Maxwell Creek Watershed Project Field Files Part 5: Experimental forest restoration methodologies
Transforming tree-farms into forests.
Tal Engel lives in the Comox Valley on land called Honey Grove where he practices ecoforestry and manages an organic (ecologically-oriented) apiary and farm alongside his wife and daughter. Tal’s involvement with the Maxwell Creek Watershed (MCW) project began serendipitously.
Though not a frequent radio listener, Tal happened to catch a segment of CBC’s Climate Changers on which Dr. Ruth Waldick, initiator of the MCW project and Director with Transition Salt Spring (TSS), was being interviewed. Waldick’s description of the need for innovative restoration regimes to reverse the degraded state of coastal forests in British Columbia, called to him through the airwaves.
After reaching out to Dr. Waldick, Tal learned the MCW project team was in the midst of researching novel methodologies to mitigate the significant fuel loads that TSS’s Maxwell thinning experiment would generate. This introduction to the team also acquainted Tal with Erik Pikkila, a veteran forest ecologist and scholar whose impressive well of knowledge has been, and continues to be, an essential contribution to this body of work. Together this community of practice has been developing new approaches to manage growing concerns around the degraded condition of BC’s forests.
Over a century of aggressive logging practices, fire suppression, and myriad additional disturbances, have resulted in a major loss of ecological functionality within BC’s forests. Mechanized logging, in conjunction with slash burning practices (or out-of-control wildfires, where too much slash remained) and salvage logging, have resulted in the near-total depletion of once seemingly inexhaustible carbon banks of Coarse Woody Material (CWM (sometimes also referred to as Coarse Woody or Large Woody Debris (CWD/LWD))—a foundational and essential element of healthy forest ecosystems. Combined with high fuel loads, lacking structural complexity, poor hydrological regulation, and severe overdensity, many forests would be more aptly described as tree farms or tree plantations due to their profound ecological deficits.
Coarse/Large Woody Debris: Sizable dead wood structures in various stages of decomposition.– Tal Engel
Excluding the miniscule proportion of coastal old-growth remaining in this province, the majority of BC’s forests are somewhere between 20 and 80 years old, and exhibit such conditions. The public attention old-growth logging has recently received, though well deserved, has had the subtle but pervasive side effect of causing protection of younger forests to be overlooked. Old-growth forests capture the public’s imagination in a way that second and third-growth forests may not, but these younger, mostly replanted forests also need to be managed with care. To mitigate the worst effects of climate change and ensure ongoing provision of vital habitat and economic (e.g. tourism, lumber, etc.) services, second and third-growth forests must be protected and restored. To convert a tree farm into a forest takes a fraction of the time and effort it would take to grow an ecologically functional forest from a clearcut. Younger forests that are being cut wholesale across the province might be our last chance—one that is rapidly being squandered.
Climate change is quickly becoming the linchpin in the story of BC’s forests. Though so many forested ecosystems have experienced profound biodiversity loss and interruptions of key ecological processes, widespread public concern has been lacking. However, the new reality is that in many cases these tree farms have become tinderboxes, at risk of burning in ruinous, unstoppable fires, the likes of which consumed Lytton following the 2021 heat dome. Further, the intensive water consumption (up to 50% higher than old growth forests, in some cases) of tree plantations coupled with their limited hydrological regulation capacity, exacerbate drought/flood cycles that are increasingly severe.
If the effects of climate change were less immediate and/or the current state of forests less degraded, the natural decomposition of wood might be enough to neutralize the threat of excessive fuel loads. Unfortunately, this is not the case. The last few years of unprecedented and once-in-a-lifetime environmental catastrophes have instilled a sense of urgency to change business-as-usual practices. From the heat dome and associated fires, to the atmospheric river and subsequent flooding in BC’s interior only four months later, to an eerily delayed summer in 2022, which turned into a nearly six-month-long drought, the writing is on the wall: This world is not as it was. We must adapt or face the consequences.
The difference between conventional and ecological forestry
What differentiates ecological forestry from traditional production forestry, is a rejection of the notion that humans can do better than Nature. Conventional forestry seems to operate on the idea that Nature is somehow flawed, and that we can fix it and make it better, or more productive. Conversely, ecological management practices are based on research into natural disturbance and succession regimes in unmanaged forest ecosystems. With the exception of the scant remnants of old-growth forests in BC, most forests have been logged at least once, often twice, and even three times in some cases, over the past 150 years. Even for ecosystems that naturally experience frequent disturbance (e.g. dry interior frequent-fire forests), humans have imposed an overly intensive disturbance regime. Thus, the key to undercovering Nature-informed forest restoration regimes lies in post-disturbance ecology.
Transforming ecologically barren tree farms into forests
Ecological thinning treatments, such as Variable Density Thinning (VDT), are primary means of restoring a degree of resilience and ecological integrity to forest ecosystems. Such treatments involve thinning dense forest stands, selling off a proportion of marketable logs to offset the costs of restoration, and what is left from the thinning treatment is burnt in large slash piles. Often, when possible, a controlled burn will be prescribed to further reduce fuel loads and enhance the forest’s fire-resilience and structural complexity (especially in terms of ladder and fine fuel reduction). This approach reestablishes structural complexity while reducing fire risk and creating ashes which reinvigorate soils and encourage regeneration. In many ways, this approach effectively replicates natural disturbance and succession regimes. However, a major shortcoming is the removal of the majority of slowly-composing CWM structures from the forest ecosystem.
Ladder fuel: Mostly made up of low hanging, dry, dead branches, ladder fuels provide the opportunity for ground fires to climb upward, into the canopy, where both their intensity and their potential to spread uncontrollably drastically increases. High concentrations of small-diameter trees, both living and dead, are another typical upward vector for ground fires.– Tal Engel
CWM increases forest moisture retention potential and fire-resilience, provides habitat for countless organisms, and generates organic inputs that dramatically improve forest soil health and nutrient availability. Unlike clearcuts, natural disturbances, even extreme and rare wildfires, leave behind biological abundance which supports regeneration. However, the replacement of slowly decomposing CWM with ash means the long-term legacy of CWM is lost . Though ash can be an important soil input, its contributions are comparatively short-lived. Ash, being highly dissolvable, doesn’t stick around when there isn’t enough CWM and organic-matter soil content to absorb it. In their commonly degraded condition it is likely that much of the nutrient and mineral content of ash would be lost from forests and potentially pollute water sources in the process.
Another shortcoming of burning slash piles and CWM is the release of large amounts of carbon which would otherwise be stored in the soil or only very gradually released. Finally, the production of high levels of smoke and potentially harmful airborne particulates can exacerbate the already significant challenge of persuading the public, especially those living in wildland interface communities, as well as regulatory bodies, to accept prescribed burnings, which in some ecosystems are necessary.
As noted throughout the Field Files series, the forests of the MCW are representative of the dense and even-aged second and third growth Coastal Douglas-fir forests found throughout the Gulf Islands. These forests are remnants of intensive logging and ecologically bereft management practices. The MCW project seeks to moderately reduce canopy closure by thinning out dense stands and by so doing reintroduce biodiversity and ecological integrity to the landscape while reducing fire risk. However, this work presents a new problem: managing increased fuel loads (i.e. CWM) resulting from thinning work. Tal’s work aims to provide solutions to this problem.
Two techniques, Assembled Nurse Logs (ASNLs) and Mycelial Grafting, will be tested with the intention of providing demonstrations of ecologically-oriented options for managing fuel loads in-situ. Test sites will be established in the field by Tal under Dr. Waldick’s leadership with the assistance of Grace Fields, a Sustainable Resource Management student who works with TSS. Sites will be established in early March 2023, shortly following the first thinning treatment.
The Assembled Nurse Log technique and Mycelial Graft procedure were developed as an alternative to the shortcomings of commonly practiced approaches such as VDT. They are informed by a restoration philosophy founded on two core tenets: 1) Imitate nature as closely as possible and 2) Transform the forest’s problems into solutions. The conditions that qualify so many of BC’s forests as tree farms can be used as building blocks to transform ecological deficiencies into ecological abundance. That is, those materials constituting overdense forest structure can become the growth engine behind the forest’s ecological rebirth.
Put simply, the primary goal of the proposed techniques is to safely, effectively, and, most importantly, ecologically manage potentially hazardous fuels. This is achieved by creating conditions that exert maximal mycelial decomposition pressure upon post-thinning fuels. Considering the risks of wildfire, it is easy to understand the motivation to aggressively thin and burn all excessive forest “fuel.” Yet, there is so much potential in natural fungal decomposition to minimize fire threat in a manner that safeguards carbon stores and ecological processes. As any organic farmer knows from their experience with practices like composting, mulching, and cover-cropping, there are countless simple ways to augment and hasten natural decomposition processes. This forest restoration regime is a marriage between ecological forestry and organic agriculture principles.
It is essential to stress here that nothing can replace the key ecological processes decomposing old-growth trees facilitate, however, it takes hundreds of years for trees to grow, die, fall, and decompose sufficiently to perform this role. It is hypothesized that the methods described here, which will be tested by the MCW Project, have the potential to accelerate maturation toward old-growth conditions, while simultaneously providing surrogate structures until such conditions develop naturally.
Assembled Nurse Log
The ASNL technique is inspired by both old-growth ecological structures and agricultural decomposition-augmenting methods. It is designed to replicate a segment of an old-growth diameter nurse log (generally ~70 cm+ in diameter, but this can vary depending upon stand condition) using smaller diameter wood. As previously mentioned, this structure is designed to exert maximal mycelial-decomposition pressure and minimize the structure’s flammability. This is achieved by layering logs, branches, and wood chips and introducing new mycelial colonization vectors. All fuel categories (i.e. branches, small-diameter logs, and medium-diameter logs), with the exception of the large-diameter log category, are incorporated into this structure.
To prevent an unnatural scenario in which the forest’s nutrients and moisture are excessively aggregated in ASNL structure areas, to the detriment of other parts of the stand, it is important to leave a proportion of medium (10~30 cm) and large (30 cm+) logs diffused throughout the forest. These logs should be limbed and bucked to an appropriate length, which maximizes soil contact and thus moisture retention and decomposition. This should be practiced with moderation to prevent excessive fuel loading. A proportion of large logs will be subjected to the Mycelial Graft procedure (described below) to accelerate decomposition.
All of the materials needed to assemble an ASNL are generated in the process of thinning an overly dense stand. Ideally, they are gathered shortly after or during the thinning process. As a prime example of transforming the forest’s problems into solutions, the fine fuels generated during thinning, which are the most flammable fuel category, are converted into moisture retaining, fire retardant elements: small diameter trees (2.5~10 cm) are chipped, and branches are utilized as insulative air traps in the moisture seal that surrounds the structure. That the fine materials most liable to spark a fire become an insulative blanket that protects CWM from combustion is true alchemy.
Putting it all together
Mycelial Grafting procedure
In contrast to the ASNL technique, which is designed to accelerate the decomposition of fine-medium fuels, the Mycelial Grafting procedure is designed to accelerate decomposition of large diameter fuels. It can be argued that treating wood of this diameter is unnecessary, since coarse fuels do not typically act as ignition sources. However, an overabundance of un-decomposed, dry, large-diameter fuels can certainly accelerate and exacerbate a burning fire. More importantly, since BC’s forests are already critically deficient of CWM structures, particularly those that are significantly decomposed, accelerating large-diameter fuel decomposition is an important goal. This procedure simultaneously reduces the forest’s fire-severity potential while expediting the reestablishment of impaired ecological functions.
This method is also inspired by natural forest processes. The crevices created imitate the essential primary deconstruction work that woodpeckers do, hence the name “woodpecker crevices.” Even prior to grafting, these crevices, like their natural counterparts, expose deeper layers of wood to mycelial colonization, accelerating the log’s decomposition rate and creating essential habitat for myriad organisms. However, when the crevices are Mycelially Grafted, the process is further accelerated and results in a more efficient fungal colonization of the log. To avoid creating waterlogged anaerobic conditions in the crevice, a perpendicular drainage slit is cut.
A typical Mycelial Graft consists of a mixture of old-growth inoculant (highly decayed and fungal-colonized wood from old stumps and logs), with needle-rich wood chips from recently thinned materials. The old-growth inoculant serves as a moisture retaining medium, as well as a source of existing fungal hyphae and spores, while the fresh chips and green needles serve as fungal food and a nitrogen source to further facilitate breakdown. Each grafted crevice can be thought of as a fungal garden, in which the inoculant serves as both the soil and the seed, while the chips and needles are the fertilizers and soil amendments. The result is the ideal fungal habitat grafted directly into a log’s heartwood. This means fungal decomposition pressure can be promptly exerted without first penetrating the natural defenses of bark and outer wood layers.
An optional final touch in sites with an abundant moss layer, is to press moss into firm contact with the mycelial grafts. This is expected to increase the log’s moisture retention and decomposition rate, and may provide better habitat for some critters.
Complementary alternative methods
To maximize ecological integrity within forest stands where methods like the ASNL are being implemented, Tal recommends incorporating a suite of additional commonly used methods, such as understory restoration (or “underplanting”) and creating wildlife trees (or “snags”). These complementary methods are outlined in more detail below.
Biodiversity is expected to naturally increase following a thinning treatment, especially when complemented by techniques outlined here. However, some species, especially long-absent tree species with remote seed sources, may be unable to naturally find their way back to the stand. Underplanting can help to re-establish species diversity. While understory species, like salal, Oregon-grape, huckleberry, salmonberry, and others, may be better able to naturally re-establish due to seed dispersal by animals, and might not require human intervention to be reintroduced, some additional planting may be helpful. Certain underplanted species require browsing protection such as fencing.
For the most part, second and third growth Coastal Douglas-fir forests are composed almost exclusively of even-aged, single canopy Douglas-firs. These forests typically lack a diverse understory shrub layer, as well as a shade-tolerant midstory tree layer. Deciduous/broadleaf species are also usually missing from these stands. Western redcedar and coastal western hemlock have significant ecological roles to play in coastal forests. These species enrich soils with their basal leaf deposits, and can be easily reintroduced due to their high shade-tolerance. Grand fir requires moderate light, and a population can be established in forest openings created by thinning techniques along with native broadleaf tree species including Pacific crab apple, bitter cherry, cascaras, maples, alders, and others. Even if these underplanted species cannot outcompete the existing Douglas-fir cohort, establishing these species in the stand is likely to create a seed bank and provide an opportunity for a population to eventually flourish as natural mortality occurs.
Undisturbed forest ecosystems are typically rich in both downed and standing CWM. Standing CWM, or standing dead trees (i.e. snags), provide critical habitat for cavity-nesting species. While ecological thinning treatments almost always avoid removing the largest trees, some medium-diameter trees can be girdled, rather than be downed, during the thinning process to create intentional snags. While these snags are unlikely to be ideal habitat for larger-cavity dwellers, and are less durable than larger-diameter snags, they can still provide viable habitat for some species and are a good option when working toward establishing ecological integrity in young forests.
Girdling : A practice of severing a tree’s cambium and phloem layers.– Tal Engel
Intentional snags are most appropriately introduced when falling a tree could be complicated or dangerous, or when caution is required due to the proximity of underrepresented tree species, valuable larger snags and stumps, or built infrastructure that might be damaged by falling trees. It is important to employ this technique in moderation to avoid accumulating an excessive fuel load.
A related restoration method is the creation of “microsnags” or tall stumps. While the creation of snags is common practice in ecoforestry, microsnags are a method developed by Tal. Shorter than snags, and taller than typical stumps, microsnags provide habitat and feeding sites for various forest dwellers (e.g. woodpeckers, insect borers, etc.) and offer an elevated spore-releasing surface through which fungal fruiting bodies can spread spores via wind more effectively than would be possible from shorter structures.
Ladder fuel limbing
Monocrop, even-sized, Douglas-fir forests younger than 60, on average, often have high volumes of low-hanging, dry ladder fuels since they have not had sufficient time to self-limb. The low humidity level in such stands (compared to old forests) limits decomposition, increasing the flammability index of ladder fuels, while delaying self-limbing timelines. Furthermore, despite typically being dead and needleless, the high density of low-hanging branches shade an already light-starved forest floor. Though ecological thinning treatments are, in essence, designed to increase light penetration, the light-depriving effect of ladder fuels is often overlooked, with fuel-management typically being the sole perceived benefit of ladder-fuel treatments.
Limbing every tree in overdense “dog hair” forests can be a daunting task, and therefore should only take place after thinning has occurred. This significantly reduces the quantity of trees that require limbing. Under a conventional ecological treatment framework the large accumulation of dry branches would pose a significant fire-hazard if not immediately burned. However, when coupled with the novel approaches laid out here, the accumulated branch woody debris are a valuable moisture-retaining substrate when chipped or incorporated whole into the ASNL moisture-seal.
Experimental alternative methods
In addition to the methods described above, Tal has been experimenting with a number of additional techniques to reintroduce complexity to the forests under his care.
Honeycomb Matrix thinning
VDT treatments typically seek to establish structural heterogeneity by creating gaps (clearings) and skips (untouched areas), with each category constituting 10-20% of the stand’s area. The remaining 60-80% of the stand is referred to as the “matrix.” The most common approach for thinning the matrix follows production forestry methods, which are generally not ecologically oriented. The alternative Honeycomb Matrix method, currently under development, draws inspiration from the structure of honeycomb. Its intention is to introduce structural complexity not only in a stand’s skips and gaps, but also in the matrix, which represents the vast majority of a stand.
The main difference between spaces created within “cells” of the honeycomb matrix, and VDT gaps, is their scale. While a VDT gap is large enough to prevent canopy closure by surrounding trees, and will remain open until sufficient regeneration occurs, honeycomb matrix gaps are small enough to eventually (though it may take a long time) be closed by the elongating canopies of surrounding trees.
Diagrams by Tal Engel.
Cedar Rehabilitation Protocol
On the tail of the total annihilation of BC’s white pine population by blister rust, and the significant impact of bark beetle on interior pine populations, another foundational conifer is in trouble. Moisture-loving western redcedar is at significant risk due to climate-change induced droughts, whose effects are exacerbated by the nutrient deficient conditions left behind by decades of industrial-scale forestry. In the case of western redcedar, depleted calcium is particularly harmful, as this species depends on calcium for hydrological function and overall health more than other species.
A riddle: although close in age and growing only 10m apart, why is the redcedar on the left still alive to its top (albeit stressed), while the redcedar on the right is alive only in its lowest branches?
Unlike the delving taproots of Douglas-fir, redcedar root systems are diffuse and shallow, and thus disproportionately affected by surface moisture levels compared to other species. Moisture retention within topsoil is heavily influenced by the presence of CWM, which both increases organic matter and nutrient levels and creates large-scale moisture capacitor structures.
Tal is currently experimenting with a three-pronged (or “trident”) procedure designed to protect, and perhaps (in some cases) reverse redcedar decline. The nature of redcedar mortality is counterintuitive: large, established trees die from the top down (“topkill”), while small trees survive, this due to an inability of tall redcedars’ to pump dwindling water supplies all the way to their tops using depleted calcium stores.
The trident approach applies a combination of the methodologies described throughout this article, with a direct focus on improving outcomes for western redcedar populations. The three approaches employed to this end include:
- increasing CWM accumulation (via establishment of ASNLs, Mycelial Grafts, Intentional and Microsnags, and diffuse chipping) around established redcedars,
- spreading wood ash (which contains ~25% calcium), and
- long, high-surface area, low branch limbing.
Low branch limbing, in particular, has potential to immediately mitigate symptoms by lowering the redcedar’s overall evapotranspiration requirement, conserving hydrologic pressure for the most afflicted canopy segment (i.e. higher branches). The small woody debris produced in the limbing process also provides a calcium-rich chipping medium. Though these three approaches are best implemented together (i.e. ashes are best deposited in CWM structures (e.g. ASNL) to limit leaching, and calcium rich redcedar foliage is best chipped (into the ASNL and diffusely)), they can each be implemented separately based on the restoration practitioner’s available resources. One final element to be considered when working to improve redcedar condition is southern-aspect shading. Being highly shade tolerant, it is best to limit thinning south of redcedars to provide shade and increase the moisture content of surrounding soil.
Ash application and collection
It is now widely understood that fire suppression has had significant impacts on forest ecosystems across BC. Yet, there are many sites where reintroduction of fire would be incredibly dangerous due to widespread loss of fire-resilience and high woodland/residential interface. There is another opportunity for infusing forests with nutrient-rich ash without open burning, however: wood stoves! While some households use ash as a soil amendment for gardens and fields, most do not make any use of it at all, and instead dispose of it. There is a significant opportunity to return ash, generated from wood, to the forest, completing a cycle of reciprocity.
Ash is incredibly concentrated. An entire winter’s worth is unlikely to exceed the volume of a typical residential garbage bin. To bring an ash application methodology to scale, a collection initiative would likely be required. For those who do not have forest lands to restore, such an initiative would provide an ecologically-oriented alternative to dumping their ash in the trash. A single truck load of ashes could potentially benefit vast tracts of forests. To minimize run-off and potential leaching into surrounding water supply, ashes can be incorporated into ASNL structures, but simply spreading them around older redcedars and newly planted trees, as well as lightly diffusing them throughout a forest during growing season could still have far-reaching benefits.
The role of community
All of the methods described in this article are labour intensive. Though there are employment opportunities under an ecological forestry model, community volunteers can take these methods a long way. Much of the work undertaken on Tal’s property has been performed by a community of dedicated international volunteers. There are countless people out there who feel hopeless and overwhelmed about the state of our planet. These feelings can breed paralysis and despair. Taking meaningful, on-the-ground action has the power to lighten this burden. This work can be made simple and accessible for the average person. It is a way for people and communities to contribute to climate change adaptation with their own two hands through ecosystem restoration.
Myriad employment opportunities could arise in a ‘restoration economy’ from the widespread adoption of ecological-informed forestry practices. As an example, there are thousands of highly capable and motivated tree-planters who might be disillusioned with endlessly planting monocrop, ecologically barren tree-farms that will be promptly harvested. Or they might just be looking for work during the off-season (though this work can take place any time, it ideally occurs in winter when possible). Tree planters have a potential to become a firm backbone of forest restoration endeavors.
Outcomes of treatment
Because the outlined methodologies are designed to replicate biological legacies following significant natural disturbance, their benefits also extend into stand developmental trends, habitat and biodiversity establishment, biological resilience, structural and functional complexity, soil enrichment, and fire and hydrological regime regulation. Varying degrees of implementation of the different methods described will result in a sliding scale of benefits; however, even when certain elements are omitted, if the overarching vision is upheld, a significant proportion of these beneficial effects are likely to be conferred. For the purpose of this discussion, a full implementation of the restoration regime will be assumed.
As discussed throughout this article, this treatment regime is designed to increase forest resilience in an ever-deteriorating climatic reality. Similar to organic agriculture, it is designed to foster overall forest health rather than focus on mechanical/chemical solutions for specific problems. In other words, the proposed treatments could increase the probability that forests will reach an old-growth state with as many integral ecological functions intact as possible.
A very tangible measure for this is the development of large trees growing at a lower density with a more heterogeneous size-class and species composition—hallmarks of old-growth forests. Such well-established trees can withstand environmental pressures—from pathogens, to invasive species, to drought, flood, windthrow, and most importantly, fire—far more effectively than small trees, and are far more efficient in their water uptake and usage. More light, less competition, increased soil moisture and nutrient levels, and numerous other factors, are conjectured to greatly accelerate large-tree development under this regime. An increase in biodiversity following these treatments is likely to mean that, as the forest matures, a higher proportion of essential players will be present and well-established.
It is important to note that most methodologies and procedures outlined in this article are still experimental. Some will be implemented in the course of the MCW project. The Climate Adaptation Research Lab has been established under the MCW project umbrella to monitor pre- and post-treatment changes and demonstrate/share potential benefits with practitioners and the broader community.
For a forest to be both mature and healthy, it must first survive. Fire-resilience is thus a crucial factor. There are many variables that determine a forest’s overall fire-resilience, but a handful are especially crucial: tree diameter, overall moisture retention potential, fine fuel volume, species composition, and structural attributes—particularly overall density, canopy closure rates, and ladder fuel conditions. When assessing a stand’s fire-resilience based on these variables, it is evident that the proposed treatment regime could have a profound effect.
Both localized and diffuse moisture levels are expected to increase following a wide scale implementation of ASNL and Mycelial Grafting procedures, which would be of particular importance throughout the drought seasons of summer and fall. As these structures decompose, the stand’s overall moisture-retention is likely to increase. Reemergence (or planting) of soil-building tree species and the understory shrub layer provides additional moisture-insulation for soil, aiding in fire suppression–particularly if practitioners focus on reintroducing species with a low flammability index. By incorporating them into ASNL structures, fine fuels and ladder fuels can be transformed from a threat to a safety-measure, both limiting the probability of in-stand combustion and preventing off-stand ground fires from climbing into the canopy. Further, the treated stand’s heterogeneous structure and composition are expected to prevent off-stand crown fires from increasing in intensity, and may even prevent them from spreading further into the stand. Finally, large-diameter trees are orders of magnitude more fire-resilient due to their thick bark, low surface area to volume ratios, and tall canopies.
Hydrological Regime Regulation
The effects of any restoration regime on hydrological functions must be considered. The critical role ecologically functional forests play in hydrological regulation cannot be overstated. Presence and proliferation of CWM structures in various stages of decay, combined with level of biodiversity, tree size, and stem density are important variables in determining the cumulative hydrological regulation potential of a forest. For example, the reintroduction of deciduous species, which are more efficient water users than their coniferous counterparts, and contribute to soil organic matter content, should have a positive hydrological effect. Similarly, a reestablished understory and shade tolerant redcedar and hemlock midstory provide rain interception layers that slow drip rates, thus reducing soil compaction, and increasing soil water retention. Reduction in tree density and the resulting heterogeneous forest structure and expedited growth of large trees, should also have a significant effect. Large, deep rooted trees are generally more efficient in their water usage, and are capable of accessing and redistributing deeper groundwater deposits than smaller trees.
Finally, soil organic matter content and CWM structures (e.g. ASNL) act as natural dams and sponges that facilitate moist conditions. It is here that the proposed regime should have the most significant advantage in terms of hydrological regulation compared to other methods. When thinned wood is redistributed back into the forest rather than being burned or harvested, then its hydrological potential has been maximized. An increase in both soil and air moisture can be expected once sufficient decomposition takes place. When implemented across an entire watershed, these structures are likely to have a significant rainwater-interception effect, yielding a more balanced hydrological regime to buffer against both floods and droughts.
Habitat and biodiversity
It is hypothesized that practically every layer of the ecosystem will benefit from the proposed restoration regime—from bacteria to apex predators. For herbivores (e.g. deer), omnivores (e.g. bears), distinct predators (e.g. eagles), and the many bird and invertebrate species in between, the understory is a fundamental part of forest food chains. The surge of light and enhanced moisture and nutrient regimes provided by the proposed treatments should result in a revitalization of the understory. However, it is in terms of habitat provision that the wildlife potential of this regime truly shines.
The concept of “life boating” refers to structures that sustain small populations that depend upon them after severe disturbances, like a lifeboat safeguarding survivors after a shipwreck. Ecological lifeboats allow certain species, which would otherwise be entirely wiped out of an area, to survive. If/when surrounding conditions improve these survivors function as “seeds” to repopulate the area. When life boat structures are absent, as is the case with clearcuts, repopulation can take a very long time, and in some cases it does not happen at all. For example, amphibians and other drought-sensitive species may find ideal habitat in an ASNL structure during drier months.
In addition to climatic stressors, forests are grappling with increasing competition from invasive species. Poor overall condition make forests more susceptible to invasion. Common invaders like English holly and Scotch broom tend to be more prevalent in more degraded ecosystems. Likewise, bacteria and pests tend to be more impactful on already-stressed individuals. For example, arbutus trees have historically peacefully coexisted with a number of bacteria and fungi, but under changing climatic conditions are becoming more susceptible to their impacts, resulting in root rot and defoliation. Restoring ecological integrity to forest ecosystems is the best way to prepare them for worsening climatic conditions and potentially new or intensifying biological invasions.
As noted earlier in this article, continuous cycles of intensive harvest have resulted in a dramatic decline, and, in some cases, the complete loss of many essential soil-building species. Forest soils are now critically depleted of essential components and nutrients. Nitrogen is a prime example. Salmon were once a significant nitrogen source, with salmon caracasses being carried into ecosystems by predator species including bears and eagles. Salmon are now far less abundant. Similarly, once virtually omnipresent nitrogen-fixing cyanobacteria and lichens (e.g. Lungwort (Lobaria Pulmonaria)), are no longer significant nitrogen contributors. Finally, alder trees, having been targeted by production foresters for decades using aggressive herbicides (Roundup) are another dwindling nitrogen-fixation source; even where they haven’t been exterminated, excessive cash-crop tree competition has wiped them out.
This treatment regime, particularly thinning combined with the two MCW project experiment methods (ASNL and Mycelial Graft), and the reintroduction of essential understory species, is hypothesized to increase soil fertility and integrity. Large volumes of decomposing wood, both above and belowground, are expected to provide a slow release of essential nutrients over time. Perhaps by reestablishing ecological integrity, essential nitrogen-fixing species like Lungwort will reemerge on the landscape. Additionally, planting soil-building tree species like maple, alder, willow, redcedar and hemlock is likely to help increase soil nutrient levels as time passes.
About Tal Engel
Tal Engel lives in the Comox Valley on land called Honey Grove. There, ecology is the name of the game: from two ecotourism venues, Elderwood Yurt, and Rose Cottage, to an ecologically treated demonstration forest where tours are held, to an organic (ecologically-oriented) apiary and farm, everything that Tal and his wife do is dedicated to seeking a new balance between the human and the natural. The relationship between forest and farm has, hitherto, been a violent and abusive one; but on Honey Grove, Tal hopes to form a new kind of relationship—a reciprocal, sustainable, and productive bond in which an ecologically enriched forest offers a significant portion of the farm’s inputs. If you are interested in visiting Honey Grove or have questions about the methodologies outlined in this article, please contact Tal.
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