Background Spanish citizens are unaware that 80% of large trees and mature forests are being lost and the consequences that this has for biodiversity. They play an invaluable role in the preservation of numerous species of birds, plants, fungi and insects. These ‘survivors’ are also relevant genetic reservoirs that can contribute to the study of climate change whilst enhancing Spain's biodiversity. Their loss should be halted immediately. The Spanish Law 47/2007 of Natural Heritage and Biodiversity has declared some of these trees as Natural Monuments (most of which are included in regional catalogues). Despite this, old trees and forests do not have adequate legal protection either nationally or internationally. Objectives The general objective of the 'BIGTREES4LIFE' project is to improve the conservation of large trees and mature forests in the Spanish Natura 2000 network and the Spanish Network of Natural Protected Areas. This includes 1 040 municipalities with an overall population of some 17 million (38% of the total Spanish population); thus the target population is nearly 20 million citizens (50% of the total population of Spain). Actions foreseen include a series of communications and information activities aimed at increasing awareness levels among the Spanish population of the importance of these trees as havens of biodiversity, witnesses of climate change, creators of landscape, motors for sustainable development of rural economies and symbols of environmental education. A 'European Network for Knowledge Exchange on Big Trees and Mature Forests and their Protection' is also foreseen to improve communication and information exchange at EU level. In addition, the project aims to highlight the risks these trees and forests are facing (genetic erosion, indiscriminate logging, vandalism, forest fires, urban sprawl, agricultural transformation, diseases, atmospheric agents, transplants etc.) and thus the need to put in place effective legal measures and sustainable management to ensure their protection. Expected results: At least 5 million citizens (25% of the target population) will have a basic awareness of the importance of big trees and mature forests as havens of biodiversity and identify them as important elements of the Spanish national heritage; At least 2.5 million citizens (10% of the target population) will have a basic awareness of the natural importance of big trees and their strategic role in the sustainable development of their area, after receiving direct information about the project; At least 4.6 million citizens will have a basic knowledge of the natural importance of big trees and mature forests as havens of biodiversity and identify them as part of the national heritage of the areas selected for the project; At least 50 city councils will pass local legislation to protect their notable trees, create or update their catalogues of notable trees and/or their pledges to conserve them; and At least 100 big trees in the Natura 2000 network and the Spanish Network of Protected Natural Areas will have an improved conservation status at the end of the project. This will also improve their associated biodiversity.