Medicinal plants face climate change
Dawn Rae Downton
Plants are affected by climate change. Medicinal plant conservation is working to preserve natures botanical remedies.
Bakeapples. The tart amber berries were the talk of Newfoundland last August, not the splendid summer weather or even the approach of Hurricane Bill, who blew in much earlier in the season than tropical storms normally do.
Both the weather and the untimely storm were unusual, and either might have turned the talk to climate change. Instead, it was all bakeapples, all the time—just because there were none, or almost none. Where had they gone, and why?
Newfoundlanders love their bakeapples, especially those from Labrador, since they seem to taste better “the colder you go.” Growing in northern and alpine climates around the world, they’re tough, weathering -40 C and beyond. They love sun and acidic bogs, but not drought.
Bakeapples—elsewhere called cloudberries—look like golden raspberries. They’re stuffed with antioxidants, but they’re also a guilty circumpolar pleasure.
In Norway they’re loaded onto waffles and ice cream and used to fill marzipan cakes.
In Finland they’re downed with local cheese.
To go with Sweden’s traditional Thursday pancakes, they’re made into hjortron chutney.
On the other side of the polar region, Alaskan Inuit eat them sugared and whipped up with reindeer fat.
In Canada they’re brewed into beer and Quebec’s chicoutai liqueur.
But Newfoundlanders have always just jammed their bakeapples, shipping parcels of bubble-wrapped jars to the diaspora in Toronto and Fort McMurray.
Dr. Alain Cuerrier of the University of Montreal’s Institut de Recherche en Biologie Végétale doesn’t think Newfoundlanders should worry about their berries—yet. “Annual variations do exist,” he cautioned from his office last fall. “Hopefully, next year will be marvellous for bakeapples!”
About the long run, though, he’s no optimist. Some biologists say that as our climate changes, they really don’t know what to expect; there are too many variables. But when it comes to medicinal and aromatic plants, especially those in fragile ecosystems, many worry. These are the plants that could be hurt first—and hurt worst.
Northern berries drying up
Cuerrier has worked in northern Quebec since 2001, and lately he’s brought his students to Nunavut and Labrador as well to study what climate change is doing to plants whose berries are important sources of antioxidants and critical to the Inuit diet—shrubs such as blueberry, crowberry, mountain cranberry, and yes, bakeapple.
The team simulates speeded-up climate change on these plants by rigging small greenhouses over them in order to track changes to chemical content as well as the altered growth patterns that result—which in the longer term will result under conditions of spontaneous warming.
Cuerrier has taught himself rudimentary Inuktitut. The Inuit tell him snow melts faster each spring, lakes brim, and gales are up, along with sudden storms and dizzying weather changes. It all stresses plants, he says, and now the Inuit also say that “berries are drying up in the land.”
Some changes to the plants seem to be unfolding less visibly, at the molecular level. Under increasingly temperate conditions, says Cuerrier, the medicinal compounds plants make to protect themselves from cold (and also from stressors such as UV and prolonged sun) are taking a hit.
That might be good news, in the short term, for the plants. But it’s bad news for anyone depending on them for antioxidants, for the essential oils of aromatherapy, and for antimicrobial, anti-inflammatory, and possibly anti-neoplastic (anticancer) compounds in those oils: terpenes, for instance, which Cuerrier thinks might alter glucose metabolism and therefore mitigate diabetes.
Louise Bondo, a Danish specialist in building plant gene banks, has also collected northern medicinal and aromatic plants—thyme, angelica, and golden root, for instance. Her fieldwork has been in Greenland, and she emails from Scandinavia that warming could be good news and bad. While she doesn’t rule out medicinal species loss if warming continues, she thinks most species can adapt.
All the same, because they’re usually scattered and isolated, Arctic species can’t easily hybridize (crossbreed); therefore, they’re less likely to host a flexible genotype and will have little of the genetic diversity they’ll need to adapt. The better news? Plants make metabolites for their own needs, not ours, she says, though some happen to help us.
Climate change won’t necessarily decrease metabolites; it might even result in the production of others. Only genotypes highly and specifically adapted to deep cold (and producing metabolites against it) are at direct risk, she says, but the therapeutic compounds we rely on are made by other genotypes, too.
Traditional healing skills threatened
Four out of five people in developing countries depend on plants for therapy. A majority of Westerners do, too, and the business of traditional medicine is flourishing worldwide. We now visit traditional practitioners far more than we do primary care physicians.
Even 10 years ago, Americans paid nearly US$3 billion for traditional therapies; currently, the world market for herbal drugs is around US$60 billion. Many Western medicines are, to some degree, herbs in disguise, too, since they’re often synthesized by copying plant chemistry. More than a third of them contain at least one plant component.
But here’s the rub: as demand skyrockets, traditional healing skills are on the wane because many of the plants on which they’re based are now extinct or endangered. In the fragile ecosystems of cold climates, such as those in the Andes and the Himalayas and in the circumpolar north, the biggest stressor is warming.
Northern species lose to new competition
Rogue storms, crazy weather shifts, dry snow—it’s all stressing northern berry plants, says Cuerrier. But the worst of it is that as temperatures climb, these plants will eventually be overrun by taller, more common shrubs as the northern edge of the treeline advances up into newly habitable territory to shade them out and block their snow.
Golden root (Rhodiola rosea)—a proven remedy for fatigue and depression that might also protect the heart—is a plant he thinks could be out-competed just when it might become commercially valuable to the Inuit, who could cultivate it. And since it grows along the ocean, it could also be drowned by rising seas.
Plants with lots of genetic diversity will be the best adapters, says Bondo. But we’re losing biodiversity in the north faster than anywhere else, says Cuerrier, and it’s a tragedy. Where will we find medicinal plants as useful as the ones we forced out?
Far below Cuerrier’s stomping grounds, around Concord, Massachusetts, researchers have also been witnessing northbound “plant creep” as temperatures rise.
Plant loss further south
Boston University’s Dr. Richard Primack leads a team that has for several years dated the greening of plants in the Concord spring, comparing that data with dates recorded more than a century and a half ago by Concord’s most famous son, writer Henry David Thoreau. Many of the region’s medicinal plants—wormwood, feverfew, cranberry, St. John’s wort, and peppermint—now enter their spring start-ups about eight days earlier than they did for Thoreau.
Some, consequently, have their precocious buds nipped by late frosts; some seed too soon; and some miss their usual pollinators (whose own body clocks may be reset by warming). Primack says the pollinator problem is still only a theory, a guess. But he’s sure of one thing: thanks to earlier springs, some Concord plant species are declining, even extinct.
“A quarter of the species Thoreau talked about, we weren’t able to find, even though Concord is a highly protected landscape with 60 percent of the land undeveloped,” he said last fall from Boston. What gives?
By mixing in another data set from Harvard’s Charles Davis, Primack’s team found that plants with inflexible flowering and, especially, leafing out times—sensitive species unable to adjust to warming—have declined most in Concord, having been outgrown and out-competed by other plants. Many of them—black birches, for instance—are medicinal.
“What it means is that global warming is already affecting the plants of Concord,” Primack says. He extrapolates his results to Canada, since we share species including blueberry, marsh marigolds, violets, and buttercups.
Are managed habitats the answer?
Primack is part of what he calls “a big debate about how we should be managing our habitats” in the face of species loss. He’s all for “assisted migration” of southern “replacement” plants up into Concord, and thinks northern neighbours such as Vermont should likewise be planting species that do well, for now, in Massachusetts.
Moved a little north, he says, rare plants such as wild ginseng and ramps (loved and protected in Quebec, and having all the benefits of the onion family to which it belongs) have virtually no chance of becoming aggressive or invasive, whereas their chances of disappearing in their own warming climates are very high.
For Arctic and alpine plants, there is no “farther north,” and other researchers are trying to keep them in their place. Dr. Rainer Bussmann, director of the William L. Brown Center for Plant Genetic Resources at the Missouri Botanical Garden, says plants became “medicinally interesting” to the West in the mid-90s. The Brown Center team studies them in northern India, east Africa, and Peru—all big producers.
The Andes, for instance, are rich in calming valerians, in antibacterial plantains effective against UTIs and ovary inflammation, and in club mosses that mitigate psychosomatic illnesses. (Bussmann notes these are not well-treated or even validated by Western medicine). Beneath the Andes, the Amazon produces herbs such as chanca piedra, also known as stonebreaker, (Phyllanthus niruri), two of whose 36 species have been used traditionally to break up kidney stones. The rest are ineffective or toxic.
“This is one way in which plant collections are invaluable,” Bussmann said. “They can identify species exactly by comparing them to a standardized collection.”
Plant collections help mitigate species loss
The Missouri Garden has a collection of 6.5 million plants of all kinds, with records for some going back to the 1800s. It hopes to identify and save many more, especially from over-harvesting by ethnic populations in alpine regions. The problem is a warming effect in disguise, because as populations grow and mountains warm, more people “move up,” more disease is borne higher by more vectors such as mosquitoes, and more disease in more people needs more remedy. Thus the stripping of wild medicinal plants.
Bussmann notes that seed banks such as Norway’s Svalbard “doomsday” vault don’t focus on medicinal plants. The world has many more of these than food plants, and no bank has the capacity to store them. Some medicinal seeds can’t be frozen or desiccated for storage and replanting in any case, and loss of their traditional habitats and the knowledge of how they grow best might mean, too, that they can’t be successfully revived. “They’re essentially unprotected right now,” he says.
One solution is to establish cultivated, sustainable “ethnobotanical” gardens all over the alpine world. Under a new scheme called Sacred Seeds, Bussmann’s people work with locals to cultivate the mountain plants they’ve been wild-harvesting.
Himalayan and Andean glaciers are melting “at a crazy rate,” he acknowledges, the treeline is advancing, the tundra is shrubby, and it’s all pretty daunting. But he thinks Sacred Seeds has a great future, as do the medicinal plants it collects and cultivates. “You can set up the garden exactly where you need it, produce exactly the plant you want, and you can also rely on the high interest the local populations have in maintaining them. Now, communities come to us.”
Working with Colorado State University, the Brown Center next plans to take plant groups that are distributed in main mountain ecosystems—gentians, for instance, the large genus of medicinal workhorses used worldwide and found “all over the place” at altitude—and compare the Andean, the Himalayan, and probably the central Alaskan versions to predict (by modelling) what will happen to them as they warm.
Bussmann says that no one has yet sampled a genus from all the major mountain systems, and it’s time: we should do it before it’s too late.