Bark Beetles Go to Town on Ouray’s White Fir Forests

05/01/14 | By | 331 views More
BEETLE KILL – As white fir trees around Ouray continue to succumb to the fir engraver beetle, residents are urged to take steps to protect the trees on their own property. (Photo by Samantha Wright)

BEETLE KILL – As white fir trees around Ouray continue to succumb to the fir engraver beetle, residents are urged to take steps to protect the trees on their own property. (Photo by Samantha Wright)

OURAY – Tiny, ravenous fir engraver beetles continue feasting on the white fir trees that grow thickly around Ouray, with growing patches of dead and dying forest becoming painfully apparent as winter’s snows recede.

Sadly, experts say that the problem is not going to go away anytime soon.

“The beetles are at an epidemic population, so we are just going to keep seeing it,” said Montrose-based U.S. Forest Service silviculturist Todd Gardiner. “What has shown up over the winter is a net round of mortality. All of the trees infested last summer are now becoming evident.”

Soon, the millions of beetles that have hatched and spent the winter munching between the cambium and phloem layer of those newly dying trees will start flying again in search of new healthy hosts, which in turn will die off in a year’s time.

“We will continue to see waves of this for the next several years,” Gardiner predicted.

In the Amphitheater Campground near Ouray, the U.S. Forest Service is in the process of cutting down 75 more trees that have succumbed to the beetles over the winter. This is in addition to 150 trees that were felled last summer.

While the towering dead trees are unsightly, the main focus of the tree removal project is public safety. “We want to make sure any trees we have identified as being dangerous are removed from the area before the campground opens for the year,” Gardiner said.

The City of Ouray is also looking into hiring someone to cut down dead and dying trees growing on parklands within its jurisdiction, including Box Canyon Falls Park and the area surrounding Cascade Falls.

The only way to protect white fir trees from fir engraver beetles is to spray them before they become infested, which is not practical on a forest-wide level, but recommended for private landowners who want to save individual trees.

It takes a specialist with the right equipment, Gardiner said, because mature white fir trees are very tall, and the beetles start by attacking the tops of the trees.

“This is a critical year,” Gardiner said. “You are seeing that these bugs are continuing to attack trees. I would urge people if they have valuable, important trees they want to maintain, they should consider contacting a tree service to get them sprayed. The sooner the better because these beetles will be flying any time now.”

While the USFS focuses on tree health on public lands around Ouray, the Colorado State Forest Service is available to help private landowners and homeowners associations identify what kind of trees they have, and can also recommend arborists to conduct spraying, and contractors to cut down dead trees.

Currently, CSFS foresters are working with members of the Whispering Pines Homeowners Association to help them come up with a hazard tree inventory for their subdivision three miles north of Ouray.

“They have a lot of beetle in there, but their main threat is falling trees,” said CSFS forester Austin Shelby. “It’s really tight. They have really small parcels, and it’s difficult to get the trees down because they are so big and there are so many houses.”

The hazard tree inventory will identify which trees are already infested, which are at risk of becoming infested but could still be saved through spraying, and which trees have structural flaws that need to be mitigated by an arborist for public safety.

“What it will take to complete the inventory is simple permission from landowners to participate,” Shelby said. The cost of the inventory is dependent upon how many landowners participate, and grant opportunities might be available to help mitigate that cost.

“We generally do the first site visit for free,” Shelby added.

According to U.S. Forest Service Entomologist Roy Mask, a Service Center Leader at the USDA Forest Service Gunnison Service Center who gave a presentation on bark beetles in Ouray last fall, there are “two main players” that are infesting fir forests in and around Ouray – the fir engraver beetle and Douglas fir beetle.

Each beetle is endemic to the area and exceedingly species-specific; the fir engraver beetle (scolytus ventralis) attacks white fir trees almost exclusively, while the Douglas fir beetle (dentdroctonus pseudotsugae) specializes in the Douglas fir tree.

Douglas firs can be more easily protected from infestation by attaching a patch to the tree that contains NCH, an anti-aggregate pheromone that tricks the beetles into thinking that the tree is already infested.

The City of Ouray and USFS are both deploying patches this spring to protect Douglas firs in the area, and private property owners are encouraged to do so as well before it’s too late.

Foresters agree that healthy snowpack levels this winter coupled with a good monsoon last summer have helped restore some vigor to Ouray’s drought-stressed forests. “But when the beetles get to epidemic levels and there are enough of them, all bets are off,” Gardiner said. “They will even attack vigorously growing strong trees. Now is the time, if you have a tree you care about, you should consider doing something to save it.”

Gardiner also stressed that what is happening to Ouray’s white fir forests is part of a natural cycle. “These forests are dynamic. They are always changing,” he said. “A lot of people have grown up with dense forests around them and view that to be the norm, but these forests are constantly changing.”

Ultimately, the die-off of the white fir might make way for other tree species to take root. “It’s just that white fir has found its niche right here, and has done really well. But there are other trees out there,” Gardiner said. “It’s a dynamic, changing system and the future of what vegetation there will be is largely driven by climate and drought cycles.”

For people who live in and near Ouray, it is hard to see beyond the fir engraver beetle epidemic that is decimating the forests in their own backyards. But ultimately, the much more aggressive spruce beetle is the one that foresters and entomologists are really worried about as it begins making inroads into the forests of the southern San Juans, potentially putting vast swaths of forest at risk.

“Every species of tree out there has a different beetle that likes it,” Gardiner said. “It’s a very dynamic time. It’s a hard time to be a tree.”

swright@watchnewspapers.com or Tweet @iamsamwright

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