California Fish & Game Report Holds Threat To Joshua Tree Habitat Is Less Than Critical

The Center for Biological Diversity’s petition to have the western Joshua tree listed as a threatened species suffered a setback last month after a panel of scientists concluded available data does not conclusively demonstrate the plant’s habitat will fully disappear in the foreseeable future.
In October 2019, the environmental group made a request of the California Department of Fish and Wildlife that the western Joshua tree be listed as a threatened species under the California Endangered Species Act. The Fish and Game Commission is scheduled to make an ultimate decision on that request on June 16, 2022.
On April 13, the California Department of Fish & Wildlife released a report and recommendation completed in March which included a peer review of the available data relating to the Joshua tree assembled by Dr. Cameron Barrows of the University of California Riverside, Dr. Erica Fleishman of the Oregon Climate Change Research Institute, Dr. Timothy Krantz with the University of Redlands, Dr. Lynn Sweet with the University of California, Riverside and Dr. Jeremy B. Yoder from California State University Northridge.
Barrows, Fleishman, Krantz, Sweet and Yoder acknowledge the outlook for the plant, known by its scientific name Yucca brevifolia Engelm, is grim. “The population size and area occupied by [the] western Joshua tree have declined since European settlement largely due to habitat modification and destruction, a trend that has continued to the present,” the report states. “Primary threats to the species are climate change, development and other human activities, and wildfire. Available species distribution models suggest that areas predicted to be suitable for [the] western Joshua tree based on 20th Century climate data will decline substantially through the end of the 21st Century as a result of climate change, especially in the southern and lower elevational portions of its range.”
Nevertheless, the scientists said, “the department does not currently have information demonstrating that loss of areas with 20th Century suitable climate conditions will result in impacts on existing populations that are severe enough to threaten to eliminate the species from a significant portion of its range by the end of the 21st Century. The effects of development and other human activities will cause western Joshua tree habitat and populations to be lost, particularly in the southern part of the species’ range, but many populations within the range of the species are protected from development, suggesting that a significant portion of the species’ range will not be lost by development alone. Wildfire can also kill over half of western Joshua trees in areas that burn, and wildfire impacted approximately 2.5% of the species’ range in each of the last two decades, but wildfire does not appear to result in loss of range, only lowering of abundance within the species’ range.”
Barrows, Fleishman, Krantz, Sweet and Yoder said that “While the department recognizes the threats faced by the species, and the evidence presented in favor of the petitioned action, the scientific evidence that is currently possessed by the department does not demonstrate that populations of the species are negatively trending in a way that would lead the department to believe that the species is likely to be in serious danger of becoming extinct throughout all or a significant portion of its range in the foreseeable future. The department recommends that the commission find that the recommended action to list [the] western Joshua tree as a threatened species is not warranted.”
Brendan Cummings, the Center for Biological Diversity’s conservation director, decried the recommendation as one in which, “California wildlife officials just proposed open season on Joshua trees.” Inaction, Cummings said, will doom the species. “Before state protections took effect, developers were bulldozing these beautiful, fragile trees by the thousands to build roads, warehouses, power plants, strip malls and vacation rentals. If Joshua trees are to have any hope of surviving in a warming world, we have to stop the widespread killing of them.”

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