High-altitude krumholtz in British Columbia, photo by Kevin Teague
Information Forestry, December 2012

British Columbia is home to some of Canada’s highest-elevation forests. In the very highest of these—growing at treeline in or near the true alpine—evergreens hug the ground, twisted and bent by wind and snow pack, with vertical leaders repeatedly pruned by severe winter temperatures, ice, and wind. Many models that predict how changing climate will affect species distribution assume temperature limits both growth and spread of these forests. As global temperatures rise with climate change, these models forecast the forests will straighten, grow tall, and colonize ever-higher slopes.

However, a recent study by Natural Resources Canada Research Scientist Eliot McIntire suggests these assumptions need re-examination. McIntire and colleague Alex Fajardo, of the University of Montana, tracked growth at high-altitude treelines in the Chilean Andes and Montana’s Rocky Mountains. Basal tree cores at the sites show tree growth and colonization up the slopes improved for most of the past 200 to 300 years. This corresponds to a period when global temperatures were just beginning to climb to today’s levels out of the very coldest decades of the last millennium.

“Synchrony between temperature and growth and temperature and recruitment clearly occurred during that period in both regions,” says McIntire. “Then, during the past half-century, it was lost at all sites.”

In fact, any improvements in growth that had occurred have since disappeared or reversed.

This decoupling of temperature and high-altitude growth and recruitment rates may indicate that the world is entering a period in which temperature no longer drives growth and colonization at treelines, McIntire says. Other factors, such as availability of water, may now be the main constraints.

The findings suggest climate models may need to be modified to separate high-altitude growth and recruitment drivers if they are to capture what is really going on under British Columbia’s—and the world’s—highest forest canopies.

© Natural Resources Canada 2013

Mars Waterbomber bombing, photo by ToddBF, flickr

Information Forestry, December 2012—The biggest challenge in forecasting fire-season resource needs in Canada, says Canadian Forest Service Forest Inventory and Analysis Research Scientist Steen Magnussen, is the variability in the country’s fire regimes.

“The environment, the size of Canada, the weather, the forest structure, larger climate patterns, the fire danger—all that combines to create the variability that we face year to year, location to location,” he says. “That’s why it is so difficult to predict how many resources are going to be needed anywhere and at any one time across the country.”

Borrowing methodologies from the insurance industry, Magnussen has developed a statistical framework that captures the variability and other key characteristics of Canada’s fire regimes on a weekly basis. The framework enabled him and Natural Resources Canada Fire Officer Steve Taylor to estimate how fire events in Canada are distributed in relation to one another across and between 48 regions and throughout a fire season.

“Resource sharing works because we don’t usually get major fires occurring in different regions at the same time,” Magnussen says. “We wanted to see if that pattern is stable enough that we could do estimates of likelihood: What is the probability of one, two, three provinces experiencing peaks in fire activity at one time?”

Kelowna fire, photo by Pierre Gazzola

The resulting fire-event distribution revealed that, in recent decades, Ontario’s fire numbers tend to peak in spring, after snowmelt but before the forest greens up. British Columbia’s fire season usually peaks later in the summer—after drought sets in—as happened with the 2003 Kelowna fire.

“This lack of synchrony is essential,” Taylor says. “How many regions aren’t experiencing fire-occurrence peaks when other regions are? And which regions? Not all jurisdictions have the same amount of resources. For resource sharing to work, it’s important to track synchrony and asynchrony with regard to those resource-wealthy regions.”

The study is the first step in a project Taylor is leading to determine possible effects of climate change on future fire-resource sharing. “We needed to assess the current situation: What are the chances of peak overlap occurring between jurisdictions now?”

Fire in the British Columbia Interior, photo by Digital_Image_fan, Flickr

One of the questions Taylor and Magnussen wanted to answer was whether daily, weekly, or biweekly patterns in historical use of fire-fighting resources exist. The amount of data on resource use exists only for the last 25 years, and even that is inconsistent and in some places non-existent.

“Most fire-management agencies don’t track number of firefighters or number of person days,” Taylor says. “They can tell you what was used through a season, but not on a day-by-day basis. Even for a particular fire, it can be hard to find that information.”

With fire patterns and the statistical joint distribution of fire events now mapped and established in time and space, fire managers can use the system created by Magnussen to determine the likelihood of various fireevent scenarios across the country. And when resource-needs information for individual fires becomes available, the system will enable fire managers and researchers to quantify opportunities for and constraints on sharing resources across jurisdictions.

 © Natural Resources Canada 2012

Information Forestry, December 2009

pinewood nematode, photo by L.D. Dwinell, USDA Forest Service

International sanctions by countries in Europe and Asia target the trade and transport of North American wood that may be infected with pinewood nematode, the cause of pine wilt disease.

A new molecular diagnostics method developed by Natural Resources Canada to detect live pinewood nematode in wood caught the attention of forest health officials from around the world.

“Scientists from countries with forests infested by pinewood nematode expressed a great deal of interest, as did those who are developing phytosanitary treatments,” says Canadian Forest Service Research Scientist Eric Allen, who presented the method’s preliminary results at the 2009 International Symposium on Pine Wilt Disease in Nanjing.

Pinewood nematode is the microscopic roundworm that causes pine wilt disease. Native to North America, pinewood nematode rarely, if ever, affects North American tree species. However, it has caused serious damage in Asia and Portugal prompting quarantine regulations by concerned countries. In 1993, Europe banned imports of untreated softwood commodities from North America, resulting in significant decreases in markets.

The new detection method, developed by Canadian Forest Service Molecular Biologist Isabel Leal and colleagues, allows forest health officials to analyse wood samples for messenger-RNA associated with pinewood nematode heat-shock proteins. Unlike DNA, which can survive in dead tissues for years, mRNA degrades after an organism dies. Its absence indicates lack of viable nematodes in a sample.

“It’s important to have a method to differentiate between deal and live nematodes, because only live nematodes are a risk to forest health,” says Leal.

Many major wood-importing countries, including China, Korea and Europe, require all softwood commodities exported from countries where pinewood nematode is found be treated prior to export with heat according to international standards. Leal and colleagues’ method will allow plant health officials to test and verify the effectiveness of treatments against the damaging nematode.

The method will also protect trade, by allowing exporters to demonstrate that their softwood lumber, chips, logs, prefabricated housing and wood packaging is free of living nematodes.

© Natural Resources Canada 2009

Information Forestry, April 2008 — In order to measure a disease’s impact on a tree, you need to know when it became infected. This is difficult to do with root diseases: infection and disease progression occur underground, and above-ground symptoms may not show until years later, if ever. As well, root diseases progress through a stand with time of infections varying between trees.

Natural Resources Canada Root Diseases Research Scientist Mike Cruickshank recently determined how to date infections by root-rot fungus Armillaria ostoyae years after they occur.

His method traces a defense mechanism that occurs in most trees. When a tree is wounded or stressed, ducts called traumatic resin canals form under the tree’s cambium and around the affected tissue. If enough develop, the canals create a physical barrier between affected and healthy tissues. The barrier helps contain the infection.

Traumatic resin canals, by Mike Cruickshank

Traumatic resin canal barriers form beneath a tree’s cambium layer in response to fungus infection. By tracing the canal positions preserved within tree rings to nearby lesions, researchers can determine when past infection events occurred.

The canals are preserved within the annual rings of root wood, which is how Cruickshank is able to trace them across the rings to specific fungus-caused lesions.

“Traumatic resin canals allow us to create a profile of infection events over time,” he says. If attacked once, a tree may contain an infection with canals, but the fungus may grow around the edges of the resin barrier and attack the roots elsewhere. “Being able to date infection events by year means we can go back and determine impacts of that particular infection—on growth and production in the tree, as well as subsequent effects in the stand.”

Knowing root disease impact would enable forest managers to more accurately predict future timber supply from high-risk stands, as well as to assess broader economic, silviculture, and climate change impacts.

Root diseases exist in most forests, but are especially common in tree plantations, particularly those where stumps of previously harvested trees are left in place before replanting.

Armillaria attacks the roots of all trees and many shrub and herb species native to British Columbia, but causes greatest mortality among Douglas-fir trees planted in the province’s interior. The fungus is prevalent across Canada and the northern hemisphere.

© Natural Resources Canada 2008

Information Forestry,  December 2007

western spruce budworm, by William Ciesla, Forest Health Management International

Western spruce budworm’s prefers feeding on Douglas-fir needles.

A century-long ocean-warming trend may explain the rarity of western spruce budworm outbreaks on southern Vancouver Island since the 1930s, according to a study by Canadian Forest Service scientists Alan Thomson and Ross Benton.

Mild winter temperatures, linked to a rise in sea temperature, have de-synchronized budworm–host interactions in the region: budworm larvae now emerge earlier in the year, while timing of bud flush of Douglas-fir, the defoliator’s preferred host, remains unchanged. The trees do not respond to the early warming because their photoperiod requirements are already met by that time.

Race Rocks Lighthouse in distance. Photo by Evan Leeson

Scientists compared more than 80 years of sea-surface temperatures from Race Rocks Lighthouse (seen in distance) near the southern tip of Vancouver Island with historic air temperatures.

More than eight decades of sea-surface temperatures, collected at the Race Rocks Lighthouse near the southern tip of Vancouver Island, were compared with corresponding historic Environment Canada air temperatures. Mean sea surface temperatures and the mean maximum and minimum air temperatures from January to March correlated, with all temperatures from this region increasing over the period studied.

The good news does not extend beyond the south island, however: changing climate is believed to be contributing to a widespread, 30-year budworm infestation in the interior, far from the influence of sea-surface temperatures.

© Natural Resources Canada 2007

Information Forestry, December 2007 — Canada’s climate is changing, and forest pests are on the move.

In order to track and predict long-term effects of a warming climate on pests, Natural Resources Canada scientists use a software tool originally developed to help forest managers plan short-term pest control or sampling activities.

Distribution of gypsy moth in Canada from 1964 to 1970. Image © Natural Resources Canada

Distribution of gypsy moth in Canada from 2001 to 2006. Image © Natural Resources Canada

This tool, called BioSIM, links insect life-cycle models to weather data and manages their output to determine the timing of specific stages in an insect’s life cycle—for instance, when an insect reaches the stage most vulnerable to pesticide applications. BioSIM has recently been extended to help in forecasting where current or future climates might favour invasion by an alien species because the weather is, or will be, more suitable for its survival.

“The success of forest pest control programs hinges on the vulnerability of pest populations at the moment of intervention,” says Canadian Forest Service scientist Jacques Régnière, who studies insect population dynamics and developed BioSIM. “With insects, weather conditions are a controlling factor.”

In order to predict long-term climate effects on insect populations, the researchers use data from climate scenarios generated by the Canadian Global Circulation Model that extend many decades into the future.

“Taking BioSIM from immediate applications to seasonality modeling and establishing probability over long time periods was a bit of a leap in complexity, but not much of a change in paradigm,” says Régnière. “Whether you’re looking for short-term or long-term views, it uses the same technology: weather-data management and model-output synthesis.”

Régnière teamed up with fellow-Canadian Forest Service researchers Vince Nealis and Kevin Porter to determine probable range expansion of gypsy moth in Canada. At the Canadian Food Inspection Agency (CFIA)’s request, they analyzed historical records from Natural Resources Canada’s Forest Invasive Alien Species Database, and current and likely future range of gypsy moth in Canada, based on the Gypsy Moth Life Stage model, climate suitability and host distribution. Using the results, the researchers devised recommendations for gypsy moth management strategies, which they then submitted to the CFIA.

Potential distribution of gypsy moth in Canada, #1. Image © Natural Resources Canada

Potential distribution of gypsy moth in Canada, #2. Image © Natural Resources Canada

“The real benefits of models like BioSIM from a quarantine management point of view,” says CFIA Forestry Specialist Shane Sela, “are that they allow us to better assess risks, and more effectively allocate resources to critical areas where potential risk is highest.”

Régnière also worked with Insect Ecologist Allan Carroll to predict range expansion of mountain pine beetle in western Canada. According to their results, eastward invasion by the beetle will continue if current climate trends persist.

BioSIM is capable of determining probability of future range for any species—insect, pathogen or plant—because it is designed to work with any model that encompasses an organism’s life history and response to climate. This emphasizes the need to quickly acquire such information for any species that represents a significant risk to Canada’s forests.

© Natural Resources Canada 2007

Information Forestry, August 2006 —Budworms are among the most destructive forest insects in North America. During outbreaks, eastern spruce budworm, western spruce budworm, jack pine budworm and their relatives strip foliage from tens of thousands of hectares of susceptible conifers across the continent.

Western spruce budworm. Photo by William M. Ciesla, Forest Health Management International

Western spruce budworm is one of several budworm species that eat evergreen needles in Canada's conifer forests.

Now, thanks to indicators identified by Canadian Forest Service scientists, forest managers may be able to use simple chemical analyses to identify areas at particular risk to budworm outbreaks. Insect Ecologist Vince Nealis and Research Scientist Jason Nault plotted changing chemistry within developing Douglas-fir needles against the ability of western spruce budworms to feed successfully on the trees’ buds. From that, they determined that the same molecular compounds that give evergreens their distinctive smell also indicate the potential success of budworms in a given year.

“An important part of the life history of the budworm has to do with how well it is synchronized with the flush of new buds in the spring,” says Nealis. “We wanted to quantify the relationship between emergence of western spruce budworm and development of the insect’s preferred food, Douglas-fir buds.”

Key to the prediction method is a mixture of complex, aromatic hydrocarbon molecules, called terpenes, found in all evergreen needles. The proportions of different terpenes in the mixture within buds change rapidly, but predictably, as buds develop in the spring. The rate of progression from one dominant terpene to another is closely tied to site temperature. In cooler places or during cooler years, the progression—and bud development—occurs more slowly. This can upset the timing of budworm emergence to bud suitability, with consequences to outbreak risk.

According to retired, now-volunteer U.S. Forest Service Research Entomologist Karen Clancy, who studies resistance in Douglas-fir to western spruce budworm, budworm population success depends on that timing. “Phenology of bud break is probably the most important factor driving resistance in individual trees to western spruce budworm damage, and driving budworm population dynamics.”

Western spruce budworm emerges from its winter shelters in early spring and subsists on older Douglas-fir needles and pollen cones until its preferred food—tender, developing buds—comes into season. If larvae emerge too early or if bud development is delayed, greater numbers of budworms die, and that particular forest stand may benefit from a year without an outbreak.

By measuring the terpene profiles of developing buds using gas chromatography, Nealis and Nault found they can pinpoint where and when host trees would be most suitable for budworm outbreak in a given year and where the risk of damage is greatest. Knowing this allows forest managers to better plan and implement pest management options, and better manage forests in their care.

“They appear to have found a good, reliable, relatively easy way to measure the bud break phenology of individual trees and populations of trees,” says Clancy. “Measuring bud break phenology with other methods like going out and collecting samples and visually assessing each of the buds is very time consuming. If you can clip just one branch from a tree and analyze its foliar terpenes, that’s a phenomenal result.”

Although Nealis and Nault identified the correlation between terpene profile and bud suitability for budworm by performing linked biological and chemical assays on western spruce budworm and its host, Douglas-fir, Nealis suspects “the method can be applied to jack pine budworm or eastern spruce budworm or any of the other budworms.”
Conifer forest damaged by western spruce budworm. Photo by USDA, David McComb.


Scents of suitability

Terpenes, the molecules that give conifers their distinct smell, indicate tree-bud suitability to budworm attack. In linked chemical and biological assays of foliage from test trees at eight sites in British Columbia’s interior, Canadian Forest Service researchers identified terpene profiles that can be used to predict host suitability for the insect, severity of defoliation, and identify tree resistance to budworm damage.


© Natural Resources Canada 2006