It protects a region of dense rainforest, cerrado fields and flooded riparian zones that is rich in biodiversity.

Later it became the property of the American millionaire Daniel K. Ludwig, founder of Jari project, which aimed to develop forestry, agriculture and mining.

[4] A group of Brazilian businessmen with government backing took over the Jari project in 1981, but faced many problems including low soil fertility, erosion, failure of the exotic species to adapt to the climate, pests and diseases.

In 1985 the Rural Workers Union of Macapa joined the struggle for the creation of protected areas for rubber tappers, and the concept began to be accepted by the government.

A decree of 30 September 1997 declared that the Brazilian Institute of Environment and Renewable Natural Resources (IBAMA) could expropriate an area of about 501,771 hectares (1,239,900 acres) covered by the reserve.

[6] The reserve is to ensure sustainable use and conservation of renewable natural resources used by the traditional extractive populations.

[7] On 3 June 2003 the National Institute for Colonization and Agrarian Reform (INCRA) recognized the reserve as supporting 700 families.

In the lower course the river merges with other water bodies, which form meanders, lakes and channels.

The characteristic dense rainforest has many Brazil nuts (Bertholletia excelsa) and açaí palms (Euterpe oleracea).

[4] The main agricultural products are corn, beans, rice, pineapple, cassava, yams and sweet potatoes.

Rubber is being phased out, and the main non-timber extractive products are now Brazil nuts and açaí hearts of palm and fruit.

The residents practice subsistence hunting of birds of the Galliformes and Tinamiformes orders, and mammals such as peccary, paca, agouti and monkey.