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October 8, 2020 – As our state continues to grapple with the most intense fire season in recorded history, views of fire and their drivers, roles, and impacts have once again been thrust into the spotlight. We here in Nevada County are all too familiar; the Jones Fire undoubtedly left scars—both physical and emotional—on the Nevada County community, and so close to the burn scar of the 2017 Lobo Fire and the 1988 49er Fire.

This happened even as private landowners and public agencies in our region have continued to expand forest management projects to reduce the chance of just such an outcome.

In fact, we here at Sierra Streams Institute (SSI), a local citizen-science, education, and restoration group also suffered a total loss of our office and equipment in the Jones Fire. But as we and others in our community look toward rebuilding and recovery, it is important to once again reflect on our relationship with fire and its role on our landscape, and use the response of both our community and our forest to further understand what it means to be resilient.

Figure 1

Resilience is a term tossed around a lot in the context of fire, and for different reasons. Forests and people are just two examples of entities that can exhibit resilience. In both cases, resilience is actually a quantifiable trait; resilience is the ratio of recovery from stress to resistance to that same stress (Figure 11). We can think of this as, in trees for example, growth after the stress divided by the change in growth because of the stress. Forest resilience to fire is thus a function of both the immediate reduction in traits like tree growth, carbon storage wildlife community diversity, and soil nutrient turnover, as well as the vegetative re-growth, wildlife re-colonization, and boon in carbon uptake that comes from increased light availability on the forest floor the following season. Resilience is about more than just damage. It is about recovery and rebirth.

This resilience is no accident; millions of years of fires have driven the evolution of Sierra ecosystems. Fire ecologist and historian Steven Pyne has pointed out that fire and the ecosystems that it helped to create cannot be separated: “fire’s environs make its very existence possible. Describe fire’s setting, and you describe fire”2. Forests of the Sierra Nevada were forged in fire. Reconstructions of fire return intervals (the length of time between burns) in pre-settlement forests based on fire scars in tree rings point to fires occurring as often as every 5-11 years in forests like those surrounding Nevada City3-5. And that is only the result of fires that burned hot enough to scar trees but not enough to kill them. Many Sierra plant species either require fire directly to reproduce (such as the majestic endemic Giant Sequoia), or are negatively impacted when reduced fire occurrence allows other, less-fire tolerant species to outperform them (such as fire-intolerant white fir outcompeting the ubiquitous but ecologically and economically significant Ponderosa Pine). These species exemplify resilience; their very way of life is dependent on burning and rising from the ashes.

A classic ecological hypothesis posits that diversity in many ecosystems is governed by disturbance, with the highest levels of diversity being found in locations with intermediate levels of disturbance. This “Intermediate Disturbance Hypothesis”6 does not always hold true, but fire-prone ecosystems serve as real-world examples of its applicability. High-severity fires are often termed “stand-replacing” fires because they kill everything; mature canopy trees and understory vegetation are all lost, and often the organic soil layer and seedbank are heavily damaged due to heat intensity. Thus, diversity in these systems can often depend entirely on the ability of some “pioneer” plant species to colonize the scorched landscape, which can take years. Low-severity fires, meanwhile, consume overly dense leaf litter on the forest floor, rapidly mobilizing nutrients and removing low herbaceous fuels to allow new seed germination. But these new seedlings are then competing for light in the limited gaps available under a dense mature canopy. “Mixed-severity” fires—with their mosaic pattern of high-severity patches mixed within a low-severity background—provide the best of both worlds via forest floor recycling and new germination but with a few bigger gaps for the next generation of trees to take over. Forests of the Sierra Nevada are resilient to fire, but in particular are resilient to these mixed-severity fires, which shaped what they are today. The Jones Fire was no different; mapping fire severity has shown a mosaic of high severity and low severity areas (Figure 2) in a landscape that was overdue for just such a fire.

The natural balance of “fire-tolerant” and “fire-intolerant” species was historically maintained via natural lightning-ignited fires, and later through cultural burning practices implemented by native people. But following colonization during and after the gold rush, fires began to be viewed as a direct threat to human life and property, leading to a policy of total fire suppression, as well as a move away from cultural burning practices. The evidence from decades of study of this policy is clear: as fires were immediately suppressed, densities of small stems, fire-intolerant species, shrubby fuels, and surface fuels reached unprecedented levels, leading to the fuel-laden tinderboxes we have today. These overburdened forests have inherently lower resilience than historically stocked forests, as dense fuel loads lead to high-severity stand-replacing crown fires that kill all trees and scorch the soil and seedbank, delaying recovery for many years as opposed to simply resetting the system for native plants to germinate the following season.

Burn severity map of the Jones Fire

The realization that a century of fire suppression has resulted in near-catastrophic declines in forest resilience to fire is not new. The National Park Service had implemented a “let burn” policy for wildland fires beginning in the 1970s based on the recognition of fires significant ecological role. But fear of fire, primarily in the wake of the 1988 Yellowstone fires and driven by media coverage of fire damage, has already led to weakening or full cancellation of those policies. Recent policies have slowly begun to re-integrate “let burn” policies, and success is being seen in wilderness fires, allowed to burn when far away from human habitation.

There are two opposing views of fire in western forest ecosystems. One casts fire as a threat and a danger, but one that can be attacked or controlled via human cleverness, ingenuity, and persistence. The other views fire as an integral part of a functioning forest system that is inherently beyond our control. The former view may be referred to as utilitarian, while the latter can be viewed as ecologically-informed but potentially idealist. The reality in a community like ours is somewhere in between. The wildland urban interface (WUI) is the boundary between developed communities and wildlands. Nevada County is almost entirely a WUI-based county, with a large portion being “intermix” WUI, with homes and businesses distributed within as opposed to adjacent to fuel-laden areas. This means that fire, while a natural and integral part of our local landscape, will inevitably threaten human life and property. But how severe the threat and how beneficial its ecological impacts are dependent entirely on the forest conditions of the last century.

Management activities (“fuel treatment”, “fuel reduction”, “thinning”) have attempted to catch up and mimic the effects of fire by removing low, dead, and “ladder” fuels (low-hanging and shrubby vegetation that can help a fire climb into the crowns of trees). But it is arguably not feasible to make up for all of the lost time. The “fire debt” built into the system is extremely high, and our predictions of increased fire severity and frequency as a result of the combination of this heavy fuel load and increasing temperatures and decreasing moisture as a result of climate change are simply playing out as anticipated. On the other hand, the frequency of fires is built in to the system, but the severity may not be. By both not letting the forests burn and not addressing fuel loads that haven’t burned, we have artificially inflated the likelihood of the “megafires” seen throughout the state, which are only increasing each year. Living in these forests as climate continues to change will require acknowledgement of our responsibilities as forest stewards, as well as acceptance of the reality of (low and mixed-severity) fire.

Management and fire must be viewed as two sides of the same coin. A recent return to prescribed burning in western forests broadly, and driven locally by the wonderful Bear Yuba Burn Cooperative and locals interested in re-introducing fire to the landscape, along with stakeholder groups focused on standardizing views and approaches to forest management such as SYRCL’s Yuba Forest Network are pushes in the right direction. What is needed is more than tools or specific projects; what is needed is a cultural shift, a return to viewing fire as a partner instead of an enemy. For example, “off-season” forest management and fuel reduction should be viewed through the lens of helping fire to safely serve its ecological purpose as opposed to fully preventing it. As a WUI community, we must live with and embrace low and mixed-severity fire, while acknowledging areas that have not burned in the past and now need a bit of our help. That help can come in the form of management including fuel reduction and prescribed burns. But we must acknowledge that manual fuel reduction is a blunt instrument applied without the grace with which nature clears its own fuels, and must view fire as the preferred forest treatment. If we are able to harness the power of manual fuel reduction, natural fires, and prescribed burns, when the next fire inevitably comes, we can view it as naturally as the changing of the seasons, knowing that our forests and our community are resilient instead of feeling under siege.

Outwardly, SSI’s resistance to the fire, along with others who lost homes and other property in the fire, appears low. We evacuated and left everything behind, hoping to return and resume normal life. This didn’t happen. And the impacts were significant, with a sudden and rapid decline in our ability to do some of our work. But our community’s resilience is immense. Our response to the Jones Fire, like the forest, is not a function of what was lost, but instead is defined by what comes next.

Sierra Streams Institute is excited to be working toward building resilient forests in our region, including a new project working with the Woolman School, Nevada City School of the Arts, Shady Creek Outdoor School, and the Jones Bar FireWise Community on forest management for post-fire recovery, and increased resilience to future fire using the principles discussed above. If you would like to support Sierra Streams Institute in our post-fire recovery efforts to continue monitoring, restoring, and educating local communities about our ecosystems, please see our GoFundMe page at: https://www.gofundme.com/f/sierra-streams-institute-jones-fire-recovery

References

  1. Lloret, F., Keeling, E.G. and Sala, A. (2011), Components of tree resilience: effects of successive low‐growth episodes in old ponderosa pine forests. Oikos, 120: 1909-1920. doi:10.1111/j.1600-0706.2011.19372.x
  2. Pyne, S. 2006. The Fire of Life: Thinking about the biological basis for fire. In: Wildfire: A century of failed forest policy. Wuerthner, G. (Ed.). Island Press.
  3. Safford, Hugh D.; Van de Water, Kip M. 2014. Using fire return interval departure (FRID) analysis to map spatial and temporal changes in fire frequency on national forest lands in California. Res. Pap. PSW-RP-266. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station. 59 p.
  4. K.S. McKelvey; C.N. Skinner; C. Chang; D.C. Erman; S.J. Husari; D.J. Parsons; J.W. van Wagtendonk; C.P. Weatherspoon. 1996. An Overview of Fire in the Sierra Nevada. In: Sierra Nevada Ecosystem Project, Final Report to Congress, Vol. II, Assessments and Scientific Basis for Management Options. Davis, CA: University of California, Centers for Water and Wildland Resources. Report No. 37.
  5. Skinner, C. & Chang, C. 1996. Fire regimes, past and present. In: Sierra Nevada Ecosystem Project, Final Report to Congress, Vol. II, Assessments and Scientific Basis for Management Options. Davis, CA: University of California, Centers for Water and Wildland Resources. Report No. 37.
  6. Connell, J. H. 1978. Diversity in Tropical Rain Forests and Coral Reefs. Science. 199 (4335): 1302–10.