By Emilio Godoy
Mexico’s oases encompass significant environmental, cultural, social and economic wealth that must be properly assessed and preserved, warn experts.
Of the roughly 200 oases in Mexico, 184 are in the state of Baja California Sur, while the others are in Baja California Norte and Sonora, according to the Ministry of Environment and Natural Resources. All three states are in the country’s northwest corner.
“They are highly vulnerable to the pressures of modernity. All of them are threatened, and they are not being properly addressed because for a long time there was no recognition of their heritage value and agricultural practices,” said Micheline Cariño, a researcher at the public Autonomous University of Baja California Sur (UABCS).
“They are all diverse and face different problems, which is why they must be handled with great care,” Cariño told Tierramérica.
Oases are complex ecosystems: isolated areas of vegetation in a desert, home to their own unique variety of flora and fauna, with the distinctive feature of a natural source of water.
Oases provide a habitat for animal species from northern, temperate and tropical zones, and serve as supply stations for migratory birds and points of attraction for all nearby fauna.
They are rarely more than two square kilometers in size, and can be used for human activities like the cultivation of fruits and vegetables – dates, grapes, citrus fruits, tomatoes and lettuce – and raising cattle and goats.
They also contribute to the capture of carbon dioxide, one of the greenhouse gases responsible for global warming.
Oases and the economic and subsistence services they provide in arid regions are traditionally associated with the Arab and Amazigh (Berber) cultures of the Middle East and North Africa. As populated physical sites, the oases of Mexico were established by Jesuit missionaries and ranchers who brought these traditions from Spain beginning in the 17th century.
Cariño is one of the founders of the Interdisciplinary Network for the Integrated and Sustainable Development of Oases in Baja California Sur (RIDISOS), created in 2006 by scientists from UABCS, the Biological Research Center of the Northwest (Mexico), the University of San Diego (United States), and Miguel Hernández de Elche University and the University of Granada, both in Spain, for the study of the environmental, cultural and social aspects of these areas.
An article published in 2003 in the Annals of the Institute of Biology of the National Autonomous University of Mexico (UNAM) highlighted the importance of oases for birds, “both for resident species, because they represent favorable habitats for local species, and for migratory and wintering birds.”
The article, “Observaciones recientes de aves en el oasis de La Purísima, Baja California Sur, México” (Recent observations of birds in the oasis of La Purísima, Baja California Sur, Mexico), authored by UABCS researchers, reported the sighting of 60 different species.
In Baja California Sur the federal government has invested some 45 million dollars in the protection of this natural wealth since 2011.
But these ecosystems remain “little identified. They are reservoirs for many species and supply good quality water for communities,” Gerardo Rodríguez, a researcher at the UNAM Institute of Ecology, told Tierramérica.
When it rains in these areas, the lowlands are flooded. The water, while retreating, gives rise to the emergence of oases which create plant communities. These in turn retain water, fostering the appearance of fish, crustaceans and invertebrates.
“They end up being the only place where certain species remain until the next rainy season,” explained Rodríguez, who specializes in the study of ecosystems that form in the lowlands of the Yucatán Peninsula in southeast Mexico.
Oases face a variety of threats. Some are abandoned by the human population because of a lack of livelihood opportunities. Others are targeted for tourism and real estate investment. Their freshwater resources are overexploited, native trees are cleared, and invasive species of fish and plants are introduced and kill off the endemic species. According to Rodríguez, “the biggest threat is the poor planning of water use.” There is “uncontrolled consumption” of water resources and “no initiatives for their recharge or treatment.”
RIDISOS is concluding research on the knowledge, valuation and sustainable development of oases, focusing on the municipality of Comondú, one of the most seriously threatened wetlands in Baja California Sur.
Comondú is one of the 55 sites designated as Wetlands of International Importance under the Ramsar Convention, and is home to seven species of birds and 18 species of reptiles with some degree of national protection status.
The government strategy of “rapidly intervening has not had the most desirable effect for addressing the concise and precise problems of oases,” said Cariño. “They did not take the time to carry out a diagnosis of the problems of each oasis and define the most appropriate way to intervene in each.”
Experts propose the definition and categorization of oases and the development of an inventory. They would also like the mountainous regions of Baja California Sur to be designated as Mexican cultural and natural heritage sites.