R o Negro. Considered a world centre of floral genetic diversity, numerous rare and threatened species of flora and fauna are supported. Some livestock rearing, timber extraction, and poaching take place. A border is shared with both Bolivia and Brazil. An alluvial plain along the Pilcomayo River which is flooded much of the year and characterized by patches of forest, extensive, clustered lakes, and savannas of palm groves.
Watercourses follow ancient riverbeds, with gallery forest growing alongside.
Another sector is composed of vast, dry plains of grasses and shrubs. Located in the tropical deciduous dry forest biogeographical region, the site, in outstanding condition, is a good representative of biodiversity. Situated along the migration route, birds are abundant in species and number. The site is important for Potamogeton striatus , a critically endangered plant, and supports a distinct mammalian fauna. Extensive ranching, extraction of forest products, and poaching occur.