Humans are changing the planet rapidly. Plants can adapt to the new conditions, but some will do it better than others. At the Smithsonian, John Kress and Gary Krupnick have analysed more than 86,000 plants to identify what will make a plant a winner or a loser in the future. Sadly, they find that many more species of plants are poised to “lose” rather than “win” in their study published in Plants People Planet.
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.
Kress said in a press release, “I actually started this project from a place of optimism. 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 involved in legal and illegal global trade.
In total, the researchers were able to place 86,592 species of vascular plants 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 just under 30% of the nearly 300,000 known species of vascular plants. Kress said that there was not enough data to categorise the remaining 70% of global plant diversity, which reflects how much is left to learn about Earth’s botanical riches.
The most significant factor in determining winners and losers is whether or not a plant is useful to humans. Kress and Krupnick found almost seven thousand species were winners, but all those species had a use, except for 164 of them. In contrast, there were over twenty thousand losers, and the vast majority were not considered useful to humans.
The botanists looked for evolutionary patterns to see if there were biological biases between the winners and losers. They wanted to know if winners were randomly distributed in the tree of life or if some lineages were luckier than others.
As it turned out, winners and losers were, for the most part, evenly distributed across plant orders. The exceptions came primarily from small lineages, which were more prone than lineages, with many species leaning heavily in favour of winners or losers, Krupnick said. Three of the lineages most at risk of extinction include cycads, the cypress family (which includes redwoods and junipers) and an ancient family of conifers called the araucariales, which are today mostly found in New Caledonia.
Branches of the plant evolutionary tree with few species and more losers than winners such as these have an elevated risk of being lost altogether, taking with them everything there is yet to learn about their biology and their lineage’s genetic uniqueness.
Krupinick said: “Now and in the future, plants have to adapt to the environment humans have created or they will go extinct. Our results suggest that this means the plant communities of the future will be more homogenized than those of today.”
This increased homogeneity is likely to have severe consequences for ecosystems around the world as well as humanity. Losing plant diversity can drive a loss of animal diversity, Kress said, making ecosystems less resilient in the face of hardship or change.
“The list of winners shows that we’ve selected certain species that are useful to us, but as that pool of plants we have to select from decreases in the future, humanity will have many fewer options when we want to reforest the planet, find new medicines or foods, or develop new products,”
Kress said he hopes that these lists will afford other researchers opportunities to look more in-depth into why certain species of lineages are winning or losing in the age of humans and identify the plants that are most in need of conservation.
“It still looks green outside my window, and that can create the illusion that plants are doing well,” Kress said. “But this study suggests we’re on course for a big loss of plant diversity, and we better wake up.”
Kress, W.J. and Krupnick, G.A. (2022) “Lords of the biosphere: Plant winners and losers in the Anthropocene,” Plants People Planet, https://doi.org/10.1002/ppp3.10252