Fading Bloom

The Haleakalā silversword is a striking plant that takes anywhere from 20 to 90 years to flower and grows only on one Maui volcano. But changing climate patterns could “signify a bleak outlook” for this plant, researchers warn in Global Change Biology.

Each year, more than a million people visit Haleakalā National Park, where the silverswords grow. In the early 1900s, the plant’s future was in doubt: Goats and cows were eating the silverswords, and people were collecting them. With government protection and recovery efforts, the plants bounced back. But the study authors worried that climate change was erasing these gains.

The team drew on silversword population data going back to 1982 and catalogued 28,492 silverswords in 2010. The researchers also studied rain and temperature records from 1950 to 2010.

Rainfall in the area has decreased, and the number of days without rain has gone up, the team reports. Starting around 1990, the number of living silverswords “began an almost unbroken decline,” according to the study. The more days the area went without rain in the dry season, the lower the silverswords’ population growth rate.

The data suggest that the silverswords’ recovery is in danger, the authors say. Since this plant has so many admirers, they write, “it is positioned to become one of the most visible examples of climate change-induced biodiversity loss if climate trends on the mountain do not reverse course.” Roberta Kwok | 12 December 2012

Source: Krushelnycky, P.D. et al. 2012. Climate-associated population declines reverse recovery and threaten future of an iconic high-elevation plant. Global Change Biology doi: 10.1111/gcb.12111.

Image © Brent Wong | Shutterstock.com