TROPICAL DRY FORESTS
This ecological region stretches in a narrow and interrupted strip from Eastern Sonora and
Southeastern Chihuahua to Chiapas; at Michoacán it includes the Balsas Basin. In the
Tehuantepec isthmus, it splits to embrace the Central Chiapas Depression where it stretches
along the Pacific to Central America and the northern extreme of South America. It also occupies
the Northern Gulf Coastal Plain, the north of the Yucatán Peninsula and the southern tip of
the Baja California Peninsula, covering almost 13 percent of Mexico.
Biological setting
A diverse flora is present, particularly in the tree and bush layers that are dominant in most of
this area. Southern floristic elements are prominent, along with numerous endemic genera in
the Mexican Pacific side. Low deciduous and sub-deciduous forests dominate. This implies a
marked seasonal pattern and a physiognomic difference between dry and humid seasons. These
forests are from 4 to 15 m tall and have three distinct strata. The low deciduous forests contain
about 6,000 vascular plant species, of which 40 percent are endemic to Mexico. In its composition,
legumes are predominant, and the floristic richness decreases from southeast to northwest.
In the Balsas Basin, a large number of endemic species occurs, and it is the most significant
region for the family of copales (papelillos), trees that are harvested for commercial and
ritualistic uses. Other species of economic importance include parota, cuéramo, Mexican red
cedar, palo de rosa, sabicú, jabin and henequen (false sisal).
Fauna include hare, squirrel, deer, lynx, ocelot and coati. Of the 253 vertebrates associated with
Tropical Dry Forests, eight are endangered. Thirteen species of vertebrates associated with the
sub-deciduous forests are also close to extinction.