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Southwestern Ecuador and Northwestern Peru

The dry forest of Tumbes and Piura is an ecoregion that is home to the largest dry forest remnant in western South America and also has a high level of species endemism (Rodríguez 1996). The vegetation of this area plays an important role in controlling the northward advance of the Sechura Desert; therefore, conservation of this ecoregion's vegetation is part of the worldwide effort against desertification (INRENA 1998).

  • Scientific Code
    (NT0232)
  • Ecoregion Category
    Neotropical
  • Size
    15,900 square miles
  • Status
    Critical/Endangered
  • Habitats


Description
Location and General Description
This Tumbes/Piura dry forest ecoregion is located in the equatorial region of South American between the Pacific Ocean and the western slope of the Andes Mountains. It includes a small section in southern Ecuador and the departments of Tumbes, Piura, Lambayeque and Cajamarca in northern Peru. The total area covered by the ecoregion has been estimated at 46,341 km2 (Roca 1996). The climate is warm and dry although wetter towards the north. It has a rainy season during the months of January to March, with rainfall varying in normal years between 100 and 500 mm and a well defined dry season (Pulgar 1967). Average annual temperature varies between 24 and 27ºC.

Most of the ecoregion is covered by recent sands and clays from the Holocene, while higher elevations have soils composed of granites, Precambrian amphibolites, Paleozoic granites, quartzites and black slate from the Devonian, dark limestone, sandstone and lutites from the Carboniferous period (Rodríguez, 1996). The principal rivers flowing through this ecoregion are the Guayas in Ecuador and the Zarumilla, Tumbes, Piura and Chira Rivers in Peru. Most of these rivers begin in Ecuador and have a regular flow throughout the year. The remaining waterways are temporary only carrying high volumes of water during the raining season (January - March) and then remain almost completely dry throughout the dry season. The topography is generally flat with plains and low hills in coastal areas and small mountain chains toward the continent’s interior. There are some dry forest remnants of the old coastal range at elevations below 1300 masl (Wust 1999).

This ecoregion has large areas covered by seasonal dry forests that grow green during the rainy season. These forests consist of species adapted to the extremely arid conditions of the dry season. There is a wide variety of plant associations such as the ceibal consisting primarily of ceiba (Ceiba trichistandra), which is one of the species endemic to the region. Chaparral consists primarily of shrub species like the papelillo (Bouganvillea sp.), some cacti and the overo (Cordia lutea) among others and the algarrobal dominated by species of algarrobo (Prosopis spp.) are also vegetative associations of this ecoregion. Other dominant species in the dry forest zone are the hualtaco (Loxopterigium huasango), guayacán (Tabebbuia billbergii), palo santo (Bursera graveolens), ébano (Ziziphus thyrsiflora), charán (Caesalpinea corymbosa), sapote (Capparis angulata), pasallo (Bombax discolor), angolo (Pitthecellobium multiflorum) and almendro (Geoffroya striata) (Ferreyra 1988; Rodríguez 1996; Wust 1999).

Biodiversity Features
There is a significant degree of endemism, primarily among species of flora and birds, with the latter group being richest in species (14 orders of birds). In addition, there are six orders of mammals, two of reptiles and one of amphibians and a still undetermined number of fish and arthropods. There is great plant diversity, particularly among arboreal species adapted to the arid conditions. In terms of the abundance of species, this ecoregion is important because it is one of the areas with the highest concentration of mezquite (Prosopis spp.)

Carob, like other plant species in the ecoregion, has the peculiar characteristic of capturing and fixing nitrogen in its roots. This contributes to improving the conditions where it lives, so that it carries out important ecological functions, promoting the survival of a large number of species of flora and fauna in the area surrounding it. The most important cyclical event is the El Niño- Southern Oscillation, during which precipitation increases and helping the seeds of thousands of individual plant species to germinate and become a source of food for a similarly large number of animal species. These periods of excessive moisture in a generally dry environment have a great impact on the recovery of the natural vegetation. In this way, many species of flora and some species of fauna remain in intact habitat blocks that are an important source of water and seeds for the locations most subject to human intervention. The ecoregion has some species threatened by operations to which they have been subject, particularly forest species such as the guayacán (Tabebbuia billbergii), hualtaco (Loxopterigium husango), and palo santo (Bursera graveolens), among others.

Characteristic species of fauna in the ecoregion include the anteater (Tamandua tetradactyla punensus), the black napped squirrel (Sciurus stramineus), the iguana (Iguana iguana), and various species of birds such as parrots and parakeets, magpies and some furnarids. Some bird species like the Brotogeris pyrrhopterus, Pionus chalcopterus and Carduelis semiradskii are endangered and others have limited distribution including Forpus coelestis, Aratinga erythrogenis, and Cyanocorax mystacalis (Rodriguez 1996; Bibby et al. 1992).

Current Status
The ecoregion has traditionally been subject to the selective extraction of species of flora and fauna. However, recently a recovery of the forest and its fauna can be observed. This is likely due to the establishment of the Cerros de Amotapes National Park as well as the positive effect of El Niño’s increasing the amount of water available in the ecosystem (INRENA 2000).

Types and Severity of Threats
The protected area master plan as well as various territorial organization approaches at the community level is attempting to establish strategies to mitigate the threats to local biodiversity. These threats relate to habitat degradation, as there is selective extraction of forest species for firewood, coal and manufacturing of crates just to name a few uses. The illegal capture of parrot and parakeet species for sale as pets, as well as the hunting of some mammals and reptiles for consumption (Brack 1988).

Justification of Ecoregion Delineation
This dry forest ecoregion spans the borders of Peru and Ecuador, and forms the transition from the xeric Sechura desert to the south and the moist and dry forests of the Andean slopes and foothills to the north. In Peru out linework follows Instituto Geográfico Nacional (1987), who classifies this region as "equatorial dry forest". From this initial classification we distinguished this region from the Marañon Valley, which we consider a separate ecoregion due to marked species endemism and unique species assemblages.

References
Bibby J., J. Collar, and M. Crosby. 1992. Putting biodiversity on the map: Priority areas for global conservation. Birdlife International, UK.

Brack A. 1988. Ecología de un País Complejo. Gran Geografía del Perú. Lima.

Brack A, M. Ríos, and F. Reyes 1973. Evaluación y bases para el establecimiento de un coto de caza y un parque nacional en la cordillera de los Amotapes.(Piura-Tumbes). Lima.

CDC-UNALM. 1991. Plan director del SINUC una aproximación desde la diversidad biológica. Lima.

CDC-UNALM. 1992. Estado de Conservación de la diversidad Natural de la Región Noroeste del Perú. Lima.

CLIRSEN/DINAF. 1990. Mapa forestal de la Republica de Ecuador. Map 1:1,000,000. Quito, Ecuador. Instituto Geográfico Nacional. 1987. Ecoregiones del Peru. Map 1:5,000,000. Atlas del Peru, Lima, Peru.

Ferreyra R. 1988. Flora y Vegetación del Perú. Gran Geografía del Perú. Lima.

INRENA, Proyecto Algarrobo. 1998. Bosques secos y desertificación. Memorias del Seminario Internacional. Lima-Perú.

INRENA. 2000. Perú-Areas Naturales Protegidas. Instituto Nacional de Recursos Naturales. Lima.

Pulgar Vidal J. 1967. Geografía del Perú. Las 8 regiones naturales. Lima.

Pulido V. 1991. El Libro Rojo de la Fauna Silvestre del Perú. Lima.

Roca R., L. Adkins et al. 1996. Wings from afar, An ecoregional approach to conservation of Neotropical migratory birds in Southamerica.

Rodríguez L. 1996. Diversidad Biológica del Perú: Zonas Prioritarias para su Conservación. Proyecto Fanpe GTZ-INRENA.

Weberbauer A. 1945. El mundo vegetal de los Andes Peruanos. Estación Experimental Agrícola de La Molina.(776p) Lima.

Prepared by: Juan Carlos Riveros Salcedo
Reviewed by: In process

 

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