Ecological Importance of bajadas in the Chihuahuan Desert

Bajadas are transition zones between the foothills of the mountainous areas and the valleys in the arid zones of North America; given their microclimatic characteristics (geomorphological composition, high humidity, and low solar radiation) they are probably a refuge for many plant species; however, there are no reports for the bajadas in the Cuatro Cienegas Basin. This work describes the structure, composition, and diversity of the plant community found in bajadas in the Cuatro Cienegas Basin (CCB) in the Chihuahuan desert, where we sampled 0.6 ha. We found 38 plant species, 26 genera, and 11 families. The Shannon diversity index was 3.2, higher than those registered in other arid zones. The Cactaceae family includes the greatest number of species (22 species), seven of them are classified under some threat category; other cacti species had a restricted distribution into the so-called mega Coahuilan region. The most important species based on their density and volume were: Grusonia bradtiana (importance value, IV =35.3%), Larrea tridentata (IV=15.9%), and Jatropha dioica (IV=14.12%), these species might strongly contribute to the composition of bajadas since they function as nurse plants for other plant species. As the CCB is one of the most diverse of the Chihuahuan Desert, the knowledge of the diversity, structure, and composition of bajadas is relevant to define important sites and strategies for the conservation of North America’s largest desert.