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| Mediterranean Garden: Longwood Gardens in Kennett Square, Pa., now displays more cold-tolerant plants, such as these, that
save on heating. Courtesy of L. Albee/Longwood Gardens |
Botanical conservatories take on urgent new role
Speed of climate change makes glasshouses bulwarks in the battle to preserve biodiversity.
from the February 20, 2008 edition
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Jan Salick, senior curator of ethnobotany at the Missouri Botanical Garden, studies how Tibetan people use high-alpine plants on the eastern edge of the Himalayas, where temperatures are rising quickly. The region is experiencing the fastest glacial retreats in the world and dramatic increases in rainfall. High-alpine meadows, rich in biodiversity, contain rare plants. Dr. Salick's field research shows that as temperatures climb, so do plants – they migrate uphill. The ones migrating fastest are not those endemic to the region, but widespread species that reproduce quickly, outcompeting slower-maturing alpine plants.
The snow lotus, for example, which Tibetans regard as an important medicinal plant, takes 10 years to reproduce and must be pollinated by high-alpine bumblebees. Salick has watched this plant diminish in both size and numbers. "Not until after the fact do you get to see the effect of changes in plant communities on such things as the bumblebees and other long-coevolved, intricate relationships with animal species," she says.
Making 'greener' greenhouses
As the climate changes, Salick and others foresee changes in the form and content of conservatories. Tomasz Anisko, curator of plants at Longwood Gardens in Kennett Square, Pa., says the institution, which focuses primarily on horticultural display, renovated its east conservatory in 2006, in part to improve energy efficiency. With each renovation of Longwood's 1920s-era buildings, the heating systems have been updated to heat soil at the root zone and concentrate hot air immediately around the plants, instead of heating the whole space.
Energy use has also influenced which species to display. "In the past, we exhibited mainly exotic tropical plants that required high temperatures, and we've been replacing them with subtropical and Mediterranean plants that can grow in more moderate temperatures," Anisko says, and visitors approve. "That's an important point: You can still design attractive displays and achieve energy savings."
Educating visitors is something Anisko and others believe is a significant opportunity for conservatories. "People don't come to see seeds in the freezer, but to see beautiful plants," Havens observes.
Salick recalls the success story of educating people about the destruction of tropical rain forests. "Public awareness of that issue is amazing," she says. "Kindergartners will ask me about it."
Todd Forrest, vice president for horticulture and living collections at the New York Botanical Garden, says they are targeting average gardeners through an educational program called Gardening in a Changing Climate. "It's important to keep people gardening and give them hope," he says. "Gardens and green spaces are part of the solution to climate change. They provide cool spots, and they store carbon. The more of these we have, the better off our environment will be."
How gardeners adjust to a changing climate
“Climatologists tell us that climate change is not as simple as just getting warmer weather,” says Todd Forrest, vice president for horticulture and living collections at the New York Botanical Garden. “They predict that it will become warmer year-round, significantly so in winter, but there will also be great variety in precipitation, increased drought, and more frequent extreme precipitation events. This means we have to take a broad approach to keeping gardens healthy.”
While it is relatively easy to avoid pesticides, gardeners may have a harder time figuring out how to reduce gardening practices that contribute to climate change – and perhaps more worrisome, how climate change is affecting their gardens. Mr. Forrest, who has launched an educational program called Gardening in a Changing Climate, offers guidance in the face of climbing temperatures and “weather weirding” – sudden, often violent, shifts in temperature, wind, and precipitation.
Much of what horticulturists at the New York Botanical Garden have learned from these ventures runs true to the good-gardening practices that have been evolving since the first Earth Day in 1970: “We teach people how to use fuels more efficiently, to choose plants adapted to the local climate, that are drought-tolerant, that aren’t prone to insects and diseases,” he says. “It’s also important to design gardens that take advantage of the natural topography, instead of fighting it.” Rain gardens, for instance, can store water collected on site for use in a later drought.
Unpredictable snowfall, combined with sudden drops in temperature, can mean uncovered plants damaged from freezing, sunburn, and windburn more often than in the past. “We may need to bundle up more of our shrubs in burlap,” he says, to make up for the lack of insulating blankets of snow.
At the New York Botanical Garden, Forrest says, “We are removing pavement where we can and looking at permeable pavements and the overall impact of what we do. It’s not just about temperature, but about the whole landscape.”
Forrest’s most comforting guidance relates to “gardening as a spiritual act” during a confusing and distressing age: “Gardening keeps people in touch with nature. Some say we’ve always been learning to adapt to changing weather, and we can teach others to do the same thing. Good gardening practices are good for the environment. At first blush, everything we do – whether drive or use electric lights – is part of the problem. But gardens are part of the solution. So we should garden wisely by being as efficient as we can, but we should never feel bad about gardening.”
For more information, visit www.nybg.org.
A brief history of conservatories
The longing for exotic flora from far-away places is centuries old. As new plants such as citrus and oleander began arriving in Western Europe from Asia between the 16th and 19th centuries, gardeners at private estates went to great lengths to ensure their survival. Punctuating the low, clipped hedges in Italian and French gardens, these subtropical showpieces symbolized wealth and sophistication.
They also proved too tender for European winters. But instead of giving up their exotic trees, gardeners were challenged to design winter quarters.
Modern conservatories evolved from primitive wood or stone plant houses to heated orangeries with glass or waxed-canvas windows to glass-and-wood greenhouses and, finally, to the Victorian iron-and-glass palm houses. The most famous of these is at the Royal Botanic Gardens at Kew, in London. It was completed in 1848.
The Victorian period, perhaps the most plant-crazed in Western history, fueled and fed on worldwide “botanizing” expeditions. Newly discovered plants traveled in miniature greenhouses called Wardian cases, after their inventor, Nathaniel Bagshaw Ward. Grand glass conservatories became fixtures at botanical gardens and, like zoos, became popular attractions.
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