By Ken Laustsen, former biometrcian, Maine Forest Service
Within the last 100 years, Maine has experienced two major spruce budworm outbreaks (circa 1910 – 1920 and circa 1972 – 1985). The most recent outbreak was severe enough to require a massive spray program and accelerated harvesting in attempts to mitigate inventory losses due to mortality.
An apparent peak, the 1970 statewide inventory estimated 127 million spruce/fir cords of pulpwood quality. By 1981, the inventory had declined 9% to 115 million cords. This data from Maine’s 1981 periodic inventory was used in various modeling projections and the bulk of those indicated that a continuing epidemic and harvest levels would totally deplete the spruce/fir resource by the year 2020.
The next available inventory in 1986, was a state-led effort to again get an estimate of inventory levels, right after the circa 1985 collapse of the outbreak. This estimate of 91 million cords was a 21 percent decrease in just five years from 1981. Inventories continued to decline mostly due to harvesting, bottoming out in 2008 and 2010 at 71 million cords of spruce/fir inventory.
Putting this into context with the previous epidemic, in 2008, 25 years after the start of the circa 1973 epidemic the spruce/fir inventory was 87 percent higher than a similar point in 1944, which had an inventory estimate of 38 million cords, which was 25 years after the circa 1919 outbreak. The spray program, targeted harvesting, pulp mill conversion to hardwoods, and professional forest management; all helped to alleviate the dire projections of the early 1980s.
If you’re the kind of person who always asks “Why?” or can’t resist a good mystery, you should be cheering on Rob Johns, an entomologist with the Canadian Forest Service and his colleagues. I know I am, especially after Johns told us researching spruce budworm while coping with a growing infestation is like “trying to build a plane and fly it at the same time.”
The Cooperative Forestry Research Unit (CFRU) at the University of Maine, which was founded in response to the budworm outbreak in the 1970s-80s, invited Johns to the Augusta Civic Center on April 10 to update our forest industry on New Brunswick’s ongoing research and intervention efforts.
Fortunately for Maine, the Canadians set aside $18 million in 2014 to develop and implement their Spruce Budworm Early Intervention program over the next few years. That initiative was funded not long after an economic impact study estimated New Brunswick’s forest industry could take a $1 billion hit from the current budworm outbreak.
Over the years, the Canadians have put a lot of effort into researching all aspects of budworm. They’re the ones, for example, who tracked outbreaks back thousands of years. And their efforts benefit Maine because they’re willing to share.
“The Canadians really have the knowledge that we are going to draw on a lot as this Maine outbreak occurs,” said Dr. Robert Wagner, CFRU director. “We drew that knowledge into the statewide plan that we pulled together.”
About 35 people gathered at the Augusta Civic Center for Johns’ presentation, entitled Harmonizing Spruce Budworm management approaches in the northeast: Ongoing research and opportunities.” Many MFPC members were present, as well as state officials, such as Maine State Forester Doug Denico and Sen. Peter Edgecombe, co-chair of the ACF Committee, and representatives of environmental groups, such as Cathy Johnson of the Natural Resources Council of Maine.
Dr. Johns has been studying the dynamics of rising spruce budworm populations in the Canadian Maritimes and is part of the team of researchers working on early intervention strategies in Quebec and New Brunswick. His presentation focused on SBW research; outreach/citizen science efforts; early research results, and New Brunswick’s plans for this summer. He also led a lively Q&A that lasted nearly as long as his presentation.
I’ll try to give some of the highlights, but if you’re really interested watch the video above. I taped his narration and paired it with his PowerPoint presentation. It’s definitely not a Martin Scorsese production (sorry about the coughing from the audience, many of us were still shaking off winter), but Johns is very knowledgeable and has a talent for summarizing science for non-scientists. I learned a great deal.
There was one slide (above right) in his presentation that I love. I’ve read reports from the 1970s of people using snowplows to scrape the budworm debris off roads, but I wondered if those were exaggerations. But Johns’ presentation includes the photo (left) of a front-loader being used to remove budworm moths after a big migration in Rimouski in 2013.
I also got to ask him why the last infestation ended so abruptly. Two years ago, Seven Island forester Bill Brown told me, “All the entomologists and people from the spray program went out and they said, ‘Where did they all go?’ It was like they had disappeared right off the face of the earth – the whole population just collapsed. Nobody had predicted that or expected that. It just disappeared.”
Johns’ answer: “It’s basically driven by natural enemies, c, that’s what pulls the population down. And that’s what maintains it (low populations) in between.”
He also told us that what happens in New Brunswick is likely to be reflected here, just a little bit later. So Maine’s forest products industry is paying close attention to everything learned, developed or attempted across the border. Collaboration also is important to New Brunswick, Johns said.
“Certainly if it’s going to work in New Brunswick, there are some scenarios that will have to be coordinated with Maine. Even in the best-case scenario, we can’t imagine the budworm infestation will wrap around New Brunswick and miss Maine,” Johns said, getting a big laugh from the audience.
His comments about the relationship between budworm and pre-commercial thinning (PCT) also sparked questions.
“PCT is one of the things we are worried about in New Brunswick,” Johns said. “That’s basically where they are thinning for foliage quality. One of our researchers argues that is probably going to be a bit of a problem. It may be offset, at least in New Brunswick, because we’ve planted a lot more spruce since the last outbreak instead of just encouraging balsam fir to return.”
Since there was so much interest in this point, I emailed Johns this week asking him to explain a bit more. Here’s his answer.
“There is some debate on the PCT question, which is probably why the answer seemed a bit ambiguous,” he wrote. “People originally thought that increasing tree vigor through PCT would help trees recover more quickly or maintain their foliage even after heavy defoliation by spruce budworm. However, it turns out that mortality is actually higher in thinned (i.e., spaced) stands, perhaps because the foliage nutritional quality is better and is thus able to sustain larger, healthier budworm populations (…there may be other reasons as well, but this seems to be a plausible hypothesis).”
For those who want to delve deeper, Johns also sent an article from the Canadian Journal of Forest Research.
Communication/outreach: “Part of the communication strategy is getting people on board for this because if we have areas of higher density that are rising, we want to hit all of them. Most of our agencies, the parks for example, are worried about spruce budworm coming through there and killing all their spruce.”
Early intervention: “The big question is the cost/benefit, because that’s what all these systems come down to. If it costs way more to do early intervention than it does to do foliage protection and the benefit is not there, then it doesn’t matter if it works.”
What to do or not to do: “It’s not just a question of developing a strategy that works. It’s making sure we can evaluate why it doesn’t work — if it doesn’t work — as well.”
Many landowners and MFS personnel trekked to Quebec City Feb. 19-20 to participate in the CFS/MRNQ Spruce Budworm Conference. Two days of research and operations presentations were informative to the group and provide a better understanding of the possible outbreak scenarios that we may encounter in Maine this time around.
It appears that Quebec will be trying to harvest threatened stands along with targeting aerial applications of Bt to protect stands from severe defoliation. In New Brunswick, which just received $18 million to tackle budworm, it appears a more aggressive intervention of insecticide applications to kill budworm larva before populations can multiply will be tried.
Maine has a small window of time before we think the budworm will invade (1-2 years) so we can continue to benefit from the research conducted by our Canadian neighbors. The Maine Budworm task force will present its current report on the Maine budworm strategy at the New England Regional Council on Forest Engineering (NERCOFE) meeting on March 10 at the University of Maine and at a meeting of the Keeping Maine’s Forest Committee on March 14.