Limits to post‐fire vegetation recovery under climate change

Plant Cell & Environment, Journal Year: 2021, Volume and Issue: 44(11), P. 3471 - 3489

Published: Aug. 28, 2021

Abstract Record‐breaking fire seasons in many regions across the globe raise important questions about plant community responses to shifting regimes (i.e., changing frequency, severity and seasonality). Here, we examine impacts of climate‐driven shifts on vegetation communities, likely coinciding with severe drought, heatwaves and/or insect outbreaks. We present scenario‐based conceptual models how overlapping disturbance events interact differently limit post‐fire resprouting recruitment capacity. demonstrate that, although communities will remain resilient short‐term, longer‐term changes structure, demography species composition are likely, a range subsequent effects ecosystem function. Resprouting be most regimes. However, even these susceptible if exposed repeated short‐interval combination other stressors. Post‐fire is highly vulnerable increased particularly as climatic limitations propagule availability intensify. Prediction under climate change greatly improved by addressing knowledge gaps disturbances change‐induced regime affect resprouting, recruitment, growth rates, species‐level adaptation

Language: Английский

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Lack of hydraulic recovery as a cause of post‐drought foliage reduction and canopy decline in European beech

New Phytologist, Journal Year: 2022, Volume and Issue: 234(4), P. 1195 - 1205

Published: March 3, 2022

European beech (Fagus sylvatica) was among the most affected tree species during severe 2018 drought. It not only suffered from instant physiological stress but also showed symptoms of defoliation and canopy decline in following year. To explore underlying mechanisms, we used Swiss-Canopy-Crane II site studied branches healthy symptomatic trees repair hydraulic function concentration carbohydrates drought 2019. We found loss conductance 2018, which did recover 2019 that developed year after Reduced branch foliation associated with a gradual wood starch throughout summer Visualization water transport confirmed close relationship between xylem functionality supported leaf area. Our findings embolized does regain season sustained dysfunction is counterbalanced by reduction suggests acclimation development to mitigate disturbances function.

Language: Английский

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Mutually inclusive mechanisms of drought‐induced tree mortality

Global Change Biology, Journal Year: 2022, Volume and Issue: 28(10), P. 3365 - 3378

Published: March 5, 2022

Unprecedented tree dieback across Central Europe caused by recent global change-type drought events highlights the need for a better mechanistic understanding of drought-induced mortality. Although numerous physiological risk factors have been identified, importance two principal mechanisms, hydraulic failure and carbon starvation, is still debated. It further remains largely unresolved how local neighborhood composition affects individual mortality risk. We studied 9435 young trees 12 temperate species planted in diversity experiment 2013 to assess traits, dynamics, pest infestation, height competition influence Following most extreme since record 2018, one third these died. Across species, safety margins (HSMs) were negatively shift towards higher sugar fraction non-structural carbohydrate (NSC) pool positively associated with Moreover, infested bark beetles had risk, taller lower Most interactions beneficial, although effects highly species-specific. Species that suffered more from drought, especially Larix spp. Betula spp., tended increase survival probability their neighbors vice versa. While severe tissue dehydration marks final stage mortality, we show interrelated series other, mutually inclusive processes. These include shifts NSC pools driven osmotic adjustment and/or starch depletion as well infestation are modulated size identity its neighbors. A holistic view accounts multiple causes required improve predictions trends forest dynamics identify beneficial combinations.

Language: Английский

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European beech dieback after premature leaf senescence during the 2018 drought in northern Switzerland

Plant Biology, Journal Year: 2022, Volume and Issue: 24(7), P. 1132 - 1145

Published: Sept. 14, 2022

During the particularly severe hot summer drought in 2018, widespread premature leaf senescence was observed several broadleaved tree species Central Europe, European beech (Fagus sylvatica L.). For beech, it is yet unknown whether evoked a decline towards mortality or trees can recover longer term. In this study, we monitored crown dieback, and secondary damage symptoms 963 initially live that exhibited either normal 2018 three regions northern Switzerland from to 2021. We related multiple climate- stand-related parameters. Cumulative continuously increased up 7.2% 1.3% 2021 for with respectively. Mean dieback surviving peaked at 29.2% 2020 8.1% 2019 senescence, Thereafter, showed first signs of recovery. Crown more pronounced recovery slower growing on drier sites, larger trees. The presence bleeding cankers 24.6% 10.7% bark beetle holes 22.8% 14.8% Both occurred frequently had higher proportions and/or 2018. Our findings demonstrate context-specific differences reflecting importance regional local climate soil conditions. Adapting management increase forest resilience gaining importance, given expected further dry sites Switzerland.

Language: Английский

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Warmer and drier conditions have increased the potential for large and severe fire seasons across south‐eastern Australia

Global Ecology and Biogeography, Journal Year: 2022, Volume and Issue: 31(10), P. 1933 - 1948

Published: April 26, 2022

Abstract Aim The aims were: (1) to identify the environmental drivers of interannual variation in wildfire extent and severity; (2) examine temporal trends climatic potential for large severe wildfires; (3) assess whether conditions experienced during 2019–2020 mega‐fire season were anomalous. Location South‐eastern Australia. Time period 1953–2020. Major taxa studied Temperate forests. Methods We used satellite‐derived fire severity mapping from 1988 2020 model effects drought, weather fuels on annual area burned proportion that was impacted by high‐severity across four bioregions. Trends then estimated 1953 using these derived models gridded climate data changes wildfires. Estimates assessed against prior seasons (1953–2019). Results Annual positively related seasonal drought frequency promote substantial daily growth. Wildfire elevated years with increased increasing antecedent without weather. Fuels had a lesser effect than climate. Potential have over time response an worsening conditions. approached upper extreme within each bioregion, owing widespread Main conclusions forest fires has south‐eastern Australia since 1950s, probably because anthropogenic change. magnitude reflected are driving increase size

Language: Английский

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The Carbon Cycle of Southeast Australia During 2019–2020: Drought, Fires, and Subsequent Recovery

AGU Advances, Journal Year: 2021, Volume and Issue: 2(4)

Published: Dec. 1, 2021

Abstract 2019 was the hottest and driest year on record for southeast Australia leading to bushfires of unprecedented extent. Ecosystem carbon losses due drought fire are believed have been substantial, but not well quantified. Here, we utilize space‐based measurements trace gases (TROPOspheric Monitoring Instrument X CO , Orbiting Carbon Observatory 2 ) up‐scaled GPP (FluxSat GPP) quantify cycle anomalies resulting from in during 2019–2020 growing season. We find that biomass burning released 113–236 TgC while fire‐induced net ecosystem exchange reduced season uptake by an additional 19–52 . These were concentrated spring early summer, when hot‐dry conditions most severe. A shift cooler with above average rainfall February is found result a partial recovery greening unburned ecosystems, fire‐impacted areas. The loss substantially exceeded interannual variations over 2010–2019 estimated top‐down constraints (∼5 σ anomaly), Australia's annual fossil fuel emissions (∼104 −1 ). Top‐down show regional budget strongly regulated climate variability, suggest cool‐wet required rapid stocks. This has implications as more frequent climate‐change‐driven heat events may increase frequency time threatening stocks region.

Language: Английский

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Living on the edge: A continental‐scale assessment of forest vulnerability to drought

Global Change Biology, Journal Year: 2021, Volume and Issue: 27(15), P. 3620 - 3641

Published: April 15, 2021

Abstract Globally, forests are facing an increasing risk of mass tree mortality events associated with extreme droughts and higher temperatures. Hydraulic dysfunction is considered a key mechanism drought‐triggered dieback. By leveraging the climate breadth Australian landscape national network research sites (Terrestrial Ecosystem Research Network), we conducted continental‐scale study physiological hydraulic traits 33 native species from contrasting environments to disentangle complexities plant response drought across communities. We found strong relationships between site aridity. Leaf turgor loss point xylem embolism resistance were correlated minimum water potential experienced by each species. Across data set, there was coordination traits, including those linked safety, stomatal regulation cost carbon investment into woody tissue. These results illustrate that aridity has acted as selective pressure, shaping landscape. safety margins constrained sites, wetter tending have smaller margin compared at drier suggesting trees operating close their thresholds forest biomes spectrum may be susceptible shifts in result intensification drought.

Language: Английский

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What Do the Australian Black Summer Fires Signify for the Global Fire Crisis?

Fire, Journal Year: 2021, Volume and Issue: 4(4), P. 97 - 97

Published: Dec. 17, 2021

The 2019–20 Australian fire season was heralded as emblematic of the catastrophic harm wrought by climate change. Similarly extreme wildfire seasons have occurred across globe in recent years. Here, we apply a pyrogeographic lens to fires examine range causes, impacts and responses. We find that extensive area burnt due climatic circumstances. However, antecedent hazard reduction burns (prescribed with aim reducing fuel loads) were effective severity house loss, but their effectiveness declined under weather conditions. Impacts disproportionately borne socially disadvantaged regional communities. Urban populations also impacted through prolonged smoke exposure. produced large carbon emissions, fire-sensitive ecosystems exposed areas risk biodiversity decline being too frequently future. argue rate change delivered is outstripping capacity our ecological social systems adapt. A multi-lateral approach required mitigate future risk, an emphasis on vulnerability people reinvigoration community-level for targeted actions complement mainstream management capacity.

Language: Английский

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Small and slow is safe: On the drought tolerance of tropical tree species

Global Change Biology, Journal Year: 2022, Volume and Issue: 28(8), P. 2622 - 2638

Published: Jan. 10, 2022

Understanding how evolutionary history and the coordination between trait trade-off axes shape drought tolerance of trees is crucial to predict forest dynamics under climate change. Here, we compiled traits related fast-slow stature-recruitment in 601 tropical woody species explore their covariations phylogenetic signals. We found that xylem resistance embolism (P50) determines risk hydraulic failure, while functional significance leaf turgor loss point (TLP) relies on its with water use strategies. P50 TLP exhibit weak signals substantial variation within genera. closely associated axis: slow maintain functioning higher stress. both axes: small more resistant xylem. Lower phosphorus concentration xylem, which suggests a (nutrient drought) stress-tolerance syndrome tropics. Overall, our results imply (1) strong selective pressure forests, result from repeated adaptation taxa, (2) coordinated ecological strategies governing demography. These findings provide physiological basis interpret drought-induced shift toward slow-growing, smaller, denser-wooded observed tropics, implications for restoration programmes.

Language: Английский

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Megafire‐induced interval squeeze threatens vegetation at landscape scales

Frontiers in Ecology and the Environment, Journal Year: 2022, Volume and Issue: 20(5), P. 327 - 334

Published: March 22, 2022

Wildfires in 2019–2020 broke global records for extent and severity, affirming the arrival of megafire era. Frequent megafires reflect changes to fire regimes that can negatively impact species ecosystems. Here, we offer what believe be first comprehensive analysis impacts on southeastern Australian vegetation communities, combining remote‐sensing data, fire‐history records, plant trait‐derived interval thresholds. In our study area, fires burned over 5.5 million ha. We found one‐third all native this region has too frequently following megafires, particularly impacting fire‐sensitive (for example, rainforests). This represents a single‐year increase 36% at risk squeeze (vegetation transitions driven by altered regimes) compared previous 59 years combined. demonstrate overrun recently infiltrate refugia, reducing intervals beyond persistence thresholds increasing ecosystem collapse. Averting will require innovative approaches management. However, if climate change is not addressed, collapse may unavoidable especially ecosystems adapted infrequent, high‐severity fire.

Language: Английский

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