South America: In the mountain valleys of southern central Bolivia

This ecoregion is quite restricted, forming a transition between the Yungas and Puna zones in Bolivia. This dry region is characterized by steep hillsides, cliffs, and valleys and contains a number of endemic species of avifauna including the Bolivian recurvebill and Bolivian blackbird. A number of national parks protect a significant area of habitat, however more are needed in order to preserve this region heavily affected by urban expansion.

  • Scientific Code
  • Ecoregion Category
  • Size
    31,000 square miles
  • Status
  • Habitats

Location and General Description
This ecoregion is restricted to south-central Bolivia, barely touching northwest Argentina. The Bolivian Montane Dry Forests are tightly interdigitated to the east and west with Southern Andean Yungas and Puna, respectively (Olson et al. 2000). The northern, southern, western and eastern boundaries of this ecoregion terminate at approximately the 160 and 230 south latitudes and 690 and 630 west longitudes, respectively (Anon. 1980). The altitude ranges from 360 – 700 m asl (Erguetes y Morales 1996).

This ecoregion essentially forms a xeric habitat that lies between the mesic Yungas to the east, and the Puna to the west (Olson et al. 2000). Unfortunately, much of the habitat serves as an ideal model of ecoregions that are largely altered by man (Erguetes y Morales 1996). The original spiny forest contained species such as Acacia caven, Prosopis aplataco, Dodonea viscosa, with some regions including species such as Schinopsis haenckeana and Aspidosperma quebracho colorado (Erguetes y Morales 1996). Dense chapparal thickets also contained species such as Acacia, Proustia and Kentrothamnus (Erguetes y Morales 1996).

Biodiversity Features
A variety of endemic birds are present in this region, including Bolivian Recurvebill (Simoxenops striatus), Bolivian Blackbird (Oreopsar bolivianus), and a number of finches including Citron-headed Yellow Finch (Sicalis luteocephala) and Warbling Finches (Poospiza garleppi and P. boliviana). Other rare and endemic species include the Torrent Duck (Merganetta armatta), Wedge-tailed Hillstar (Oreotrochilus adela), Black-hooded Sunbeam (Aglaeactis pamela), and Carbonated Flower-piercer (Diglossa carboniaria).

Many strongly tropical species meet their southern limits of geographic distribution in this region (Ojeda and Mares 1989). Additionally, the Felid diversity is apparently high in this region, with potential species including Puma (Felis concolor), Ocelot (F. pardalis), Pampas Cat (F. colocolo), Geoffroy’s Cat (F. geoffroyi) and Jaguarundi (Herpailurus yagouaroundi) (Tarifa 1996).

Current Status
The extent of deforestation in this region has not been documented with certainty, but there are apparently large areas of degraded land (Fjeldså and Mayer 1996).

There are a number of National Parks (NPs) and protected areas in this ecoregion, including: Tariquía National Reserve (2469 km2) and the slightly smaller Cama Valley Biological Reserve and Toro Toro NP (Ergueta y Morales 1996). However, these three sites combined probably do not exceed 6000 km2 and more reserves within this region would be ideal.

Types and Severity of Threats
This region is heavily impacted by urban sprawl and the ramifications of an increasing human population; overhunting, conversion to agriculture, collection of fuelwood, and other impacts. Fragmentation of the remaining forests is thus the dominant threat.

Justification of Ecoregion Delineation
These dry forests flank the slopes and valleys of the eastern Andes of Bolivia – extending as both large and small patches among valleys and between the high puna habitats and the lowland chaco. This region has very diverse microclimates, and species assemblages can differ from one mountain or valley to the next. Beta diversity is very high, as are species diversity and endemism. The linework for this ecoregion follows Ribera et al. (1994) who classifies this as "microfoliate matorral and remnants of deciduous dry forest".

Anon. 1980. Time-Hammond world atlas. U.S.: Hammond, Inc.

Ergueta-S. P., y C. de Morales. 1996. Libro Rojo de los Vertebrados de Bolivia. Bolivia, CDC.

Fjeldså, J., and S. Mayer. 1996. Recent ornithological surveys in the Valles region, southern Bolivia and the possible role of Valles for the evolution of the Andean avifauna. Cntr. Rsrch. Cult. Biol. Divers. Andean Rainforests, Danish Envion. Rsrch. Prog.

Ojeda, R. A., and M. A. Mares. 1989. A biogeographic analysis of the mammals of Salta Province, Argentina: Patterns of species assemblages in the Neotropics. Spec. Publ., Mus. Texas Tech Univ. 27.

Olson, D., E. Dinerstein, P. Hedao, S. Walters, P. Allnutt, C. Loucks, Y. Kura, K. Kassem, A. Webster, and M. Bookbinder. 2000. Terrestrial Ecoregions of the Neotropical Realm (map). D. C:.Conserv. Sci. Program, WWF-US.

Ribera, M.O., M. Libermann, S. Beck, and M. Moraes. 1994. Mapa de la vegetacion y areas protegidea de Bolivia. 1:1,500,000. Centro de Investigaciones y Manejo de Recursos Naturales (CIMAR) and Universidad Autónoma Gabriel Rene Moreno (UAGRM), La Paz, Bolivia.

Tarifa, T., 1996. Mamíferos. Pages 165-264 in S. Ergueta, y C. de Morales, editors , Libro rojo de los vertebrados de Bolivia. Bolivia: CDC.

Prepared by: Dr. Daniel Brooks
Reviewed by: In process