Quercus – National Association for Nature Conservation, founded on October 31, 1985, is a non-governmental environmental organization operating at the national level, recognized as a public utility entity since May 29, 2000. It operates throughout Portugal, with a network of regional branches that strengthen its local presence and connection to communities. Its work covers areas such as nature conservation, environmental monitoring, environmental education and awareness, participation and influence in public policy, sustainability project management, and the promotion of responsible practices.

Currently, Quercus is represented in entities and networks at the international, national, and regional levels, contributing to cooperation and coordination on environmental matters. Among its ongoing projects, in the field of environmental education, initiatives include Green Cork Schools, SOS Pollinators, and Minuto Verde. In nature conservation, its activities include wildlife recovery centers (CRASM, CERAS, and CRASSA) and projects such as Creating Forests, Biodiverse Gardens, Power Lines and Birds, the Micro-Reserves Network, and the Monte Barata Biological Reserve.

In the areas of waste and energy, key initiatives include the Waste Information Center (CIR) and the Topten project; in forests and agriculture, the Montado Conservation Project and the Reforestation Project; and, in the area of pesticides, the Glyphosate/Herbicide-Free Municipalities campaign. Throughout its history, Quercus has received national and international awards, totaling 18 recognitions. These include the United Nations Global 500 Award (1992) and the honorary membership of the Order of Prince Henry, awarded by the President of the Republic, Dr. Mário Soares. More recently, in 2025, it received an international award from the MedWet Initiative for the project “Between Margins,” developed at Pateira de Fermentelos.