Wildfire and climate change adaptation of western North American forests: a case for intentional management

Abstract

Forest landscapes across western North America (wNA) have experienced extensive changes over the last two centuries, while climatic warming has become a global reality over the last 4 decades. Resulting interactions between historical increases in forested area and density and recent rapid warming, increasing insect mortality, and wildfire burned areas, are now leading to substantial abrupt landscape alterations. These outcomes are forcing forest planners and managers to identify strategies that can modify future outcomes that are ecologically and/or socially undesirable. Past forest management, including widespread harvest of fire-and climate-tolerant large old trees and old forests, fire exclusion (both Indigenous and lightning ignitions), and highly effective wildfire suppression have contributed to the current state of wNA forests. These practices were successful at meeting short-term demands, but they match poorly to modern realities. Hagmann et al. (in press) review a century of observations and multi-scale, multi-proxy research evidence that details widespread changes in forested landscapes and wildfire regimes since the influx of European colonists. Over the preceding 10 millennia, large areas of wNA were already settled and proactively managed with intentional burning by Indigenous tribes. Prichard et al. (in press) then review the research on management practices historically applied by Indigenous tribes and currently applied by some managers to intentionally manage forests for resilient conditions. They address ten questions surrounding the application and relevance of these management practices. Here, we highlight the main findings of both papers and offer recommendations for management. We discuss progress paralysis that often occurs with strict adherence to the precautionary principle; offer insights for dealing with the common problem of irreducible uncertainty and suggestions for reframing management and policy direction; and identify key knowledge gaps and research needs.

Projected increases in western US forest fire despite growing fuel constraints

“…As most area burned is low or moderate-severity fire, such increases in fire activity could ultimately facilitate ecosystem restoration, but mitigating fire disasters will be crucial. Managers and policymakers can carefully consider where management actions are most beneficial, the challenges of implementing such actions, and how these approaches scale geographically to meaningfully alter widespread outcomes 43 .…”

Evidence for widespread changes in the structure, composition, and fire regimes of western North American forests

“…Fire regimes are multi-dimensional.-Multiple dimensions of individual fires (Hessburg et al 2021: Table 1) interacting in a relatively persistent pattern over long periods of time collectively comprise a holistic notion of a fire regime (Agee 1996, Sugihara et al 2018. Fire frequency and severity are major drivers of ecological and evolutionary response (Keeley 2012).…”

“…Social and ecological impacts of large and intense wildfires present enormous challenges to land and resource managers of western North America (Franklin and Agee 2003, North et al 2015, Moreira et al 2020, Hessburg et al 2021). In the near term, wildfire frequency, area burned, and area burned at high severity will likely continue to increase as the climate warms; however, despite recent climatically driven increases in area burned, fire deficits in seasonally dry forests remain high (reviewed by Hessburg et al 2021). After more than a century of fire exclusion (Fig.…”

“…Proactive management informed by historical and contemporary forest and fire ecology can strengthen resistance to disturbance and better align forest ecosystems with rapidly changing climatic and disturbance regimes (reviewed by Hessburg et al 2021. Reducing the abundance and connectivity of fuels that accumulated over more than a century of fire exclusion can moderate ecosystem transitions and provide numerous ecological and socioeconomic benefits (reviewed by Prichard et al 2021).…”

“…While integral to the development of knowledge, dissent in the scientific literature can contribute to conflict, confusion, and lack of consensus in stakeholders, e.g., environmental and conservation organizations and the general public (Maier and Abrams 2018). When fostered by incomplete assessment of the best available science (Esch et al 2018), this lack of consensus may unnecessarily delay development and implementation of constructive new solutions and policies (reviewed by Hessburg et al 2021).…”