The Barcelona Provincial Council and the Ter Consortium have started a project to control invasive plant species along the River Ter in Osona, Central Catalonia. The work, which began on 14 May 2026, focuses on removing the Ailanthus altissima, known as tree-of-heaven, to protect river ecosystems and biodiversity.
The project aims to stop the spread of this invasive exotic species into natural areas of the river basin. These efforts are part of a collaboration agreement between the two institutions, specifically the Natural Spaces Services Management of the Provincial Council, for the management of the River Ter and its basin within the Network of Natural Parks in Osona from 2025 to 2028.
The areas targeted include high-value natural spaces such as Montesquiu Castle Park and the Guilleries-Savassona Natural Area. The current work follows a "Diagnosis and Control Plan" for the species, developed in 2023 under the Barcelona Provincial Council's Services Catalogue. This plan identified key areas where the plant is present and set priorities for intervention.
Targeting Invasive Species in Osona
This year's activities include maintaining previously treated areas in Montesquiu, Sant Quirze de Besora, Orís, Sant Vicenç de Torelló, and Torelló. New control work will start in Orís, Sant Vicenç de Torelló, Manlleu, and Les Masies de Roda. The project will prioritise treating female plants to prevent seed dispersal and further expansion of the species.
Specific intervention points in Montesquiu include Font d'en Nando and the Can Trinxet weir. In Sant Quirze de Besora, work will take place around Rec de la Mare de Déu-la Coromina, Rambla de la Concepció, Font de la Verneda, the sports area, the C-17 surroundings, and the Can Guixà canal.
Further actions are planned for Orís, covering the forest track and Saderra. In Sant Vicenç de Torelló, efforts will focus on the BV-5226 surroundings and Borgonyà station. Torelló will see work at Cal Feiner. If the budget allows, additional interventions are planned for Manlleu, specifically the forest path, El Dolcet, and the wastewater treatment plant, and at Font del Molins in Les Masies de Roda.
Protecting River Ecosystems
The tree-of-heaven is one of the most damaging invasive exotic species in river ecosystems. It displaces native riverside vegetation and harms the ecological health of rivers. These control efforts help conserve biodiversity and improve the natural spaces around the River Ter.
This initiative aligns with Sustainable Development Goals (SDGs) number 11, "Sustainable Cities and Communities," and number 15, "Life on Land." The United Nations General Assembly proclaimed the 17 SDGs on 25 September 2015, as part of the global agenda for 2030. The Barcelona Provincial Council supports local governments in the province in meeting these SDGs.
