Humid Chaco


The Humid Chaco is tropical grasslands, savannas, and shrublands ecoregion in South America. It lies in the basin of the Paraná River, covering portions of central Paraguay and northern Argentina, and with a small portion extending into southwestern Brazil. The natural vegetation is a mosaic of grasslands, palm savanna, and forest.

Geography

The Humid Chaco lies in the lowlands of the Paraná river and its tributaries, including the Paraguay River. It is bounded on the west by the Dry Chaco, a semi-arid region of dry forests and savannas. The Alto Paraná Atlantic forests lie to the east, and the Cerrado grasslands to the northeast. It borders on some large flooded grasslands and savannas, including the Paraná flooded savanna along the lower Paraná and Paraguay rivers, the Pantanal to the north, and the Southern Cone Mesopotamian savanna to the southeast between the Paraná and Uruguay rivers.
The topography is generally flat or gently rising, and the soils are mostly fine alluvium deposited by the area's rivers.
Asuncion, Paraguay's capital, lies in the ecoregion.

Climate

The climate is tropical, becoming subtropical towards the south. Average annual rainfall generally decreases towards the west, and ranges from 1,300 mm in the wetter eastern portions to 750 mm in the west near the transition to the Dry Chaco. Rainfall is highest in the summer months and lowest in the winter months.

Flora

The flora is a mosaic of grassland, savanna, forests, and bogs. Grasslands and savannas are generally found on higher ground, and forests along streams and in river floodplains. Bogs form seasonally or year-round over impermeable soil layers.
Grasslands are characterized by tall, coarse grass. Palm savannas are common, including the palm Copernicia alba.
The most common trees in the forests are quebracho colorado and quebracho blanco, together with guayacán, espina corona, urunday, viraró, palo piedra, guayaibí, zapallo caspini, lapacho negro, palo borracho del flor rosada, and itin.

Fauna

Native mammals include puma, jaguar, maned wolf, red brocket, gray brocket, marsh deer, pampas deer, White-lipped peccary, collared peccary, giant anteater, capybara, black howler monkey, and Azara’s night monkey.
Birds species include the greater rhea or ñandú, undulated tinamou, savanna hawk, and pale-crested woodpecker.

Protected areas

A 2017 assessment found that 35,949 km², or 12%, of the ecoregion is in protected areas.
Protected areas include Chaco National Park, Río Pilcomayo National Park, and Mburucuyá National Park in Argentina, and Ypoá National Park in Paraguay. The Iberá Wetlands, located in the southeast of the ecoregion adjacent to the Southern Cone Mesopotamian savanna, are protected by Argentina's Iberá Provincial Reserve and Iberá National Park.