The impact of climate change on the environment is significant and diverse. Sea level rise is just one example, but one that could have led to the first ecological “casualty” in the U.S.
Local extinction. Climate change is the potential reason for the extinction of a species of rare cactus in the U.S. This is the first known case of a (animal or plant) species disappearing from the country due to climate change and, specifically, sea level rise.
Pilosocereus Millspaughii. The cactus in question is the Key Largo tree cactus (Pilosocereus Millspaughii), which was previously only found in the Key Largo area of Florida but is now limited to certain Caribbean islands such as Cuba and the Bahamas.
Experts initially believed that this particular cactus, discovered in 1992 and found in mangrove forests, was a subspecies of the protected Key tree cactus (Pilosocereus robini) found in the Florida Keys area.
Both species share some characteristics, such as the appearance of the cactus and its flowers (including the garlic aroma of the flowers, which can attract pollinators), as well as its striking red and purple fruits. The key difference between the species is the wool-like tufts of hair at the base of the flowers and fruits of the Key Largo species.
Sea level rise and erosion. Studies on the disappearance of this cactus on the mainland point to soil erosion as one cause. These cacti used to grow in an area with a low limestone outcrop surrounded by mangroves.
In the latest study on this cactus published in the Journal of the Botanical Research Institute of Texas, the team of researchers explains that this area had a particular type of soil and organic matter that allowed the plants to grow. Now, erosion caused by storms and exceptionally high tides has taken this favorable combination of factors with it.
Between a rock and a hard place. In recent years, the team found that plants that can tolerate a certain level of soil salinity had been migrating to higher altitudes due to increased salinity. They also discovered that soils containing dead cacti tended to have higher salinity compared to those supporting living plants.
However, this migration to higher altitudes brought additional challenges. The region experienced storms, and during these times, the cacti faced threats from numerous thirsty mammals. These animals, lacking access to fresh water, further reduced the local cactus population.
A challenging mission. The team isn’t particularly optimistic about the possibility of reversing the situation. Although some of the surviving specimens (six) have been preserved and are now protected in greenhouses, there are currently no known environments in the U.S. where they or their descendants could be planted to ensure the long-term survival of the species.
Moreover, the story of this cactus serves as a warning of a phenomenon that could escalate, not only wiping out species locally but also extinguishing them from the face of the Earth. “Unfortunately, the Key Largo tree cactus may be a bellwether of how other low-lying coastal plants will respond to climate change,” study co-author Jennifer Possley said in a press release.
Image | Florida Museum
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