The Sonoran-Sinaloan transition subtropical dry forest is a tropical dry broadleaf forest

Tropical and subtropical dry broadleaf forests

The tropical and subtropical dry broadleaf forest biome, also known as tropical dry forest, is located at tropical and subtropical latitudes. Though these forests occur in climates that are warm year-round, and may receive several hundred centimeters of rain per year, they have long dry seasons...

 ecoregion

Ecoregion

An ecoregion , sometimes called a bioregion, is an ecologically and geographically defined area that is smaller than an ecozone and larger than an ecosystem. Ecoregions cover relatively large areas of land or water, and contain characteristic, geographically distinct assemblages of natural...

 in northwestern Mexico

Mexico

The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

.

Location and description

This ecoregion forms a transition belt between the Sonoran Desert

Sonoran Desert

The Sonoran Desert is a North American desert which straddles part of the United States-Mexico border and covers large parts of the U.S. states of Arizona and California and the northwest Mexican states of Sonora, Baja California, and Baja California Sur. It is one of the largest and hottest...

 to the north and the Sinaloan dry forests to the south, running south from the foothills of the Sierra Madre Occidental

Sierra Madre Occidental

The Sierra Madre Occidental is a mountain range in western Mexico.-Setting:The range runs north to south, from just south of the Sonora–Arizona border southeast through eastern Sonora, western Chihuahua, Sinaloa, Durango, Zacatecas, Nayarit, Jalisco, Aguascalientes to Guanajuato, where it joins...

 highlands of the state of Sonora

Sonora

Sonora officially Estado Libre y Soberano de Sonora is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided into 72 municipalities; the capital city is Hermosillo....

 to the Pacific Ocean

Pacific Ocean

The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

 coasts of Sonora and Sinaloa

Sinaloa

Sinaloa officially Estado Libre y Soberano de Sinaloa is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided in 18 municipalities and its capital city is Culiacán Rosales....

. This region is also part of the transition zone between the Nearctic and Neotropic ecozone

Ecozone

An ecozone is the broadest biogeographic division of the Earth's land surface, based on distributional patterns of terrestrial organisms.Ecozones delineate large areas of the Earth's surface within which organisms have been evolving in relative isolation over long periods of time, separated from...

s and as such habitats of the region range from sparse semi-desert in the north to dry forest in the south. It covers an area of 51000 km² (19,691.2 sq mi) from sea level to 2000 m (6,561.7 ft). Average annual rainfall is 100–200 mm (3.9–7.9 in)

Flora

The northern section is home to typical desert vegetation such as cacti such as organ pipe (Stenocereus thurberi), jumping cholla (Cylindropuntia fulgida) and barrel cactus (Ferocactus wislizeni

Ferocactus wislizeni

Ferocactus wislizeni, the fishhook barrel cactus, also called Arizona barrel cactus, candy barrel cactus, and Southwestern barrel cactus, is a cylindrical barrel-shaped cactus.-Characteristics:...

). Further south the habitats are dry woodland with trees including Acacia

Acacia

Acacia is a genus of shrubs and trees belonging to the subfamily Mimosoideae of the family Fabaceae, first described in Africa by the Swedish botanist Carl Linnaeus in 1773. Many non-Australian species tend to be thorny, whereas the majority of Australian acacias are not...

s such as Boatthorn Acacia (Acacia cochliacantha), and Tree Catclaw (Acacia occidentalis).

Threats and preservation

This woodland is vulnerable to logging and clearance for livestock grazing, particularly around the cities of Navojoa

Navojoa

Navojoa is the fifth-largest city in the northern Mexican state of Sonora and is situated in the southern part of Sonora, south of the state's border with the U.S. state of Arizona. It is the administrative seat of a large municipality, located in the Mayo River Valley.-History:The city name...

 and Álamos

Álamos

The town and municipality of Álamos in the Mexican state of Sonora was founded in the late 17th century following discoveries of silver in the region. It was named by the conquistador Francisco Vásquez de Coronado, and became the capital of the surrounding region...

, while the wildlife is vulnerable to hunting. Areas of particular conservation importance include the Yaqui River

Yaqui River

The Yaqui River is a river in the state of Sonora in northwestern Mexico. Being the largest river system in the state of Sonora, the Yaqui river is used for irrigation....

basin .