An alert has been given: according to US scientists, without action against climate change, the Joshua Tree (the iconic tree of the state of California) could disappear by 2070.
The species has been around for 2.5 million years, but could be extinct in a few decades. The Joshua Tree is a tree species endemic to the deserts of North America. It is found especially in the Mojave Desert in southern California. It is an atypical tree that has become a symbol of the American state, which millions of people come to observe each year in the heart of Joshua Tree National Park.
In 1987, the Irish band U2 even stuck it in the center of the cover of their fifth album, The Joshua Tree. The park in question becomes a place of pilgrimage for fans of the group.
4000 trees studied
Precious as it may be, the tree may well become a vague memory for the younger generations. According to a recent study by scientists at the University of California Riverside, climate change could kill the species before the end of the century.
After studying nearly 4,000 trees, the team of scientists drew a cold and lucid report on the future of the tree, in an article published in early June, in the American ecological journal Ecosphere.
According to their results, in the best of scenarios, efforts to combat global warming could save 19% of the habitat suitable for the growth of the tree after 2070. In the worst case, the Californian park would retain only 0.02% of the favorable Joshua tree environment.
The leader of the research, Lynn Sweet, calls for collective awareness. “The fate of these particular trees is in our hands. For sure, their numbers will decrease, but everything now depends on us.”
The study has already demonstrated an evolution of the tree’s behavior in relation to climate. The latter gradually moved towards the higher areas of the park, to find a cooler atmosphere and a wetter land. The researchers also observed that in the aridest areas, the few plants produced by adult trees did not survive.
Joshua’s tree can live up to 300 years, storing large reserves of water to cope with droughts. But California is increasingly confronted with these climatic phenomena. “The last one lasted 376 weeks. In some places, it has dried up the soil too much to allow young plants to survive,” says the University of California Riverside website.
Fires are another big threat to these trees. “Less than 10 % of trees survive forest fires, favored in recent years by car and industry exhaust,” the website says. According to the study, the nitrogen deposited on shrubs easily cause fires.
Local actions are possible to reduce risks, such as weeding. “By protecting these trees, it also protects a host of ‘ insects and animals that depend on them,” says Lynn Sweet. That is a message scientists hope to make heard, in a country where the head of state, Donald Trump, calls climate change a “hoax”.