Officials at the Kenai Peninsula Borough’s Spruce Bark Beetle Mitigation program have started a summer-long project they hope will mitigate the high wildfire risk left by massive prior infestations of bark beetles.
The project, which calls for planting more than 500,000 young spruce trees on 2,000 acres of land held by a variety of owners, could place a “substantial” dent in those fire-based worries, said Wade Wahrenbrock, forestry and fire behavior specialist.
“Most of the risk that we are most focused on in the program is around subdivisions and residential areas and human developments,” he said. “The trees that are back up on the hills and more removed on the land space we are much less focused on because public safety and reducing public risk is one of the goals of ours.”
The Peninsula experienced a large, eight-year infestation of bark beetles in the 1990s.
“In terms of the density of beetles and the amount of mortalities, it is one of the most significant on record in North America, or so we are told,” Wahrenbrock said.
The conditions then — including lack of a major disturbance or fire in older forested areas and ideal weather climates — made for a “perfect storm” of beetle activity, he said.
After the beetles’ activity, many of the area’s large spruces were killed and left for property owners to cut down and sell to the forest industry.
As a result, native blue joint grass was able to take hold because of growth opportunities created by the lack of shade from the original trees — either from the logging or from the loss of canopy due to the beetles.
The blue joint grass created a thick root mass layer — called the rhizome layer — making it hard for seeds from trees not affected by the beetles to become established, planted and natural regeneration to run its course, Wahrenbrock said.
“Plus, it catches fire easily and it burns hot and fast,” he said.
The program’s mitigation efforts are restrained to areas containing 50-percent or less of full spruce stocking. Areas with more than 50 percent were deemed to have a good amount of natural reforestation, Wahrenbrock said.
The department plans to spend $814,000 in contract work for various mitigation efforts throughout the summer, including money for the seedlings.
The first phase of the project — site preparation — began last weekend and will continue for several weeks. Crews will work in approved areas to tear up and mix the rhizome layer and mix it with the soils underneath.
“This will retard the grass growth for a couple or three years and you’ll get seedlings in there and that’ll get the seedlings a chance to really get established and survive,” Wahrenbrock said.
The half-million seedlings, which were grown from the seeds of local trees and grown in a nursery in Canada, will arrive for planting by a separate company in mid-July. Wahrenbrock hopes to have all the new trees in the ground by September.
“That’ll give the seedlings a little bit of time to get established before the winter freeze sets in,” he said. “Once you put them in the ground, they usually have a lot of energy and they grow real fast.”
The fast growing nature of the new trees will help stymie the growth of the blue joint grass, which would have severely hindered natural reforestation.
“Grass was going to continue to be on these sites and continue to dominate the surface growth,” Wahrenbrock said. “From what we had observed it was going to be many decades for natural regeneration to eventually move into these sites — 30 to 50 years is not out of reach.”
Even though bark beetles are a natural part of spruce tree forests, an infestation matching the one from the 1990s isn’t likely for quite some time, he said.
“As far as their life cycles, they typically get into the larger diameter trees that are weakened because of old age … so in the case of the Peninsula, given the intensity of this infestation during the 90s, there are very few large trees left,” he said. “So, there is not a suitable amount of host material for the beetles to propagate in for many decades.”