Mechanisms of woody-plant mortality under rising drought, CO2 and vapour pressure deficit

Nature Reviews Earth & Environment, Год журнала: 2022, Номер 3(5), С. 294 - 308

Опубликована: Март 29, 2022

Язык: Английский

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A First Assessment of Canopy Cover Loss in Germany’s Forests after the 2018–2020 Drought Years

Remote Sensing, Год журнала: 2022, Номер 14(3), С. 562 - 562

Опубликована: Янв. 25, 2022

Central Europe was hit by several unusually strong periods of drought and heat between 2018 2020. These droughts affected forest ecosystems. Cascading effects with bark beetle infestations in spruce stands were fatal to vast areas Germany. We present the first assessment canopy cover loss Germany for period January 2018–April 2021. Our approach makes use dense Sentinel-2 Landsat-8 time-series data. computed disturbance index (DI) from tasseled cap components brightness, greenness, wetness. Using quantiles, we generated monthly DI composites calculated anomalies a reference (2017). From resulting map, statistics administrative entities. results show 501,000 ha Germany, large regional differences. The losses largest central reached up two-thirds coniferous some districts. map has high spatial (10 m) temporal (monthly) resolution can be updated at any time.

Язык: 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, Год журнала: 2022, Номер 234(4), С. 1195 - 1205

Опубликована: Март 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.

Язык: Английский

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

Plant Biology, Год журнала: 2022, Номер 24(7), С. 1132 - 1145

Опубликована: Сен. 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.

Язык: Английский

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Addressing controversies in the xylem embolism resistance–vessel diameter relationship

New Phytologist, Год журнала: 2023, Номер 238(1), С. 283 - 296

Опубликована: Янв. 13, 2023

Summary Although xylem embolism is a key process during drought‐induced tree mortality, its relationship to wood anatomy remains debated. While the functional link between bordered pits and resistance known, there no direct, mechanistic explanation for traditional assumption that wider vessels are more vulnerable than narrow ones. We used data from 20 temperate broad‐leaved species study inter‐ intraspecific of water potential at 50% loss conductivity ( P 50 ) with hydraulically weighted vessel diameter D h tested pit membrane thickness T PM specific K s on level. Embolism‐resistant had thick membranes vessels. was weakly associated , – remained highly significant after accounting . The interspecific pattern mirrored by but evidence an relationship. Our results provide robust across our species. As cause inconsistencies in published relationships, analysis suggests differences range trait values covered, level aggregation (species, or sample level) studied.

Язык: Английский

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The AP2/ERF transcription factor PtoERF15 confers drought tolerance via JA‐mediated signaling in Populus

New Phytologist, Год журнала: 2023, Номер 240(5), С. 1848 - 1867

Опубликована: Сен. 10, 2023

Drought stress is one of the major limiting factors for growth and development perennial trees. Xylem vessels act as center water conduction in woody species, but underlying mechanism its morphogenesis under water-deficient conditions remains elucidation. Here, we identified characterized an osmotic stress-induced ETHYLENE RESPONSE FACTOR 15 (PtoERF15) target, PtoMYC2b, which was involved mediating vessel size, density, cell wall thickness response to drought Populus tomentosa. PtoERF15 preferentially expressed differentiating xylem poplar stems. Overexpression contributed stem potential maintaining, thus promoting tolerance. RNA-Seq biochemical analysis further revealed that directly regulated encoding a switch JA signaling pathway. Additionally, our findings verify three sets homologous genes from NAC (NAM, ATAF1/2, CUC2) gene family: PtoSND1-A1/A2, PtoVND7-1/7-2, PtoNAC118/120, targets are regulation morphology poplar. Collectively, study provides molecular evidence involvement PtoERF15-PtoMYC2b transcription cascade maintaining through development, ultimately improving tolerance

Язык: Английский

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Satellite data reveal differential responses of Swiss forests to unprecedented 2018 drought

Global Change Biology, Год журнала: 2022, Номер 28(9), С. 2956 - 2978

Опубликована: Фев. 19, 2022

Extreme events such as the summer drought of 2018 in Central Europe are projected to occur more frequently future and may cause major damages including increased tree mortality negative impacts on forest ecosystem services. Here, we quantify response >1 million pixels 10 × m across Switzerland terms resistance, recovery, resilience. We used Normalized Difference Water Index (NDWI) derived from Sentinel-2 satellite data a proxy for canopy water content analyzed its relative change. calculated NDWI change between 2017 pre-drought years (indicating resistance), 2019 post-drought recovery), 2017-2019 resilience). Analyzing this large natural experiment, found that 4.3% Swiss declined 2018, indicating areas with low resistance effects. While roughly 50% area recovered, 2.7% forested continued decline 2019, suggesting prolonged effects or delayed damage. differential responses associated site topographic characteristics stand characteristics, lesser extent climatic conditions interactions these drivers. Low high recovery were most prominent at edges, but also south-facing slopes lower elevations. Tree functional type was important driver resilience, damage stands conifer abundance. Our results demonstrate suitability satellite-based quantification drought-induced spatial resolution areas. Such information is predict how local impact vulnerability extreme help search appropriate adaptation strategies.

Язык: Английский

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Central European 2018 hot drought shifts scots pine forest to its tipping point

Plant Biology, Год журнала: 2022, Номер 24(7), С. 1186 - 1197

Опубликована: Июль 23, 2022

The occurrence of hot drought, i.e. low water availability and simultaneous high air temperature, represents a severe threat to ecosystems. Here, we investigated how the 2018 drought in Central Europe caused tipping point tree ecosystem functioning Scots pine (Pinus sylvestris L.) forest southwest Germany. Measurements stress indicators, such as needle potential, carbon assimilation volatile organic compound (VOC) emissions, dominant P. trees were deployed evaluate during drought. Ecosystem impact recovery assessed exchange, normalized difference vegetation index (NDVI) from satellite data mortality data. During summer 2018, potentials dropped minimum values -7.5 ± 0.2 MPa, which implied hydraulic impairment sylvestris. Likewise, VOC emissions strongly declined after mid-July. Decreasing NDVI August onwards detected, along with defoliation sylvestris, impairing flux 2019, shifting into year-round source. A total 47% all monitored (n = 368) died by September 2020. recovered pre-2018 levels likely emerging broadleaved understorey species. had negative impacts on co-occurrence unfavourable site-specific conditions recurrent droughts resulted accelerated mortality. Thus, pushed stand towards its point, subsequent shift broadleaf-dominated forest.

Язык: Английский

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Networking the forest infrastructure towards near real-time monitoring – A white paper

The Science of The Total Environment, Год журнала: 2023, Номер 872, С. 162167 - 162167

Опубликована: Фев. 11, 2023

Язык: Английский

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Daytime stomatal regulation in mature temperate trees prioritizes stem rehydration at night

New Phytologist, Год журнала: 2023, Номер 239(2), С. 533 - 546

Опубликована: Май 26, 2023

Trees remain sufficiently hydrated during drought by closing stomata and reducing canopy conductance (Gc ) in response to variations atmospheric water demand soil availability. Thresholds that control the reduction of Gc are proposed optimize hydraulic safety against carbon assimilation efficiency. However, link between ability stem tissues rehydrate at night remains unclear. We investigated whether species-specific responses aim prevent branch embolisms, or enable night-time rehydration, which is critical for turgor-dependent growth. For this, we used a unique combination concurrent dendrometer, sap flow leaf potential measurements collected branch-vulnerability curves six common European tree species. Species-specific was weakly related potentials 50% xylem conductivity lost (P50 ). Instead, found stronger relationship with rehydration. Species were less effective refilling stem-water storage as dries, appeared their architecture. Our findings highlight importance rehydration water-use regulation mature trees, likely relates maintenance adequate turgor. thus conclude must complement widely accepted safety-efficiency stomatal paradigm.

Язык: Английский

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