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Prescribed fires

Out of the Blue and into the Black: reflections on riding in a prescribed burn

“Out of the blue and into the black, you pay for this and they give you that”-Neil Young

It’s a gorgeous early spring day in the White Mountains and as we look off to the southwest towards the seemingly endless sea of green trees, I notice columns of white smoke rising from dozens of spots across the landscape. Living here in the White Mountains for many years, I am certain that these columns of smoke are part of a “prescribed burn” (no longer referred to as a “controlled burn” for several reasons). I think that many of us are, in some deep-seeded way, attracted to fire, and I can’t wait for the day to be over so that I can go take a look since the smoke seems to be coming from areas very close to where I live and right in the area where I spend most of my outdoor time hiking and mountain biking: Land of Pioneers. Prescribed burns have an extremely important role in the care and management of Ponderosa Pine forest ecosystems. Impressively, the Coconino National forest of Arizona has the largest contiguous Ponderosa Pine forest in the world and the White Mountains contains additional millions of acres of pines. Ponderosa pines generally live in areas which receive 25 or fewer inches of rain a year and evolved with low intensity fires burning through stands every 5-25 years. Young trees up to approximately 5 years old are extremely susceptible to fire and low-intensity burns passing through the forest. The low intensity fires are essential both in reducing the number and density of seedlings and in reducing brush and ground cover that complete with the surviving seedlings. As trees mature, the older trees begin to lose their lower limbs, their bark thickens, and they become much less susceptible to fire-kill due to low-intensity fires. Regular low-intensity burning in a Ponderosa Pine dominated forest keeps the forest density lower, reduces ladder fuels which can spread fire to tree canopies and cause crown fires and helps desired grasses compete as an understory. Contrary to popular belief, the thick layer of pine needles in a Ponderosa Pine forest is essential to the low-intensity burns that the trees require. The needles block understory fuels from growing too close to tree trunks. Provide moisture-locking mulch for the tree roots and also provides the perfect avenue for a fire to smolder rather than burn with large flames. Pines are most flammable and susceptible to fire damage in the spring, when old dry needles have yet to be replaced by new needles and again in the fall when the trees are ready to shed dried needles for over-wintering. It is interesting that these times of year are when most prescribed burns are planned, causing the highest probability of tree fire-kill death. The ideal Ponderosa Pine forest would consist of well-spaced mature trees with lower limbs beginning higher than 10’ surrounded by thick layers of needles and sparce younger replacement trees of varying ages. Openings between trees groups would be covered in grasses and shrubby plants, understory growth limited by canopy shade. I worked on a USFS timber crew for over a decade and one of our primary tasks was to try to help re-create this ideal forest structure by marking “leave trees” to be spaced and grouped in this historically natural manner. The picture gets much more complex though when the Ponderosa Pine forest is at the edge of, and blending in with the more xeric Pinon-Juniper dominated forest. Immature Junipers tend to form an extremely brushy and flammable understory which quickly acts as ladder fuels, spreading ground fires up into the remaining lower limbs of the maturing pines. Young oaks, too, form thickets of dangerous ladder fuels and prevent grasses from being able to grow. This blending edge habitat is different in another way in the Land of Pioneers and Vernon area. Much of the Ponderosa Pine forest to the south is soil-based and has a good protective layer of needles. In the rocky Land of Pioneers area, many of the hills and ridges, including Ecks Mountain, Doyle Mountain, Wishbone Mountain, Timber Knoll and many more, are old cinder cone volcanoes and the trees are growing, but struggling to thrive, on a thin and sparce soil layer on top of porous cinders. The pine needles and soil in standard pine areas act as a buffer to the conductive heat of the fire and without ladder fuels, the radiant heat of a low-intensity fire cannot reach the canopies of mature pines and is easily blocked from the trunk by the thick bark. In an area in which the soil is more cinder-based, the heat from the smoldering sparce pine needles combined with the heat from burning juniper understory passes through the lose cinders and directly to the fine root hairs and mycelium webbing of the mature trees, causing nearly instant tree death from the bottom up, regardless of the thickness of the protective bark layer of a mature tree. It is extremely difficult to machine-log these steep-sloped slippery cinder cone mountains, and with increased fire suppression efforts over the years, they often have developed a thick, nearly impenetrable meshwork of mixed age pines, large older junipers, young, very flammable scrubby junipers, large fire resistant older oaks and young oaks providing an undesirably thick understory of ladder fuels. Complicating the issue even further, is the fact that fire burns uphill as the heat from the flames rises and dries material above it. Burning steep cindercones is difficult because it is nearly impossible to maintain a low intensity burn on these slopes. Every sample burn location on the exploratory Timber Knoll project resulted in high percentage fire-kill tree death. Burning at the base of these knolls, results in fires which climb quickly to the top and leave large fire scars. The fire scars to provide some fire safety protection but it takes decades for older fire-killed trees to fall and be replaced by younger trees, resulting in habitat loss and potential regrowth of juniper brush and undergrowth which often precludes any pine regeneration in those xeric areas. Timber Knoll was successfully hand-thinned several years ago, but the issue became the problem of how to remove the resultant slash and wood. Pile burning was tried with some successes and several failures, and in the end, most of the burned areas have been regrown in non-native plants and juniper scrub, with few to no young pine seedlings present. Cut fuel was left in place, overall probably improving individual tree health and fire defensiveness, but not the perfect solution to fire safety or habitat protection. Finally, spring is a conundrum for prescribed burning. In a natural-state forest, most fires would start just prior to, and during monsoon season with a lightning start beginning from a mature pine and spreading via slow-moving smoldering in pine needles from area to area until it is extinguished by the following rains. Spring is not the natural time for fires to start in a historic Ponderosa Pine forest and trees are vulnerable and flammable during this transition time between old winter needle drop and new growth. Birds are nesting on slopes and turkeys require the thick oak and scrubby cover to nest on the ground and raise vulnerable young. Elk are calving and in general, the forest is doing its major growing and pruning itself for the coming summer months. Spring is a good time for human prescribed fire ignition though, because of the low temperatures, remaining moisture from winter precipitation and relatively predictable wind patterns. The introduction of man and fire suppression into the ecosystem has resulted in thick hard-to manage forests and even harder to control fires moving quickly through the unnaturally thick underbrush and quickly into the crowns of the trees causing devastatingly large and intense forest fires. The USFS tries to use experience and science to mitigate all of these factors and has a final, and very difficult goal of trying to return our forests back to their natural state. So, having a bit of background on fire in Ponderosa Pine forests, let’s take a ride through a burn area. I am drawn towards the smoke and having already seen pictures fire near the Old Vernon Cabin, my first goal is checking on this old friend, which is fine. Heading out through the smoke towards where I can see active burning, I begin to mentally ask questions. We are taught to believe that “they” know what they are doing and to “trust the experts” but I start to wonder…why is this nice stringer of lone pines ignited? Why are these random sections of meadow burned? Why is that large old tree stump, cut over a century ago now smoldering and spreading the fire underground to continue burning until monsoons come? Why, when the forest was thinned earlier, was the ladder fuel stacked close to mature trees and then ignited? As I follow the LOP trail, I see that the fire fighters also passed through here, igniting spots along the trail with drip torches, seemingly at random. Perhaps the goal is to create burned patches to prevent possible future fires from being able to pass through, but the burned spots are less than a couple of dozen feet in diameter and seem to be in areas that are already open and fire-safe. Are we just burning spots to collect “acres treated” or are we really treating the area? I notice a large pine that has been ringed by drip torch and is already beginning to turn color as its roots are heavily damaged by the convective heat. I climb towards Ecks along the trail and find an interesting lesson in prescribed fire effectiveness. In the lower areas of the trail, the fire has behaved exactly as it should have. Low intensity fire has consumed small undergrowth and left a blackened matt of charred pine needles. The thinned pines have a few lower branches browned by the radiant heat and this is great! The fewer lower branches there are on the mature pines, the better for future fire suppression. The trail has acted as somewhat of a fire break and is a white line in the dark needles. Farther up, however, the story is different. Sections of fire-killed oaks dominate the trail edge and I wonder how these dry-leaved oaks are less effective as ladder fuels than their previous spring-green leaves? There is a large section of ground that has burned at extremely high temperatures, burned to bare soil and devoid of biologic matter, which will cause erosion issues once rains to do come. The prescribed burn on Wishbone Mountain resulted in devastating erosion and the depletion and loss of much of the soil present on portions of the burn. In this area I see that both large old-growth junipers and mature pines are dead, some fallen over, and I wonder again. How are standing dead pines, downed partially burned logs and bare ground, more fire-safe and healthier for the forest than standing mature pines and old-growth junipers? Just questions I have… Up on the higher inaccessible slopes, and ridgelines, I can see the silhouettes of completely burned stands of trees which were ignited by helicopter via “ping pong ball” drops. I was told that the drop lines of these ignition balls were planned so that the fire would burn to the top of the mountain to provide a buffer for the base but as fire burns upwards, I wonder… were the nesting turkeys and elk calves able to successfully move away from the blaze? Will the pines be able to reclaim their stands, or will junipers move in and take over? Questions to ponder. Making the descent through the “Slitherin” section, I look over to where some of the fire prep work was done. Last fall, there was some juniper and oak thinning done and the cut branches were left in long piles adjacent to the road. How did this fare in the burn? The piles are scorched but still partially present and the pines above them are largely dead from both the convective and the radiant heat of these burning piles. The primary thinning of the pine stands went well and the thinning of the understory was great, but the resulting fire-kill from the burning slash seems unnecessary. Why? Just questions I have… Take a ride or hike and make mental notes. Is this what benefits the forest most? Is it a good idea to burn all around a very popular trail at the height of tourist and riding season? Could these areas be burned in fall rather than spring so that the trees and animals have more chance at surviving until monsoons? Should 2000 acres of varied terrain and varied amounts of prep work be attempted at once, or should the less complex, flatter thinned areas and extremely complex cindercone slopes be treated as separate fire environments? Is it worth it to fire-kill trees on the cindercones as fire prevention if the flatter surrounding areas are treated and thinned back to their open-forest state? Just questions to ponder. Disclaimer: The opinions expressed in this essay are solely those of the author and are based on experiences working with the USFS on a timber crew, discussions with both timber and fire employees of the USFS and observations over two decades of living, working, riding and hiking in the Apache-Sitgreaves National Forest.


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