Fri, Oct 11, 2019 - Page 9 News List

‘A big job’: the race to save the giant sequoia

A conservation group has made a deal to buy the largest privately owned sequoia grove in a bid to protect the species as the effects of the climate crisis worsen

By Maanvi Sing  /  The Guardian, San Francisco

Few living beings have experienced as much as the giant sequoias. With ancestors dating back to the Jurassic era, some of the trees that now grow along California’s Sierra Nevada Mountains have been alive for thousands of years, bearing witness to most of human history — from the fall of the Roman empire to the rise of Beyonce.

A couple hundred years of human encroachment on to the sequoias’ habitat, combined with the climate crisis, increasingly intense wildfires and drought have threatened the species’ future.

The last of the world’s most massive trees now live on just 73 groves scattered across the Sierras. Most lie within protected national parks such as Sequoia National Park, where visitors flock from around the world to marvel at General Sherman, the world’s most massive tree.

However, not all sequoias are protected within the park’s system.

Now, in an ambitious bid to secure a future for them, a conservation group has struck an unusual deal to acquire the last, largest privately owned sequoia grove.

The deal is the result of two decades of discussions between the nonprofit conservation group Save the Redwoods and the Rouch family, which has owned the 214.48 hectare Alder Creek grove since before World War II. The forest is home to hundreds of sequoias, including the Stagg Tree which — at more than 74m tall and 33m around — is the fifth-largest in the world.

The Rouches agreed to sell their land for US$15 million, which the organization hopes to raise by the end of this year. Once they acquire the land, the group plans to work with ecologists to help the forest build resilience against global heating and its catastrophic consequences.

“The forest is truly ancient, and we’ve now got this extraordinary, unique opportunity to restore and protect it,” Save the Redwoods president Sam Hodder said.

Although sequoias have evolved to withstand temperature changes, extreme heat and fire, drought and destructive wildfires are now proving to be the biggest threats to their survival. Curiously, decades of humans fighting fires has made the problem worse.

“Giant sequoias really need wildfire,” Save the Redwoods forest ecologist Kristen Shive said, adding that their cones are cued up to open with the heat of a fire, releasing seeds that like to germinate in freshly burned, fertile forest floor.

For millions of years, “sequoias adapted to survive and thrive with regular, low-level fires,” Shive said.

With their thick barks and high crowns, most mature giant sequoias are immune to fires that burn through almost everything else around them.

“But over the past century, we moved in, and started stopping fires everywhere,” Shive said.

Woody debris began to accumulate on the forest floor, and small trees and saplings began to overcrowd it.

“That serves as kindling,” Shive said, adding that it feeds fires that burn longer and hotter than sequoias could bear.

Smaller trees serve as “ladders,” allowing the fires to climb up to the sequoia’s crowns and kill them.

Climate change has not helped. Intense heat waves and drawn-out periods of drought have left California’s forests drier, and more prone to wildfires.

Droughts also depleted giant sequoias, weakening them and leaving them vulnerable to bark beetles that chomp through their bark and spread a fungus that could kill them. Healthy trees are usually able to fight off a beetle attack — but dehydrated trees are defenseless.

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