Mega‐disturbances cause rapid decline of mature conifer forest habitat in California

Ecological Applications, Год журнала: 2022, Номер 33(2)

Опубликована: Окт. 20, 2022

Abstract Mature forests provide important wildlife habitat and support critical ecosystem functions globally. Within the dry conifer of western United States, past management fire exclusion have contributed to forest conditions that are susceptible increasingly severe wildfire drought. We evaluated declines in cover southern Sierra Nevada California during a decade record disturbance by using spatially comprehensive structure estimates, perimeter data, eDaRT tracking algorithm. Primarily due combination wildfires, drought, drought‐associated beetle epidemics, 30% region's extent transitioned nonforest vegetation 2011–2020. In total, 50% mature 85% high density either lower or types. spotted owl protected activity centers (PAC) experienced greater canopy decline (49% 2011 cover) than non‐PAC areas (42% decline). Areas with initial without tall trees were most vulnerable declines, likely explaining disproportionate within PACs. Drought attack caused cumulative where drought mortality overlapped, both types natural far outpaced attributable mechanical activities. disproportionately affects large conifers is particularly problematic specialist species reliant on trees. However, patches degraded perimeters larger core area those outside burned areas, remnant habitats more fragmented affected alone. The percentage survived potentially benefited from severity increased over time as total declined. These some opportunity for improved resilience future disturbances, but strategic interventions also necessary mitigate worsening mega‐disturbances. Remaining may be complete loss coming decades rapid transition conservation paradigm attempts maintain static one manages sustainable dynamics.

Язык: Английский

---

State of Wildfires 2023–2024

Earth system science data, Год журнала: 2024, Номер 16(8), С. 3601 - 3685

Опубликована: Авг. 13, 2024

Abstract. Climate change contributes to the increased frequency and intensity of wildfires globally, with significant impacts on society environment. However, our understanding global distribution extreme fires remains skewed, primarily influenced by media coverage regionalised research efforts. This inaugural State Wildfires report systematically analyses fire activity worldwide, identifying events from March 2023–February 2024 season. We assess causes, predictability, attribution these climate land use forecast future risks under different scenarios. During 2023–2024 season, 3.9×106 km2 burned slightly below average previous seasons, but carbon (C) emissions were 16 % above average, totalling 2.4 Pg C. Global C record in Canadian boreal forests (over 9 times average) reduced low African savannahs. Notable included record-breaking extent Canada, largest recorded wildfire European Union (Greece), drought-driven western Amazonia northern parts South America, deadly Hawaii (100 deaths) Chile (131 deaths). Over 232 000 people evacuated Canada alone, highlighting severity human impact. Our revealed that multiple drivers needed cause areas activity. In Greece, a combination high weather an abundance dry fuels probability fires, whereas area anomalies weaker regions lower fuel loads higher direct suppression, particularly Canada. Fire prediction showed mild anomalous signal 1 2 months advance, Greece had shorter predictability horizons. Attribution indicated modelled up 40 %, 18 50 due during respectively. Meanwhile, seasons magnitudes has significantly anthropogenic change, 2.9–3.6-fold increase likelihood 20.0–28.5-fold Amazonia. By end century, similar magnitude 2023 are projected occur 6.3–10.8 more frequently medium–high emission scenario (SSP370). represents first annual effort catalogue events, explain their occurrence, predict risks. consolidating state-of-the-art science delivering key insights relevant policymakers, disaster management services, firefighting agencies, managers, we aim enhance society's resilience promote advances preparedness, mitigation, adaptation. New datasets presented this work available https://doi.org/10.5281/zenodo.11400539 (Jones et al., 2024) https://doi.org/10.5281/zenodo.11420742 (Kelley 2024a).

Язык: Английский

---

The outsized role of California’s largest wildfires in changing forest burn patterns and coarsening ecosystem scale

Forest Ecology and Management, Год журнала: 2022, Номер 528, С. 120620 - 120620

Опубликована: Ноя. 14, 2022

Although recent large wildfires in California forests are well publicized media and scientific literature, their cumulative effects on forest structure implications for resilience remain poorly understood. In this study, we evaluated spatial patterns of burn severity 18 exceptionally fires compared impacts to the hundreds smaller that have burned across decades. We used a atlas over 1,800 predominantly conifer between 1985 2020 calculated landscape metrics evaluate spatiotemporal unburned refugia, low-moderate-severity, high-severity post-fire effects. Total annual area burned, mean fire size, total core at high all significantly increased study period. Exceptionally (i.e., top 1% by size) were responsible 58% 42% low-moderate severities, respectively, With larger patch sizes, our results suggest coarsen pattern California’s forests, reducing fine-scale heterogeneity which supports much biodiversity as wildfire climate resilience. Thus far, most modern management has focused restoring cover minimizing ecotype conversion large, patches. These fires, however, also provided extensive areas burns where managers could leverage wildfire’s initial “treatment” with follow-up fuel reduction treatments help restore finer-scale

Язык: Английский

---

Forest restoration and fuels reduction work: Different pathways for achieving success in the Sierra Nevada

Ecological Applications, Год журнала: 2023, Номер 34(2)

Опубликована: Ноя. 10, 2023

Abstract Fire suppression and past selective logging of large trees have fundamentally changed frequent‐fire‐adapted forests in California. The culmination these changes produced that are vulnerable to catastrophic change by wildfire, drought, bark beetles, with climate exacerbating this vulnerability. Management options available address problem include mechanical treatments (Mech), prescribed fire (Fire), or combinations (Mech + Fire). We quantify forest structure composition, fuel accumulation, modeled behavior, intertree competition, economics from a 20‐year restoration study the northern Sierra Nevada. All three active (Fire, Mech, Mech Fire) conditions were much more resistant wildfire than untreated control. included lowest surface duff loads hazards. low hazards beginning 7 years after initial treatment had lower tree growth controls. only competition somewhat similar historical California mixed‐conifer was Fire, indicating stands under would likely be resilient enhanced stressors. While reduced hazard reintroduced fundamental ecosystem process, it done at net cost landowner. Using mastication thinning resulted positive revenues also relatively strong as an investment reducing hazard. represents compromise between desire sustain financial feasibility reintroduce fire. One key component long‐term conservation will continued maintain improve restoration. Many Indigenous people speak “active stewardship” one principles land management aligns well need for increased western US forests. If we do not use knowledge 20+ research longer tradition cultural practices knowledge, frequent‐fire continue degraded lost.

Язык: Английский

---

Scattered tree death contributes to substantial forest loss in California

Nature Communications, Год журнала: 2024, Номер 15(1)

Опубликована: Янв. 20, 2024

Abstract In recent years, large-scale tree mortality events linked to global change have occurred around the world. Current forest monitoring methods are crucial for identifying hotspots, but systematic assessments of isolated or scattered dead trees over large areas needed reduce uncertainty on actual extent mortality. Here, we mapped individual in California using sub-meter resolution aerial photographs from 2020 and deep learning-based detection. We identified 91.4 million 27.8 hectares vegetated (16.7-24.7% underestimation bias when compared field data). Among these, a total 19.5 appeared isolated, 60% all small groups ( ≤ 3 within 30 × m grid), which is largely undetected by other state-level methods. The widespread impacts carbon budget sequestration capacity forests can be considered threat health fuel source future wildfires.

Язык: Английский

---

Climate change and California’s terrestrial biodiversity

Proceedings of the National Academy of Sciences, Год журнала: 2024, Номер 121(32)

Опубликована: Июль 29, 2024

In this review and synthesis, we argue that California is an important test case for the nation world because terrestrial biodiversity very high, present anticipated threats to from climate change other interacting stressors are severe, innovative approaches protecting in context of being developed tested. We first salient dimensions California's physical, biological, human diversity. Next, examine four facets threat their sustainability these posed by change: direct impacts, illustrated a new analysis shifting diversity hotspots plants; interactive effects involving invasive species, land-use change, stressors; impacts changing fire regimes; land-based renewable energy development. recent policy responses each areas, representing attempts better protect while advancing adaptation mitigation. conclude ambitious 30 × Initiative its efforts harmonize conservation with development areas progress. Adapting traditional suppression-oriented policies reality regimes area which much progress remains be made.

Язык: Английский

---

Modeling the probability of bark beetle-caused tree mortality as a function of watershed-scale host species presence and basal area

Forest Ecology and Management, Год журнала: 2025, Номер 580, С. 122549 - 122549

Опубликована: Фев. 9, 2025

Язык: Английский

---

Climate change is narrowing and shifting prescribed fire windows in western United States

Communications Earth & Environment, Год журнала: 2023, Номер 4(1)

Опубликована: Окт. 3, 2023

Abstract Escalating wildfire activity in the western United States has accelerated adverse societal impacts. Observed increases severity and impacts to communities have diverse anthropogenic causes—including legacy of fire suppression policies, increased development high-risk zones, aridification by a warming climate. However, intentional use as vegetation management tool, known “prescribed fire,” can reduce risk destructive fires restore ecosystem resilience. Prescribed implementation is subject multiple constraints, including number days characterized weather conditions conducive achieving desired outcomes. Here, we quantify observed projected trends frequency seasonality prescribed days. We find that while ~2 C global 2060 will such overall (−17%), particularly during spring (−25%) summer (−31%), winter (+4%) may increasingly emerge comparatively favorable window for especially northern states.

Язык: Английский

---

Potential operational delineations: new horizons for proactive, risk-informed strategic land and fire management

Fire Ecology, Год журнала: 2022, Номер 18(1)

Опубликована: Авг. 4, 2022

Abstract Background The PODs (potential operational delineations) concept is an adaptive framework for cross-boundary and collaborative land fire management planning. Use of increasingly recognized as a best practice, are seeing growing interest from federal, state, local, tribal, non-governmental organizations. Early evidence suggests provide utility planning, communication, coordination, prioritization, incident response strategy development, fuels mitigation forest restoration. Recent legislative action codifies the importance by devoting substantial financial resources to their expansion. intent this paper explore new horizons that would help organizations better address risks capitalize on opportunities. Specifically, we focus how natural platform improvement related two core elements risk management: leverage preparation foresight prepare future; learn past understand improve performance its alignment with strategy. Results We organize our exploration around three key areas, suggesting can enable climate-smart inform more agile allocation suppression resources, risk-informed measurement. These efforts be synergistic self-reinforcing, argue expanded application at local levels could enhance broader wildland system. rationales each problem area offer growth opportunities attendant explanations illustrations. Conclusions With commitment careful effort, rich innovation in both backward-looking evaluative forward-looking anticipatory frameworks. In addition continued elements, attention must paid being inclusive participatory building sufficient capacity expand applications meaningful boundary spanning ways, ensure continuity relevance over time through maintenance updating, deliver necessary information responders effective wildfires. Lastly, ongoing monitoring evaluation initiatives essential support organizational learning continual improvement.

Язык: Английский

---

Quail on fire: changing fire regimes may benefit mountain quail in fire-adapted forests

Fire Ecology, Год журнала: 2023, Номер 19(1)

Опубликована: Апрель 3, 2023

Fire-adapted forests in western North America are experiencing rapid changes to fire regimes that outside the range of historic norms. Some habitat-specialist species have been negatively impacted by increases large, high-severity fire, yet, responses many especially at longer time scales, remain ambiguous. We studied response a widely distributed species, mountain quail (Oreortyx pictus), wildfire across Sierra Nevada California, because its habitat selection patterns provided an opportunity evaluate potentially contrasting among specialists. used passive acoustic monitoring > 22,000 km2 and Bayesian hierarchical occupancy modeling conduct first study effects habitat, severity, since (1–35 years) on little-understood management indicator quail. Mountain responded positively neutrally low-moderate-severity fire. Occupancy peaked 6–10 years after remained high even 11–35 area burned severity. Our work demonstrates is strongly related occupancy, which markedly different than previously also concern Nevada. Taken together, our results suggest may actually be "winners" face altered Given forecasted intensification severe wildfires fire-adapted forests, understanding ecology nuanced beyond those historically considered important time-sensitive effort. The relationship between reminder there will both winners losers as dynamics change era climate change.

Язык: Английский

---