1
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Mencuccini M, Anderegg WRL, Binks O, Knipfer T, Konings AG, Novick K, Poyatos R, Martínez-Vilalta J. A new empirical framework to quantify the hydraulic effects of soil and atmospheric drivers on plant water status. Glob Chang Biol 2024; 30:e17222. [PMID: 38450813 DOI: 10.1111/gcb.17222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 02/12/2024] [Accepted: 02/12/2024] [Indexed: 03/08/2024]
Abstract
Metrics to quantify regulation of plant water status at the daily as opposed to the seasonal scale do not presently exist. This gap is significant since plants are hypothesised to regulate their water potential not only with respect to slowly changing soil drought but also with respect to faster changes in air vapour pressure deficit (VPD), a variable whose importance for plant physiology is expected to grow because of higher temperatures in the coming decades. We present a metric, the stringency of water potential regulation, that can be employed at the daily scale and quantifies the effects exerted on plants by the separate and combined effect of soil and atmospheric drought. We test our theory using datasets from two experiments where air temperature and VPD were experimentally manipulated. In contrast to existing metrics based on soil drought that can only be applied at the seasonal scale, our metric successfully detects the impact of atmospheric warming on the regulation of plant water status. We show that the thermodynamic effect of VPD on plant water status can be isolated and compared against that exerted by soil drought and the covariation between VPD and soil drought. Furthermore, in three of three cases, VPD accounted for more than 5 MPa of potential effect on leaf water potential. We explore the significance of our findings in the context of potential future applications of this metric from plant to ecosystem scale.
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Affiliation(s)
| | - William R L Anderegg
- Wilkes Center for Climate Science and Policy, University of Utah, Salt Lake City, Utah, USA
- School of Biological Sciences, University of Utah, Salt Lake City, Utah, USA
| | | | - Thorsten Knipfer
- Faculty of Land and Food Systems, The University of British Columbia, Vancouver, British Columbia, Canada
| | | | - Kim Novick
- University of Indiana, Bloomington, Indiana, USA
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2
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Famiglietti CA, Worden M, Anderegg LDL, Konings AG. Impacts of climate timescale on the stability of trait-environment relationships. New Phytol 2024; 241:2423-2434. [PMID: 38037289 DOI: 10.1111/nph.19416] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Accepted: 11/02/2023] [Indexed: 12/02/2023]
Abstract
Predictive relationships between plant traits and environmental factors can be derived at global and regional scales, informing efforts to reorient ecological models around functional traits. However, in a changing climate, the environmental variables used as predictors in such relationships are far from stationary. This could yield errors in trait-environment model predictions if timescale is not accounted for. Here, the timescale dependence of trait-environment relationships is investigated by regressing in situ trait measurements of specific leaf area, leaf nitrogen content, and wood density on local climate characteristics summarized across several increasingly long timescales. We identify contrasting responses of leaf and wood traits to climate timescale. Leaf traits are best predicted by recent climate timescales, while wood density is a longer term memory trait. The use of sub-optimal climate timescales reduces the accuracy of the resulting trait-environment relationships. This study concludes that plant traits respond to climate conditions on the timescale of tissue lifespans rather than long-term climate normals, even at large spatial scales where multiple ecological and physiological mechanisms drive trait change. Thus, determining trait-environment relationships with temporally relevant climate variables may be critical for predicting trait change in a nonstationary climate system.
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Affiliation(s)
| | - Matthew Worden
- Department of Earth System Science, Stanford University, Stanford, CA, 94305, USA
| | - Leander D L Anderegg
- Department of Ecology, Evolution, & Marine Biology, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Alexandra G Konings
- Department of Earth System Science, Stanford University, Stanford, CA, 94305, USA
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3
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Giardina F, Gentine P, Konings AG, Seneviratne SI, Stocker BD. Diagnosing evapotranspiration responses to water deficit across biomes using deep learning. New Phytol 2023; 240:968-983. [PMID: 37621238 DOI: 10.1111/nph.19197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Accepted: 07/23/2023] [Indexed: 08/26/2023]
Abstract
Accounting for water limitation is key to determining vegetation sensitivity to drought. Quantifying water limitation effects on evapotranspiration (ET) is challenged by the heterogeneity of vegetation types, climate zones and vertically along the rooting zone. Here, we train deep neural networks using flux measurements to study ET responses to progressing drought conditions. We determine a water stress factor (fET) that isolates ET reductions from effects of atmospheric aridity and other covarying drivers. We regress fET against the cumulative water deficit, which reveals the control of whole-column moisture availability. We find a variety of ET responses to water stress. Responses range from rapid declines of fET to 10% of its water-unlimited rate at several savannah and grassland sites, to mild fET reductions in most forests, despite substantial water deficits. Most sensitive responses are found at the most arid and warm sites. A combination of regulation of stomatal and hydraulic conductance and access to belowground water reservoirs, whether in groundwater or deep soil moisture, could explain the different behaviors observed across sites. This variety of responses is not captured by a standard land surface model, likely reflecting simplifications in its representation of belowground water storage.
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Affiliation(s)
- Francesco Giardina
- Institute of Agricultural Sciences, Department of Environmental Systems Science, ETH Zürich, Zürich, CH-8092, Switzerland
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf, CH-8903, Switzerland
| | - Pierre Gentine
- Department of Earth and Environmental Engineering, Columbia University, New York, NY, 10027, USA
- Center for Learning the Earth with Artificial Intelligence and Physics (LEAP), Columbia University, New York, NY, 10027, USA
| | - Alexandra G Konings
- Department of Earth System Science, Stanford University, Stanford, CA, 94305, USA
| | - Sonia I Seneviratne
- Institute for Atmospheric and Climate Science, Department of Environmental Systems Science, ETH Zurich, Zürich, CH-8092, Switzerland
| | - Benjamin D Stocker
- Institute of Agricultural Sciences, Department of Environmental Systems Science, ETH Zürich, Zürich, CH-8092, Switzerland
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf, CH-8903, Switzerland
- Institute of Geography, University of Bern, Hallerstrasse 12, Bern, 3012, Switzerland
- Oeschger Centre for Climate Change Research, University of Bern, Falkenplatz 16, Bern, 3012, Switzerland
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4
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Famiglietti CA, Worden M, Quetin GR, Smallman TL, Dayal U, Bloom AA, Williams M, Konings AG. Global net biome CO 2 exchange predicted comparably well using parameter-environment relationships and plant functional types. Glob Chang Biol 2023; 29:2256-2273. [PMID: 36560840 DOI: 10.1111/gcb.16574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 12/13/2022] [Indexed: 05/28/2023]
Abstract
Accurate estimation and forecasts of net biome CO2 exchange (NBE) are vital for understanding the role of terrestrial ecosystems in a changing climate. Prior efforts to improve NBE predictions have predominantly focused on increasing models' structural realism (and thus complexity), but parametric error and uncertainty are also key determinants of model skill. Here, we investigate how different parameterization assumptions propagate into NBE prediction errors across the globe, pitting the traditional plant functional type (PFT)-based approach against a novel top-down, machine learning-based "environmental filtering" (EF) approach. To do so, we simulate these contrasting methods for parameter assignment within a flexible model-data fusion framework of the terrestrial carbon cycle (CARDAMOM) at a global scale. In the PFT-based approach, model parameters from a small number of select locations are applied uniformly within regions sharing similar land cover characteristics. In the EF-based approach, a pixel's parameters are predicted based on underlying relationships with climate, soil, and canopy properties. To isolate the role of parametric from structural uncertainty in our analysis, we benchmark the resulting PFT-based and EF-based NBE predictions with estimates from CARDAMOM's Bayesian optimization approach (whereby "true" parameters consistent with a suite of data constraints are retrieved on a pixel-by-pixel basis). When considering the mean absolute error of NBE predictions across time, we find that the EF-based approach matches or outperforms the PFT-based approach at 55% of pixels-a narrow majority. However, NBE estimates from the EF-based approach are susceptible to compensation between errors in component flux predictions and predicted parameters can align poorly with the assumed "true" values. Overall, though, the EF-based approach is comparable to conventional approaches and merits further investigation to better understand and resolve these limitations. This work provides insight into the relationship between terrestrial biosphere model performance and parametric uncertainty, informing efforts to improve model parameterization via PFT-free and trait-based approaches.
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Affiliation(s)
| | - Matthew Worden
- Department of Earth System Science, Stanford University, Stanford, California, USA
| | - Gregory R Quetin
- Department of Geography, University of California at Santa Barbara, Santa Barbara, California, USA
| | - T Luke Smallman
- School of GeoSciences and National Centre for Earth Observation, University of Edinburgh, Edinburgh, UK
| | - Uma Dayal
- Department of Earth System Science, Stanford University, Stanford, California, USA
| | - A Anthony Bloom
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Mathew Williams
- School of GeoSciences and National Centre for Earth Observation, University of Edinburgh, Edinburgh, UK
| | - Alexandra G Konings
- Department of Earth System Science, Stanford University, Stanford, California, USA
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5
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Stocker BD, Tumber-Dávila SJ, Konings AG, Anderson MC, Hain C, Jackson RB. Global patterns of water storage in the rooting zones of vegetation. Nat Geosci 2023; 16:250-256. [PMID: 36920146 PMCID: PMC10005945 DOI: 10.1038/s41561-023-01125-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 01/06/2023] [Indexed: 06/02/2023]
Abstract
The rooting-zone water-storage capacity-the amount of water accessible to plants-controls the sensitivity of land-atmosphere exchange of water and carbon during dry periods. How the rooting-zone water-storage capacity varies spatially is largely unknown and not directly observable. Here we estimate rooting-zone water-storage capacity globally from the relationship between remotely sensed vegetation activity, measured by combining evapotranspiration, sun-induced fluorescence and radiation estimates, and the cumulative water deficit calculated from daily time series of precipitation and evapotranspiration. Our findings indicate plant-available water stores that exceed the storage capacity of 2-m-deep soils across 37% of Earth's vegetated surface. We find that biome-level variations of rooting-zone water-storage capacities correlate with observed rooting-zone depth distributions and reflect the influence of hydroclimate, as measured by the magnitude of annual cumulative water-deficit extremes. Smaller-scale variations are linked to topography and land use. Our findings document large spatial variations in the effective root-zone water-storage capacity and illustrate a tight link among the climatology of water deficits, rooting depth of vegetation and its sensitivity to water stress.
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Affiliation(s)
- Benjamin D. Stocker
- Department of Earth System Science, Stanford University, Stanford, CA USA
- Department of Environmental Systems Science, ETH, Zürich, Switzerland
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf, Switzerland
- Institute of Geography, University of Bern, Bern, Switzerland
- Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland
| | - Shersingh Joseph Tumber-Dávila
- Department of Earth System Science, Stanford University, Stanford, CA USA
- Harvard Forest, Harvard University, Petersham, MA USA
| | | | | | | | - Robert B. Jackson
- Department of Earth System Science, Stanford University, Stanford, CA USA
- Woods Institute for the Environment, Stanford University, Stanford, CA USA
- Precourt Institute for Energy, Stanford University, Stanford, CA USA
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6
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Oner D, Kozinski M, Citraro L, Dadap NC, Konings AG, Fua P. Promoting Connectivity of Network-Like Structures by Enforcing Region Separation. IEEE Trans Pattern Anal Mach Intell 2022; 44:5401-5413. [PMID: 33881988 DOI: 10.1109/tpami.2021.3074366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We propose a novel, connectivity-oriented loss function for training deep convolutional networks to reconstruct network-like structures, like roads and irrigation canals, from aerial images. The main idea behind our loss is to express the connectivity of roads, or canals, in terms of disconnections that they create between background regions of the image. In simple terms, a gap in the predicted road causes two background regions, that lie on the opposite sides of a ground truth road, to touch in prediction. Our loss function is designed to prevent such unwanted connections between background regions, and therefore close the gaps in predicted roads. It also prevents predicting false positive roads and canals by penalizing unwarranted disconnections of background regions. In order to capture even short, dead-ending road segments, we evaluate the loss in small image crops. We show, in experiments on two standard road benchmarks and a new data set of irrigation canals, that convnets trained with our loss function recover road connectivity so well that it suffices to skeletonize their output to produce state of the art maps. A distinct advantage of our approach is that the loss can be plugged in to any existing training setup without further modifications.
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7
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Jian J, Bailey V, Dorheim K, Konings AG, Hao D, Shiklomanov AN, Snyder A, Steele M, Teramoto M, Vargas R, Bond-Lamberty B. Historically inconsistent productivity and respiration fluxes in the global terrestrial carbon cycle. Nat Commun 2022; 13:1733. [PMID: 35365658 PMCID: PMC8976082 DOI: 10.1038/s41467-022-29391-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Accepted: 02/28/2022] [Indexed: 11/09/2022] Open
Abstract
The terrestrial carbon cycle is a major source of uncertainty in climate projections. Its dominant fluxes, gross primary productivity (GPP), and respiration (in particular soil respiration, RS), are typically estimated from independent satellite-driven models and upscaled in situ measurements, respectively. We combine carbon-cycle flux estimates and partitioning coefficients to show that historical estimates of global GPP and RS are irreconcilable. When we estimate GPP based on RS measurements and some assumptions about RS:GPP ratios, we found the resulted global GPP values (bootstrap mean [Formula: see text] Pg C yr-1) are significantly higher than most GPP estimates reported in the literature ([Formula: see text] Pg C yr-1). Similarly, historical GPP estimates imply a soil respiration flux (RsGPP, bootstrap mean of [Formula: see text] Pg C yr-1) statistically inconsistent with most published RS values ([Formula: see text] Pg C yr-1), although recent, higher, GPP estimates are narrowing this gap. Furthermore, global RS:GPP ratios are inconsistent with spatial averages of this ratio calculated from individual sites as well as CMIP6 model results. This discrepancy has implications for our understanding of carbon turnover times and the terrestrial sensitivity to climate change. Future efforts should reconcile the discrepancies associated with calculations for GPP and Rs to improve estimates of the global carbon budget.
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Affiliation(s)
- Jinshi Jian
- State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A&F University, Yangling, 712100, China. .,Pacific Northwest National Laboratory, Joint Global Change Research Institute at the University of Maryland-College Park, 5825 University Research Court, Suite 3500, College Park, MD, 20740, USA. .,University of Chinese Academy of Sciences, Beijing, 100049, China. .,Institute of Soil and Water Conservation, Northwest A & F University, Yangling, Shaanxi, 712100, China.
| | - Vanessa Bailey
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, 99354, USA
| | - Kalyn Dorheim
- Pacific Northwest National Laboratory, Joint Global Change Research Institute at the University of Maryland-College Park, 5825 University Research Court, Suite 3500, College Park, MD, 20740, USA
| | - Alexandra G Konings
- Department of Earth System Science, Stanford University, 473 Via Ortega, Room 140, Stanford, CA, 94305, USA
| | - Dalei Hao
- Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, WA, 99354, USA
| | - Alexey N Shiklomanov
- NASA Goddard Space Flight Center, 8800 Greenbelt Rd., Building 33, Greenbelt, MD, 20771, USA
| | - Abigail Snyder
- Pacific Northwest National Laboratory, Joint Global Change Research Institute at the University of Maryland-College Park, 5825 University Research Court, Suite 3500, College Park, MD, 20740, USA
| | - Meredith Steele
- School of Plant and Environmental Sciences, Virginia Tech, 183 Aq Quad Ln, Blacksburg, VA, 24061, USA
| | - Munemasa Teramoto
- National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, 305-8506, Japan.,Arid Land Research Center, Tottori University, 1390 Hamasaka, Tottori, 680-0001, Japan
| | - Rodrigo Vargas
- Department of Plant and Soil Sciences, University of Delaware, Newark, DE, 19716, USA
| | - Ben Bond-Lamberty
- Pacific Northwest National Laboratory, Joint Global Change Research Institute at the University of Maryland-College Park, 5825 University Research Court, Suite 3500, College Park, MD, 20740, USA
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8
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Novick KA, Ficklin DL, Baldocchi D, Davis KJ, Ghezzehei TA, Konings AG, MacBean N, Raoult N, Scott RL, Shi Y, Sulman BN, Wood JD. Confronting the water potential information gap. Nat Geosci 2022; 15:158-164. [PMID: 35300262 PMCID: PMC8923290 DOI: 10.1038/s41561-022-00909-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 02/02/2022] [Indexed: 06/14/2023]
Abstract
Water potential directly controls the function of leaves, roots, and microbes, and gradients in water potential drive water flows throughout the soil-plant-atmosphere continuum. Notwithstanding its clear relevance for many ecosystem processes, soil water potential is rarely measured in-situ, and plant water potential observations are generally discrete, sparse, and not yet aggregated into accessible databases. These gaps limit our conceptual understanding of biophysical responses to moisture stress and inject large uncertainty into hydrologic and land surface models. Here, we outline the conceptual and predictive gains that could be made with more continuous and discoverable observations of water potential in soils and plants. We discuss improvements to sensor technologies that facilitate in situ characterization of water potential, as well as strategies for building new networks that aggregate water potential data across sites. We end by highlighting novel opportunities for linking more representative site-level observations of water potential to remotely-sensed proxies. Together, these considerations offer a roadmap for clearer links between ecohydrological processes and the water potential gradients that have the 'potential' to substantially reduce conceptual and modeling uncertainties.
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Affiliation(s)
- Kimberly A. Novick
- O’Neill School of Public and Environmental Affairs, Indiana University – Bloomington. Bloomington, IN USA
| | - Darren L. Ficklin
- Department of Geography, Indiana University – Bloomington. Bloomington, IN USA
| | - Dennis Baldocchi
- Department of Environmental Science, Policy, and Management. University of California, Berkeley. Berkeley, CA, USA
| | - Kenneth J. Davis
- Department of Meteorology and Atmospheric Science and Earth and Environmental Systems Institute, The Pennsylvania State University, University Park, PA, USA
| | - Teamrat A. Ghezzehei
- Life and Environmental Sciences Department, University of California – Merced. Merced, CA, USA
| | | | - Natasha MacBean
- Department of Geography, Indiana University – Bloomington. Bloomington, IN USA
| | - Nina Raoult
- Laboratoire des Sciences du Climat et de l’Environnement. Paris, France
| | - Russell L. Scott
- Southwest Watershed Research Center, USDA – Agricultural Research Service. Tucson, AZ, USA
| | - Yuning Shi
- Department of Plant Science. The Pennsylvania State University, University Park, PA, USA
| | - Benjamin N. Sulman
- Environmental Sciences Division, Oak Ridge National Laboratory. Oak Ridge, TN, USA
| | - Jeffrey D. Wood
- School of Natural Resources, University of Missouri, Columbia, MO, USA
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9
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Rao K, Williams AP, Diffenbaugh NS, Yebra M, Konings AG. Plant-water sensitivity regulates wildfire vulnerability. Nat Ecol Evol 2022; 6:332-339. [PMID: 35132185 PMCID: PMC8913365 DOI: 10.1038/s41559-021-01654-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 12/17/2021] [Indexed: 11/16/2022]
Abstract
Extreme wildfires extensively impact human health and the environment. Increasing vapour pressure deficit (VPD) has led to a chronic increase in wildfire area in the western United States, yet some regions have been more affected than others. Here we show that for the same increase in VPD, burned area increases more in regions where vegetation moisture shows greater sensitivity to water limitation (plant-water sensitivity; R2 = 0.71). This has led to rapid increases in human exposure to wildfire risk, both because the population living in areas with high plant-water sensitivity grew 50% faster during 1990–2010 than in other wildland–urban interfaces and because VPD has risen most rapidly in these vulnerable areas. As plant-water sensitivity is strongly linked to wildfire vulnerability, accounting for ecophysiological controls should improve wildfire forecasts. If recent trends in VPD and demographic shifts continue, human wildfire risk will probably continue to increase. The authors show that an ecosystem’s sensitivity to drought, measured as the amount of change in vegetation moisture content for a given change in background moisture, predicts the fire hazard in that location.
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10
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Konings AG, Saatchi SS, Frankenberg C, Keller M, Leshyk V, Anderegg WRL, Humphrey V, Matheny AM, Trugman A, Sack L, Agee E, Barnes ML, Binks O, Cawse‐Nicholson K, Christoffersen BO, Entekhabi D, Gentine P, Holtzman NM, Katul GG, Liu Y, Longo M, Martinez‐Vilalta J, McDowell N, Meir P, Mencuccini M, Mrad A, Novick KA, Oliveira RS, Siqueira P, Steele‐Dunne SC, Thompson DR, Wang Y, Wehr R, Wood JD, Xu X, Zuidema PA. Detecting forest response to droughts with global observations of vegetation water content. Glob Chang Biol 2021; 27:6005-6024. [PMID: 34478589 PMCID: PMC9293345 DOI: 10.1111/gcb.15872] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Accepted: 08/23/2021] [Indexed: 05/11/2023]
Abstract
Droughts in a warming climate have become more common and more extreme, making understanding forest responses to water stress increasingly pressing. Analysis of water stress in trees has long focused on water potential in xylem and leaves, which influences stomatal closure and water flow through the soil-plant-atmosphere continuum. At the same time, changes of vegetation water content (VWC) are linked to a range of tree responses, including fluxes of water and carbon, mortality, flammability, and more. Unlike water potential, which requires demanding in situ measurements, VWC can be retrieved from remote sensing measurements, particularly at microwave frequencies using radar and radiometry. Here, we highlight key frontiers through which VWC has the potential to significantly increase our understanding of forest responses to water stress. To validate remote sensing observations of VWC at landscape scale and to better relate them to data assimilation model parameters, we introduce an ecosystem-scale analog of the pressure-volume curve, the non-linear relationship between average leaf or branch water potential and water content commonly used in plant hydraulics. The sources of variability in these ecosystem-scale pressure-volume curves and their relationship to forest response to water stress are discussed. We further show to what extent diel, seasonal, and decadal dynamics of VWC reflect variations in different processes relating the tree response to water stress. VWC can also be used for inferring belowground conditions-which are difficult to impossible to observe directly. Lastly, we discuss how a dedicated geostationary spaceborne observational system for VWC, when combined with existing datasets, can capture diel and seasonal water dynamics to advance the science and applications of global forest vulnerability to future droughts.
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Affiliation(s)
| | - Sassan S. Saatchi
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
| | | | - Michael Keller
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
- United States Forest ServiceWashingtonDCUSA
| | | | | | | | | | - Anna Trugman
- University of California ‐ Santa BarbaraSanta BarbaraCAUSA
| | - Lawren Sack
- University of California ‐ Los AngelesLos AngelesCAUSA
| | | | | | - Oliver Binks
- The Australian National UniversityCanberraACTAustralia
| | | | | | | | | | | | | | | | - Marcos Longo
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
| | - Jordi Martinez‐Vilalta
- Centre de Recerca Ecològica i Aplicacions Forestals (CREAF)BarcelonaSpain
- Universitat Autònoma de BarcelonaBarcelonaSpain
| | - Nate McDowell
- Pacific Northwest National LaboratoryRichlandWAUSA
- Washington State UniversityPullmanWAUSA
| | - Patrick Meir
- The Australian National UniversityCanberraACTAustralia
- University of EdinburghEdinburghUK
| | - Maurizio Mencuccini
- Centre de Recerca Ecològica i Aplicacions Forestals (CREAF)BarcelonaSpain
- Institució Catalana de Recerca i Estudis Avançats (ICREA)BarcelonaSpain
| | - Assaad Mrad
- University of California ‐ IrvineIrvineCAUSA
| | | | | | | | | | - David R. Thompson
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
| | - Yujie Wang
- California Institute of TechnologyPasadenaCAUSA
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11
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Kannenberg SA, Guo JS, Novick KA, Anderegg WRL, Feng X, Kennedy D, Konings AG, Martínez‐Vilalta J, Matheny AM. Opportunities, challenges and pitfalls in characterizing plant water‐use strategies. Funct Ecol 2021. [DOI: 10.1111/1365-2435.13945] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
| | - Jessica S. Guo
- Department of Geology and Geophysics University of Utah Salt Lake City UT USA
- Arizona Experiment Station, College of Agriculture and Life Sciences University of Arizona Tucson AZ USA
| | - Kimberly A. Novick
- O’Neill School of Public and Environmental Affairs Indiana University Bloomington IN USA
| | | | - Xue Feng
- Department of Civil, Environmental, and Geo‐Engineering University of Minnesota Minneapolis MN USA
- Saint Anthony Falls Laboratory University of Minnesota Minneapolis MN USA
| | | | | | - Jordi Martínez‐Vilalta
- CREAF, Bellaterra (Cerdanyola del Vallès) Catalonia Spain
- Universitat Autònoma de Barcelona, Bellaterra (Cerdanyola del Vallès) Catalonia Spain
| | - Ashley M. Matheny
- Department of Geological Sciences Jackson School of Geosciences University of Texas Austin TX USA
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12
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Xu X, Konings AG, Longo M, Feldman A, Xu L, Saatchi S, Wu D, Wu J, Moorcroft P. Leaf surface water, not plant water stress, drives diurnal variation in tropical forest canopy water content. New Phytol 2021; 231:122-136. [PMID: 33539544 DOI: 10.1111/nph.17254] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 01/27/2021] [Indexed: 05/25/2023]
Abstract
Variation in canopy water content (CWC) that can be detected from microwave remote sensing of vegetation optical depth (VOD) has been proposed as an important measure of vegetation water stress. However, the contribution of leaf surface water (LWs ), arising from dew formation and rainfall interception, to CWC is largely unknown, particularly in tropical forests and other high-humidity ecosystems. We compared VOD data from the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) and CWC predicted by a plant hydrodynamics model at four tropical sites in Brazil spanning a rainfall gradient. We assessed how LWs influenced the relationship between VOD and CWC. The analysis indicates that while CWC is strongly correlated with VOD (R2 = 0.62 across all sites), LWs accounts for 61-76% of the diurnal variation in CWC despite being < 10% of CWC. Ignoring LWs weakens the near-linear relationship between CWC and VOD and reduces the consistency in diurnal variation. The contribution of LWs to CWC variation, however, decreases at longer, seasonal to inter-annual, time scales. Our results demonstrate that diurnal patterns of dew formation and rainfall interception can be an important driver of diurnal variation in CWC and VOD over tropical ecosystems and therefore should be accounted for when inferring plant diurnal water stress from VOD measurements.
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Affiliation(s)
- Xiangtao Xu
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, 14850, USA
| | - Alexandra G Konings
- Department of Earth System Science, Stanford University, Stanford, CA, 94305, USA
| | - Marcos Longo
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, 91109, USA
| | - Andrew Feldman
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Liang Xu
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, 91109, USA
| | - Sassan Saatchi
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, 91109, USA
- Institute of Environment and Sustainability, University of California, Los Angeles, CA, 90024, USA
| | - Donghai Wu
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, 14850, USA
| | - Jin Wu
- School of Biological Sciences, University of Hong Kong, Hong Kong, China
| | - Paul Moorcroft
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA
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13
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Wu G, Guan K, Li Y, Novick KA, Feng X, McDowell NG, Konings AG, Thompson SE, Kimball JS, De Kauwe MG, Ainsworth EA, Jiang C. Interannual variability of ecosystem iso/anisohydry is regulated by environmental dryness. New Phytol 2021; 229:2562-2575. [PMID: 33118166 DOI: 10.1111/nph.17040] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 10/16/2020] [Indexed: 06/11/2023]
Abstract
●Plants are characterized by the iso/anisohydry continuum depending on how they regulate leaf water potential (ΨL ). However, how iso/anisohydry changes over time in response to year-to-year variations in environmental dryness and how such responses vary across different regions remains poorly characterized. ●We investigated how dryness, represented by aridity index, affects the interannual variability of ecosystem iso/anisohydry at the regional scale, estimated using satellite microwave vegetation optical depth (VOD) observations. This ecosystem-level analysis was further complemented with published field observations of species-level ΨL . ●We found different behaviors in the directionality and sensitivity of isohydricity (σ) with respect to the interannual variation of dryness in different ecosystems. These behaviors can largely be differentiated by the average dryness of the ecosystem itself: in mesic ecosystems, σ decreases in drier years with a higher sensitivity to dryness; in xeric ecosystems, σ increases in drier years with a lower sensitivity to dryness. These results were supported by the species-level synthesis. ●Our study suggests that how plants adjust their water use across years - as revealed by their interannual variability in isohydricity - depends on the dryness of plants' living environment. This finding advances our understanding of plant responses to drought at regional scales.
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Affiliation(s)
- Genghong Wu
- College of Agricultural, Consumer and Environmental Sciences, University of Illinois at Urbana Champaign, Urbana, IL, 61801, USA
| | - Kaiyu Guan
- College of Agricultural, Consumer and Environmental Sciences, University of Illinois at Urbana Champaign, Urbana, IL, 61801, USA
- National Center for Supercomputing Applications, University of Illinois at Urbana Champaign, Champaign, IL, 61820, USA
| | - Yan Li
- State Key Laboratory of Earth Surface Processes and Resources Ecology, Faculty of Geographical Science, Beijing Normal University, Beijing, 100875, China
| | - Kimberly A Novick
- O'Neill School of Public and Environmental Affairs, Indiana University Bloomington, Bloomington, IN, 47405, USA
| | - Xue Feng
- Department of Civil, Environmental, and Geo-Engineering, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Nate G McDowell
- Earth Systems Science Division, Pacific Northwest National Laboratory, Richland, WA, 99352, USA
| | - Alexandra G Konings
- Department of Earth System Science, Stanford University, Stanford, CA, 94305, USA
| | - Sally E Thompson
- Department of Civil and Environmental Engineering, University of California Berkeley, Berkeley, CA, 94720, USA
- Department of Civil, Environmental and Mining Engineering, University of Western Australia, Crawley, WA, 6009, Australia
| | - John S Kimball
- Numerical Terra dynamic Simulation Group, College of Forestry & Conservation, University of Montana, Missoula, MT, 59812, USA
| | - Martin G De Kauwe
- ARC Australia Centre of Excellence for Climate Extremes, Sydney, NSW, 2052, Australia
- Climate Change Research Centre, University of New South Wales, Sydney, NSW, 2052, Australia
- Evolution and Ecology Research Centre, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Elizabeth A Ainsworth
- Department of Plant Biology, University of Illinois at Urbana Champaign, Urbana, IL, 61801, USA
- USDA ARS Global Change and Photosynthesis Research Unit, Urbana, IL, 61801, USA
| | - Chongya Jiang
- College of Agricultural, Consumer and Environmental Sciences, University of Illinois at Urbana Champaign, Urbana, IL, 61801, USA
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14
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Ciais P, Yao Y, Gasser T, Baccini A, Wang Y, Lauerwald R, Peng S, Bastos A, Li W, Raymond PA, Canadell JG, Peters GP, Andres RJ, Chang J, Yue C, Dolman AJ, Haverd V, Hartmann J, Laruelle G, Konings AG, King AW, Liu Y, Luyssaert S, Maignan F, Patra PK, Peregon A, Regnier P, Pongratz J, Poulter B, Shvidenko A, Valentini R, Wang R, Broquet G, Yin Y, Zscheischler J, Guenet B, Goll DS, Ballantyne AP, Yang H, Qiu C, Zhu D. Empirical estimates of regional carbon budgets imply reduced global soil heterotrophic respiration. Natl Sci Rev 2020; 8:nwaa145. [PMID: 34691569 PMCID: PMC8288404 DOI: 10.1093/nsr/nwaa145] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 06/17/2020] [Accepted: 06/24/2020] [Indexed: 11/15/2022] Open
Abstract
Resolving regional carbon budgets is critical for informing land-based mitigation policy. For nine regions covering nearly the whole globe, we collected inventory estimates of carbon-stock changes complemented by satellite estimates of biomass changes where inventory data are missing. The net land–atmospheric carbon exchange (NEE) was calculated by taking the sum of the carbon-stock change and lateral carbon fluxes from crop and wood trade, and riverine-carbon export to the ocean. Summing up NEE from all regions, we obtained a global ‘bottom-up’ NEE for net land anthropogenic CO2 uptake of –2.2 ± 0.6 PgC yr−1 consistent with the independent top-down NEE from the global atmospheric carbon budget during 2000–2009. This estimate is so far the most comprehensive global bottom-up carbon budget accounting, which set up an important milestone for global carbon-cycle studies. By decomposing NEE into component fluxes, we found that global soil heterotrophic respiration amounts to a source of CO2 of 39 PgC yr−1 with an interquartile of 33–46 PgC yr−1—a much smaller portion of net primary productivity than previously reported.
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Affiliation(s)
- Philippe Ciais
- Laboratoire des Sciences du Climat et de l’Environnement, CEA-CNRS-UVSQ-UPSACLAY, Gif sur Yvette 91191, France
- Sino-French Institute for Earth System Science, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China
| | - Yitong Yao
- Laboratoire des Sciences du Climat et de l’Environnement, CEA-CNRS-UVSQ-UPSACLAY, Gif sur Yvette 91191, France
| | - Thomas Gasser
- International Institute for Applied Systems Analysis (IIASA), Laxenburg A-2361, Austria
| | | | - Yilong Wang
- The Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100871, China
| | - Ronny Lauerwald
- Laboratoire des Sciences du Climat et de l’Environnement, CEA-CNRS-UVSQ-UPSACLAY, Gif sur Yvette 91191, France
- Department Geoscience, Environment & Society, Université Libre de Bruxelles, Bruxelles 1050, Belgium
| | - Shushi Peng
- Sino-French Institute for Earth System Science, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China
| | - Ana Bastos
- Department für Geographie, Ludwig-Maximilians-Universität München, München D-80333, Germany
| | - Wei Li
- Department of Earth System Science, Tsinghua University, Beijing 100084, China
| | - Peter A Raymond
- Yale School of Forestry and Environmental Studies, Yale University, New Haven, CT 06511, USA
| | - Josep G Canadell
- Global Carbon Project, CSIRO Oceans and Atmosphere, Canberra ACT 2601, Australia
| | - Glen P Peters
- CICERO Center for International Climate Research, Oslo 0349, Norway
| | - Rob J Andres
- Environmental Sciences Division and Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Jinfeng Chang
- Laboratoire des Sciences du Climat et de l’Environnement, CEA-CNRS-UVSQ-UPSACLAY, Gif sur Yvette 91191, France
| | - Chao Yue
- Laboratoire des Sciences du Climat et de l’Environnement, CEA-CNRS-UVSQ-UPSACLAY, Gif sur Yvette 91191, France
- State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A&F University, Yangling 712100, China
| | - A Johannes Dolman
- Department of Earth Science, Vrije Universiteit Amsterdam, Amsterdam HV 1081, The Netherlands
| | - Vanessa Haverd
- CSIRO Oceans and Atmosphere, Canberra ACT 2601, Australia
| | - Jens Hartmann
- Institute for Geology, CEN—Center for Earth System Research and Sustainability, University of Hamburg, Hamburg D-20146, Germany
| | - Goulven Laruelle
- Department Geoscience, Environment & Society, Université Libre de Bruxelles, Bruxelles 1050, Belgium
| | - Alexandra G Konings
- Department of Earth System Science, Stanford University, Stanford, CA 94305, USA
| | - Anthony W King
- Environmental Sciences Division and Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Yi Liu
- School of Geographical Sciences, Nanjing University of Information Science and Technology, Nanjing 210044, China
| | - Sebastiaan Luyssaert
- Department of Ecological Sciences, Vrije Universiteit Amsterdam, Amsterdam HV 1081, The Netherlands
| | - Fabienne Maignan
- Laboratoire des Sciences du Climat et de l’Environnement, CEA-CNRS-UVSQ-UPSACLAY, Gif sur Yvette 91191, France
| | - Prabir K Patra
- Research Institute for Global Change, JAMSTEC, Kanagawa 236-0001, Japan
- Center for Environmental Remote Sensing, Chiba University, Chiba 263–8522, Japan
| | - Anna Peregon
- Laboratoire des Sciences du Climat et de l’Environnement, CEA-CNRS-UVSQ-UPSACLAY, Gif sur Yvette 91191, France
- Institute of Soil Science and Agrochemistry, Siberian Branch of the Russian Academy of Sciences (SB RAS), Novosibirsk 630090, Russia
- Tuva State University, Republic of Tuva, 667000, Russian
| | - Pierre Regnier
- Department Geoscience, Environment & Society, Université Libre de Bruxelles, Bruxelles 1050, Belgium
| | - Julia Pongratz
- Department Geoscience, Environment & Society, Université Libre de Bruxelles, Bruxelles 1050, Belgium
- Max Planck Institute for Meteorology, Hamburg 20146, Germany
| | - Benjamin Poulter
- NASA Goddard Space Flight Center, Biospheric Sciences Lab., Greenbelt, MD 20771, USA
| | - Anatoly Shvidenko
- International Institute for Applied Systems Analysis (IIASA), Laxenburg A-2361, Austria
| | - Riccardo Valentini
- Department for Innovation in Biological, Agro-food and Forest systems (DIBAF), University of Tuscia, Viterbo 01100, Italy
- RUDN University, Moscow 117198, Russia
| | - Rong Wang
- Department of Environmental Science and Engineering, Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Institute of Atmospheric Sciences, Fudan University, Shanghai 200433, China
| | - Grégoire Broquet
- Laboratoire des Sciences du Climat et de l’Environnement, CEA-CNRS-UVSQ-UPSACLAY, Gif sur Yvette 91191, France
| | - Yi Yin
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA
| | - Jakob Zscheischler
- Climate and Environmental Physics and Oeschger Centre for Climate Change Research, University of Bern, Bern 3012, Switzerland
| | - Bertrand Guenet
- Laboratoire des Sciences du Climat et de l’Environnement, CEA-CNRS-UVSQ-UPSACLAY, Gif sur Yvette 91191, France
| | - Daniel S Goll
- Laboratoire des Sciences du Climat et de l’Environnement, CEA-CNRS-UVSQ-UPSACLAY, Gif sur Yvette 91191, France
| | - Ashley-P Ballantyne
- Department of Ecosystem and Conservation Science, University of Montana, Missoula, MT 59801, USA
| | - Hui Yang
- Laboratoire des Sciences du Climat et de l’Environnement, CEA-CNRS-UVSQ-UPSACLAY, Gif sur Yvette 91191, France
| | - Chunjing Qiu
- Laboratoire des Sciences du Climat et de l’Environnement, CEA-CNRS-UVSQ-UPSACLAY, Gif sur Yvette 91191, France
| | - Dan Zhu
- Laboratoire des Sciences du Climat et de l’Environnement, CEA-CNRS-UVSQ-UPSACLAY, Gif sur Yvette 91191, France
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15
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Konings AG, Rao K, Steele-Dunne SC. Macro to micro: microwave remote sensing of plant water content for physiology and ecology. New Phytol 2019; 223:1166-1172. [PMID: 30919449 DOI: 10.1111/nph.15808] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Accepted: 03/05/2019] [Indexed: 05/04/2023]
Abstract
Although primarily valued for their suitability for oceanographic applications and soil moisture estimation, microwave remote sensing observations are also sensitive to plant water content (Mw ). Since Mw depends on both plant water status and biomass, these observations have the potential to be useful for a range of plant drought response studies. In this paper, we introduce the principles behind microwave remote sensing observations to illustrate how they are sensitive to plant water content and discuss the relationship between landscape-scale Mw and common stand-scale metrics, including plant-scale relative water content, live fuel moisture content and leaf water potential. Lastly, we discuss how various sensor types can be leveraged for specific applications depending on the spatio-temporal resolution needed.
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Affiliation(s)
- Alexandra G Konings
- Department of Earth System Science, Stanford University, 473 Via Ortega, Room 140, Stanford, CA, 94305, USA
| | - Krishna Rao
- Department of Earth System Science, Stanford University, 473 Via Ortega, Room 140, Stanford, CA, 94305, USA
| | - Susan C Steele-Dunne
- Faculty of Civil Engineering and Geosciences, Delft University of Technology (TU Delft), Stevinweg 1, Delft, 2628 CN, the Netherlands
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16
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Novick KA, Konings AG, Gentine P. Beyond soil water potential: An expanded view on isohydricity including land-atmosphere interactions and phenology. Plant Cell Environ 2019; 42:1802-1815. [PMID: 30632172 DOI: 10.1111/pce.13517] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Revised: 01/02/2019] [Accepted: 01/07/2019] [Indexed: 05/21/2023]
Abstract
Over the past decade, the concept of isohydry or anisohydry, which describes the link between soil water potential (ΨS ), leaf water potential (ΨL ), and stomatal conductance (gs ), has soared in popularity. However, its utility has recently been questioned, and a surprising lack of coordination between the dynamics of ΨL and gs across biomes has been reported. Here, we offer a more expanded view of the isohydricity concept that considers effects of vapour pressure deficit (VPD) and leaf area index (AL ) on the apparent sensitivities of ΨL and gs to drought. After validating the model with tree- and ecosystem-scale data, we find that within a site, isohydricity is a strong predictor of limitations to stomatal function, though variation in VPD and leaf area, among other factors, can challenge its diagnosis. Across sites, the theory predicts that the degree of isohydricity is a good predictor of the sensitivity of gs to declining soil water in the absence of confounding effects from other drivers. However, if VPD effects are significant, they alone are sufficient to decouple the dynamics of ΨL and gs entirely. We conclude with a set of practical recommendations for future applications of the isohydricity framework within and across sites.
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Affiliation(s)
- Kimberly A Novick
- School of Public and Environmental Affairs, Indiana University Bloomington, Bloomington, Indiana
| | - Alexandra G Konings
- Department of Earth System Science, Stanford University, Stanford, California
| | - Pierre Gentine
- Department of Earth and Environmental Engineering, Columbia University, New York, New York
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17
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Feldman AF, Short Gianotti DJ, Konings AG, McColl KA, Akbar R, Salvucci GD, Entekhabi D. Moisture pulse-reserve in the soil-plant continuum observed across biomes. Nat Plants 2018; 4:1026-1033. [PMID: 30518832 DOI: 10.1038/s41477-018-0304-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 10/15/2018] [Indexed: 06/09/2023]
Abstract
The degree to which individual pulses of available water drive plant activity across diverse biomes and climates is not well understood. It has previously only been investigated in a few dryland locations. Here, plant water uptake following pulses of surface soil moisture, an indicator for the pulse-reserve hypothesis, is investigated across South America, Africa and Australia with satellite-based estimates of surface soil and canopy water content. Our findings show that this behaviour is widespread: occurring over half of the vegetated landscapes. We estimate spatially varying soil moisture thresholds at which plant water uptake ceases, noting dependence on soil texture and proximity to the wilting point. The soil type and biome-dependent soil moisture threshold and the plant soil water uptake patterns at the scale of Earth system models allow a unique opportunity to test and improve model parameterization of vegetation function under water limitation.
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Affiliation(s)
- Andrew F Feldman
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.
| | - Daniel J Short Gianotti
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Alexandra G Konings
- Department of Earth System Science, Stanford University, Stanford, California, USA
| | - Kaighin A McColl
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, USA
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Ruzbeh Akbar
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Guido D Salvucci
- Department of Earth and Environment, Boston University, Boston, MA, USA
| | - Dara Entekhabi
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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18
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Anderegg WRL, Konings AG, Trugman AT, Yu K, Bowling DR, Gabbitas R, Karp DS, Pacala S, Sperry JS, Sulman BN, Zenes N. Hydraulic diversity of forests regulates ecosystem resilience during drought. Nature 2018; 561:538-541. [PMID: 30232452 DOI: 10.1038/s41586-018-0539-7] [Citation(s) in RCA: 120] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Accepted: 08/14/2018] [Indexed: 11/09/2022]
Abstract
Plants influence the atmosphere through fluxes of carbon, water and energy1, and can intensify drought through land-atmosphere feedback effects2-4. The diversity of plant functional traits in forests, especially physiological traits related to water (hydraulic) transport, may have a critical role in land-atmosphere feedback, particularly during drought. Here we combine 352 site-years of eddy covariance measurements from 40 forest sites, remote-sensing observations of plant water content and plant functional-trait data to test whether the diversity in plant traits affects the response of the ecosystem to drought. We find evidence that higher hydraulic diversity buffers variation in ecosystem flux during dry periods across temperate and boreal forests. Hydraulic traits were the predominant significant predictors of cross-site patterns in drought response. By contrast, standard leaf and wood traits, such as specific leaf area and wood density, had little explanatory power. Our results demonstrate that diversity in the hydraulic traits of trees mediates ecosystem resilience to drought and is likely to have an important role in future ecosystem-atmosphere feedback effects in a changing climate.
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Affiliation(s)
| | | | - Anna T Trugman
- School of Biological Sciences, University of Utah, Salt Lake City, UT, USA
| | - Kailiang Yu
- School of Biological Sciences, University of Utah, Salt Lake City, UT, USA
| | - David R Bowling
- School of Biological Sciences, University of Utah, Salt Lake City, UT, USA
| | - Robert Gabbitas
- School of Biological Sciences, University of Utah, Salt Lake City, UT, USA
| | - Daniel S Karp
- Department of Wildlife, Fish, and Conservation Biology, University of California, Davis, Davis, CA, USA
| | - Stephen Pacala
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, USA
| | - John S Sperry
- School of Biological Sciences, University of Utah, Salt Lake City, UT, USA
| | - Benjamin N Sulman
- Program in Atmospheric and Oceanic Sciences, Princeton University, Princeton, NJ, USA.,School of Natural Sciences, University of California, Merced, Merced, CA, USA
| | - Nicole Zenes
- School of Biological Sciences, University of Utah, Salt Lake City, UT, USA
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19
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Alemohammad SH, Fang B, Konings AG, Aires F, Green JK, Kolassa J, Miralles D, Prigent C, Gentine P. Water, Energy, and Carbon with Artificial Neural Networks (WECANN): A statistically-based estimate of global surface turbulent fluxes and gross primary productivity using solar-induced fluorescence. ACTA ACUST UNITED AC 2017; 14:4101-4124. [PMID: 29290755 DOI: 10.5194/bg-14-4101-2017] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A new global estimate of surface turbulent fluxes, latent heat flux (LE) and sensible heat flux (H), and gross primary production (GPP) is developed using a machine learning approach informed by novel remotely sensed Solar-Induced Fluorescence (SIF) and other radiative and meteorological variables. This is the first study to jointly retrieve LE, H and GPP using SIF observations. The approach uses an artificial neural network (ANN) with a target dataset generated from three independent data sources, weighted based on triple collocation (TC) algorithm. The new retrieval, named Water, Energy, and Carbon with Artificial Neural Networks (WECANN), provides estimates of LE, H and GPP from 2007 to 2015 at 1° × 1° spatial resolution and on monthly time resolution. The quality of ANN training is assessed using the target data, and the WECANN retrievals are evaluated using eddy covariance tower estimates from FLUXNET network across various climates and conditions. When compared to eddy covariance estimates, WECANN typically outperforms other products, particularly for sensible and latent heat fluxes. Analysing WECANN retrievals across three extreme drought and heatwave events demonstrates the capability of the retrievals in capturing the extent of these events. Uncertainty estimates of the retrievals are analysed and the inter-annual variability in average global and regional fluxes show the impact of distinct climatic events - such as the 2015 El Niño - on surface turbulent fluxes and GPP.
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Affiliation(s)
- Seyed Hamed Alemohammad
- Department of Earth and Environmental Engineering, Columbia University, New York, 10027, USA.,Columbia Water Center, Columbia University, New York, 10027, USA
| | - Bin Fang
- Department of Earth and Environmental Engineering, Columbia University, New York, 10027, USA.,Columbia Water Center, Columbia University, New York, 10027, USA
| | - Alexandra G Konings
- Department of Earth System Science, Stanford University, Stanford, 94305, USA
| | - Filipe Aires
- Department of Earth and Environmental Engineering, Columbia University, New York, 10027, USA.,Observatoire de Paris, Paris, 75014, France
| | - Julia K Green
- Department of Earth and Environmental Engineering, Columbia University, New York, 10027, USA.,Columbia Water Center, Columbia University, New York, 10027, USA
| | - Jana Kolassa
- Universities Space Research Association/NPP, Columbia, MD, 21046, USA.,Global Modeling and Assimilation Office, NASA Goddard Spaceflight Center, Greenbelt, MD, 20771, USA
| | - Diego Miralles
- Department of Earth Sciences, VU University Amsterdam, Amsterdam, 1081HV, The Netherlands.,Laboratory of Hydrology and Water Management, Ghent University, Ghent, B-9000, Belgium
| | - Catherine Prigent
- Department of Earth and Environmental Engineering, Columbia University, New York, 10027, USA.,Global Modeling and Assimilation Office, NASA Goddard Spaceflight Center, Greenbelt, MD, 20771, USA
| | - Pierre Gentine
- Department of Earth and Environmental Engineering, Columbia University, New York, 10027, USA.,Columbia Water Center, Columbia University, New York, 10027, USA.,Earth Institute, Columbia University, New York, 10027, USA
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20
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Green JK, Konings AG, Alemohammad SH, Berry J, Entekhabi D, Kolassa J, Lee JE, Gentine P. Regionally strong feedbacks between the atmosphere and terrestrial biosphere. Nat Geosci 2017; Volume 10:410-414. [PMID: 31709007 PMCID: PMC6839712 DOI: 10.1038/ngeo2957] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 04/20/2017] [Indexed: 05/19/2023]
Abstract
The terrestrial biosphere and atmosphere interact through a series of feedback loops. Variability in terrestrial vegetation growth and phenology can modulate fluxes of water and energy to the atmosphere, and thus affect the climatic conditions that in turn regulate vegetation dynamics. Here we analyze satellite observations of solar-induced fluorescence, precipitation, and radiation using a multivariate statistical technique. We find that biosphere-atmosphere feedbacks are globally widespread and regionally strong: they explain up to 30% of precipitation and surface radiation variance. Substantial biosphere-precipitation feedbacks are often found in regions that are transitional between energy and water limitation, such as semi-arid or monsoonal regions. Substantial biosphere-radiation feedbacks are often present in several moderately wet regions and in the Mediterranean, where precipitation and radiation increase vegetation growth. Enhancement of latent and sensible heat transfer from vegetation accompanies this growth, which increases boundary layer height and convection, affecting cloudiness, and consequently incident surface radiation. Enhanced evapotranspiration can increase moist convection, leading to increased precipitation. Earth system models underestimate these precipitation and radiation feedbacks mainly because they underestimate the biosphere response to radiation and water availability. We conclude that biosphere-atmosphere feedbacks cluster in specific climatic regions that help determine the net CO2 balance of the biosphere.
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Affiliation(s)
- Julia K. Green
- Department of Earth and Environmental Engineering, Columbia University, New York, NY
- Correspondence to:
| | - Alexandra G. Konings
- Department of Earth and Environmental Engineering, Columbia University, New York, NY
- Department of Earth System Science, Stanford University, Stanford, CA
| | - Seyed Hamed Alemohammad
- Department of Earth and Environmental Engineering, Columbia University, New York, NY
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA
| | - Joseph Berry
- Department of Global Ecology, Carnegie Institution of Washington, Stanford, CA
| | - Dara Entekhabi
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA
| | - Jana Kolassa
- University Space Research Association, Columbia, MD
- Global Modeling and Assimilation Office, NASA Goddard Space Flight Center, Greenbelt, MD
| | - Jung-Eun Lee
- Department of Earth, Environment and Planetary Sciences, Brown University, Providence, RI
| | - Pierre Gentine
- Department of Earth and Environmental Engineering, Columbia University, New York, NY
- The Earth Institute, Columbia University, New York, NY
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Abstract
Droughts are expected to become more frequent and more intense under climate change. Plant mortality rates and biomass declines in response to drought depend on stomatal and xylem flow regulation. Plants operate on a continuum of xylem and stomatal regulation strategies from very isohydric (strict regulation) to very anisohydric. Coexisting species may display a variety of isohydricity behaviors. As such, it can be difficult to predict how to model the degree of isohydricity at the ecosystem scale by aggregating studies of individual species. This is nonetheless essential for accurate prediction of ecosystem drought resilience. In this study, we define a metric for the degree of isohydricity at the ecosystem scale in analogy with a recent metric introduced at the species level. Using data from the AMSR-E satellite, this metric is evaluated globally based on diurnal variations in microwave vegetation optical depth (VOD), which is directly related to leaf water potential. Areas with low annual mean radiation are found to be more anisohydric. Except for evergreen broadleaf forests in the tropics, which are very isohydric, and croplands, which are very anisohydric, land cover type is a poor predictor of ecosystem isohydricity, in accordance with previous species-scale observations. It is therefore also a poor basis for parameterizing water stress response in land-surface models. For taller ecosystems, canopy height is correlated with higher isohydricity (so that rainforests are mostly isohydric). Highly anisohydric areas show either high or low underlying water use efficiency. In seasonally dry locations, most ecosystems display a more isohydric response (increased stomatal regulation) during the dry season. In several seasonally dry tropical forests, this trend is reversed, as dry-season leaf-out appears to coincide with a shift toward more anisohydric strategies. The metric developed in this study allows for detailed investigations of spatial and temporal variations in plant water behavior.
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Affiliation(s)
- Alexandra G Konings
- Department of Earth and Environmental Engineering, Columbia University, New York, NY, 10027, USA
- Department of Earth System Science, Stanford University, Stanford, CA, 94305, USA
| | - Pierre Gentine
- Department of Earth and Environmental Engineering, Columbia University, New York, NY, 10027, USA
- Earth Institute, Columbia University, New York, NY, 10027, USA
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Alemohammad SH, Fang B, Konings AG, Aires F, Green JK, Kolassa J, Miralles D, Prigent C, Gentine P. Water, Energy, and Carbon with Artificial Neural Networks (WECANN): A statistically-based estimate of global surface turbulent fluxes and gross primary productivity using solar-induced fluorescence. Biogeosciences 2017; 14:4101-4124. [PMID: 29290755 DOI: 10.5194/bg-2016-495] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
A new global estimate of surface turbulent fluxes, latent heat flux (LE) and sensible heat flux (H), and gross primary production (GPP) is developed using a machine learning approach informed by novel remotely sensed Solar-Induced Fluorescence (SIF) and other radiative and meteorological variables. This is the first study to jointly retrieve LE, H and GPP using SIF observations. The approach uses an artificial neural network (ANN) with a target dataset generated from three independent data sources, weighted based on triple collocation (TC) algorithm. The new retrieval, named Water, Energy, and Carbon with Artificial Neural Networks (WECANN), provides estimates of LE, H and GPP from 2007 to 2015 at 1° × 1° spatial resolution and on monthly time resolution. The quality of ANN training is assessed using the target data, and the WECANN retrievals are evaluated using eddy covariance tower estimates from FLUXNET network across various climates and conditions. When compared to eddy covariance estimates, WECANN typically outperforms other products, particularly for sensible and latent heat fluxes. Analysing WECANN retrievals across three extreme drought and heatwave events demonstrates the capability of the retrievals in capturing the extent of these events. Uncertainty estimates of the retrievals are analysed and the inter-annual variability in average global and regional fluxes show the impact of distinct climatic events - such as the 2015 El Niño - on surface turbulent fluxes and GPP.
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Affiliation(s)
- Seyed Hamed Alemohammad
- Department of Earth and Environmental Engineering, Columbia University, New York, 10027, USA
- Columbia Water Center, Columbia University, New York, 10027, USA
| | - Bin Fang
- Department of Earth and Environmental Engineering, Columbia University, New York, 10027, USA
- Columbia Water Center, Columbia University, New York, 10027, USA
| | - Alexandra G Konings
- Department of Earth System Science, Stanford University, Stanford, 94305, USA
| | - Filipe Aires
- Department of Earth and Environmental Engineering, Columbia University, New York, 10027, USA
- Observatoire de Paris, Paris, 75014, France
| | - Julia K Green
- Department of Earth and Environmental Engineering, Columbia University, New York, 10027, USA
- Columbia Water Center, Columbia University, New York, 10027, USA
| | - Jana Kolassa
- Universities Space Research Association/NPP, Columbia, MD, 21046, USA
- Global Modeling and Assimilation Office, NASA Goddard Spaceflight Center, Greenbelt, MD, 20771, USA
| | - Diego Miralles
- Department of Earth Sciences, VU University Amsterdam, Amsterdam, 1081HV, The Netherlands
- Laboratory of Hydrology and Water Management, Ghent University, Ghent, B-9000, Belgium
| | - Catherine Prigent
- Department of Earth and Environmental Engineering, Columbia University, New York, 10027, USA
- Global Modeling and Assimilation Office, NASA Goddard Spaceflight Center, Greenbelt, MD, 20771, USA
| | - Pierre Gentine
- Department of Earth and Environmental Engineering, Columbia University, New York, 10027, USA
- Columbia Water Center, Columbia University, New York, 10027, USA
- Earth Institute, Columbia University, New York, 10027, USA
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Katul GG, Konings AG, Porporato A. Mean velocity profile in a sheared and thermally stratified atmospheric boundary layer. Phys Rev Lett 2011; 107:268502. [PMID: 22243189 DOI: 10.1103/physrevlett.107.268502] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Indexed: 05/31/2023]
Abstract
A stability correction function φ(m)(ζ) that accounts for distortions to the logarithmic mean velocity profile (MVP) in the lower atmosphere caused by thermal stratification was proposed by Monin and Obukhov in the 1950s using dimensional analysis. Its universal character was established from many field experiments. However, theories that describe the canonical shape of φ(m)(ζ) are still lacking. A previous link between the spectrum of turbulence and the MVP is expanded here to include the effects of thermal stratification on the turbulent kinetic energy dissipation rate and eddy-size anisotropy. The resulting theory provides a novel explanation for the power-law exponents and coefficients already reported for φ(m)(ζ) from numerous field experiments.
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Affiliation(s)
- Gabriel G Katul
- Nicholas School of the Environment, Box 80328, Duke University, Durham, North Carolina 27708, USA
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Konings AG, Dekker SC, Rietkerk M, Katul GG. Drought sensitivity of patterned vegetation determined by rainfall-land surface feedbacks. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2011jg001748] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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