Magdalena Valley dry forests

Magdalena Valley dry forests (NT0221)
West of Neiva, Huila, in the south of the dry valley
Ecology
Realm	Neotropical
Biome	Tropical and subtropical dry broadleaf forests
Geography
Area	19,748 km2 (7,625 sq mi)
Countries	Colombia
Coordinates	4°00′N 74°59′W / 4.0°N 74.98°W / 4.0; -74.98Coordinates: 4°00′N 74°59′W / 4.0°N 74.98°W / 4.0; -74.98
Climate type	Am: equatorial, monsoonal

The Magdalena Valley dry forests (NT0221) is an ecoregion in Colombia along the upper Magdalena River, a large river that runs from south to north between the two main cordilleras of the Andes. There are many endemic species, but much of the original habitat has been destroyed by agriculture and over-grazing, mainly by goats. The habitat is not protected by any national park, and is at risk of complete destruction.

The Magdalena Valley dry forests ecoregion is in the valley of the upper Magdalena River, a river that flows north through the Andes to the Caribbean. It has an area of 19,748 square kilometres (7,625 sq mi). The Magdalena River is the largest in Colombia. The dry forests are almost entirely surrounded by the Magdalena Valley montane forests ecoregion. At its northern end the dry valley merges into the Magdalena-Urabá moist forests. It holds a small patch of the Northern Andean páramo ecoregion.

The Magdalena River runs from the Central Massif between the Eastern and Central cordilleras of the Andes north to the Caribbean. The dry forest is in the upper section. Lower down the river runs through rainforest and then through swamps and wetlands. The average elevation of the dry forest section is 450 metres (1,480 ft). The valley floor is flat, with fertile alluvial soils and large deposits of ash from the Huila and Puracé volcanoes. The dry Tatacoa Desert holds many vertebrate fossils dating from the Miocene era.

The best soils are in areas with piedmont and alluvial valley landscapes, which cover 54.41% of the valley and are irrigated for agriculture. Areas of structural-erosional mountainous landscape cover 18.13% of the area and have no value for farming, so may be conserved as protected areas. Most soils are neither strongly acidic nor alkaline, with pH levels of 5.8–7.5. They have low or very low amounts of organic material, and low to medium levels of phosphorous. 69% of the soils are very susceptible to erosion and these mostly have low or very low natural fertility. Where these soils are not covered by vegetation they may be washed away during the rainy seasons.