Continuous Isoprene Measurements in a UK Temperate Forest for a Whole Growing Season: Effects of Drought Stress During the 2018 Heatwave

Ferracci, Valerio; Bolas, Conor G.; Freshwater, Ray; Staniaszek, Zosia; King, Thomas; Jaars, Kerneels; Otu‐Larbi, Frederick; Beale, John; Malhi, Yadvinder; Waine, Toby; Jones, R. L.; Ashworth, Kirsti; Harris, Neil

doi:10.1029/2020gl088885

Cited by 12 publications

(33 citation statements)

References 69 publications

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“…Brilli et al, ; Penuelas et al, ; Sharkey & Loreto, ). The isoprene measurements made during the WIsDOM campaign (Ferracci et al, in prep) together with the findings from our model simulations support the observation that isoprene emissions can increase under moderate drought conditions and after rewetting resulting in strong enhancements in canopy concentrations. Our model results (Figure S4) also provide evidence in support of the previous observations that isoprene emissions and photosynthesis (often quantified as gross primary production, at an ecosystem scale; e.g.…”

Section: Discussionsupporting

confidence: 86%

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Modelling the effect of the 2018 summer heatwave and drought on isoprene emissions in a UK woodland

Otu‐Larbi

Bolas

Ferracci

et al. 2020

Global Change Biology

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Projected future climatic extremes such as heatwaves and droughts are expected to have major impacts on emissions and concentrations of biogenic volatile organic compounds (bVOCs) with potential implications for air quality, climate and human health. While the effects of changing temperature and photosynthetically active radiation (PAR) on the synthesis and emission of isoprene, the most abundant of these bVOCs, are well known, the role of other environmental factors such as soil moisture stress are not fully understood and are therefore poorly represented in land surface models. As part of the Wytham Isoprene iDirac Oak Tree Measurements campaign, continuous measurements of isoprene mixing ratio were made throughout the summer of 2018 in Wytham Woods, a mixed deciduous woodland in southern England. During this time, the United Kingdom experienced a prolonged heatwave and drought, and isoprene mixing ratios were observed to increase by more than 400% at Wytham Woods under these conditions. We applied the state‐of‐the‐art FORest Canopy‐Atmosphere Transfer canopy exchange model to investigate the processes leading to these elevated concentrations. We found that although current isoprene emissions algorithms reproduced observed mixing ratios in the canopy before and after the heatwave, the model underestimated observations by ~40% during the heatwave–drought period implying that models may substantially underestimate the release of isoprene to the atmosphere in future cases of mild or moderate drought. Stress‐induced emissions of isoprene based on leaf temperature and soil water content (SWC) were incorporated into current emissions algorithms leading to significant improvements in model output. A combination of SWC, leaf temperature and rewetting emission bursts provided the best model‐measurement fit with a 50% improvement compared to the baseline model. Our results highlight the need for more long‐term ecosystem‐scale observations to enable improved model representation of atmosphere–biosphere interactions in a changing global climate.

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Section: Discussionsupporting

confidence: 86%

“…This covers the full extent of peak growth with roughly equal periods before, during and after the heatwave–drought. For full details of the WIsDOM campaign, readers are referred to Ferraci, Bolas, and Harris ().…”

Section: Methodsmentioning

confidence: 99%

Modelling the effect of the 2018 summer heatwave and drought on isoprene emissions in a UK woodland

Otu‐Larbi

Bolas

Ferracci

et al. 2020

Global Change Biology

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“…Direct comparison between MEGAN and flux measurements in various drought conditions has been only possible for the MOFLUX site. Other campaigns including isoprene concentration measurements in drought-impacted ecosystems ( [39,40]) provide qualitative insights but no direct constraint on the fluxes. A possible avenue for drought stress parameterizations could be the development of empirical relationships making use of remotely sensed photosynthetic parameters or vegetation indices such as SIF [47], Emissivity Difference Vegetation Index (EDVI; [107]) or Photochemical Reflectance Index (PRI; [108]).…”

Section: Discussionmentioning

confidence: 99%

“…The effects of drought stress on isoprene emissions have been investigated in several studies, most of which were conducted in the laboratory [33][34][35][36][37][38]. Field observations at ecosystem-scale during natural droughts are scarce [30,32,39,40] and, to the authors' knowledge, only one site provides measurements of isoprene fluxes. During the 2011-2012 field campaigns in central U.S., at the Missouri Ozarks AmeriFlux (MOFLUX) site, isoprene and other BVOC fluxes were monitored for two consecutive growing seasons concomitant to two drought events [30,32].…”

Section: Introductionmentioning

confidence: 99%

Impact of Drought on Isoprene Fluxes Assessed Using Field Data, Satellite-Based GLEAM Soil Moisture and HCHO Observations from OMI

et al. 2022

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Biogenic volatile organic compounds (BVOCs), primarily emitted by terrestrial vegetation, are highly reactive and have large effects on the oxidizing potential of the troposphere, air quality and climate. In terms of global emissions, isoprene is the most important BVOC. Droughts bring about changes in the surface emission of biogenic hydrocarbons mainly because plants suffer water stress. Past studies report that the current parameterization in the state-of-the-art Model of Emissions of Gases and Aerosols from Nature (MEGAN) v2.1, which is a function of the soil water content and the permanent wilting point, fails at representing the strong reduction in isoprene emissions observed in field measurements conducted during a severe drought. Since the current algorithm was originally developed based on potted plants, in this study, we update the parameterization in the light of recent ecosystem-scale measurements of isoprene conducted during natural droughts in the central U.S. at the Missouri Ozarks AmeriFlux (MOFLUX) site. The updated parameterization results in stronger reductions in isoprene emissions. Evaluation using satellite formaldehyde (HCHO), a proxy for BVOC emissions, and a chemical-transport model, shows that the adjusted parameterization provides a better agreement between the modelled and observed HCHO temporal variability at local and regional scales in 2011–2012, even if it worsens the model agreement in a global, long-term evaluation. We discuss the limitations of the current parameterization, a function of highly uncertain soil properties such as porosity.

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“…2) On the land surface, heat and droughts cause declines in gross primary productivity (Cias et al 2005, Fu et al 2020) and evapotranspiration, leading to increased net CO2 emissions (Reichstein et al 2013, Green et al 2019) and uncertain flux changes of greenhouse gases (GHGs) such as N2O or CH4 (Yan et al 2018). Vegetation stress and insect pests increase biogenic VOC emissions (Joutsensaari et al 2015, Ferracci et al 2020, resulting in additional aerosol and ozone formation in the boundary layer by atmospheric oxidation (Penuelas and Staudt 2010).…”

Section: Investigating Event Chainsmentioning

confidence: 99%

MOSES: A Novel Observation System to Monitor Dynamic Events across Earth Compartments

Weber

Attinger

Baschek

et al. 2022

Bulletin of the American Meteorological Society

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MOSES (Modular Observation Solutions for Earth Systems) is a novel observation system that is specifically designed to unravel the impact of distinct, dynamic events on the long-term development of environmental systems. Hydro-meteorological extremes such as the recent European droughts or the floods of 2013 caused severe and lasting environmental damage. Modelling studies suggest that abrupt permafrost thaw events accelerate Arctic greenhouse gas emissions. Short-lived ocean eddies seem to comprise a significant share of the marine carbon uptake or release. Although there is increasing evidence that such dynamic events bear the potential for major environmental impacts, our knowledge on the processes they trigger is still very limited. MOSES aims at capturing such events, from their formation to their end, with high spatial and temporal resolution. As such, the observation system extends and complements existing national and international observation networks, which are mostly designed for long-term monitoring.Several German Helmholtz Association centers have developed this research facility as a mobile and modular “system of systems” to record energy, water, greenhouse gas and nutrient cycles on the land surface, in coastal regions, in the ocean, in polar regions, and in the atmosphere – but especially the interactions between the Earth compartments. During the implementation period (2017-2021), the measuring systems were put into operation and test campaigns were performed to establish event-driven campaign routines. With MOSES’ regular operation starting in 2022, the observation system will then be ready for cross-compartment and cross-discipline research on the environmental impacts of dynamic events.

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Continuous Isoprene Measurements in a UK Temperate Forest for a Whole Growing Season: Effects of Drought Stress During the 2018 Heatwave

Cited by 12 publications

References 69 publications

Modelling the effect of the 2018 summer heatwave and drought on isoprene emissions in a UK woodland

Modelling the effect of the 2018 summer heatwave and drought on isoprene emissions in a UK woodland

Impact of Drought on Isoprene Fluxes Assessed Using Field Data, Satellite-Based GLEAM Soil Moisture and HCHO Observations from OMI

MOSES: A Novel Observation System to Monitor Dynamic Events across Earth Compartments

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