From Plant Press, Vol. 25, No. 2, April 2022.
A new analysis spanning more than 86,000 plant species from John Kress, botany curator emeritus at the Smithsonian’s National Museum of Natural History, and Gary Krupnick, head of the museum’s plant conservation unit, finds that on this human-dominated planet, many more species of plants are poised to “lose” rather than “win.” The study was published in the journal Plants, People, Planet (https://doi.org/10.1002/ppp3.10252).
Losers that are useful to humans tend to be overexploited wild species that may be medicinal, ornamental or used for timber. One such species is Ekman’s magnolia tree (Magnolia ekmanii), a critically endangered tree only found in Haiti that was most likely harvested for its wood to produce charcoal and building materials. Credit: Copyright Martin Reith, some rights reserved (CC BY-NC)
From changing Earth’s climate to destroying, degrading and altering ecosystems on a massive scale, human choices now largely dictate the environmental conditions across much of the globe and, as a result, which species of plants and animals can survive and persist and which will go extinct. Species lucky enough to be directly or indirectly aided by human activities are likely to survive and can be thought of as “winners,” while those that are pushed to ecological irrelevance or extinction by those same activities are the ultimate “losers” in evolutionary terms.
Kress encountered this concept of evolutionary winners and losers in the age of humans (known to some researchers as the Anthropocene), in the writings of John McNeill and wanted to see if it might be possible to tally the plant species that were winning and losing now and in the future.
“I actually started this project from a place of optimism,” Kress said. “I had just planted all these trees around my house in Vermont and thought to myself that maybe there are actually more winners than losers, and we are just focused on everything that’s disappearing.”
In the summer of 2019, Kress brought Krupnick into the fold to help compile and analyze the mountains of data required to put every plant species for which there was enough information into the categories of winners and losers. The researchers split the winners and losers into species that are and are not useful to humans.
In addition to these four categories, Kress and Krupnick created four others: Species that appeared likely to win or lose in the future were deemed tentative winners or potential losers, and species that do not seem to be winning or losing at present were considered currently neutral. A fourth and final category included 571 species that have already gone extinct.
To place plants in these categories, Kress and Krupnick combed through databases that listed endangered plant species, economically important species such as crops, invasive and weedy plants, and endangered plants that are involved in legal and illegal global trade.
In total, the researchers were able to place 86,592 species of vascular plants—a large group of plants that have vascular tissue which transport water, nutrients and other substances—into the eight categories that describe their prospects for survival in the Anthropocene. That may sound like an inconceivably large number of species, but it is actually just under 30% of the nearly 300,000 known species of vascular plants. There simply was not enough data to categorize the remaining 70% of global plant diversity, which reflects how much is left to learn about Earth’s botanical riches, Kress said.
The analysis revealed that losers currently outnumber winners, and that losers are likely to continue to outpace winners in the future if human impact on the planet maintains its current trajectory. Kress and Krupnick categorized 20,293 species of plants as losers, with the vast majority of those losing species being identified as not useful to humans. By contrast, the researchers found just 6,913 species of winners, with all but 164 of those species having some human use.