Campo de Perizes is an extensive fluvial-marine plain, with halophilous floodplain grasslands, located between the cities of São Luís, Bacabeira, and Rosário, in the Golfão Maranhense [pt] region.

[3] The coast of Maranhão is marked by the presence of mangroves; a plant formation of arboreal or shrubby size, adapted to marshy terrain, subject to the direct influence of tides and salinity.

Some of the existing species are the piri or piripiri (Cyperus giganteus), which inspired the place's name; the aturiá (Machaerium lunatum); canarana (Panicum spp); as well as reeds from the Cyperaceae family.

The work involved the construction of a viaduct in Bacabeira (Km 51), allowing access to the city of Rosário, at the junction with the BR-402 highway, the gateway to Barreirinhas and the Lençóis Maranhenses.

[10] The presence of the highway, together with electrical, railway, and supply infrastructures, as well as irregular urban expansion, are contributing factors to changes in the ecosystem of Campo de Perizes and other conservation units.