Ríos Blanco y Negro Wildlife Reserve, Wildlife reserve in Santa Cruz Department, Bolivia.

Ríos Blanco y Negro Wildlife Reserve is a 1,400,000-hectare departmental protected area spanning the municipalities of Concepción, Ascensión de Guarayos and Urubichá in northern Santa Cruz Department. It lies where the Chiquitano dry forests meet the Madeira-Tapajós moist forests, and the nutrient-rich San Pablo and Blanco rivers flood seasonally to form Várzea forests.

The reserve was created on 10 August 1990 by Ministerial Resolution 139/90, covering 1,400,000 hectares in the provinces of Ñuflo de Chávez and Guarayos. Its stated aim was to preserve biological diversity and promote ecologically and economically sustainable use of natural resources. A management start-up plan (PIG) was later drawn up with the municipalities of Concepción, Ascensión de Guarayos and Urubichá, the Guarayo and Chiquitano peoples, and Fundación Amigos de la Naturaleza.

Guarayo and Chiquitano communities live near the reserve and gather forest fruits, hunt and fish for subsistence, and farm; they sell the produce at local markets. Among the plants they use are the marayaú palm (Bactris major), chontilla, turo, big-leaf mahogany and cusi, taken for construction wood, resins, fibres, fruit and medicine.

The reserve lies in northern Santa Cruz Department, spanning the municipalities of Concepción, Ascensión de Guarayos and Urubichá; the San Pablo and Blanco rivers are the main routes in. Seasonal flooding of the plains forms Várzea forest and can cut off access, so plan travel outside the rainy season. Park rangers and technicians of the departmental government work in the area, and the management plan calls for local knowledge or experienced guides.

The reserve connects two very different forest types where the dry Chiquitano forests meet the humid Amazon forests of the Madeira-Tapajós region. This overlap creates unusual ecological conditions with high species diversity and distinct habitats in close proximity.