Observational evidence for soil-moisture impact on hot extremes in southeastern Europe

Hirschi, Martin; Seneviratne, Sonia I.; Alexandrov, V.; Boberg, Fredrik; Boroneanţ, C.; Christensen, Ole; Formayer, Herbert; Orlowsky, Boris; Štěpánek, Petr

doi:10.1038/ngeo1032

Cited by 643 publications

(528 citation statements)

References 27 publications

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“…An additional impact of soil on microclimate results from evaporative cooling or latent heat flux. Moist soils thus attenuate warming-up of the air and lowering of RH (Fischer et al 2007;Hirschi et al 2011;Seneviratne et al 2006;Ferranti & Viterbo 2006;Jaeger & Seneviratne 2011). While basic principles of forest microclimate and the relationships with open-area microclimate therefore seem established, a more functional and quantitative view on how the properties of forest ecosystems influence below-canopy microclimate is largely missing.…”

Section: Introductionmentioning

confidence: 99%

Microclimate in forests with varying leaf area index and soil moisture: potential implications for seedling establishment in a changing climate

et al. 2013

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Summary1. Forest microclimate is crucial for the growth and survival of tree seedlings and understorey vegetation. This high ecological relevance contrasts with the poor functional and quantitative understanding of how the properties of forest ecosystems influence forest microclimate. 2. In a long-term (1998-2011) trial, we investigated how temporal patterns of microclimate below sparse and dense forest canopy related to those of nearby open areas and how this relationship was influenced by soil moisture and seasonality. Air temperature (T), vapour pressure deficit (VPD), soil matrix potential and leaf area index (LAI) were measured in a unique set-up of below-canopy and open-area meteorological stations at eleven distinct forest ecosystems, characteristic of subalpine and temperate climate zones. Data from these plots were analysed for the moderating capacity of the canopy, that is, the differences between below-canopy and open-area microclimate, with respect to (i) long-term means, (ii) dynamics within homogeneous moist-vs. dry-soil periods and (iii) diurnal patterns. 3. The long-term mean moderating capacity of the canopy was up to 3.3°C for daily T max and 0.52 kPa for daily VPD max , of which soil moisture status alone accounted for up to 1.2°C (T max ) and 0.21 kPa (VPD max ). Below dense canopy (LAI > 4), the moderating capacity was generally higher when soils were dry and increased during dry-soil periods, particularly in spring and somewhat less in summer. The opposite pattern was found below sparse canopy (LAI < 4). At the diurnal level, moderating capacity below dense canopy was strongest in mid-afternoon and during dry-soil conditions, whereas peak moderation below sparse canopy occurred in mid-morning and during moist-soil conditions. 4. Synthesis. Our results suggest a threshold canopy density, which is probably linked to sitespecific water availability, below which the moderating capacity of forest ecosystems switches from supportive to unsupportive for seedling establishment. Under supportive moderating capacity, we understand a stronger mitigation during physiologically most demanding conditions for plant growth. Such a threshold canopy density sheds new light on forest resilience to climate change. Climate change may alter forest canopy density in a way that precludes successful establishment of tree species and ultimately changes forest ecosystem structure and functioning.

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Section: Introductionmentioning

confidence: 99%

Microclimate in forests with varying leaf area index and soil moisture: potential implications for seedling establishment in a changing climate

et al. 2013

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“…Several works have stressed the role of land-atmosphere coupling, particularly soil-moisture feedbacks, in climate variability and extremes in Europe (Seneviratne et al, 2006;Hirschi et al, 2011). Both 2003 and 2010 heatwaves were associated with persistent anti-cyclonic conditions from late spring to summer and with precipitation deficits from late winter until August.…”

Section: A Bastos Et Al: Impacts Of 2003 and 2010 Heatwaves In Planmentioning

confidence: 99%

Analysing the spatio-temporal impacts of the 2003 and 2010 extreme heatwaves on plant productivity in Europe

et al. 2014

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Abstract. In the last decade, Europe has been stricken by two outstanding heatwaves, the 2003 event in western Europe and the 2010 episode over Russia. Both events were characterized by record-breaking temperatures and widespread socioeconomic impacts, including significant increments on human mortality, decreases in crop yields and in hydroelectric production.Previous works have shown that an extreme climatic event does not always imply an extreme response by ecosystems. This work attempts to assess how extreme was the vegetation response to the heatwaves during 2003 and 2010 in Europe, in order to quantify the impacts of the two events on carbon fluxes in plant productivity and to identify the physical drivers of the observed response.Heatwave impacts in vegetation productivity were analysed using MODIS products from 2000 to 2011. Both 2003 and 2010 events led to marked decreases in plant productivity, well below the climatological range of variability, with carbon uptake by vegetation during August reaching negative anomalies of more than 2 standard deviations, although the 2010 event affected a much larger extent. A differentiated response in autotrophic respiration was observed, depending on land-cover types, with forests increasing respiration rates in response to the heatwaves, while in crops respiration rates decreased.The widespread decrease in carbon uptake matched the regions where very high temperature values were also preceded by a long period of below-average precipitation, leading to strong soil moisture deficits. In the case of the 2003 heatwave, results indicate that moisture deficits coupled with high temperatures drove the extreme response of vegetation, while for the 2010 event very high temperatures appear to be the sole driver of very low productivity.

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“…Ensuring that soil moisture is continuous therefore also likely constrains the history of the weather, which in turn increases the temporal consistency in atmospheric conditions in the stitched time series (for example, simulations with wet soils at the end of a year are likely to have exhibited wet conditions in December, while simulations with dry soils at the end of the year likely display less rainfall and higher temperature in December). Finally, soil moisture has been shown to be involved in key feedbacks relevant to droughts and heat waves (Seneviratne et al, 2010), such as soil moisture-temperature (Hirschi et al, 2011;Miralles et al, 2014) and soil moisture-precipitation (Roundy et al, 2013;Guillod et al, 2015) feedbacks. Therefore, ensuring continuous soil moisture avoids biases in the statistics of the weather in the following few weeks.…”

Section: Generation Of Continuous Time Series From Single Yearsmentioning

confidence: 99%

A large set of potential past, present and future hydro-meteorological time series for the UK

Guillod

Jones

Dadson

et al. 2018

Hydrol. Earth Syst. Sci.

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Abstract. Hydro-meteorological extremes such as drought and heavy precipitation can have large impacts on society and the economy. With potentially increasing risks associated with such events due to climate change, properly assessing the associated impacts and uncertainties is critical for adequate adaptation. However, the application of riskbased approaches often requires large sets of extreme events, which are not commonly available. Here, we present such a large set of hydro-meteorological time series for recent past and future conditions for the United Kingdom based on weather@home 2, a modelling framework consisting of a global climate model (GCM) driven by observed or projected sea surface temperature (SST) and sea ice which is downscaled to 25 km over the European domain by a regional climate model (RCM). Sets of 100 time series are generated for each of (i) a historical baseline , (ii) five nearfuture scenarios (2020-2049) and (iii) five far-future scenarios . The five scenarios in each future time slice all follow the Representative Concentration Pathway 8.5 (RCP8.5) and sample the range of sea surface temperature and sea ice changes from CMIP5 (Coupled Model Intercomparison Project Phase 5) models. Validation of the historical baseline highlights good performance for temperature and potential evaporation, but substantial seasonal biases in mean precipitation, which are corrected using a linear approach. For extremes in low precipitation over a long accumulation period (> 3 months) and shorter-duration high precipitation (1-30 days), the time series generally represents past statistics well. Future projections show small precipitation increases in winter but large decreases in summer on average, leading to an overall drying, consistently with the most recent UK Climate Projections (UKCP09) but larger in magnitude than the latter. Both drought and high-precipitation events are projected to increase in frequency and intensity in most regions, highlighting the need for appropriate adaptation measures. Overall, the presented dataset is a useful tool for assessing the risk associated with drought and more generally with hydro-meteorological extremes in the UK.

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Observational evidence for soil-moisture impact on hot extremes in southeastern Europe

Cited by 643 publications

References 27 publications

Microclimate in forests with varying leaf area index and soil moisture: potential implications for seedling establishment in a changing climate

Microclimate in forests with varying leaf area index and soil moisture: potential implications for seedling establishment in a changing climate

Analysing the spatio-temporal impacts of the 2003 and 2010 extreme heatwaves on plant productivity in Europe

A large set of potential past, present and future hydro-meteorological time series for the UK

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