Background Pollarded trees provide particular habitat features for saproxylic invertebrates (i.e. species that depend on dead or decaying wood). Saproxylic insects are regarded as effective indicators of woodland biodiversity, and it is the most mature and untouched tracts of woodland that have the most diverse communities of saproxylic insects. Spain’s upland forest areas in Gipuzkoa host a diverse community of saproxylic insects, including species of Community interest, which favour pollarded tree habitats that are cut back extensively in order to obtain firewood. Pollarding causes holes and rotting in the wood, thereby creating habitat for saproxylic species, and also extends the life of the tree. However, this relationship has been affected by socio-economic changes in the region and the abandonment of intensive pollarding since the 1950s. Today, only a small fraction of the Gipuzkoa forests remain managed in ways that help to sustain the availability of pollarded tree habitats and this poses a threat to associated biodiversity. Objectives The main objective of the BIODIVERSIDADY Y TRASMOCHOS project was to enhance the conservation status of saproxylic (decaying wood) coleopteran (beetle) populations in Gipuzkoa forests. Data showed that there are nearly 150 000 pollarded trees in Gipuzkoa, most of them being beech trees, though there are also oaks, ash trees and chestnut trees, but only a small fraction of these are currently being managed. The project aimed to manage and value these trees to conserve and improve the habitats of the target beetle species Osmoderma eremita and Rosalia alpina, and other saproxylic beetles in the Gipuzkoa forests. Results The coordinating beneficiary, the regional authority responsible for natural resources in the Gipuzkoa forests (Pais Vasco), and four associated beneficiaries contributed to the protection of saproxylic species through mapping and other preparatory actions, the publication of a best practice guide for pollarding, and concrete conservation actions. Preparatory actions included the GIS mapping of priority habitats in the forested areas based on detailed cartography, an ecological characterisation of pollarded trees, and a compilation of pollarding techniques. The pollarded forest areas can be seen on a map viewer on the project’s website (www.lifetrasmochos.net), which allows users to find information about all the pollarded patches detected within this action. The project increased knowledge about the biodiversity value and management requirements of pollarded trees in the project area and, in particular, about the two priority beetle species: Osmoderma eremita, the hermit beetle in the family Scarabaeidae, and Rosalia alpina, a large longicorn beetle in the family Cerambycidae. For instance, project results showed that the most suitable habitats for Rosalia alpina seemed to be standing dead beech trees and wide clearings not affected by northwest humid winds. Data for population distribution and population size were obtained for the two target species. The project also provided data to support the listing of Osmoderma eremita, Rosalia alpina, the great Capricorn beetle Cerambyx cerdo and the stag beetle Lucanus cervus in the Basque Catalogue of Threatened Species). Reports were produced defining the core areas for Rosalia alpina and the importance of connectivity between their habitat patches. The project’s results showed that intra-population connectivity is generally high. Based on the results, the beneficiaries selected eight core areas and 10 connecting areas (stepping stones) as the focus for management actions. In order to enhance connectivity between habitats and reduce habitat fragmentation within the 10 connecting areas, the project issued proposals to maintain dead wood within the forest and to open small clearings to reduce the tree density in order to increase sunlight exposure. Concrete conservation actions, involving pollarding and maintenance, improved the availability of habitats for saproxylic coleopteran populations in Gipuzkoa forests. Aged pollarded trees were maintained, while new pollards were created. A total of 15 ha of forest area containing high concentrations of managed pollarded trees was newly designated as nature reserve, and around 212 ha of forest was bought through public acquisition, guaranteeing the long-term availability of habitats for saproxylic coleopteran. Management actions, including the implementation of different pollarding techniques, were conducted to improve habitat features on 150 ha of acidophilic beechwood (habitat type 9120). The guide book ‘Notes on Pollards: Best practices’ guide for pollarding’, the documentary film ‘Pollards: The echoes of a way of life’, and details of all the other project outcomes, are accessible via the website. Training workshops were held to demonstrate best practice in pollarding techniques. Dissemination actions included the installation of information panels in forest areas and the publication of leaflets, two brochures, technical conferences and the layman’s report. A long-term management strategy for pollarded trees in the project area was elaborated and is currently being implemented. Further information on the project can be found in the project's layman report and After-LIFE Conservation Plan (see "Read more" section).