Short-term recovery of post-fire vegetation is primarily limited by drought in Mediterranean forest ecosystems

Fire Ecology, Journal Year: 2023, Volume and Issue: 19(1)

Published: Nov. 7, 2023

Abstract Background Climate change is altering the fire regime and compromising post-fire recovery of vegetation worldwide. To understand factors influencing cover restoration, we calculated in 200,000 hectares western Mediterranean forest burned by 268 wildfires over a 27-year period (1988–2015). We used time series Tasseled Cap Transformation Brightness (TCTB) spectral transformation Landsat imagery to calculate recovery. Then, quantified importance main drivers (climate, severity, topography) along an aridity gradient (semi-arid, sub-humid, humid) using Random Forest models. Results In most models (99.7%), drought duration was important factor, negatively affecting especially extremes gradient. Fire severity second factor for recovery, with its effect varying gradient: there positive relationship between sub-humid humid areas, while semi-arid areas showed opposite pattern. Topographic variables were least driver had marginal on Additionally, exhibited low mean rate, indicating limitations short-term after fire. Conclusions Our study highlights key role that plays basin and, particularly, forests located climatically extreme areas. The results suggest predicted increase coupled higher frequency intensity large fires may modify structure composition ecosystems. analysis provides relevant information evaluate design adaptive management strategies hotspots

Language: Английский

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Reproductive collapse in European beech results from declining pollination efficiency in large trees

Global Change Biology, Journal Year: 2023, Volume and Issue: 29(16), P. 4595 - 4604

Published: May 13, 2023

Abstract Climate warming increases tree mortality which will require sufficient reproduction to ensure population viability. However, the response of climate change remains poorly understood. Warming can reduce synchrony and interannual variability seed production (“masting breakdown”) increase predation decrease pollination efficiency in trees. Here, using 40 years observations individual European beech ( Fagus sylvatica ), we showed that masting breakdown results declining viable over time, contrast positive trend apparent raw count data. Furthermore, size modulates consequences on production. While increased time mainly small trees, disproportionately decreased larger individuals. Consequently, fecundity declined across all classes, but overall effect was greatest large Our study a fundamental biological relationship—correlation between production—has been reversed as has warmed. That reversal diverse for forest dynamics; including stand‐ biogeographical‐level dynamics regeneration. The effects suggest management options resilience under changing climates.

Language: Английский

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‘Mind the Gap’—reforestation needs vs. reforestation capacity in the western United States

Frontiers in Forests and Global Change, Journal Year: 2024, Volume and Issue: 7

Published: May 29, 2024

Tree establishment following severe or stand-replacing disturbance is critical for achieving U.S. climate change mitigation goals and maintaining the co-benefits of intact forest ecosystems. In many contexts, natural post-fire tree regeneration sufficient to maintain cover associated ecosystem services, but increasingly pattern scale exceeds ecological thresholds active reforestation may be warranted. Our capacity plant trees, however, not keeping pace with needs. This shortfall uniquely apparent in western U.S., where wildfire size severity have increased recent decades long-term divestment supply chain has limited our ability respond existing Here we present an analysis key facets both demand side address six questions: (1) What current backlog potential needs driven by high-severity wildfire?; (2) How will increasing activity through end century affect needs?; (3) meet future (4) can demands?; (5) approaches promote resilience (6) Where are opportunities emerging from policy initiatives, innovative public-private partnerships, capital markets scaling reforestation? Between 1984 2000, annual planting met cumulatively over last two (2000 2021) it fallen short fire-driven estimated 1.5 million ha ( ca. 3.8 ac). We anticipate this gap increase 2 3 fold 2050. Scaling up efforts close require investment across all chain, novel that forests drought wildfire. highlight initiatives conservation finance expanding efforts.

Language: Английский

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Assessing giant sequoia mortality and regeneration following high‐severity wildfire

Ecosphere, Journal Year: 2024, Volume and Issue: 15(3)

Published: March 1, 2024

Abstract Fire is a critical driver of giant sequoia ( Sequoiadendron giganteum [Lindl.] Buchholz) regeneration. However, fire suppression combined with the effects increased temperature and severe drought has resulted in fires an intensity size outside historical norm. As result, recent mega‐fires have killed significant portion world's population (13%–19%), uncertainty surrounds whether severely affected groves will be able to recover naturally, potentially leading loss grove area. To assess likelihood natural recovery, we collected spatially explicit data assessing mortality, crown condition, regeneration within four that were impacted by SQF‐ (2020) KNP‐Complex (2021) wildfires Sequoia Kings Canyon National Parks. In total, surveyed 5.9 ha for seedlings assessed condition 1104 sequoias. inform management, used statistical methodology robustly quantifies inherently “noisy” seedling takes advantage readily available remote sensing metrics would make our findings applicable other recently burned groves. A area consequence tree mortality followed failure We found areas experienced very high‐severity (above ~800 RdNBR) are at substantial risk area, rapidly increasing density simultaneously decreasing severity. Such comprised 17.8, 142.0, 14.6, 1.6 ~90%, ~14%, ~53%, ~27% Board Camp, Redwood Mountain, Suwanee, New Oriole Lake groves, respectively. all sampling areas, densities fell far below average measured after prescribed fires, where numbers almost certainly adequate maintain populations postfire conditions more keeping norms. Importantly, spatial pattern also important loss, two Suwanee Lake, patches not always contiguous, making some resilient due proximity surviving trees.

Language: Английский

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Untrammeling the wilderness: restoring natural conditions through the return of human-ignited fire

Fire Ecology, Journal Year: 2024, Volume and Issue: 20(1)

Published: Aug. 26, 2024

Abstract Historical and contemporary policies practices, including the suppression of lightning-ignited fires removal intentional ignited by Indigenous peoples, have resulted in over a century fire exclusion across many USA’s landscapes. Within designated wilderness areas, this has clearly altered ecological processes thus constitutes fundamental ubiquitous act trammeling . Through framework that recognizes four orders , we demonstrate substantial, long-term, negative effects on natural conditions fire-adapted ecosystems. In order to un trammel more than exclusion, implementation active programs burning may be necessary some We also suggest greater recognition accommodation cultural burning, practice which Tribes used shape maintain landscapes for thousands years before Euro-American colonization, today as wilderness. Human-ignited critical restoring character can support ecocultural restoration efforts sought peoples.

Language: Английский

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Consistent spatial scaling of high‐severity wildfire can inform expected future patterns of burn severity

Ecology Letters, Journal Year: 2023, Volume and Issue: 26(10), P. 1687 - 1699

Published: June 21, 2023

Increasing wildfire activity in forests worldwide has driven urgency understanding current and future fire regimes. Spatial patterns of area burned at high severity strongly shape forest resilience constitute a key dimension regimes, yet remain difficult to predict. To characterize the range burn expected within contemporary we quantified scaling relationships relating size severity. Using 1615 fires occurring across Northwest United States between 1985 2020, evaluated regimes tested whether vary space time. Patterns high-severity demonstrate consistent behaviour; as increases, patches consistently increase homogeneity. Scaling did not differ substantially or time scales considered here, suggesting that fire-size distributions potentially shift, stationarity patch-size can be used infer

Language: Английский

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System-level feedbacks of active fire regimes in large landscapes

Fire Ecology, Journal Year: 2023, Volume and Issue: 19(1)

Published: July 31, 2023

Abstract Background Climate is a main driver of fire regimes, but recurrent fires provide stabilizing feedbacks at several spatial scales that can limit spread and severity—potentially contributing to form self-regulation. Evaluating the strength these in wildland systems difficult given temporal observation required. Here, we used REBURN model directly examine relative strengths top-down bottom-up drivers over 3000-year simulation period, within 275,000-ha conifer-dominated landscape north central Washington State, USA. Results We found strong support for controls on patterns. Fire weather was large occurrence, area burned moderated by ignition frequencies areas limited fuels fuel contagion (i.e., fences). Landscapes comprised >40% fences rarely experienced years. When did occur during recovery time 100–300 years or more generally required recover pre-fire vegetation Conclusions Simulations showed interactions between weather, contagion, topography, ignitions manifest variability size severity patch distributions. Burned recovering mosaics provided functional feedbacks, kind meta stability, which future severity, even under extreme conditions. be applied new geographic physiographic landscapes simulate represent natural culturally influenced regimes historical, current, climatic settings.

Language: Английский

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Refuge‐yeah or refuge‐nah? Predicting locations of forest resistance and recruitment in a fiery world

Global Change Biology, Journal Year: 2023, Volume and Issue: 29(24), P. 7029 - 7050

Published: Sept. 14, 2023

Climate warming, land use change, and altered fire regimes are driving ecological transformations that can have critical effects on Earth's biota. Fire refugia-locations burned less frequently or severely than their surroundings-may act as sites of relative stability during this period rapid change by being resistant to supporting post-fire recovery in adjacent areas. Because value forest ecosystem persistence, there is an urgent need anticipate where refugia most likely be found they align with environmental conditions support tree recruitment. Using biophysical predictors patterns burn severity from 1180 recent events, we mapped the locations potential across upland conifer forests southwestern United States (US) (99,428 km2 area), a region highly vulnerable fire-driven transformation. We low pre-fire cover, flat slopes topographic concavities, moderate weather conditions, spring-season burning, areas affected low- moderate-severity within previous 15 years were commonly associated refugia. Based current (i.e., 2021) predicted 67.6% 18.1% our study area would contain under extreme weather, respectively. However, 36.4% (moderate weather) 31.2% (extreme more common experienced fires, increased prescribed resource objective fires promote fire-resistant landscapes. When overlaid models recruitment, 23.2% 6.4% classified high recruitment surrounding landscape. These may disproportionately valuable for sustainability, providing habitat fire-sensitive species maintaining persistence increasingly fire-prone world.

Language: Английский

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Future transition from forests to shrublands and grasslands in the western United States is expected to reduce carbon storage

Communications Earth & Environment, Journal Year: 2024, Volume and Issue: 5(1)

Published: Feb. 12, 2024

Abstract Climate change is expected to impact vegetation in the western United States, leading shifts dominant Plant Functional Types and carbon storage. Here, we used a biogeographic model integrated with biogeochemical predict changes Type by 2070−2100. Results show that under Representative Concentration Pathway 4.5 scenario, 40% of originally forested areas will transition shrubland (7%) or grassland (32%), while 8.5 58% shift (18%) (40%). These result net overall loss storage equal −60 gigagram −82 8.5, respectively. Our findings highlight need for urgent action mitigate effects climate on region.

Language: Английский

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Contemporary fires are less frequent but more severe in dry conifer forests of the southwestern United States

Communications Earth & Environment, Journal Year: 2024, Volume and Issue: 5(1)

Published: Oct. 11, 2024

Abstract Wildfires in the southwestern United States are increasingly frequent and severe, but whether these trends exceed historical norms remains contested. Here we combine dendroecological records, satellite-derived burn severity, field measured tree mortality to compare (1700-1880) contemporary (1985-2020) fire regimes at tree-ring fire-scar sites Arizona New Mexico. We found that frequency, including recent, record years, is still <20% of levels. Since 1985, return interval averages 58.8 compared 11.4 years before 1880. Fire however, has increased. At where trees historically survived many fires over centuries, 42% recent resulted high mortality. Suppressed wildfires tended more severely than prescribed burns managed for resource benefit. These findings suggest expanded use low-severity would help restore forest resilience dry conifer forests.

Language: Английский

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