New bug brings back memories of spruce bark beetle devastation

CHINA POOT BAY — It looks like the start of the spruce bark beetle kill of the 1990s, when mountainsides across the Kenai Peninsula turned gray, the biggest tree blight in North American history to that time. But it started just last year.

A warming climate has powered the explosion of the spruce aphid (Elatobium abietinum) in the same areas where the bark beetle took off, on the south side of Kachemak Bay. Trees are losing their needles and turning gray, and some owners are cutting them down for fear of fire.

But this pest is different in several ways. The trees have better chances of survival. Southcentral Alaska forests probably do face permanent transformation, but the spruce aphid may be only a step on that path, not the final stop.

Marian Beck, owner of the Saltry Restaurant in Halibut Cove, saved 80 spruce trees from the devastation of the spruce bark beetles with careful spraying and watering. But now she is facing her second year of trees without needles due to the aphid. A visiting entomologist found four other pests in the weakened trees.

"There's just too many things going too fast," she said. "We were caught off guard, and kind of beyond the point of handling it, and that's just the way it is."

Mike McBride lost all his trees to the bark beetle, but in the years since, young spruce trees have grown up at his home overlooking China Poot Bay, along with weeping willow, weeping birch and other ornamental trees he planted to replace the massive Sitka spruce that once towered there. Now the new spruce trees have lost their needles.

"We cut down a few," McBride said. But only a few. "We realized that if we kept going, we'd have to cut them all down."

The heartbreak of the spruce bark beetle kill accustomed McBride to losses in the place he has loved since 1966. Today's brown trees are only one sign.

"These are the big, visible things," McBride said. "The things that are really consequential are not these visible things. They're out in the tide pools."

Over the last year, residents around Kachemak Bay have seen alarming numbers of dead sea otters, sea stars and murres washing up on beaches. When I visited last weekend, the winter's carnage of sea birds remained in evidence, with bones and feathers littering the tide line and in the forest near the shore.

Those ocean changes are complex and pinning down the cause is difficult. But the blight on the trees is relatively simple.

Ed Berg documented the climate change link to the spruce bark beetle kill in the early 2000s, when he was a research biologist with the Kenai National Wildlife Refuge. It was the world's first biological calamity proven to be caused by the warming climate. The pine bark beetle plague in the West subsequently dwarfed Alaska's die-off and was even more thoroughly linked to climate change.

[Read more: Wohlforth on the facts of climate change]

The spruce aphid came from Europe a century ago, but never made it this far north in Alaska until our recent string of warm winters. A single winter cold snap can knock down its numbers, forcing it to recolonize. But a winter as warm as the one just past lets the aphids continue to breed and to eat without a break, producing a population explosion.

"This is a new era. The climate's changing. Things are on the move," said John Lundquist, supervisory entomologist with the U.S. Forest Service, in Anchorage. "A lot of crazy things are happening with diseases in our forests."

Lundquist said the blight has spread rapidly and unexpectedly. In quick succession, the aphids jumped from Kenai Fjords National Park to Halibut Cove and now to Homer.

He made five trips to Homer to investigate the outbreak so far this year, including taking a large team of experts and technicians in late March.

"What has happened in Halibut Cove now is going to be what Homer looks like next year," Lundquist said.

Without cold winter weather, the aphid appears poised to keep moving north on the peninsula toward Anchorage. Lundquist's team set up monitoring sites, but so far the bugs remain near Kachemak Bay, attacking only at low elevation, near the water.

Where it has hit hardest, all the trees are brown. But Lundquist advised against cutting them down. The aphid is not usually a tree killer. It attacks mature spruce needles, leaving green shoots on the ends of branches, which can be enough for a tree to make it through the year. Weak trees die, but healthy ones can survive.

If the same trees get hit year after year, however, they can be weakened. Beck said the green tips are falling off of her trees after two years without many needles.

Entomologists agree that the spruce aphid will not be as bad as the bark beetle was. For one thing, ecologist Berg said, there aren't that many spruce trees left.

Spruce bark beetles were always with us, but a series of warm springs in the 1990s let them take off. Now those temperatures are routine. Climate change has brought warmer minimum temperatures year-round, spreading the range and increasing the impact of many insects.

"Spruce are essentially on the way out here, at least on the multi-decadal scale," Berg said.

Natural landscapes have always changed. One hundred centuries ago, the climate of our region was icy, with different vegetation and wildlife than we have today.

But those changes happened slowly, over millennia, with forests imperceptibly developing through many generations. For the natural world to turn upside down within the span of a single human lifetime, that's new.

These changes are coming much faster than ecosystems can reach equilibrium. They make the natural world poorer.

We know the cause. The forests are transforming as our use of fossil fuels warms the climate. That's a choice we make whenever we waste energy or otherwise drag our feet on reducing carbon emissions.

We are dismantling Alaska.