Cutting out the middleman: calibrating and validating a dynamic vegetation model (ED2-PROSPECT5) using remotely sensed surface reflectance

Geoscientific model development, Journal Year: 2021, Volume and Issue: 14(5), P. 2603 - 2633

Published: May 12, 2021

Abstract. Canopy radiative transfer is the primary mechanism by which models relate vegetation composition and state to surface energy balance, important light- temperature-sensitive plant processes as well understanding land–atmosphere feedbacks. In addition, certain parameters (e.g., specific leaf area, SLA) that have an outsized influence on model behavior can be constrained observations of shortwave reflectance, thus reducing predictive uncertainty. Importantly, calibrating against outputs allows directly use remote sensing reflectance products without relying highly derived (such MODIS area index) whose assumptions may incompatible with target uncertainties are usually not quantified. Here, we created EDR coupling two-stream representation canopy in Ecosystem Demography version 2 (ED2) a (PROSPECT-5) simple soil predict full-range, high-spectral-resolution dependent underlying ED2 state. We then calibrated this estimates hemispherical (corrected for directional effects) from NASA Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) survey data 54 temperate forest plots northeastern United States. The calibration significantly reduced uncertainty related biochemistry morphology structure five functional types. Using single common set across all sites, was able accurately reproduce sites varied structure. However, model's predictions index (LAI) were less robust, capturing only 46 % variability observations. Comparing another soil–leaf–canopy commonly used studies (PRO4SAIL) illustrated structural errors direct radiation backscatter resulted systematic underestimation reflectance. also highlight that, compare like EDR, had perform additional processing step convert AVIRIS (also known “albedo”). future work, recommend add capability allow them more assimilate wide range airborne satellite products. ultimately conclude despite these challenges, using dynamic promising avenue validation data.

Language: Английский

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Towards species‐level forecasts of drought‐induced tree mortality risk

New Phytologist, Journal Year: 2022, Volume and Issue: 235(1), P. 94 - 110

Published: April 1, 2022

Predicting species-level responses to drought at the landscape scale is critical reducing uncertainty in future terrestrial carbon and water cycle projections. We embedded a stomatal optimisation model Community Atmosphere Biosphere Land Exchange (CABLE) land surface parameterised for 15 canopy dominant eucalypt tree species across South-Eastern Australia (mean annual precipitation range: 344-1424 mm yr-1 ). conducted three experiments: applying CABLE 2017-2019 drought; 20% drier with doubling of atmospheric dioxide (CO2 The severity was highlighted as least 25% their distribution ranges, 60% experienced leaf potentials beyond potential which 50% hydraulic conductivity lost due embolism. identified areas severe stress within-species' but we also pinpointed resilience found predominantly semiarid areas. importance role CO2 ameliorating consistent species. Our results represent an important advance our capacity forecast individual species, providing evidence base decision-making around restoration plantings or net-zero emission strategies.

Language: Английский

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Recent extreme drought events in the Amazon rainforest: assessment of different precipitation and evapotranspiration datasets and drought indicators

Biogeosciences, Journal Year: 2022, Volume and Issue: 19(16), P. 3843 - 3861

Published: Aug. 24, 2022

Abstract. Over the last decades, Amazon rainforest has been hit by multiple severe drought events. Here, we assess severity and spatial extent of extreme years 2005, 2010 2015/16 in region their impacts on regional carbon cycle. As an indicator stress rainforest, use widely applied maximum cumulative water deficit (MCWD). Evaluating nine state-of-the-art precipitation datasets for region, find that 2005 ranges from 2.2 to 3.0 (mean =2.7) ×106 km2 (37 %–51 % basin, mean =45 %), where MCWD indicates at least moderate conditions (relative anomaly <-0.5). In 2010, affected area was about 16 larger, ranging up 4.4 =3.6) (51 %–74 %, =61 %). 2016, between =3.2×106 km2; 55 basin), but general disagreement 2.4 4.1×106 (40 %–69 addition, compare differences similarities among using self-calibrating Palmer Drought Severity Index (scPDSI) a dry-season rainfall index (RAI). We scPDSI shows stronger RAI much weaker impact terms year 2016 compared MCWD. further investigate varying evapotranspiration indicators two datasets. Generally, variability is most dependent (60 followed choice dataset (20 %) Using fixed, constant rate instead variable can lead overestimation parts basin have more pronounced dry season (for example 2010). highlight even well-known events intensity strongly depend upon data sources it calculated with. only one source potential danger under- or overestimating regions with high measurement uncertainty, such as basin.

Language: Английский

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Potential of Sentinel-1 SAR to Assess Damage in Drought-Affected Temperate Deciduous Broadleaf Forests

Remote Sensing, Journal Year: 2023, Volume and Issue: 15(4), P. 1004 - 1004

Published: Feb. 11, 2023

Understanding forest decline under drought pressure is receiving research attention due to the increasing frequency of large-scale heat waves and massive tree mortality events. However, since assessing on ground challenging costly, this study explores capability satellite-borne Copernicus Sentinel-1 (S-1) C-band radar data for monitoring drought-induced canopy damage. As droughts cause water deficits in trees eventually lead early foliage loss, S-1 radiometric signal polarimetric indices are tested regarding their sensitivities these effects, exemplified a deciduous broadleaf forest. Due scattered nature site, we employed temporal-only time series filtering scheme that provides very high spatial resolution (10 m ×10 m) measuring at scale single trees. Finally, anomaly between heavily damaged non-damaged samples (n = 146 per class) was used quantify level With maximum −0.50 dB ± 1.38 Span (VV+VH), significant hydrostructural scattering (moisture geometry scatterers as seen by SAR) found second year after onset. By contrast, (cross-ratio, RVI, Hα) showed limited detecting effects. From our evaluation, infer canopies exhibit both lower leaf-on leaf-off backscatters compared unaffected canopies. We further introduce an NDVI/Span hysteresis showing lagged behind NDVI (by ca. one year). This time-lagged correlation implies SAR able add complementary information optical remote sensing damage its sensitivity physiological hydraulic Our lays out promising potential impact assessment forests.

Language: Английский

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The potential of optical and SAR time-series data for the improvement of aboveground biomass carbon estimation in Southwestern China’s evergreen coniferous forests

GIScience & Remote Sensing, Journal Year: 2024, Volume and Issue: 61(1)

Published: April 26, 2024

Accurate assessments of forest biomass carbon are invaluable for managing resources, evaluating effects on ecological protection, and achieving goals related to climate change sustainable development. Currently, the integration optical synthetic aperture radar (SAR) data has been extensively utilized in estimating aboveground (AGC), while it is limited by using single-phase remote sensing images. Time-series data, which capture interannual dynamic growth seasonal variations photosynthetic phenology forests, can sufficiently describe characteristics. However, there remains a gap research focusing utilizing satellite-based time-series AGC estimation, especially SAR sensors. This study investigated potential AGC. Here, we undertook nine quantitative experiments estimation from Landsat 8 Sentinel-1 tested several regression algorithms (including multiple linear (MLR), random forests (RF), artificial neural network (ANN), extreme gradient boosting (XGBoost)) explore contributions spatiotemporal features estimation. The results suggested that XGBoost algorithm was suitable with explanatory solid power stable performance. temporal representing trends periodic characteristics (such as coefficients continuous wavelet transform) were more valuable than spatial both sensor types, accounting around 40% ~50% variance compared 17% ~25%. combination produced best performance (R2 = 0.814, RMSE 18.789 Mg C/ha, rRMSE 26.235%), when or alone (optical: R2 0.657 35.317%; SAR: 0.672 34.701%). Feature importance analysis also verified vegetation indices, SWIR 1/2 bands, backscatter VV polarization most critical variables Furthermore, incorporating into modeling illustrated be effective reducing saturation within high-biomass forests. demonstrated superiority While applicability this methodology only evergreen coniferous may provide viable approach needed make full use increasingly better free satellite estimate high accuracy, supporting policy making management

Language: Английский

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Convergent Isobilateral Leaves Increase the Risk for Mangroves Facing Human‐Induced Rapid Environmental Changes

Plant Cell & Environment, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 8, 2025

ABSTRACT Understanding plant adaptations in extreme environments is crucial, as these often confer advantages for survival. However, a significant gap exists regarding the genetic mechanisms underlying and their responses to human‐induced rapid environmental change (HIREC). This study addresses question of whether convergence occurs among plants with similar adaptive features, specifically focusing on isobilateral leaves mangrove species. Here, we analyse mangroves that have independently adapted coastal intertidal zones. Our findings reveal evident gene families involved leaf abaxial adaxial development, strong selection pressures identified photosynthesis polarity pathways. Despite adaptations, species occupy narrower ecological niches face diminishing suitable habitat areas projected under various HIREC scenarios. These results indicate while convergent traits enhance local adaptation, they may also increase vulnerability ongoing changes. research provides valuable insight into interplay between adaptation resilience, underscoring necessity targeted biodiversity conservation strategies safeguard specific amid shifts.

Language: Английский

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Temperature Is Likely an Important Omission in Interpreting Vegetation Optical Depth

Geophysical Research Letters, Journal Year: 2024, Volume and Issue: 51(15)

Published: July 30, 2024

Abstract Vegetation optical depth (VOD) satellite microwave retrievals provide significant insights into vegetation water content and responses to hydroclimatic changes. While VOD variations are commonly linked dry biomass live fuel moisture ( LFMC ), the impact of canopy temperature T c ) remains overlooked in large‐scale studies. Here, we investigated on L‐band (1.4 GHz) X‐band (10.7 at diurnal seasonal timescales. Synthetic benchmark was created using realistic fields , an electromagnetic model. Perturbation experiments revealed that strongly affects both X‐band. Seasonally, while emerges as largest contributor 70% (at X‐band) 90% L‐band) our study region, still play substantial roles. The findings stress importance refining retrieval algorithms distinguish effects for future applications ecohydrology.

Language: Английский

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Error Propagation in Microwave Soil Moisture and Vegetation Optical Depth Retrievals

IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, Journal Year: 2021, Volume and Issue: 14, P. 11311 - 11323

Published: Jan. 1, 2021

Satellite soil moisture and vegetation optical depth [(VOD); related to the total water mass per unit area] are increasingly being used study relations in soil-plant continuum across globe. However, VOD typically jointly estimated, where errors optimization approach can cause compensation between both variables confound such studies. It is thus critical quantify how satellite microwave measurement propagate into VOD. Such a especially important for given limited investigations of whether reflects situ plant physiology. Furthermore, despite new approaches that constrain (or regularize) dynamics reduce errors, there regularization reduces without obscuring true temporal dynamics. Here, we find that, globe, less robust error (more difficult methods solution) than their joint estimation. moderate degree (via time-constrained VOD) greater spurious moisture-VOD coupling. constraining time dynamics, regularized variations on subweekly scales closer simulated series have global post-rainfall responses with reduced signatures compared retrievals regularization. Ultimately, recommend moderately use large scale studies because it suppresses noise coupling removing physical signal.

Language: Английский

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Emerging Methods to Validate Remotely Sensed Vegetation Water Content

Geophysical Research Letters, Journal Year: 2024, Volume and Issue: 51(14)

Published: July 16, 2024

Abstract Satellite‐retrieved vegetation optical depth (VOD) has provided extensive insights into global plant function (such as, carbon stocks, water stress, crop yields) because of VOD's ability to monitor stress and biomass at near daily temporal frequency under all‐weather conditions. However, arguably, the greatest challenge with broadly applying VOD is its lack validation partly simultaneous sensitivity status changes, as well intensive methods required measure these properties in‐situ. Here, inspired by recent Yao et al. (2024), https://doi.org/10.1029/2023GL107121 article, I argue that estimated from navigation satellite systems (GNSS) land surface models hydraulic schemes are two emerging show promise for more widely validating satellite‐based VOD. encourage wider adoption approaches validate further advance research.

Language: Английский

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Intra-annual variation in microclimatic conditions in relation to vegetation type and structure in two tropical dry forests undergoing secondary succession

Forest Ecology and Management, Journal Year: 2022, Volume and Issue: 511, P. 120132 - 120132

Published: March 5, 2022

Language: Английский

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