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It’s hard to imagine a world without palm trees. Members of the recognizable Arecaceae family drop coconuts onto white-sand beaches, pierce their fronds through the greenery of rainforests and line glamorous boulevards from Los Angeles to Miami.
But a new study published in Nature Ecology & Evolution Monday warns that we might have to. A research team from the Royal Botanic Gardens (RBG), Kew; the University of Zurich; and the University of Amsterdam used a mix of conservation data and innovative machine learning techniques to determine that more than half of palm species are likely threatened with extinction.
“Palms are the most iconic plant group in the tropics and one of the most useful too,” study co-author and University of Zurich senior researcher Dr. Rodrigo Cámara-Leret said in an RBG, Kew, press release shared with EcoWatch. “After this study, we have a much better idea of how many, and which, palm species are under threat.”
Why Palms Matter
There are around 2,600 known species of palm in the world, according to PlantSnap. They are normally found in the tropics and subtropics, where they play a vitally important ecological role.
“In some tropical rainforests, palms are among the dominant plant families, which means that they contribute significantly to store carbon and to the general functioning of the forest ecosystem,” study co-author and RBG, Kew, research leader Dr. Sidonie Bellot told EcoWatch in an email.
They also provide habitat and nutrients for animals and fungi. For example, ant colonies make their homes in certain species of rattan palms. Further, their fruit feeds dozens of bird and mammal species.
Including humans. The relationship between homo sapiens and the Arecaceae family goes back 5,000 years to ancient Mesopotamia, where humans grew date palms for food and religious purposes, according to PlantSnap. The Bible references them 30 times and the Quran at least 22. In Indian mythology, the coconut palm is regarded as “the tree that provides all the necessities of life,” according to earthstoriez. Today, millions of people rely on palms for everything from building materials to tools to food to medicine, according to RBG, Kew. Yet like many natural-human relationships in recent years, the relationship between some humans and palms has soured. While the study didn’t focus on identifying specific threats that human activity poses to palms, some leading dangers are clear.
“[L]and use change, especially deforestation and forest fragmentation, is increasing the extinction risk of palms by decreasing their population sizes,” Bellot said.
Other potential threats are the overuse of some species for palm hearts, diseases and the climate crisis.
Gilding the Gold Standard
To better understand the risks faced by palm species worldwide, the research team turned to the International Union for Conservation of Nature (IUCN) Red List of Threatened Species, which is considered the “gold standard” extinction-risk assessment for plants, animals and fungi, according to the press release. However, the Red List does not currently provide accurate data on the extinction threat faced by every species out there because conducting a risk-assessment is labor intensive and funding is not always available. For palms, assessments have been published for only 508 species, according to the study.
The research team thought they could provide a more comprehensive estimate by turning to artificial intelligence (AI) and machine learning.
“The biodiversity crisis dictates that we take urgent action to stem biodiversity loss. We need to use all the tools at our disposal, such as prediction and automation, to generate rapid and robust assessments,” study co-author and Research Leader in Kew’s Conservation Assessment and Analysis team Dr. Steven Bachman said in the press release. ”The addition of plants to the Red List is one of the vital steps conservationists can take to raise awareness of species at risk.”
How exactly can AI help predict a species’ extinction risk?
“We know that palm extinction risk is related to their distribution range size and population size, but also to human density and deforestation intensity. However, we did not know exactly how to use this information to predict palm extinction risk,” Bellot said.
To get around this, the researchers used species for which an assessment had been completed either by the IUCN or the plant-specific ThreatSearch. Based on these examples, they trained a model to predict extinction risks for other species using common factors like population and range size known as “predictors.” When they tested the model on further species for which the extinction risk had already been assessed, it was right 82 percent of the time. It was then time to plug unassessed species and their predictors into the model.
“This allowed us to predict the extinction risk of 1381 species, which, combined with the [existing] Red List and ThreatSearch assessments, covers 75% of the palm family,” Bellot said.
When the researchers combined the 1,381 species assessed by their model with the 508 species conventionally assessed, they had data for a total of 1,889 species. They concluded that 56 percent of these species are likely threatened, for a total of more than 1,000 menaced palms.
“Overall, we show that hundreds of species of this keystone family face extinction, some of them probably irreplaceable, at least locally,” the study authors concluded. “This highlights the need for urgent actions to avoid major repercussions on palm-associated ecosystem processes and human livelihoods in the coming decades.”
Guiding Conservation
The researchers went further than simply calculating a total number of threatened palms, according to the press release. They also looked at three factors that make a palm species a prime target for conservation:
- Evolutionary distinctness, or whether a species is genetically different from its closest relatives
- Functional distinctness, or whether a species has unique characteristics
- Documented human use
A little less than half of the evolutionarily and functionally distinct species were threatened, the study authors found, while around one-third of the commonly used species were. Further, the research team issued some initial conservation recommendations. They said that palm conservation should focus on Madagascar, New Guinea, the Philippines, Hawaii, Borneo, Jamaica, Vietnam, Vanuatu, New Caledonia and Sulawesi, because in these locations more than 40 percent of the evolutionarily distinct, functionally distinct and/or commonly used species were likely threatened. They also recommended alternative species for 91 percent of the currently used species that are at risk for extinction, according to the study.
“Our study is global, but conservation is often best achieved at local scales, in collaboration with people who know and rely most on the plants,” Bellot told EcoWatch. “We hope that our lists of threatened species and potential alternatives for threatened used species can be the baseline for local conservation actions and research on the mechanisms that can help threatened species to be resilient to perturbations.”
In addition, the researchers hope that their work can speed the Red List assessment of more palm species and that on-the-ground investigations can be done to assess the more than 600 palm species that the team didn’t know enough about to feed into their model.
“[A] main goal for follow-up research is to gather more data about the least-studied palm species, so that their extinction risk can be more reliably estimated,” Bellot said.