Triggers of tree mortality under drought

Nature, Journal Year: 2018, Volume and Issue: 558(7711), P. 531 - 539

Published: June 1, 2018

Language: Английский

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Hanging by a thread? Forests and drought

Science, Journal Year: 2020, Volume and Issue: 368(6488), P. 261 - 266

Published: April 16, 2020

Trees are the living foundations on which most terrestrial biodiversity is built. Central to success of trees their woody bodies, connect elevated photosynthetic canopies with essential belowground activities water and nutrient acquisition. The slow construction these carbon-dense, skeletons leads a generation time, leaving forests highly susceptible rapid changes in climate. Other long-lived, sessile organisms such as corals appear be poorly equipped survive changes, raises questions about vulnerability contemporary future climate change. emerging view that, similar corals, tree species have rather inflexible damage thresholds, particularly terms stress, especially concerning. This Review examines recent progress our understanding how looks for growing hotter drier atmosphere.

Language: Английский

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Adjustments and coordination of hydraulic, leaf and stem traits along a water availability gradient

New Phytologist, Journal Year: 2019, Volume and Issue: 223(2), P. 632 - 646

Published: Jan. 13, 2019

Trait variability in space and time allows plants to adjust changing environmental conditions. However, we know little about how this is distributed coordinated at different organizational levels. For six dominant tree species northeastern Spain (three Fagaceae three Pinaceae) quantified the inter- intraspecific of a set traits along water availability gradient. We measured leaf mass per area (LMA), nitrogen (N) concentration, carbon isotope composition leaves (δ13 C), stem wood density, Huber value (Hv, ratio cross-sectional sapwood area), sapwood-specific leaf-specific hydraulic conductivity, vulnerability xylem embolism (P50 ) turgor loss point (Ptlp ). Differences between families explained largest amount for most traits, although was also relevant. Species occupying wetter sites showed higher N, P50 Ptlp , lower LMA, δ13 C Hv. when trait relationships with were assessed within they held only Hv . Overall, our results indicate that adjustments gradient relied primarily on changes resource allocation relations.

Language: Английский

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Low Vulnerability to Xylem Embolism in Leaves and Stems of North American Oaks

PLANT PHYSIOLOGY, Journal Year: 2018, Volume and Issue: 177(3), P. 1066 - 1077

Published: May 22, 2018

Although recent findings suggest that xylem embolism represents a significant, drought-induced damaging process in land plants, substantial debate surrounds the capacity of long-vesseled, ring-porous species to resist embolism. We investigated whether methodological developments could help resolve this controversy within Quercus, temperate angiosperm genus, and shed further light on importance vulnerability as an indicator drought tolerance. used optical technique quantify leaf stem eight Quercus from Mediterranean-type climate region California examine absolute measures resistance well any potential hydraulic segmentation between tissue types. demonstrated our assessment reflected flow impairment for subset sample by quantifying changes conductance dehydrating branches. Air-entry water varied 2-fold leaves, ranging -1.7 ± 0.25 MPa -3.74 0.23 MPa, 4-fold stems, -1.17 0.04 -4.91 0.3 MPa. Embolism occurred earlier leaves than stems only one out species, plants always lost turgor before experiencing Our results show long-vesseled North American are more resistant previously thought support hypothesis avoiding is critical component tolerance woody trees. Accurately essential understanding distributions along aridity gradients predicting plant mortality during drought.

Language: Английский

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Identifying areas at risk of drought‐induced tree mortality across South‐Eastern Australia

Global Change Biology, Journal Year: 2020, Volume and Issue: 26(10), P. 5716 - 5733

Published: June 8, 2020

Abstract South‐East Australia has recently been subjected to two of the worst droughts in historical record (Millennium Drought, 2000–2009 and Big Dry, 2017–2019). Unfortunately, a lack forest monitoring made it difficult determine whether widespread tree mortality resulted from these droughts. Anecdotal observations suggest Dry may have led more significant than Millennium drought. Critically, be able robustly project future expected climate change effects on Australian vegetation, we need assess vulnerability trees Here implemented model plant hydraulics into Community Atmosphere Biosphere Land Exchange (CABLE) land surface model. We parameterized drought response behaviour five broad vegetation types, based common garden dry‐down experiment with species originating across rainfall gradient (188–1,125 mm/year) Australia. The new significantly improved (~35%–45% reduction root mean square error) CABLE’s previous predictions latent heat fluxes during periods water stress at eddy covariance sites Landscape‐scale greatest percentage loss hydraulic conductivity (PLC) about 40%–60%, were broadly consistent satellite estimates regions both In neither did CABLE predict that would reached critical PLC areas (i.e. projected low risk), although highlighted levels near desert where few live. Overall, our experimentally constrained results imply resilience conferred by function, but also highlight data scientific gaps. Our approach presents promising avenue integrate experimental make regional‐scale potential drought‐induced failure.

Language: Английский

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Drought response strategies and hydraulic traits contribute to mechanistic understanding of plant dry-down to hydraulic failure

Tree Physiology, Journal Year: 2019, Volume and Issue: 39(6), P. 910 - 924

Published: March 5, 2019

Drought-induced tree mortality alters forest structure and function, yet our ability to predict when how different species die during drought remains limited. Here, we explore stomatal control tolerance traits influence the duration of stress leading critical levels hydraulic failure. We examined growth physiological responses four woody plant (three angiosperms one conifer) representing a range water-use over course two controlled drought-recovery cycles followed by an extended dry-down. At end final dry-down phase, measured changes in biomass ratios leaf carbohydrates. During first second phases, plants all closed their stomata response decreasing water potential, but only conifer avoided potentials associated with xylem embolism as result early closure relative thresholds dysfunction. The time it took reach was similar among (ranging from 39 57 days stemP88) longer (156 stemP50). Plant influenced number factors including stomatal-hydraulic safety margin (gsP90 - stemP50), well succulence minimum conductance. Leaf carbohydrate reserves (starch) were not depleted at any species, irrespective drought. These findings highlight need consider multiple structural functional predicting timing failure plants.

Language: Английский

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Plant functional traits differ in adaptability and are predicted to be differentially affected by climate change

Ecology and Evolution, Journal Year: 2019, Volume and Issue: 10(1), P. 232 - 248

Published: Nov. 28, 2019

Climate change is testing the resilience of forests worldwide pushing physiological tolerance to climatic extremes. Plant functional traits have been shown be adapted climate and evolved patterns trait correlations (similar distribution) coordinations (mechanistic trade-off). We predicted that would differentiate between populations associated with gradients, suggestive adaptive variation, correlated adapt future scenarios in similar ways.We measured genetically determined variation described correlation for seven traits: photochemical reflectance index (PRI), normalized difference vegetation (NDVI), leaf size (LS), specific area (SLA), δ

Language: Английский

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Hydraulic failure and tree size linked with canopy die‐back in eucalypt forest during extreme drought

New Phytologist, Journal Year: 2021, Volume and Issue: 230(4), P. 1354 - 1365

Published: Feb. 25, 2021

Eastern Australia was subject to its hottest and driest year on record in 2019. This extreme drought resulted massive canopy die-back eucalypt forests. The role of hydraulic failure tree size three species during this examined. We measured pre-dawn midday leaf water potential (Ψleaf ), per cent loss stem conductivity quantified vulnerability drought-induced xylem embolism. Tree health also surveyed. Trees with most, or all, their foliage dead exhibited high rates native embolism (78-100%). is contrast trees partial (30-70% die-back: 72-78% embolism), relatively healthy (little evidence 25-31% embolism). Midday Ψleaf significantly more negative exhibiting (-2.7 -6.3 MPa), compared (-2.1 -4.5 MPa). In two the majority individuals showing complete were small classes. Our results indicate that strongly associated study provides valuable field data help constrain models predicting mortality risk.

Language: Английский

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Linking Forest Flammability and Plant Vulnerability to Drought

Forests, Journal Year: 2020, Volume and Issue: 11(7), P. 779 - 779

Published: July 20, 2020

Globally, fire regimes are being altered by changing climatic conditions. New have the potential to drive species extinctions and cause ecosystem state changes, with a range of consequences for services. Despite co-occurrence forest fires drought, current approaches modelling flammability largely overlook large body research into plant vulnerability drought. Here, we outline mechanisms through which responses drought may affect flammability, specifically fuel moisture ratio dead live fuels. We present framework content (moisture foliage twigs) from soil water traits, including rooting patterns leaf traits such as turgor loss point, osmotic potential, elasticity mass per area. also evidence that physiological stress contribute previously observed thresholds in south-eastern Australia. Of particular relevance is cavitation subsequent shedding, transforms fuels fuels, drier, thus easier ignite. suggest capitalising on inform wildfire presents major opportunity develop new insights wildfires, predictive models seasonal dynamics.

Language: Английский

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Plant profit maximization improves predictions of European forest responses to drought

New Phytologist, Journal Year: 2019, Volume and Issue: 226(6), P. 1638 - 1655

Published: Dec. 16, 2019

Knowledge of how water stress impacts the carbon and cycles is a key uncertainty in terrestrial biosphere models. We tested new profit maximization model, where photosynthetic uptake CO2 optimally traded against plant hydraulic function, as an alternative to empirical functions commonly used models regulate gas exchange during periods stress. conducted multi-site evaluation this model at ecosystem scale, before major droughts Europe. Additionally, we asked whether maximum conductance soil-plant continuum kmax (a parameter which not measured) could be predicted from long-term site climate. Compared with control soil moisture improved simulation evapotranspiration growing season, reducing normalized mean square error by c. 63%, across mesic xeric sites. also showed that estimated climate, improvements eight out 10 forest sites drought. Although generalization approach contingent upon determining , it presents mechanistic trait-based canopy global

Language: Английский

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