Photo Credit: Recent aerial surveys captured alarming photographs of the tree mortality in and around Sierra National Forest, including the one shown here. At a recent workshop, FireScape Mendocino participants discussed the potential impacts of bark beetle infestations on the Mendocino National Forest that could lead to similar conditions. Photo by Sierra National Forest via Flickr Creative Commons

Years of drought in northern California are contributing to forest conditions ripe for bark beetle infestations on a much larger scale than the region has seen in recent history. This invasion of bark beetles is currently having incredibly destructive effects – over 100 million trees have died in California since 2010. Additional areas are predicted to experience further, massive tree die-off in the near future. Why is this happening? There are many factors at play, including climate change and its influence on many beetles’ lifecycles. These variables are exacerbated in times of drought. When drought-stressed, trees aren’t able to produce enough sap to prevent certain beetles, like the mountain pine beetle and other bark beetles, from boring through their bark, laying eggs and eating the cambium (the tree’s vascular system). Without an effective nutrient transport system, the weakened tree can die within a matter of weeks. The ripple effects of massive tree mortality span far and wide, including having serious impacts on forests and on the human communities nearby.

A close-up photograph of a beetle's entry into a pine tree, leaving behind sawdust over the pine tree's pitch.

When a tree can’t successfully produce enough pitch due to drought or other conditions, the beetle successfully enters the tree, leaving behind sawdust as the first sign of its entry.” Credit: USFS Region 5 via Flickr Creative Commons

Although this may seem grim, bark beetles aren’t all bad. Historically, they’ve provided a valuable role in maintaining forest ecosystems. Because they typically kill already weakened and/or diseased trees rather quickly, they can help speed up the process of ridding a landscape of its unhealthy trees, making room for healthier ones.

The proverbial scale has tipped, however, and things are out of balance. With so many trees being weakened by drought across California and the West, bark beetles are thriving and multiplying at staggering rates. More beetles combined with more susceptible trees make for a self-perpetuating cycle of tree mortality. With the increasingly extended periods of warmer-than-average temperatures and lesser-than-average precipitation that California is experiencing, large-scale bark beetle infestations are inevitable, and for the most part, they are unstoppable.

Although this problem has been characterized as originating in the Southern Sierras, it is moving north, and quickly. (Check out an interactive map hosted by California Tree Mortality Task Force for a visualization of this trend.) In the wake of this reality and with continued support of the Fire Learning Network (FLN), members of FireScape Mendocino are discussing ways to preemptively deal with this issue before it is in full swing. At a recent FireScape Mendocino workshop held in Paskenta, CA, nearly 60 local participants shared a day in the Mendocino National Forest, followed by an all-day meeting in the Paskenta Community Hall, trying to decide what to do with the dead trees once the beetle kill reaches the northern parts of the state. Aside from knowing that the area needs more controlled burning, some common themes emerged from the two days of dialogue, including:

  1. Too many drought-stressed trees exist within the boundaries of FireScape Mendocino’s mixed conifer forests to stave off a bark beetle infestation. As a result, widespread tree mortality is almost certain.
  2. Even without serious beetle kill currently, wildfire is already a serious threat to local human and forest communities within the project area.
  3. The science around what to do with bark beetle infestations is complex, can be contradictory and doesn’t always jive with land management plans and interest groups’ preferred actions.
  4. Despite all of this, the group recognizes that it has options as well as many knowledgeable resources to utilize when weighing the benefits and challenges of possible alternatives.
FireScape Mendocino participants discuss forest management concepts in the Upper Lake Ranger District. Credit: Kimberly Baker

FireScape Mendocino participants discuss forest management concepts in the Upper Lake Ranger District. Credit: Kimberly Baker

One of the discussions that arose during the workshop and continued over email afterward focused on the role that beetle-killed trees play in the future fire susceptibility of a forest like the Mendocino. The assumption is that an overstocked forest with many dead trees has an increased fire risk, but the group began to discuss an important question: Is that true? The answer is: It’s complicated.

The consequences of any management decision are important for everyone to understand, at least on a basic level. This remains true even if potential outcomes raise many more questions. Therefore, the group is also discussing the question, When trees die standing, do we leave them standing? They’ll eventually come down on their own. Standing, dead trees can serve many benefits to wildlife, but they’re dangerous to recreationists and to infrastructure. When dead trees do come down in dry forests like the Mendocino, they often create a jackstraw scenario, where trees don’t reach the ground when they fall. Since decomposition occurs mostly on the ground, this mesh of fallen, dead trees can linger in this position for decades, shading the ground and contributing significantly to fuel loading for both surface and crown fires. As one participant noted, Wouldn’t it be a relief to know that some thinning was done to help prevent these conditions we’re predicting? On the other hand, some new research suggests that increased biomass and fuel loading might not directly increase fire severity.

Workshop participants eating sack lunches in the forest.

Learning over lunch! Credit: Mary Huffman, The Nature Conservancy

So, the group is working through more questions: Do we thin the trees, and if so, how and how many? What do we do with the trees we cut? Do we leave them where they fall? Do we chip them? Do we haul them to mills? On lands designated for a certain extent of timber production, the potential exists to harvest significant amounts of board feet via forest thinning. Obviously, all of these options have an entirely unique set of tradeoffs, and the answers are almost never clear nor absolute.

Four participants having a field discussion.

Mendocino National Forest employees participating in the Field Learning Exchange answer questions about bark beetles and ways the forest can prepare for a likely infestation. Credit Mary Huffman, The Nature Conservancy

Community groups like FireScape Mendocino foster relationships and trust forged from respectful interactions among participants. Open and transparent workshops provide an opportunity to check assumptions and discuss a diversity of scientific and personal perspectives. A critical element in this group’s success is keeping the discussion moving, and involving as many voices in the dialogue as possible. Participants can leave with a greater understanding of the issues, and decision makers can know more intimately how the public feels about the important issues facing the lands under their joint care. Despite the numerous unknowns the group is facing, one thing is known for certain: An “all hands” effort is needed now, perhaps, more than ever!

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