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Thinking about the sustainability of carbon sequestration in forests

Bugs are one of the most common killers of trees, their common names associated with the tree they attack- Douglas Fir Tussock Moth, Emerald Ash Borer, Spruce Budworm, White Pine Weevil. The mountain pine beetle is similar in name, but was first known to a few households as the carrier of blue-stain fungi, creator of the elegantly-stained boards popular during the 1970s and 80s for interior paneling and woodwork. As a pest, the mountain pine beetle didn’t reach the national stage until the 1980s, when large-scale infestations began killing entire stands of trees. Today, the beetle is known for the deaths of large swaths of forest across the Rockies, especially in Colorado, Wyoming, Montana, and British Columbia. Sometimes, these forests burn, as happened in 2009 when over 600,000 acres of partially-beetle-killed-timber burned in British Columbia, leading to thousands of evacuations and highway closures the province and neighboring Alberta (where I was bicycling at the time). Other times the forests are clear-cut before either the bug or fire hits, and often the entire forest just slowly decomposes. The situation is so dire in many areas that entire government departments are now dedicated to the beetle; the state of Montana and the province of Alberta even have web prefixes, beetles.mt.gov and mpb.alberta.ca, to address the spread of bark beetles. Today western forests, according to Warner Kurz’s study in Nature, are reversing their trend as carbon sinks and are releasing more carbon than they originally took in. Pines, like other plants, breathe carbon dioxide, the very gas that warms our planet now. So anything that absorbs carbon is generally a good thing, but too much of a good thing, in the case of pines, can turn into a potentially very bad thing. In British Columbia and the rest of Rockies, there now exists a positive feedback loop contributing to global warming. The mountain pine beetle benefits from warming climates and can move to higher altitudes and latitudes because of warmer winters. The mountain pine beetle can expand terrain as its victims contribute more CO₂ to the atmosphere and contribute global warming, which then helps the mountain pine beetle. It has been estimated that 7.5% of Canada’s CO₂ emissions come from British Columbia forests, and that by 2020 990 megatons of CO₂ will have been released by the forests. This transition of forests from carbon sinks to carbon emitters is problematic for life as a whole. In 2008, the Natural Resources Defense Council filed an endangered species listing for the Whitebark Pine, a relative of the Ponderosa common at elevations around 6000 feet. A June 2011 decision by the US Fish and Wildlife Service denied the listing, but the Whitebark Pine was found to be at risk due to climate change exacerbating existing threats, including the bark beetle. The US government at last recognized the connection between global warming and bark beetles. Mountain pine beetles are also not the only insects aided by global warming, and when forests are planted or replanted, as suggested as an easy way to sequester or contain CO₂, the even age distribution of trees will make the forests once again vulnerable to infestation. In this larger scale, the mountain pine beetle is just one of thousands of players, all of which have the power to turn forests from sinks into emitters of CO₂. While there is no obvious solution to global warming, the pine bark beetle is a reminder that sequestering all of our carbon into forests may be an evil rather than a good, and a plea to the world to think beyond the storage of carbon.

A little bit about burns, beetles, and forest death

In light of recent wildfires in the Cascade range that hit very close to home off of Blewett Pass, it seems to be the right time to post about bark beetles. The Leavenworth-Blewett area in North-central Washington, where Trakka is located, depended on logging and faux-Bavarian tourism for its livelihood. That is, before the Longview Fibre mill in Winston shut down in 2006. Before the faux-Bavarian village sprung up, timber was king. Locals resisted against lawsuits, appeals, or lobbying that sought to limit timber harvests. Clear cuts, in which all the trees are chopped down save a few so-called wildlife trees, were the most common, leaving left areas void of important, thin soils and living root mass. Bare hillsides became the norm for years, and in the place of the old-growth stands there grew even denser, even-aged forests. Before fire suppression began in the early 20th century, the Leavenworth area burned regularly, with most lands facing fire every dozen or so years. These ground-burning fires controlled excessive undergrowth, enabled large, fire-resistant trees to survive, and killed off most seedlings, all of which led to diverse-aged forests. But when fire suppression began, these small seedlings grew, and dense, even-aged forests became the norm. When fire struck these stands, where trees exhibited vertical and horizontal closeness, stand replacement fires- where the fire reached into the crowns of trees- burned at high temperatures and destroyed the forests, creating room for new, even less diverse ages of trees. Today, according to the Chelan County Conservation District, 98% of Leavenworth-area forests are recognized as Class II or III stands based on US Forest Service standards, meaning that the forests are not functioning and are prone to disease and infestation after 70 or more years without fire. With the decline in logging in the Leavenworth area, few natural or human population controls restrict the forests, and those that do are risky, insect-based infestations. After wildfires in 1994 swept the Icicle and Peshastin drainages, which encompass most of the greater Leavenworth area, and destroyed the biological and structural mainstay of the land, there was valid concern against logging due to the forest and soil health. The large and intense fires extended well into the crowns of trees and destroyed forests of Ponderosa pines known for their resilience and symbiotic relationship with fire. With watershed and soil health degraded following the fires, my grandparents worked towards new challenges against timber harvests, appealing and delaying sales on surrounding lands and enjoining timber sales on Tip Top. Around the same time, in the late 1980s through 1990s, the spotted owls’ preservation, using the newly-enacted Endangered Species Act, was successful in limiting timber sales. Forest management in the Leavenworth area was changed for good, and a number of suits and management plans pitted loggers and timber companies against conservationists and the general public. Little did conservationists and loggers know, however, that the very trees being saved for the owls would be dying as well due to pine bark beetles. The culprit in new forest deaths: a small, black creature, the mountain pine beetle, Dendroctonus ponderosae. A string of dry and fire-free summers combined with warmer winters to produce weakened trees and surviving beetle larvae. Only then did the small, black bodies appear across the property, complete with hundreds of dimples across their backs and a pair of powerful jaws. Each beetle was less than a quarter inch, but caused damage that extended a few feet around the trunk of each tree. After peeling away the bark, maps resembling flatland streams or coastal fjords appeared; the interconnected, weaving strands of destruction were filled with sawdust. Small pupa, segmented jelly-like transparent bugs, grew slowly early in the season before turning into full beetles capable of flying and creating their own homes one July or August. The parts of the land covered by meadows and trees spaced every few dozen to few hundred feet- the way the meadows and forests were before climate change and white settlement- remained healthy. But the dense forests, which hadn’t burned for decades and hadn’t been logged in almost as long, were dying due to the beetle. Trees once valued greatly for their timber were turned into dead trees, changing color to red and then grey as all foliage fell off.