About a third of the world's cactus species are threatened with extinction, the International Union for Conservation of Nature warns in a new report. The study evaluated 1,478 species and determined that 31% are endangered due to factors such as the conversion of wilderness areas to farming and ranching, urban development, and the harvest of cactus seeds and plants for trade and private collection. "We show that cacti are among the most threatened taxonomic groups assessed to date ... demonstrating the high anthropogenic pressures on biodiversity in arid lands," says the report, which was published in the journal Nature Plants.
It identified hotspots of endangered cactuses across the Americas, from the southern Brazilian state of Rio Grande do Sul and parts of neighboring Uruguay north to the Mexican states of Queretaro, San Luis Potosi, Oaxaca, and Puebla. Salvador Arias, cactus curator at the National Autonomous University of Mexico's botanical garden, said a little over a third of the country's 700 or so native species are at severe risk for survival and called the situation "alarming." He said the greatest threat comes from destruction of habitat for crops and cattle. Second is illegal collection, often by aficionados who take seeds or plants to sell in European countries. Scientists say cactuses are important elements of desert ecosystems as sources of food and water for flora and fauna. They're also a source of nourishment and building materials for local human populations.