The climate crisis is no longer a distant threat; it’s a present reality with devastating consequences. From record-breaking temperatures in Death Valley to the alarming rise of sea levels, the effects are undeniable. Tragically, the United States has witnessed its first local extinction due to sea level rise: the Key Largo tree cactus ( Pilosocereus millspaughii).
This unique cactus, only discovered in 1992, once thrived in a small population in the Florida Keys. While it still exists in the Caribbean, the Florida population has dwindled to nothing, a victim of the encroaching sea. This loss serves as a stark warning about the vulnerability of coastal ecosystems and the urgent need for action.
A Rapid Decline:
The Key Largo tree cactus, capable of reaching heights of over 20 feet, with its fragrant, moon-reflecting flowers that attract bat pollinators, was a remarkable species. However, its existence in Florida was short-lived. By 2021, the population had plummeted from 150 stems to a mere six. Harsh weather, saltwater intrusion, and grazing mammals all contributed to its demise.
“Unfortunately, the Key Largo tree cactus may be a bellwether for how other low-lying coastal plants will respond to climate change,” warned Jennifer Possley, director of regional conservation at Fairchild Tropical Botanic Garden and lead author of a study documenting the cactus’s decline.
A Unique Species:
Initially mistaken for the Key tree cactus (Pilosocereus robinii), the Key Largo tree cactus was later identified as a distinct species. Alan Franck, herbarium collection manager at the Florida Museum of Natural History, highlighted the key differences: “The most striking difference is the tuft of long, woolly hairs at the base of the flowers and fruits.” These distinctive hairs, along with longer spines, set the Key Largo tree cactus apart.
The Key tree cactus itself faces similar threats, with an 84% decline between 1994 and 2007. Both species are particularly vulnerable to herbivory and increased soil salinity caused by “king tides.”
A Desperate Rescue:
In a last-ditch effort, researchers launched a rescue mission in 2016, collecting stem fragments for cultivation in a nursery. Despite these efforts, the Florida population continued to decline. By 2021, recovery was deemed impossible. The remaining cacti were harvested, their fruits collected for viable seeds, and the green parts taken to nurseries. The species now exists only in these captive collections: 36 salvaged fragments, 25 seedlings, and over 1,000 seeds in storage.
Even after its official extinction in the wild, researchers returned in 2022 and 2023, hoping to find any missed fragments. In 2023, they found one final fragment, which was removed, knowing it would not survive the rising tides.
The extinction of the Key Largo tree cactus underscores the vulnerability of species in the Florida Keys to sea level rise. Extreme weather, habitat destruction, and poaching further threaten these fragile ecosystems. The researchers emphasize the need for long-term conservation plans and collaboration at local and governmental levels to protect at-risk species, both in their natural habitats and through ex-situ conservation efforts.
The loss of the Key Largo tree cactus is a tragedy, but it’s also a call to action. We must recognize the urgency of the climate crisis and take immediate steps to protect our planet’s biodiversity before more species are lost forever.
Leave a Reply