Magazine article National Parks

Silversword Fight

Magazine article National Parks

Silversword Fight

Article excerpt

MY BOOTS CRUNCH THROUGH THICK HOARFROST as I hike uphill on a narrow trail, my collar turned up against a biting chill. The world is stretched below me in a blanket of pillowy pink clouds catching the dawn light. Beneath those clouds, the soft sands of Maui's beaches will soon be beckoning to tourists; above the clouds soars 10,023-foot Haleakala, a dormant shield volcano comprising most of the island.

The Hawaiian alpine ecosystem is a land of extremes - surprisingly cold at night and mercilessly exposed by day. Plants and animals that call this place home balance on a thin line of survival. The line is getting even thinner for one of these plants: the Haleakala silversword. As 1 pass one by the park's visitor center, its namesake leaves bristle as if on the defensive against the threats it faces.

Sunny days like this are typical high on the mountain, but they weren't always so common. In the past, the trade wind inversion, a weather phenomenon that traps clouds at low elevations and exposes high elevations to blazing sun, was regularly punctuated by intervals of clouds and rain. Current trends show significantly fewer breaks in the inversion, resulting in scant rainfall for the silverswords.

"This can push them over a threshold," said Paul Krushelnycky, an ecologist at University of Hawai'iManoa who has studied silverswords since 2007. "If these current climate patterns continue, the silversword is going to have a really tough time."

The silversword is the product of evolution in island isolation. Several million years ago, a California tarweed seed traveled 2,000 miles across the Pacific to Hawaii. This single species evolved into the "silversword alliance," a group of more than 30 species endemic to Hawaii that range from scraggly shrubs to groundclinging cushions.

Haleakala silverswords - 'ahinahina or "very gray" in Hawaiian - live only in a 2,500-acre area at the top of the Haleakala volcano, a moonscape pocked by cinder cones and spattered with volcanic bombs. They have developed an adaptation toolkit to cope with this harsh environment: The fleshy leaves are coated with tiny silvery hairs to break the wind, prevent desiccation and collect cloud moisture.

At the end of its life, which may last over 90 years, the silversword grows a flower stalk upward of 6 feet tall. Hundreds of maroon flowers produce a luscious, pungent fragrance. Endemic winged pollinators swarm the blossoms, while damaging crawling insects are repelled by sticky hairs on the stalk. Because silverswords cannot self-pollinate, they must bloom synchronously and rely on pollinators for successful reproduction. After the plant dies, seeds are scattered by the wind, and a new cycle of life begins.

The silversword has shown itself to be one tough plant. Like many native Hawaiian species, it has faced threats brought from other parts of the world. During the 1700s, goats and cattle from Europe prospered by devouring native shrubbery. In Haleakala's spartan landscape, silverswords provided some of the only food for the plunderers.

In the early 1900s, Haleakala started to attract adventurous tourists. Hikers gleefully tore up silverswords to roll them downhill or bring them back to the beach as triumphant proof they had reached the summit. Eager to look closely, they trundled around silverswords, unaware their steps crushed the delicate roots spread beneath the cinders. …

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