooperation in Science and Technology – COST
Implementation period: 26 October 2021 – 25 October 2025
Status: Completed

UB3Guard was a European COST Action established to improve the protection of urban trees and forests from invasive insects, pathogens and other emerging biological threats.

Urban trees and forests represent an essential part of Europe’s green infrastructure. They contribute to climate-change adaptation, reduce the urban heat-island effect, improve air quality, support biodiversity and provide important social, cultural and recreational benefits. However, the health and long-term survival of urban trees are increasingly threatened by invasive alien pests and pathogens introduced through international trade and transport. Climate change can further facilitate their establishment and spread.

UB3Guard brought together researchers, forestry professionals, plant-health specialists, urban planners, arborists, public authorities and other stakeholders to strengthen urban tree biosecurity through interdisciplinary cooperation, scientific knowledge exchange and the development of practical solutions.

The Action focused on collecting and harmonising scientific and stakeholder knowledge, improving the prevention and early detection of harmful organisms, supporting rapid responses to newly introduced pests and strengthening the implementation of European plant-health policies. It also encouraged the development of innovative technological tools, education, professional training and the active participation of young researchers.

Project activities were organised through four Working Groups:

• WG1 – Identification: identification of relevant stakeholder groups, their needs and management practices affecting the vulnerability of urban trees to pests and pathogens;
• WG2 – Innovations: assessment and development of tools for prevention, early detection and rapid response to biological threats;
• WG3 – Integration: integration of scientific knowledge into public policy and support for the implementation of the European Union plant-health framework;
• WG4 – Information: communication, dissemination, capacity building, professional training and knowledge exchange.

One of the major results of UB3Guard was the development of the European Urban Tree Inventory – EUTI, which brought together harmonised information on approximately 9.5 million trees from around 200 municipalities in 31 European countries. The database provides an important basis for research into urban-tree diversity, resilience and vulnerability to invasive pests and pathogens.

The Institute of Forestry in Belgrade participated in UB3Guard through its researchers and contributed particularly to activities related to stakeholder identification, urban-tree management, policy integration and the exchange of knowledge concerning urban forest health and biosecurity. The Institute’s representative participated in Working Groups WG1 and WG3 and served as a Serbian member of the Action’s Management Committee.

Participation in UB3Guard strengthened the Institute’s cooperation with European research institutions and professionals involved in forest protection, urban forestry and plant health. It also supported the exchange of knowledge relevant to monitoring urban-tree health, managing invasive organisms and improving the resilience of urban green infrastructure in Serbia.

Although UB3Guard was formally completed in October 2025, its research network and results continue through the COST Innovators Grant project FREE3 – One-Stop Shop for Resilient, Future-proofed Urban Treescapes, which is developing an open-source platform for urban-tree inventories, risk assessment and decision support.