Detecting forest response to droughts with global observations of vegetation water content

Global Change Biology, Journal Year: 2021, Volume and Issue: 27(23), P. 6005 - 6024

Published: Sept. 3, 2021

Droughts in a warming climate have become more common and extreme, making understanding forest responses to water stress increasingly pressing. Analysis of trees has long focused on potential xylem leaves, which influences stomatal closure flow through the soil-plant-atmosphere continuum. At same time, changes vegetation content (VWC) are linked range tree responses, including fluxes carbon, mortality, flammability, more. Unlike potential, requires demanding situ measurements, VWC can be retrieved from remote sensing particularly at microwave frequencies using radar radiometry. Here, we highlight key frontiers significantly increase our stress. To validate observations landscape scale better relate them data assimilation model parameters, introduce an ecosystem-scale analog pressure-volume curve, non-linear relationship between average leaf or branch commonly used plant hydraulics. The sources variability these curves their response discussed. We further show what extent diel, seasonal, decadal dynamics reflect variations different processes relating also for inferring belowground conditions-which difficult impossible observe directly. Lastly, discuss how dedicated geostationary spaceborne observational system VWC, when combined with existing datasets, capture diel seasonal advance science applications global vulnerability future droughts.

Language: Английский

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FLUXNET-CH<sub>4</sub>: a global, multi-ecosystem dataset and analysis of methane seasonality from freshwater wetlands

Earth system science data, Journal Year: 2021, Volume and Issue: 13(7), P. 3607 - 3689

Published: July 29, 2021

Abstract. Methane (CH4) emissions from natural landscapes constitute roughly half of global CH4 contributions to the atmosphere, yet large uncertainties remain in absolute magnitude and seasonality emission quantities drivers. Eddy covariance (EC) measurements flux are ideal for constraining ecosystem-scale due quasi-continuous high-temporal-resolution measurements, coincident carbon dioxide, water, energy lack ecosystem disturbance, increased availability datasets over last decade. Here, we (1) describe newly published dataset, FLUXNET-CH4 Version 1.0, first open-source dataset EC (available at https://fluxnet.org/data/fluxnet-ch4-community-product/, access: 7 April 2021). includes half-hourly daily gap-filled non-gap-filled aggregated fluxes meteorological data 79 sites globally: 42 freshwater wetlands, 6 brackish saline formerly drained ecosystems, rice paddy sites, 2 lakes, 15 uplands. Then, (2) evaluate representativeness wetland coverage globally because majority 1.0 wetlands which a substantial source total atmospheric emissions; (3) provide estimates seasonal variability predictors fluxes. Our analysis suggests that cover bioclimatic attributes (encompassing energy, moisture, vegetation-related parameters) arctic, boreal, temperate regions but only sparsely humid tropical regions. Seasonality metrics vary considerably across latitudinal bands. In (except those between 20∘ S N) spring onset elevated starts 3 d earlier, season lasts 4 longer, each degree Celsius increase mean annual air temperature. On average, increasing lags behind soil warming by 1 month, with very few experiencing prior warming. contrast, these experience rising gross primary productivity (GPP). The timing peak summer does not correlate either temperature or GPP. results parameters modeling highlight cannot be predicted GPP (i.e., peak). is powerful new resource diagnosing understanding role terrestrial ecosystems climate drivers cycle, future additions site years collection will added value this database. All available https://doi.org/10.5281/zenodo.4672601 (Delwiche et al., Additionally, raw used extract can downloaded https://fluxnet.org/data/fluxnet-ch4-community-product/ (last 2021), complete list individual DOIs provided Table paper.

Language: Английский

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Diurnal and Seasonal Dynamics of Solar‐Induced Chlorophyll Fluorescence, Vegetation Indices, and Gross Primary Productivity in the Boreal Forest

Journal of Geophysical Research Biogeosciences, Journal Year: 2022, Volume and Issue: 127(2)

Published: Feb. 1, 2022

Abstract Remote sensing of solar‐induced chlorophyll fluorescence (SIF) provides a powerful proxy for gross primary productivity (GPP). It is particularly promising in boreal ecosystems where seasonal downregulation photosynthesis occurs without significant changes canopy structure or content. The use SIF as GPP complicated by inherent non‐linearities due to both physical (illumination effects) and ecophysiological (light efficiencies) controls at fine spatial (tower/leaf) temporal (half‐hourly) scales. To study the SIF‐GPP relationship, we investigated diurnal dynamics continuous tower‐based measurements SIF, GPP, common vegetation indices Southern Old Black Spruce Site (SOBS) Saskatchewan, CA over course two years. We find that outperforms other all scales but shows non‐linear relationship with half‐hourly resolution. At small scales, are predominantly driven light non‐linearity between saturation GPP. Averaged daily monthly linear reduction observed PAR range. Seasonal responses efficiency which co‐vary temperature, while illumination partially linearize relationship. Additionally, has dependency. Our results help clarify utility estimating carbon assimilation forests.

Language: Английский

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Informing Nature‐based Climate Solutions for the United States with the best‐available science

Global Change Biology, Journal Year: 2022, Volume and Issue: 28(12), P. 3778 - 3794

Published: March 7, 2022

Nature-based Climate Solutions (NbCS) are managed alterations to ecosystems designed increase carbon sequestration or reduce greenhouse gas emissions. While they have growing public and private support, the realizable benefits unintended consequences of NbCS not well understood. At regional scales where policy decisions often made, estimated from soil tree survey data that can miss important sources sinks within an ecosystem, do reveal biophysical impacts for local water energy cycles. The only direct observations ecosystem-scale fluxes, example, by eddy covariance flux towers, yet been systematically assessed what tell us about potentials, state-of-the-art remote sensing products land-surface models being widely used inform policymaking implementation. As a result, there is critical mismatch between point- tree-scale most assess impacts, ecosystem landscape projects implemented, continental relevant policymaking. Here, we propose research agenda confront these gaps using tools long understand mechanisms driving cycling, but applied NbCS. We outline steps creating robust assessments at both informed observations, which consider concurrent future climate feedbacks, need equitable inclusive implementation strategies. contend goals largely be accomplished shifting pre-existing blended together, although also highlight some opportunities more radical shifts in approach.

Language: Английский

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Inland Water Greenhouse Gas Budgets for RECCAP2: 1. State‐Of‐The‐Art of Global Scale Assessments

Global Biogeochemical Cycles, Journal Year: 2023, Volume and Issue: 37(5)

Published: April 26, 2023

Abstract Inland waters are important emitters of the greenhouse gasses (GHGs) carbon dioxide (CO 2 ), methane (CH 4 and nitrous oxide (N O) to atmosphere. In framework 2nd phase REgional Carbon Cycle Assessment Processes (RECCAP‐2) initiative, we review state art in estimating inland water GHG budgets at global scale, which has substantially advanced since first RECCAP nearly 10 years ago. The development increasingly sophisticated upscaling techniques, including statistical prediction process‐based models, allows for spatially explicit estimates that needed regionalized assessments continental such as those established RECCAP. A few recent also resolve seasonal and/or interannual variability emissions. Nonetheless, global‐scale assessment emissions remains challenging because limited spatial temporal coverage observations persisting uncertainties abundance distribution surface areas. To decrease these uncertainties, more empirical work on contributions hot‐spots hot‐moments overall is particularly needed.

Language: Английский

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Water-balance-based evapotranspiration for 56 large river basins: A benchmarking dataset for global terrestrial evapotranspiration modeling

Journal of Hydrology, Journal Year: 2024, Volume and Issue: 630, P. 130607 - 130607

Published: Jan. 5, 2024

Language: Английский

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Proximal remote sensing: an essential tool for bridging the gap between high‐resolution ecosystem monitoring and global ecology

New Phytologist, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 23, 2025

Summary A new proliferation of optical instruments that can be attached to towers over or within ecosystems, ‘proximal’ remote sensing, enables a comprehensive characterization terrestrial ecosystem structure, function, and fluxes energy, water, carbon. Proximal sensing bridge the gap between individual plants, site‐level eddy‐covariance fluxes, airborne spaceborne by providing continuous data at high‐spatiotemporal resolution. Here, we review recent advances in proximal for improving our mechanistic understanding plant processes, model development, validation current upcoming satellite missions. We provide best practices availability metadata sensing: spectral reflectance, solar‐induced fluorescence, thermal infrared radiation, microwave backscatter, LiDAR. Our paper outlines steps necessary making these streams more widespread, accessible, interoperable, information‐rich, enabling us address key ecological questions unanswerable from space‐based observations alone and, ultimately, demonstrate feasibility technologies critical local global ecology.

Language: Английский

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Comparing the performance of vegetation indices for improving urban vegetation GPP estimation via eddy covariance flux data and Landsat 5/7 data

Ecological Informatics, Journal Year: 2025, Volume and Issue: unknown, P. 103023 - 103023

Published: Jan. 1, 2025

Language: Английский

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Satellite solar-induced chlorophyll fluorescence and near-infrared reflectance capture complementary aspects of dryland vegetation productivity dynamics

Remote Sensing of Environment, Journal Year: 2021, Volume and Issue: 270, P. 112858 - 112858

Published: Dec. 31, 2021

Language: Английский

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Matching high resolution satellite data and flux tower footprints improves their agreement in photosynthesis estimates

Agricultural and Forest Meteorology, Journal Year: 2022, Volume and Issue: 316, P. 108878 - 108878

Published: Feb. 22, 2022

Mapping canopy photosynthesis in both high spatial and temporal resolution is essential for carbon cycle monitoring heterogeneous areas. However, well established satellites sun-synchronous orbits such as Sentinel-2, Landsat MODIS can only provide either or but not both. Recently CubeSat satellite constellations have created an opportunity to overcome this trade-off. In particular, Planet Fusion allows full utilization of the data coverage while maintaining radiometric quality. study, we used surface reflectance product calculate daily, 3-m resolution, gap-free maps near-infrared radiation reflected from vegetation (NIRvP). We then evaluated performance these NIRvP estimating by comparing with a flux tower network Sacramento-San Joaquin Delta, California, USA. Overall, captured variations individual sites, despite changes water extent wetlands frequent mowing crop fields. When combining all however, found that robust agreement between could be achieved when matching footprints. case matched footprints, showed considerably better than situ daily sum around time overpass (R2 = 0.78 vs. 0.60, case). This difference was mostly due higher degree consistency slopes NIRvP-canopy relationships across study sites footprint-matched maps. Our results show importance observations footprint demonstrate potential constellation imagery monitor remotely at spatio-temporal resolution.

Language: Английский

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