Expert blog: Deserts are brimming with life but remain one of the most poorly-understood ecosystems – here’s why that needs to change
By Sarah Curtis, PhD researcher, School of Animal, Rural and Environmental Sciences
When most people think of deserts, the word that often comes to mind is sand – and a lot of it. Deserts cover almost a quarter of the earth, yet it’s hard to imagine life thriving in such hostile environments, regulated by how much water and food is available.
However, in the immortal words of Jurassic Park: life finds a way.
Although to the naked eye deserts appear barren, there is actually a surprising amount of life to be found. Deserts are one of the top three richest biomes for terrestrial vertebrates, with a quarter of species, totalling almost 7000, found there. Three percent of these species are only found in desert environments – many of which have developed various adaptations to help them survive in environments where rainfall may be mere millimetres per year.
The evolutionary basis for traits such as tolerance of limited water and high temperatures may even provide knowledge that contributes towards human welfare and agricultural advancements.
‘Charismatic megafauna’ such as large carnivores and herbivores display various adaptations to survive in this harsh environment. Small carnivores, alongside larger scavenging species such as brown hyaena, are almost entirely water independent, obtaining most of their moisture needs from prey and high water content fruits. Many herbivores have evolved to be able to quickly respond to rainfall, covering vast distances to find water. The gemsbok (also called oryx), Namibia’s national animal, is incredibly well adapted to desert life - changing its foraging behaviour during periods of drought, alongside grazing more at night when the water content of many grass species increases.
Even at low densities large carnivores play a key role in the functioning of deserts, keeping herbivore populations at a density where sufficient vegetation to support multiple levels in the food chain is still able to persist. Desert-living carnivores are likely to exhibit unique behaviour and dietary habits compared to their temperate-region counterparts, while interactions between carnivores in deserts are likely to be more intense due to the lack of resources available.
Despite the importance and uniqueness of deserts, there is a paucity in desert research compared to many other habitats – and they are one of the most poorly understood. A combination of a lack of charismatic wildlife, difficult terrain and accessibility issues, along with unstable political environments, means that desert research has often been neglected by conservationists and ecologists in favour of more productive ecosystems.
Between 2000 and 2011, only nine percent of ecological science publications focused on deserts, compared to 67% on forests. This discrepancy is mirrored by less funding towards ecological research in deserts. Deserts also receive less benefits from ecotourism, with many visitors to Africa preferring to visit savanna habitats.
Following a global trend, many desert animal populations are decreasing. In the Sahara, nine out of 14 large vertebrates that historically occurred there have disappeared from over 90% of their range. Worryingly, there is little information about what drives biodiversity loss in deserts. As appears to be consistent across all biomes, the biggest threat to deserts and the animals within them are humans. Global warming is likely to shift deserts towards being even hotter and drier, limiting water availability further. Habitat loss and fragmentation is often exacerbated in deserts, where many species are specialised to live in this habitat. Larger desert-living animals are also considered more extinction prone – meaning that we could be at risk of losing charismatic species like elephants and lions from deserts for good.
Agricultural practices such as irrigation cause increased soil salinity, and combined with pressures from grazing animals, combine to decimate plant populations. Even at low levels, impact from tourism activities such as off-road driving can cause detrimental effects to sensitive desert habitat – some desert plants grow so slowly that it can take centuries to recover from disturbance.
Although deserts typically contain low density human populations, animals that live within them are still subjected to issues arising from human-wildlife conflict. In north-west Namibia, desert lions frequently come into contact with human settlements, having come across livestock after travelling long distances in search of food. The Desert Lion Conservation Trust work tirelessly alongside local communities, providing education, incentives for abstaining from killing lions, and monitoring lion movements – but this is still not enough. The stars of the National Geographic documentary ‘Vanishing Kings: Lions of the Namib’, a coalition of five males called ‘The Five Musketeers’, all met their end before reaching their prime at the hands of humans. With a total population of fewer than 150, the loss of just one individual is a huge blow to the continued survival of Namibia’s desert lions.
Conservation of desert ecosystems is crucial to facilitate suitable conservation management initiatives, policy implementation, and climate change mitigation strategies.
Six percent of the human population live in deserts, many of whom are defined as the poorest, hungriest, and most marginalised in the world, and these communities are especially vulnerable to changes in desert ecosystem function.
Protecting desert ecosystems therefore will not only benefit biodiversity and bolster animal populations against climate change, but will also protect and benefit some of the worlds most impoverished people.
- Subject area: Animal, equine and wildlife
- Category: Press office; Research; School of Animal, Rural and Environmental Sciences