Plant Triage: Which Imperiled Species Should Be Saved?
Growing number of rare plants creates dilemma
A freezer is the last place you'd look to find seedlings destined for planting this June. The fragile sprouts chilling out in a nursery near Boston, however, are unique. They represent the future of an endangered alpine wildflower found nowhere else in the world but on a windswept ridge along the northernmost reaches of North America's Appalachian Mountains.
The tiny sprouts also represent what could become a small success story amid the bleak tale of plant biodiversity outlined by the World Conservation Union (ICUN), which last week released an exhaustive list of plants threatened with extinction.
According to the document, 12.5 percent of nearly 34,000 species worldwide are threatened, while 380 species have become extinct in the wild. The survey - which didn't include lichens, fungi, and algae - paints the darkest pictures for North America, Australia, and southern Africa. In the United States, for example, 29 percent of the country's 16,000 plant species risk extinction.
The relatively high numbers for those areas, however, reflect the higher level of research conducted there compared with Asia, the Caribbean, South America, and the rest of Africa. "I have no doubt that once we do more research, we will find that the figure of 12.5 percent of the world's plants threatened with extinction is a very conservative estimate," notes David Brackett, chairman of the ICUN's Species Survival Commission.
The large number of threatened plants highlights an issue conservationists are struggling with as they try to turn the ICUN's Red List of threatened plants into action plans. Faced with so many troubled species, some of which may be too close to extinction to save, how should conservationists set priorities over what to save?
"This is a huge discussion in the environmental community," acknowledges Ricardo Bayon, an ICUN spokesman.
What has become clear is that trying to save endangered species one at a time is unworkable, notes Deborah Jensen, vice president for conservation science at the Nature Conservancy in Roslyn, Va. "The idea is that you focus on the species most at risk and catch the rest later," she says. "But that leaves you always behind the curve."
To get ahead of the curve, groups have changed their strategies to include habitat preservation. For example, Conservation International, based in Washington, focuses on the habitats it sees as most productive and most threatened. It estimates that the world contains 16 to 17 high-priority terrestrial "hot spots." Collectively, they account for 50 percent of the land-based biodiversity, but only about 2 percent of the earth's land mass.
Other groups, such as the Nature Conservancy, have tried to target representative habitats worldwide. "To use the Noah's Ark metaphor, with an ecosystem and its species as the ark, if the ark is a fixed size, you can't save much," Dr. Jensen says. "You have to take the rare-species and habitat-management approaches together."
In casting a geographically broader conservation net, the Nature Conservancy has had to explore more-nuanced approaches to land use in areas where species are in trouble. "We have to ask: What is the network of sites needed to protect the biodiversity of a region?" she says. That network might include preserves, as well as land humans occupy. "The next wave of conservation thinking is not people versus whatever," she says. "It's to build places were we can live together."
It's a sentiment that finds support along the Crawford Trail in New Hampshire's White Mountains, the final destination for the seedlings that sit in their frosty incubator at the New England Wild Flower Society in Framingham, Mass.
Of the plants on the ICUN's Red List, 91 percent are endemic species, found only in a single country. The Potentilla robinsiana seedlings are among them.
Known as Robbins' Cinquefoil, P. robinsiana clings to existence in a parcel of ridge between Mt. Monroe and Mt. Washington in the White Mountains. Thought to have occupied its spot since the last glaciers retreated 10,000 years ago, the species takes from seven to 13 years to produce each set of seeds.
"The plant was recognized as rare in the 1800s," says Kenneth Kimball, a botanist and director of research for the Appalachian Mountain Club (AMC).
Robinsiana became rarer still, he says, when Victorian-era naturalists picked the plant to add to their collections. Even "collecting" with cameras took its toll. People would lie down on the ground to take pictures, crushing microscopic seedlings.
In the early 1980s a committee of biologists reviewed the plants' status and had it placed on the Endangered Species List.
As part of the recovery effort, the AMC has rerouted its popular Crawford Trail to go around it.
Robinsiana's recovery effort has been relatively inexpensive, with costs running about $2,000 to $3,000 a year, Kimball says. Volunteers, many of whom carry the potted seedlings, extra soil, and water to remote sites in backpacks, help hold down costs. Because the land is part of a national forest, no large-scale land purchases or habitat-restoration efforts have been needed.
Between isolating the primary site and transplanting nursery-germinated seedlings, "the population has grown significantly; it's up about 60 percent," Dr. Kimball says. The AMC is asking that the plant's status be upgraded to threatened under the US Endangered Species Act.