The National System of Nature Conservation Units (Portuguese: Sistema Nacional de Unidades de Conservação da Natureza), abbreviated SNUC, is a set of regulations and official procedures that enable the federal, state and municipal government departments, as well as private initiative, to create, implement and manage Conservation Units (UC) in order to organize nature preservation in Brazil.^[1]

The SNUC originated in the 1970s, when the former Brazilian Forestry Development Institute - IBDF (Portuguese: Instituto Brasileiro de Desenvolvimento Florestal), supported by the Brazilian Foundation for Nature Conservation (Fundação Brasileira para a Conservação da Natureza), created the Plan for the System of Conservation Units in Brazil (Plano do Sistema de Unidades de Conservação do Brasil), officially published in 1979. The project contained specific objectives necessary for nature conservation in Brazil and proposed new categories of natural resource management, which were not provided for in the legislation of the time - the Brazilian Forest Code of 1965 and the Fauna Protection Act of 1967. A second stage of the plan, drawn up by the IBDF, was sanctioned by the government in 1982 and published under its current name and acronyms - the National System of Nature Conservation Units (SNUC).^[1]

In order to provide legal support for the system, it became necessary to create a law that incorporated the concepts defined for the categorization and establishment of conservation units in Brazil. In July 1988, the Pro-Nature Foundation - FUNATRA (Portuguese: Fundação Pró-Natureza), with resources initially provided by the Special Secretariat for the Environment - SEMA (Secretaria Especial do Meio Ambiente) and the IBDF, gathered a group of specialists to review and update the definitions of the categories of conservation units and to develop a draft law. In 1989, the work concluded and resulted in two draft laws published by IBAMA and FUNATRA.^[1]

The texts were discussed in both the executive and legislative branches. After undergoing considerable changes, they were published in the form of Law No. 9.985, of July 18, 2000. Decree No. 4.340, of August 22, 2002, regulates the SNUC.^[1][2][3]

The SNUC promotes nature conservation in Brazil by providing legal mechanisms to the federal, state and municipal governments and to private initiative in order to:^[3]

• contribute to the maintenance of biological diversity and genetic resources in the national territory and jurisdictional waters;
• protect endangered species at regional and national level;
• contribute to the preservation and restoration of the diversity of natural ecosystems;
• promote sustainable development based on natural resources;
• promote the use of nature conservation principles and practices in the development process;
• protect natural and little altered landscapes of outstanding beauty;
• protect geological, geomorphological, speleological, paleontological and cultural features;
• protect and restore water and soil resources;
• recover or restore degraded ecosystems;
• provide means and incentives for scientific research activities, studies and environmental monitoring;
• enhance the economic and social value of biological diversity;
• favor conditions and promote environmental education and interpretation, recreation in contact with nature and ecological tourism;
• protect the natural resources necessary for the subsistence of traditional populations, respecting and valuing their knowledge and culture and promoting them socially and economically.

The SNUC uses the name Conservation Unit (UC in Portuguese) to describe protected areas, which are territorial spaces, including jurisdictional waters, with relevant natural characteristics and defined conservation objectives and boundaries. The SNUC provides legal mechanisms for the creation and management of protected areas in the three levels of administration and private initiative, enabling the development of collective strategies for the preservation of natural areas. The involvement of society in the management of Conservation Units is also regulated by the system, which strengthens the connection between the state, citizens and the environment. The federal government's Conservation Units are managed by the Chico Mendes Institute for Biodiversity Conservation (ICMBio in Portuguese).^[4][2]

The SNUC provides for twelve complementary categories of conservation units organized according to their management objectives and types of use in two large groups:^[4]

• Full Protection Units: their basic objective is the preservation of nature; they allow indirect use of their natural resources, with the exception of the cases provided for in the SNUC Law;^[4]
• Sustainable Use Units: aim to harmonize nature conservation with the direct use of part of its natural resources, while maintaining the biodiversity of the site and its renewable resources.^[4]

The following table presents an overview of the categories of protected areas and compiles the correlation between the international classification of the International Union for Conservation of Nature and Natural Resources (IUCN) and the SNUC:^[5][6]

The availability of official information on all Brazilian conservation units through the National Registry of Conservation Units (CNUC) is an important step towards consolidating the SNUC.^[7]

The National Registry of Conservation Units - CNUC (Portuguese: Cadastro Nacional de Unidades de Conservação) is an integrated database system with regularized information on the protected areas of the SNUC managed by the three levels of administration and by private entities. The Ministry of the Environment is responsible for organizing the CNUC, as established in article 50 of Law No. 9,985 of 2000.^[3][2] As of September 2020, there were 2,487 Conservation Units registered with the CNUC. The specific objectives of the CNUC can be summarized as:^[7]

• Availability of official information on the Conservation Units;
• Detailed reports on the situation of the Conservation Units to facilitate diagnoses, the identification of problems and decision-making;
• Possibility of creating and monitoring indicators regarding the status of implementation of the SNUC;
• Verification of compliance of Conservation Units with the rules and criteria for creation established in Law No. 9.985 of 2000;
• Availability of information for the planning, administration and inspection of Conservation Units;
• Assistance in distributing funds from environmental compensation, as these will be earmarked exclusively for protected areas recognized by the CNUC as belonging to the SNUC (Art. 11 of CONAMA Resolution 371 of 2006).

• National park (Brazil)
• Protected areas of Brazil
• List of Atlantic Forest conservation units
• List of state parks in São Paulo