Oases: Diversity Without Protection

‘Islands of fertility,’ ‘green diamonds,’ or ‘paradise in the desert’ – the names for oases alone reflect the fascination with these ecosystems. “In science, we define oases as fertile and densely vegetated areas within harsh arid regions that are characterized by great biocultural diversity,” explains the study’s lead author, Dr. Juan Antonio Hernández-Agüero from the Senckenberg Gesellschaft für Naturforschung and the Vrije Universiteit Amsterdam, and he continues, “For thousands of years, oases have been important settlement and trade centers. They provide water sources, which support agriculture, enabling people and animals to survive. From an ecological point of view, oases are hotspots of biodiversity. They serve as isolated retreats for numerous plant and animal species as well as a variety of crops. At the same time, they are threatened by climate change, groundwater exploitation, and urbanization – which makes their protection and sustainable management ever more important.”

Despite the importance of oases, comprehensive information as to their global distribution has been lacking to date. To close this gap, Hernández-Agüero and a team of Senckenberg researchers embarked on a detailed literature search. They combined the results with a modeling approach to create a comprehensive data and knowledge base that captures the current distribution, delimitation, and status of oases worldwide, and especially in Asia and North Africa (ANA region).

“Based on 1,657 research articles, we were able to identify a total of 1,344 oases in 30 different countries,” explains Prof. Dr. Klement Tockner, Senckenberg’s Director General and the study’s senior author, and he continues, “In the ANA region, oases cover a total of around 400,000 square kilometers, which corresponds to 1.5 percent of dry areas in this region. These relatively small areas are inhabited by 150 million people, and a further 268 million people live near the edge of the oases and are dependent on their resources. With more than 1,000 inhabitants per square kilometer, oases are among the most densely populated areas in the world, which emphasizes their high fertility and productivity. The 75 UNESCO World Heritage Sites located in or adjacent to oases also underline their outstanding cultural importance.”

Worldwide, 8,281 species of mammals, reptiles, amphibians, and birds have been identified in oases. According to the Red List of the International Union for Conservation of Nature (IUCN), a total of 470 species are classified as endangered, 450 as critically endangered, and 220 as threatened with extinction.

“At the same time, less than 0.5 percent of the total oasis area is protected. In general, steppes are considered the most threatened terrestrial habitats – yet it appears that oases are even more endangered. The inclusion of oases in the ‘30 × 30’ target, which aims to protect 30 percent of terrestrial and marine habitats by 2030, is crucial for the conservation of this biodiversity,” adds Hernández-Agüero.

In their work, the researchers urge to promote conservation strategies that incorporate biological and cultural diversity, i.e., biocultural diversity. They recommend improving the conservation and management of oases by integrating ecological, socio-economic, and cultural aspects. This requires joint efforts involving indigenous populations and local communities, policy makers, researchers from different disciplines, and conservation experts.

“Our findings highlight the particular biocultural, ecological, and geopolitical importance of oases, which are increasingly threatened by climate change and direct human impacts. Oases are vital but unfortunately neglected and threatened ecosystems of global importance that play a crucial role in the promotion and conservation of biodiversity and possess a rich cultural heritage. As such, they urgently require attention and protection,” adds Tockner in conclusion.