Balancing on a steep ridgeline overlooking Utah's Alta ski area, Maura Olivos clutches a GPS device and a large tape measure. Olivos, an ecologist with Alta, records data while one of two graduate researchers screws a tree core sampler into a tall and gnarled limber pine. The tree is at least one hundred years old.
The evergreen trees clustering at the top of little cottonwood canyon, east of Salt Lake City, look mostly healthy. But on this last day of July, Olivos says they're finding one to two bark beetle infestations of their Engelmann spruce and limber pines each year. "We're in flight season right now. So beetles are out and about, looking for trees to infest."
It's difficult to see the tiny beetles in the trees – they're only 1/8th to 1/3rd of an inch long – but they leave telltale signs like boring dust and sap oozing from tree trunks. Within a year of an attack a tree's needles will turn yellow to red.
To protect their trees, Alta gets a helpful little tool from the forest service. On the trunks of their biggest and oldest limber pines they've stapled what look like small white tea bags. These pouches are actually a chemical pheromone called verbenone that simulates a scent mountain pine beetles use to communicate with each other—to say, there's no room at the inn.
"They've got multiple scents that they send out," says Olivos. "One is, 'vacancy here,' come to this tree, and let's inhabit it and let's proliferate. And they also have a 'no vacancy' pheromone... and we go and we choose the trees we want to protect the most, and put those verbenone packets on."
Mountain pine and spruce beetles are native insects. Their role is to thin out aging or sick trees. But in recent decades beetle attacks are occurring with more intensity - even on healthy trees, and across different ecosystems. Beetles infested more than 600-thousand acres of Utah forests last year. Some blame poor management that's left forests dense, and therefore more vulnerable. But scientists also point to climate change, saying winters aren't getting cold enough to kill the beetles, allowing their populations to swell. Now, forest service managers say they don't have enough resources to protect every forest.
"Whether it's ski resorts, campgrounds, where we're inviting the public up in the forest, those are the areas where we can actively manage for bark beetle," says Darren Blackford, an entomologist with the US Forest Service in Utah.
He says anti-aggregant pheromones, like verbenone, can help to protect various pine and fir species, but not Engelmann spruce. "We don't have a good one for spruce beetle."
Englemann spruce grows at high altitudes and is the most plentiful tree in Alta's canopy. Insecticide sprays can help the spruce, says Blackford, but it can harm riparian areas.
"We've had recent research projects collaborating with suppliers to come up with an anti-aggregant pheromone that would work well, but so far we've struck out."
Alta was a mining town a hundred years ago and the boom left the mountainsides ravaged and deforested. So the ski resort is protective of any older trees that still exist. Every year they recruit volunteers to plant thousands of seedlings to nurture their forest and help it diversify. And they train ski patrollers to look for signs of beetle attacks. But closely monitoring all the trees in the forest can be difficult. That's why Olivos teamed up with biologist Tim Brown two years ago to photograph Alta's canopy, using high-resolution time-lapse cameras, called GigaPan.
"What the GigaPan does is allow you to capture the pixels from any location on the mountain so that you can go there from the comfort of your desk and look at them and see what's going on in the particular tree," says Brown.
The program, which brown says is unique to Alta so far, lets employees pull up photos from different times of year, and zoom in close to study changes in individual trees. Brown says the idea is to detect any discoloration of pine needles early on, and stop infestations before they worsen. And just four GigaPan cameras can cover 70-percent of the Alta area.
"You train an observer and they go out and take observations and come back," says Brown. "But if they see something that's anomalous, you don't know if that's just because they weren't paying attention, or they made a mistake, or if it was actually a valid observation. So one of the things I think is really great about this kind of data set is that it's really easy to verify it. You know you can double check all your data in a way that everyone can agree on seeing the same thing."
The forest service is photographing forest canopies from airplanes, but that has its limitations. Blackford says aerial photographs can't always detect when, or if, certain trees have already been infested. "When we're seeing fading trees from the air, those beetles are already in there. It's almost too late, it is too late to protect those trees from dying."
By replicating Alta's approach with the GigaPan, Blackford says, forest managers might be able to catch infestations earlier and save pockets of still healthy trees. And that, says Olivos, is exactly why these tree-guarding tools are critical to Alta.
"Every tree here has taken about 50 to 100 years to grow. If we lose trees, we have decreased water quality, increased avalanche danger. For us as a ski area, it's very important that we care for our natural environment. If it wasn't for these incredible slopes, and the incredible climate, and the wildlife, we would have nothing. We wouldn't have a ski area."
Olivos hopes that skiers shushing through these trees will come to learn what it takes to keep the slopes green....... or, those skiers can see the imperiled forest for the trees – so to speak.
