Study: Droughts Threaten Cactus Species, Many Could Lose Most of Their Habitat
A model published in the journal Nature suggests most of nearly 1,000 cactus species will lose habitat by 2100, with more than a quarter losing at least 80 percent. Researchers say drought is a bigger threat to cacti than previously thought.
A new study in the scientific journal Nature indicates that climate-driven droughts endanger even cacti, plants widely seen as exceptionally resilient. Researchers built a future model that accounted not only for rising temperatures but also for the dry spells that come with them. It found that most of the nearly 1,000 cactus species examined will lose habitat by 2100, and more than a quarter could lose at least 80 percent of it.
Cacti already suffer from habitat loss and from poaching of species for private collections. Drought now joins these pressures as another threat.
Cacti are not so different from other plants
Michiel Pillet, a conservation ecologist at the University of South Florida and the paper's lead author, says the public tends to view cacti as plants that can handle anything. In reality, he says, they are not that different from other plants and evolved under particular conditions. In the deserts of the southwestern United States, for instance, they depend on seasonal monsoon rains, which usually make July or August the wettest month.
The team also drew on iNaturalist, a citizen science platform where people upload photos of plants and animals. It supplied 650,000 observations of cacti in the wild.
Not only death, but reduced reproduction
Drought may not kill plants immediately but can still interfere with reproduction. In the Sonoran Desert, the towering saguaro reproduces less often during prolonged droughts because it does not always flower. Desert ecosystems are fragile and recover over multiple decades after disturbance, and in some cases not at all, says Marcos Robles, lead scientist in Arizona for the Nature Conservancy, who was not involved in the study.
Too much water is also a risk: rising seas have caused the local extinction of the Key Largo tree cactus in Florida. High nighttime temperatures prevent saguaro and other cacti from respiring without losing water.
Conservation options
Some species might persist by gradually shifting into areas with suitable climates. Conservationists can also move cacti to botanical gardens and, in some cases, reintroduce them to the wild later. Rod Haenni, president of the Cactus and Succulent Society of America, urges governments to protect the lands where cacti are threatened.
