WorldWideScience

Sample records for repeated summer drought

  1. Contrasting effects of repeated summer drought on soil carbon efflux in hydric and mesic heathland soils

    DEFF Research Database (Denmark)

    Sowerby, Alwyn; Emmett, Bridget A.; Tietema, Albert

    2008-01-01

    storage. To test the importance of drought, and more importantly repeated drought year-on-year, we used automated retractable curtains to exclude rain and produce repeated summer drought in three heathlands at varying moisture conditions. This included a hydric system limited by water-excess (in the UK...... and DK sites during the winter re-wetting period that indicates any change in soil C storage due to changes in soil C efflux may be short lived in these mesic systems. In contrast, in the hydric UK site after 2 years of drought treatment, the persistent reduction in soil moisture throughout the year...

  2. Contrasting effects of repeated summer drought on soil carbon efflux in hydric and mesic heathland soils

    NARCIS (Netherlands)

    Sowerby, A.; Emmett, B.A.; Tietema, A.; Beier, C.

    2008-01-01

    Current predictions of climate change include altered rainfall patterns throughout Europe, continental USA and areas such as the Amazon. The effect of this on soil carbon efflux remains unclear although several modelling studies have highlighted the potential importance of drought for carbon

  3. Repeated summer drought and re-watering during the first growing year of oak (Quercus petraea delay autumn senescence and bud burst in the following spring

    Directory of Open Access Journals (Sweden)

    Kristine Vander Mijnsbrugge

    2016-03-01

    Full Text Available Climate change predicts harsher summer droughts for mid-latitudes in Europe. To enhance our understanding of the putative impacts on forest regeneration, we studied the response of oak seedlings (Quercus petraea to water deficit. Potted seedlings originating from three locally sourced provenances were subjected to two successive drought periods during the first growing season each followed by a plentiful re-watering. Here we describe survival and phenological responses after the second drought treatment, applying general linear mixed modelling. From the 441 drought treated seedlings 189 subsisted with higher chances of survival among smaller plants and among single plants per pot compared to doubles. Remarkably, survival was independent of the provenance, although relatively more plants had died off in two provenances compared to the third one with mean plant height being higher in one provenance and standard deviation of plant height being higher in the other. Timing of leaf senescence was clearly delayed after the severe drought treatment followed by re-watering, with two seedlings per pot showing a lesser retardation compared to single plants. This delay can be interpreted as a compensation time in which plants recover before entering the subsequent developmental process of leaf senescence, although it renders seedlings more vulnerable to early autumn frosts because of the delayed hardening of the shoots. Onset of bud flush in the subsequent spring still showed a significant but small delay in the drought treated group, independent of the number of seedlings per pot, and can be considered as an after effect of the delayed senescence. In both phenological models significant differences among the three provenances were detected independent from the treatment. The only provenance that is believed to be local of origin, displayed the earliest leaf senescence and the latest flushing, suggesting an adaptation to the local maritime climate. This

  4. Fourteen Annually Repeated Droughts Suppressed Autotrophic Soil Respiration and Resulted in an Ecosystem Change

    NARCIS (Netherlands)

    Kopittke, G.R.; Tietema, A.; van Loon, E.; Asscheman, D.

    2014-01-01

    Predictions of future climate over the next 100 years show that the frequency of long periods of droughts in summer will increase in the Netherlands. This study investigated the effect of 14 annually repeated droughts on soil respiration at a Dutch heathland. Field measurements of total soil

  5. Precursor conditions related to Zimbabwe's summer droughts

    Science.gov (United States)

    Nangombe, Shingirai; Madyiwa, Simon; Wang, Jianhong

    2018-01-01

    Despite the increasing severity of droughts and their effects on Zimbabwe's agriculture, there are few tools available for predicting these droughts in advance. Consequently, communities and farmers are more exposed, and policy makers are always ill prepared for such. This study sought to investigate possible cycles and precursor meteorological conditions prior to drought seasons that could be used to predict impending droughts in Zimbabwe. The Single Z-Index was used to identify and grade drought years between 1951 and 2010 according to rainfall severity. Spectral analysis was used to reveal the cycles of droughts for possible use of these cycles for drought prediction. Composite analysis was used to investigate circulation and temperature anomalies associated with severe and extreme drought years. Results indicate that severe droughts are more highly correlated with circulation patterns and embedded weather systems in the Indian Ocean and equatorial Pacific Ocean than any other area. This study identified sea surface temperatures in the average period June to August, geopotential height and wind vector in July to September period, and air temperature in September to November period as precursors that can be used to predict a drought occurrence several months in advance. Therefore, in addition to sea surface temperature, which was identified through previous research for predicting Zimbabwean droughts, the other parameters identified in this study can aid in drought prediction. Drought cycles were established at 20-, 12.5-, 3.2-, and 2.7-year cycles. The spectral peaks, 12.5, 3.2, and 2.7, had a similar timescale with the luni-solar tide, El Niño Southern Oscillation and Quasi Biennial Oscillation, respectively, and hence, occurrence of these phenomena have a possibility of indicating when the next drought might be.

  6. Linking meteorological drivers of spring-summer drought regimes to agricultural drought risk in China

    Science.gov (United States)

    Dai, L.; Wright, J. S.; Yu, C.; Huang, W. Y.

    2017-12-01

    As a drought prone country, China has experienced frequent severe droughts in recent decades. Drought frequency and severity are projected to increase in China under climate change. An understanding of the physical processes that contribute to extreme droughts is essential for seasonal forecasting, but the dominant physical mechanisms responsible for droughts in most parts of China are still unclear. Moreover, despite numerous studies on droughts in China, there are few clear connections between the meteorological and climatological drivers of extreme droughts and the associated agricultural consequences. This knowledge gap limits the capacity for decision-making support in drought management. The objectives of this study are (1) to identify robust spring-summer drought regimes over China, (2) to investigate the physical mechanisms associated with each regime, and (3) to better clarify connections between meteorological drought regimes and agricultural drought risk. First, we identify six drought regimes over China by applying an area-weighted k-means clustering technique to spatial patterns of spring-summer Standardized Precipitation Index (SPI) obtained from the ten-member ERA-20CM ensemble for 1900-2010. Second, we project these drought regimes onto agricultural drought risk maps for the three major cereal crops (rice, maize, and wheat) in China. Taking into account historical harvest areas for these crops, we then evaluate the potential impact of each drought regime on agricultural production. Third, the physical mechanisms and meteorological context behind each drought regimes are investigated based on monthly outputs from ERA20CM. We analyze the preceding and concurrent atmospheric circulation anomalies associated with each regime, and propose mechanistic explanations for drought development. This work provides a new perspective on diagnosing the physical mechanisms behind seasonal droughts, and lays a foundation for improving seasonal drought prediction and

  7. Amazon forest response to repeated droughts

    Science.gov (United States)

    Feldpausch, T. R.; Phillips, O. L.; Brienen, R. J. W.; Gloor, E.; Lloyd, J.; Lopez-Gonzalez, G.; Monteagudo-Mendoza, A.; Malhi, Y.; Alarcón, A.; Álvarez Dávila, E.; Alvarez-Loayza, P.; Andrade, A.; Aragao, L. E. O. C.; Arroyo, L.; Aymard C., G. A.; Baker, T. R.; Baraloto, C.; Barroso, J.; Bonal, D.; Castro, W.; Chama, V.; Chave, J.; Domingues, T. F.; Fauset, S.; Groot, N.; Honorio Coronado, E.; Laurance, S.; Laurance, W. F.; Lewis, S. L.; Licona, J. C.; Marimon, B. S.; Marimon-Junior, B. H.; Mendoza Bautista, C.; Neill, D. A.; Oliveira, E. A.; Oliveira dos Santos, C.; Pallqui Camacho, N. C.; Pardo-Molina, G.; Prieto, A.; Quesada, C. A.; Ramírez, F.; Ramírez-Angulo, H.; Réjou-Méchain, M.; Rudas, A.; Saiz, G.; Salomão, R. P.; Silva-Espejo, J. E.; Silveira, M.; ter Steege, H.; Stropp, J.; Terborgh, J.; Thomas-Caesar, R.; van der Heijden, G. M. F.; Vásquez Martinez, R.; Vilanova, E.; Vos, V. A.

    2016-07-01

    The Amazon Basin has experienced more variable climate over the last decade, with a severe and widespread drought in 2005 causing large basin-wide losses of biomass. A drought of similar climatological magnitude occurred again in 2010; however, there has been no basin-wide ground-based evaluation of effects on vegetation. We examine to what extent the 2010 drought affected forest dynamics using ground-based observations of mortality and growth from an extensive forest plot network. We find that during the 2010 drought interval, forests did not gain biomass (net change: -0.43 Mg ha-1, confidence interval (CI): -1.11, 0.19, n = 97), regardless of whether forests experienced precipitation deficit anomalies. This contrasted with a long-term biomass sink during the baseline pre-2010 drought period (1998 to pre-2010) of 1.33 Mg ha-1 yr-1 (CI: 0.90, 1.74, p history. Thus, there was no evidence that pre-2010 droughts compounded the effects of the 2010 drought. We detected a systematic basin-wide impact of the 2010 drought on tree growth rates across Amazonia, which was related to the strength of the moisture deficit. This impact differed from the drought event in 2005 which did not affect productivity. Based on these ground data, live biomass in trees and corresponding estimates of live biomass in lianas and roots, we estimate that intact forests in Amazonia were carbon neutral in 2010 (-0.07 Pg C yr-1 CI:-0.42, 0.23), consistent with results from an independent analysis of airborne estimates of land-atmospheric fluxes during 2010. Relative to the long-term mean, the 2010 drought resulted in a reduction in biomass carbon uptake of 1.1 Pg C, compared to 1.6 Pg C for the 2005 event.

  8. Strategies of Mediterranean Oaks to Survive Summer Drought

    Energy Technology Data Exchange (ETDEWEB)

    Siegwolf, R.T.W.; Besson, C. [Inst. Sup. de Agronomia, ISA Lisboa (Portugal); Chaves, M.M. [ISA Lisboa (Portugal); Pereira, J. [ISA Lisboa (Portugal)

    2004-03-01

    In arid, Mediterranean regions the scarce water supply during summer limits plant growth. Yet trees and shrubs often grow in areas where no water supply is apparent. By means of the deuterium isotope ratio it could be shown that various plants can access different water sources, allowing them to endure long periods of severe drought. (author)

  9. Resilient Leaf Physiological Response of European Beech (Fagus sylvatica L. to Summer Drought and Drought Release

    Directory of Open Access Journals (Sweden)

    Ellen E. Pflug

    2018-02-01

    Full Text Available Drought is a major environmental constraint to trees, causing severe stress and thus adversely affecting their functional integrity. European beech (Fagus sylvatica L. is a key species in mesic forests that is commonly expected to suffer in a future climate with more intense and frequent droughts. Here, we assessed the seasonal response of leaf physiological characteristics of beech saplings to drought and drought release to investigate their potential to recover from the imposed stress and overcome previous limitations. Saplings were transplanted to model ecosystems and exposed to a simulated summer drought. Pre-dawn water potentials (ψpd, stomatal conductance (gS, intercellular CO2 concentration (ci, net-photosynthesis (AN, PSII chlorophyll fluorescence (PItot, non-structural carbohydrate concentrations (NSC; soluble sugars, starch and carbon isotope signatures were measured in leaves throughout the growing season. Pre-dawn water potentials (ψpd, gS, ci, AN, and PItot decreased as drought progressed, and the concentration of soluble sugars increased at the expense of starch. Carbon isotopes in soluble sugars (δ13CS showed a distinct increase under drought, suggesting, together with decreased ci, stomatal limitation of AN. Drought effects on ψpd, ci, and NSC disappeared shortly after re-watering, while full recovery of gS, AN, and PItot was delayed by 1 week. The fast recovery of NSC was reflected by a rapid decay of the drought signal in δ13C values, indicating a rapid turnover of assimilates and a reactivation of carbon metabolism. After recovery, the previously drought-exposed saplings showed a stimulation of AN and a trend toward elevated starch concentrations, which counteracted the previous drought limitations. Overall, our results suggest that the internal water relations of beech saplings and the physiological activity of leaves are restored rapidly after drought release. In the case of AN, stimulation after drought may partially

  10. Summer drought predictability over Europe: empirical versus dynamical forecasts

    Science.gov (United States)

    Turco, Marco; Ceglar, Andrej; Prodhomme, Chloé; Soret, Albert; Toreti, Andrea; Doblas-Reyes Francisco, J.

    2017-08-01

    Seasonal climate forecasts could be an important planning tool for farmers, government and insurance companies that can lead to better and timely management of seasonal climate risks. However, climate seasonal forecasts are often under-used, because potential users are not well aware of the capabilities and limitations of these products. This study aims at assessing the merits and caveats of a statistical empirical method, the ensemble streamflow prediction system (ESP, an ensemble based on reordering historical data) and an operational dynamical forecast system, the European Centre for Medium-Range Weather Forecasts—System 4 (S4) in predicting summer drought in Europe. Droughts are defined using the Standardized Precipitation Evapotranspiration Index for the month of August integrated over 6 months. Both systems show useful and mostly comparable deterministic skill. We argue that this source of predictability is mostly attributable to the observed initial conditions. S4 shows only higher skill in terms of ability to probabilistically identify drought occurrence. Thus, currently, both approaches provide useful information and ESP represents a computationally fast alternative to dynamical prediction applications for drought prediction.

  11. Assessing the utility of meteorological drought indices in monitoring summer drought based on soil moisture in Chongqing, China

    Science.gov (United States)

    Chen, Hui; Wu, Wei; Liu, Hong-Bin

    2018-04-01

    Numerous drought indices have been developed to analyze and monitor drought condition, but they are region specific and limited by various climatic conditions. In southwest China, summer drought mainly occurs from June to September, causing destructive and profound impact on agriculture, society, and ecosystems. The current study assesses the availability of meteorological drought indices in monitoring summer drought in this area at 5-day scale. The drought indices include the relative moisture index ( M), the standardized precipitation index (SPI), the standardized precipitation evapotranspiration index (SPEI), the composite index of meteorological drought (CIspi), and the improved composite index of meteorological drought (CIwap). Long-term daily precipitation and temperature from 1970 to 2014 are used to calculate 30-day M ( M 30), SPI (SPI30), SPEI (SPEI30), 90-day SPEI (SPEI90), CIspi, and CIwap. The 5-day soil moisture observations from 2010 to 2013 are applied to assess the performance of these drought indices. Correlation analysis, overall accuracy, and kappa coefficient are utilized to investigate the relationships between soil moisture and drought indices. Correlation analysis indicates that soil moisture is well correlated with CIwap, SPEI30, M 30, SPI30, and CIspi except SPEI90. Moreover, drought classifications identified by M 30 are in agreement with that of the observed soil moisture. The results show that M 30 based on precipitation and potential evapotranspiration is an appropriate indicator for monitoring drought condition at a finer scale in the study area. According to M 30, summer drought during 1970-2014 happened in each year and showed a slightly upward tendency in recent years.

  12. Summer drought reconstruction in northeastern Spain inferred from a tree ring latewood network since 1734

    Science.gov (United States)

    Tejedor, E.; Saz, M. A.; Esper, J.; Cuadrat, J. M.; de Luis, M.

    2017-08-01

    Drought recurrence in the Mediterranean is regarded as a fundamental factor for socioeconomic development and the resilience of natural systems in context of global change. However, knowledge of past droughts has been hampered by the absence of high-resolution proxies. We present a drought reconstruction for the northeast of the Iberian Peninsula based on a new dendrochronology network considering the Standardized Evapotranspiration Precipitation Index (SPEI). A total of 774 latewood width series from 387 trees of P. sylvestris and P. uncinata was combined in an interregional chronology. The new chronology, calibrated against gridded climate data, reveals a robust relationship with the SPEI representing drought conditions of July and August. We developed a summer drought reconstruction for the period 1734-2013 representative for the northeastern and central Iberian Peninsula. We identified 16 extremely dry and 17 extremely wet summers and four decadal scale dry and wet periods, including 2003-2013 as the driest episode of the reconstruction.

  13. Decadal summer drought frequency in China: the increasing influence of the Atlantic Multi-decadal Oscillation

    International Nuclear Information System (INIS)

    Qian, Chengcheng; Yu, Jin-Yi; Chen, Ge

    2014-01-01

    Decadal variations in summer drought events during 1956–2005 are examined over Eastern China to identify their leading variability modes and their linkages to the Pacific Decadal Oscillation (PDO), Atlantic Multi-decadal Oscillation (AMO), and global warming. The PDO influence is found to dominate China drought frequency from the 1960s to early 1990s via modulating the Western Pacific Subtropical High and the Mongolian High. The four-pole drought pattern produced by the PDO diminished after the early 1990s, being replaced by a dipolar drought pattern that is produced by the AMO via a Eurasian wave train emanating from North Atlantic to China. The increasing influence of the AMO on China drought since the early 1990s is further shown to be a consequence of global warming. This study indicates that the early 1990s is a time when the Atlantic began to exert a stronger influence on climate over China and even larger part of Asia. (letter)

  14. Numerical simulation on the southern flood and northern drought in summer 2014 over Eastern China

    Science.gov (United States)

    Xu, Lianlian; He, Shengping; Li, Fei; Ma, Jiehua; Wang, Huijun

    2017-12-01

    In summer 2014, Eastern China suffered a typical "southern flood and northern drought" anomalous climate. Observational analyses indicated that the anomalous vertical motion, East Asian subtropical westerly jet stream, and the East Asian summer monsoon (EASM) played important roles in the formation of such precipitation anomaly. Furthermore, using the climate model (IAP-AGCM-4.1) perturbed by simultaneous observed sea surface temperature anomalies (SSTAs) in global scale and four different regions (North Pacific, Indian Ocean, North Atlantic, and Equatorial Pacific), this study investigated the potential contribution of ocean to such "southern flood and northern drought" over Eastern China in summer 2014. The simulations forced by global-scale SSTAs or North Pacific SSTAs displayed the most similarity to the observed "southern flood and northern drought" over Eastern China. It was revealed that the global-scale and North Pacific SSTAs influenced the rainfall over Eastern China via modulating the EASM. The related simulations successfully reproduced the associated atmospheric circulation anomalies. The experiment driven by Indian Ocean SSTAs could also reproduce the similar precipitation anomaly pattern and suggested that the Indian Ocean exerted pronounced influence on the North Pacific Subtropical High. Additionally, the simulations forced by SSTAs in the North Atlantic and Equatorial Pacific successfully reproduced the northern drought but failed to capture the southern flood. The simulations suggested that precipitation anomaly over Eastern China in summer 2014 was a comprehensive effect of global SSTAs and the dominant contribution to the "southern flood and northern drought" pattern came from the North Pacific and Indian Ocean.

  15. Soil microarthropods are only weakly impacted after 13 years of repeated drought treatment in wet and dry heathland soils

    DEFF Research Database (Denmark)

    Holmstrup, Martin; Sørensen, Jesper G.; Schmidt, Inger Kappel

    2013-01-01

    Studies of biological responses in the terrestrial environment to rapid changes in climate have mostly been concerned with aboveground biota, whereas less is known of belowground organisms. The present study focuses on mites and springtails of heathland ecosystems and how the microarthropod...... and temperature. This approach provided an opportunity to study biological responses on a local (within sites) and regional scale. Warming treatments increasing night time temperature (0.3–1 °C higher than ambient at 5 cm soil depth) had no detectable effects on the microarthropod communities. Increased intensity...... and frequency of drought had only weak persistent effects on springtail species composition, but practically no effect on major mite groups (Oribatida, Prostigmata or Mesostigmata) suggesting that ecosystem functions of microarthropods may only be transiently impacted by repeated spring or summer drought....

  16. Water-use strategies in two co-occurring Mediterranean evergreen oaks: surviving the summer drought.

    Science.gov (United States)

    David, T S; Henriques, M O; Kurz-Besson, C; Nunes, J; Valente, F; Vaz, M; Pereira, J S; Siegwolf, R; Chaves, M M; Gazarini, L C; David, J S

    2007-06-01

    In the Mediterranean evergreen oak woodlands of southern Portugal, the main tree species are Quercus ilex ssp. rotundifolia Lam. (holm oak) and Quercus suber L. (cork oak). We studied a savannah-type woodland where these species coexist, with the aim of better understanding the mechanisms of tree adaptation to seasonal drought. In both species, seasonal variations in transpiration and predawn leaf water potential showed a maximum in spring followed by a decline through the rainless summer and a recovery with autumn rainfall. Although the observed decrease in predawn leaf water potential in summer indicates soil water depletion, trees maintained transpiration rates above 0.7 mm day(-1) during the summer drought. By that time, more than 70% of the transpired water was being taken from groundwater sources. The daily fluctuations in soil water content suggest that some root uptake of groundwater was mediated through the upper soil layers by hydraulic lift. During the dry season, Q. ilex maintained higher predawn leaf water potentials, canopy conductances and transpiration rates than Q. suber. The higher water status of Q. ilex was likely associated with their deeper root systems compared with Q. suber. Whole-tree hydraulic conductance and minimum midday leaf water potential were lower in Q. ilex, indicating that Q. ilex was more tolerant to drought than Q. suber. Overall, Q. ilex seemed to have more effective drought avoidance and drought tolerance mechanisms than Q. suber.

  17. Heat waves, intense droughts and desertification. summer 1994 in Southeast of Spain

    International Nuclear Information System (INIS)

    Avila, F.

    2009-01-01

    The South-East of spain, which has semiarid climate, is one of the hottest and dries areas in Europe. This region is specialized in irrigated agricultures and citrus fruits (lemons). the drought can last a long period, sometimes two or three years. The lack of water is becoming the biggest problem, especially since the development of irrigated cultures. Drought and heat waves are the major climatic risks and they cause most of the economic losses in agricultural activity. 1994 summer was exceptional in this region of Spain: heat waves and drought. A major disaster that revealed a crisis that began many years ago. The need of water is growing while the volume of available water tends to go down. 1994 summer and its disasters (fire, burnt crops by heat) generated social and politic tensions. Desertification is threatening the region. This situation is not new the drought is a normal phenomenon in a semiarid area, but the accumulation of drought, aridity and human actions worsening desertification. After 1994, new droughts and heat waves increased the lack of water because agriculture needs more and more water. Nonetheless this cultural method is compacting soil by the reduction of organic matter and by the heavy falls of rain. No solution has been found yet, they have to find new resources of water or change agricultural irrigation methods to save water and build up a sustainable development of this semiarid area. (Author) 12 refs.

  18. Summer water use by California coastal prairie grasses: fog, drought, and community composition.

    Science.gov (United States)

    Corbin, Jeffrey D; Thomsen, Meredith A; Dawson, Todd E; D'Antonio, Carla M

    2005-10-01

    Plants in the Mediterranean climate region of California typically experience summer drought conditions, but correlations between zones of frequent coastal fog inundation and certain species' distributions suggest that water inputs from fog may influence species composition in coastal habitats. We sampled the stable H and O isotope ratios of water in non-photosynthetic plant tissue from a variety of perennial grass species and soil in four sites in northern California in order to determine the proportion of water deriving from winter rains and fog during the summer. The relationship between H and O stable isotopes from our sample sites fell to the right of the local meteoric water line (LMWL) during the summer drought, providing evidence that evaporation of water from the soil had taken place prior to the uptake of water by vegetation. We developed a novel method to infer the isotope values of water before it was subjected to evaporation in which we used experimental data to calculate the slope of the deltaH versus deltaO line versus the LMWL. After accounting for evaporation, we then used a two-source mixing model to evaluate plant usage of fog water. The model indicated that 28-66% of the water taken up by plants via roots during the summer drought came from fog rather than residual soil water from winter rain. Fog use decreased as distance from the coast increased, and there were significant differences among species in the use of fog. Rather than consistent differences in fog use by species whose distributions are limited to the coast versus those with broader distributions, species responded individualistically to summer fog. We conclude that fogwater inputs can mitigate the summer drought in coastal California for many species, likely giving an advantage to species that can use it over species that cannot.

  19. Effect of summer throughfall exclusion, summer drought, and winter snow cover on methane fluxes in a temperate forest soil

    Science.gov (United States)

    Borken, W.; Davidson, E.A.; Savage, K.; Sundquist, E.T.; Steudler, P.

    2006-01-01

    Soil moisture strongly controls the uptake of atmospheric methane by limiting the diffusion of methane into the soil, resulting in a negative correlation between soil moisture and methane uptake rates under most non-drought conditions. However, little is known about the effect of water stress on methane uptake in temperate forests during severe droughts. We simulated extreme summer droughts by exclusion of 168 mm (2001) and 344 mm (2002) throughfall using three translucent roofs in a mixed deciduous forest at the Harvard Forest, Massachusetts, USA. The treatment significantly increased CH4 uptake during the first weeks of throughfall exclusion in 2001 and during most of the 2002 treatment period. Low summertime CH4 uptake rates were found only briefly in both control and exclusion plots during a natural late summer drought, when water contents below 0.15 g cm-3 may have caused water stress of methanotrophs in the A horizon. Because these soils are well drained, the exclusion treatment had little effect on A horizon water content between wetting events, and the effect of water stress was smaller and more brief than was the overall treatment effect on methane diffusion. Methane consumption rates were highest in the A horizon and showed a parabolic relationship between gravimetric water content and CH4 consumption, with maximum rate at 0.23 g H2O g-1 soil. On average, about 74% of atmospheric CH4 was consumed in the top 4-5 cm of the mineral soil. By contrast, little or no CH4 consumption occurred in the O horizon. Snow cover significantly reduced the uptake rate from December to March. Removal of snow enhanced CH4 uptake by about 700-1000%, resulting in uptake rates similar to those measured during the growing season. Soil temperatures had little effect on CH4 uptake as long as the mineral soil was not frozen, indicating strong substrate limitation of methanotrophs throughout the year. Our results suggest that the extension of snow periods may affect the annual rate

  20. Combining drought survival via summer dormancy and annual biomass productivity in Dactylis glomerata L.

    Directory of Open Access Journals (Sweden)

    Rajae eKallida

    2016-02-01

    Full Text Available Under Mediterranean climates, the best strategy to produce rain-fed fodder crops is to develop perennial drought resistant varieties. Summer dormancy present in native germplasm has been shown to confer a high level of survival under severe drought. Nevertheless it has also been shown to be negatively correlated with annual biomass productivity. The aim of this study was to analyse the correlations between summer dormancy and annual biomass productivity related traits and to identify quantitative trait loci (QTL for these traits in a progeny of a summer dormant cocksfoot parent (Kasbah and a summer active parent (Medly. A total of 283 offspring and the parents were phenotyped for summer dormancy, plant growth rate and heading date in Morocco and for maximum leaf elongation rate (LERm in France. The individuals were genotyped with a total of 325 markers including 59 AFLP, 64 SSR and 202 DArT markers. The offspring exhibited a large quantitative variation for all measured traits. Summer dormancy showed a negative correlation with both plant growth rate (-0.34 p<0.005 and LERm (-0.27 p<0.005. However, genotypes with both a high level of summer dormancy and a high level of plant growth rate were detected in the progeny. One genetic map per parent was built with a total length of 377 and 423 cM for Kasbah and Medly, respectively. Both different and co-localised QTL for summer dormancy and plant growth rate were identified. These results demonstrate that it should be possible to create summer dormant cocksfoot varieties with a high annual biomass productivity.

  1. Response of water use efficiency to summer drought in a boreal Scots pine forest in Finland

    Science.gov (United States)

    Gao, Yao; Markkanen, Tiina; Aurela, Mika; Mammarella, Ivan; Thum, Tea; Tsuruta, Aki; Yang, Huiyi; Aalto, Tuula

    2017-09-01

    The influence of drought on plant functioning has received considerable attention in recent years, however our understanding of the response of carbon and water coupling to drought in terrestrial ecosystems still needs to be improved. A severe soil moisture drought occurred in southern Finland in the late summer of 2006. In this study, we investigated the response of water use efficiency to summer drought in a boreal Scots pine forest (Pinus sylvestris) on the daily time scale mainly using eddy covariance flux data from the Hyytiälä (southern Finland) flux site. In addition, simulation results from the JSBACH land surface model were evaluated against the observed results. Based on observed data, the ecosystem level water use efficiency (EWUE; the ratio of gross primary production, GPP, to evapotranspiration, ET) showed a decrease during the severe soil moisture drought, while the inherent water use efficiency (IWUE; a quantity defined as EWUE multiplied with mean daytime vapour pressure deficit, VPD) increased and the underlying water use efficiency (uWUE, a metric based on IWUE and a simple stomatal model, is the ratio of GPP multiplied with a square root of VPD to ET) was unchanged during the drought. The decrease in EWUE was due to the stronger decline in GPP than in ET. The increase in IWUE was because of the decreased stomatal conductance under increased VPD. The unchanged uWUE indicates that the trade-off between carbon assimilation and transpiration of the boreal Scots pine forest was not disturbed by this drought event at the site. The JSBACH simulation showed declines of both GPP and ET under the severe soil moisture drought, but to a smaller extent compared to the observed GPP and ET. Simulated GPP and ET led to a smaller decrease in EWUE but a larger increase in IWUE because of the severe soil moisture drought in comparison to observations. As in the observations, the simulated uWUE showed no changes in the drought event. The model deficiencies exist

  2. On the key role of droughts in the dynamics of summer fires in Mediterranean Europe.

    Science.gov (United States)

    Turco, Marco; von Hardenberg, Jost; AghaKouchak, Amir; Llasat, Maria Carmen; Provenzale, Antonello; Trigo, Ricardo M

    2017-03-06

    Summer fires frequently rage across Mediterranean Europe, often intensified by high temperatures and droughts. According to the state-of-the-art regional fire risk projections, in forthcoming decades climate effects are expected to become stronger and possibly overcome fire prevention efforts. However, significant uncertainties exist and the direct effect of climate change in regulating fuel moisture (e.g. warmer conditions increasing fuel dryness) could be counterbalanced by the indirect effects on fuel structure (e.g. warmer conditions limiting fuel amount), affecting the transition between climate-driven and fuel-limited fire regimes as temperatures increase. Here we analyse and model the impact of coincident drought and antecedent wet conditions (proxy for the climatic factor influencing total fuel and fine fuel structure) on the summer Burned Area (BA) across all eco-regions in Mediterranean Europe. This approach allows BA to be linked to the key drivers of fire in the region. We show a statistically significant relationship between fire and same-summer droughts in most regions, while antecedent climate conditions play a relatively minor role, except in few specific eco-regions. The presented models for individual eco-regions provide insights on the impacts of climate variability on BA, and appear to be promising for developing a seasonal forecast system supporting fire management strategies.

  3. Repeated drought alters resistance of seed bank regeneration in baldcypress swamps of North America

    Science.gov (United States)

    Lei, Ting; Middleton, Beth A.

    2018-01-01

    Recurring drying and wetting events are likely to increase in frequency and intensity in predicted future droughts in the central USA and alter the regeneration potential of species. We explored the resistance of seed banks to successive droughts in 53 sites across the nine locations in baldcypress swamps in the southeastern USA. Along the Mississippi River Alluvial Valley and northern Gulf of Mexico, we investigated the capacity of seed banks to retain viable seeds after successive periods of drying and wetting in a greenhouse study. Mean differences in species richness and seed density were compared to examine the interactions of successive droughts, geographical location and water regime. The results showed that both species richness and total density of germinating seedlings decreased over repeated drought trials. These responses were more pronounced in geographical areas with higher annual mean temperature. In seed banks across the southeastern swamp region, most species were exhausted after Trial 2 or 3, except for semiaquatic species in Illinois and Tennessee, and aquatic species in Texas. Distinct geographical trends in seed bank resistance to drought demonstrate that climate-induced drying of baldcypress swamps could influence the regeneration of species differently across their ranges. Despite the health of adult individuals, lack of regeneration may push ecosystems into a relict status. Seed bank depletion by germination without replenishment may be a major conservation threat in a future with recurring droughts far less severe than megadrought. Nevertheless, the protection of moist refugia might aid conservation.

  4. A Revised Set of Dendroclimatic Reconstructions of Summer Drought over the Conterminous U.S.

    Science.gov (United States)

    Zhang, Z.; Mann, M. E.; Cook, E. R.

    2002-12-01

    We describe a revised set of dendroclimatic reconstructions of drought patterns over the conterminous U.S back to 1700. These reconstructions are based on a set of 483 drought-sensitive tree ring chronologies available across the continental U.S. used previously by Cook et al [Cook, E.R., D.M. Meko, D.W. Stahle, and M.K. Cleaveland, Drought Reconstructions for the Continental United States, Journal of Climate, 12, 1145-1162, 1999]. In contrast with the "Point by Point" (PPR) local regression technique used by Cook et al (1999), the tree ring data were calibrated against the instrumental record of summer drought[June-August Palmer Drought Severity Index (PDSI)] based on application of the "Regularized Expectation Maximization" (RegEM) algorithm to relate proxy and instrumental data over a common (20th century) interval. This approach calibrates the proxy data set against the instrumental record by treating the reconstruction as initially missing data in the combined proxy/instrumental data matrix, and optimally estimating the mean and covariances of the combined data matrix through an iterative procedure which yields a reconstruction of the PDSI field with minimal error variance [Schneider, T., Analysis of Incomplete Climate Data: Estimation of Mean Values and Covariance Matrices and Imputation of Missing Values, Journal of Climate, 14, 853-871, 2001; Mann, M.E., Rutherford, S., Climate Reconstruction Using 'Pseudoproxies', Geophysical Research Letters, 29, 139-1-139-4, 2002; Rutherford, S., Mann, M.E., Delworth, T.L., Stouffer, R., The Performance of Covariance-Based Methods of Climate Field Reconstruction Under Stationary and Nonstationary Forcing, J. Climate, accepted, 2002]. As in Cook et al (1999), a screening procedure was first used to select an optimal subset of candidate tree-ring drought predictors, and the predictors (tree ring data) and predictand (instrumental PDSI) were pre-whitened prior to calibration (with serial correlation added back into the

  5. Reply to Comment on 'Drought Variability in the Eastern Australia and New Zealand Summer Drought Atlas (ANZDA, CE 1500-2012) Modulated by the Interdecadal Pacific Oscillation'

    Science.gov (United States)

    Palmer, Jonathan G.; Cook, Edward R.; Turney, Chris S. M.; Allen, Kathy; Fenwick, Pavla; Cook, Benjamin I.; O'Donnell, Alison; Lough, Janice; Grierson, Pauline; Baker, Patrick J.

    2017-01-01

    This reply is in response to Vance et al (2017), who expressed concern that their Law Dome summer sea salt record (LDsss; Vance et al 2013) and two Interdecadal Pacific Oscillation (IPO) reconstructions (PLF and DT-median; Vance et al 2015) were not compared properly in our recent study (Palmer et al 2015) describing the eastern Australian and New Zealand summer Drought Atlas (ANZDA) and that this omission mischaracterizes their records.

  6. Drought-induced changes in Amazon forest structure from repeat airborne lidar

    Science.gov (United States)

    Morton, D. C.; Leitold, V.; Longo, M.; Keller, M.; dos-Santos, M. N.; Scaranello, M. A., Sr.

    2017-12-01

    Drought events in tropical forests, including the 2015-2016 El Niño, may reduce net primary productivity and increase canopy tree mortality, thereby altering the short and long-term net carbon balance of tropical forests. Given the broad extent of drought impacts, forest inventory plots or eddy flux towers may not capture regional variability in forest response to drought. Here, we analyzed repeat airborne lidar data to evaluate canopy turnover from branch and tree fall before (2013-2014) and during (2014-2016) the recent El Niño drought in the eastern and central Brazilian Amazon. Coincident field surveys for a 16-ha subset of the lidar coverage provided complementary information to classify turnover areas by mechanism (branch, multiple branch, tree fall, multiple tree fall) and estimate the total coarse woody debris volume from canopy and understory tree mortality. Annualized rates of canopy turnover increased by 50%, on average, during the drought period in both intact and fragmented forests near Santarém, Pará. Turnover increased uniformly across all size classes, and there was limited evidence that taller trees contributed a greater proportion of turnover events in any size class in 2014-2016 compared to 2013-2014. This short-term increase in canopy turnover differs from findings in multi-year rainfall exclusion experiments that large trees were more sensitive to drought impacts. Field measurements confirmed the separability of the smallest (single branch) and largest damage classes (multiple tree falls), but single tree and multiple branch fall events generated similar coarse woody debris production and lidar-derived changes in canopy volume. Large-scale sampling possible with repeat airborne lidar data also captured strong local and regional gradients in canopy turnover. Differences in slope partially explained the north-south gradient in canopy turnover dynamics near Santarém, with larger increases in turnover on flatter terrain. Regional variability

  7. Spring Soil Temperature Anomalies over Tibetan Plateau and Summer Droughts/Floods in East Asia

    Science.gov (United States)

    Xue, Y.; Li, W.; LI, Q.; Diallo, I.; Chu, P. C.; Guo, W.; Fu, C.

    2017-12-01

    Recurrent extreme climate events, such as droughts and floods, are important features of the climate of East Asia, especially over the Yangtze River basin. Many studies have attributed these episodes to variability and anomaly of global sea surface temperatures (SST) anomaly. In addition, snow in the Tibetan Plateau has also been considered as one of the factors affecting the Asian monsoon variability. However, studies have consistently shown that SST along is unable to explain the extreme climate events fully and snow has difficulty to use as a predictor. Remote effects of observed large-scale land surface temperature (LST) and subsurface temperature variability in Tibetan Plateau (TP) on East Asian regional droughts/floods, however, have been largely ignored. We conjecture that a temporally filtered response to snow anomalies may be preserved in the LST anomaly. In this study, evidence from climate observations and model simulations addresses the LST/SUBT effects. The Maximum Covariance Analysis (MCA) of observational data identifies that a pronounce spring LST anomaly pattern over TP is closely associated with precipitation anomalies in East Asia with a dipole pattern, i.e., negative/positive TP spring LST anomaly is associated with the summer drought/flood over the region south of the Yangtze River and wet/dry conditions to the north of the Yangtze River. Climate models were used to demonstrate a causal relationship between spring cold LST anomaly in the TP and the severe 2003 drought over the southern part of the Yangtze River in eastern Asia. This severe drought resulted in 100 x 106 kg crop yield losses and an economic loss of 5.8 billion Chinese Yuan. The modeling study suggests that the LST effect produced about 58% of observed precipitation deficit; while the SST effect produced about 32% of the drought conditions. Meanwhile, the LST and SST effects also simulated the observed flood over to the north of the Yangtze River. This suggests that inclusion of

  8. Changes of ecosystem functions in a Mediterranean shrubland exposed for eight years to prolonged summer droughts

    Science.gov (United States)

    de Dato, Giovanbattista; de Angelis, Paolo; Cesaraccio, Carla; Pellizzaro, Grazia; Duce, Pierpaolo; Sirca, Costantino; Spano, Donatella; Beier, Claus

    2010-05-01

    Where water is a limiting factor, like in arid and semiarid shrubland ecosystems of the Mediterranean basin, soil moisture, strengthen by high temperatures, is the key limiting factor controlling biogeochemical cycles. During the drought season, the unavailable water reduces plant growth, litter decomposition and microbial soil respiration. In order to assess the impacts of precipitation reduction on Mediterranean shrublands, a natural community has been exposed since 2001 to prolonged summer droughts by means of mobile plastic roofs, covering three experimental plots (20 m2) during rain events, in spring and in autumn. Three additional plots were used as control. The vegetation reaches a maximum height of 1.0 m and the main shrub species are Cistus monspeliensis, Helichrysum italicum and Dorycnium pentaphyllum. Bare soil constitutes about 20% of the plot surface. The aim of this paper is to summarize the impact of the treatment on the plant community structure and on ecosystem functions, after 8 years of experimentation. A general increase of vegetation cover was observed in the whole community during the years, as result of a natural process of recolonisation. This positive temporal pattern was mainly observed in the control plots, whereas in the drought treatment it was less evident and practically null in the year 2003. At species-specific level, a clear negative effect of drought treatment was observed for C. monspeliensis. Moreover, anticipated drought reduced C assimilation and induced an earlier change of leaf morphology in Cistus. These effects produced the reduction of LAI and of whole plant productivity. The seasonal pattern of soil CO2 efflux was characterized by higher rates during the wet vegetative season (autumn-spring) and lower rates during the dry non-vegetative season (summer). Significant negative effects were occasionally recorded during the period with the treatment turned on. The relation of soil respiration with temperature and soil water

  9. Drought Variability in the Eastern Australia and New Zealand Summer Drought Atlas (ANZDA, CE 1500-2012) Modulated by the Interdecadal Pacific Oscillation

    Science.gov (United States)

    Palmer, Jonathan G.; Cook, Edward R.; Turney, Chris S. M.; Allen, Kathy; Fenwick, Pavla; Cook, Benjamin I.; O'Donnell, Alison; Lough, Janice; Grierson, Pauline; Baker, Patrick

    2015-01-01

    Agricultural production across eastern Australia and New Zealand is highly vulnerable to drought, but there is a dearth of observational drought information prior to CE (Christian Era) 1850. Using a comprehensive network of 176 drought-sensitive tree-ring chronologies and one coral series, we report the first Southern Hemisphere gridded drought atlas extending back to CE 1500. The austral summer (December-February) Palmer drought sensitivity index reconstruction accurately reproduces historically documented drought events associated with the first European settlement of Australia in CE 1788, and the leading principal component explains over 50 percent of the underlying variance. This leading mode of variability is strongly related to the Interdecadal Pacific Oscillation tripole index (IPO), with a strong and robust antiphase correlation between (1) eastern Australia and the New Zealand North Island and (2) the South Island. Reported positive, negative, and neutral phases of the IPO are consistently reconstructed by the drought atlas although the relationship since CE 1976 appears to have weakened.

  10. Extreme late-summer drought causes neutral annual carbon balance in southwestern ponderosa pine forests and grasslands

    International Nuclear Information System (INIS)

    Kolb, Thomas; Dore, Sabina; Montes-Helu, Mario

    2013-01-01

    We assessed the impacts of extreme late-summer drought on carbon balance in a semi-arid forest region in Arizona. To understand drought impacts over extremes of forest cover, we measured net ecosystem production (NEP), gross primary production (GPP), and total ecosystem respiration (TER) with eddy covariance over five years (2006–10) at an undisturbed ponderosa pine (Pinus ponderosa) forest and at a former forest converted to grassland by intense burning. Drought shifted annual NEP from a weak source of carbon to the atmosphere to a neutral carbon balance at the burned site and from a carbon sink to neutral at the undisturbed site. Carbon fluxes were particularly sensitive to drought in August. Drought shifted August NEP at the undisturbed site from sink to source because the reduction of GPP (70%) exceeded the reduction of TER (35%). At the burned site drought shifted August NEP from weak source to neutral because the reduction of TER (40%) exceeded the reduction of GPP (20%). These results show that the lack of forest recovery after burning and the exposure of undisturbed forests to late-summer drought reduce carbon sink strength and illustrate the high vulnerability of forest carbon sink strength in the southwest US to predicted increases in intense burning and precipitation variability. (letter)

  11. Extreme late-summer drought causes neutral annual carbon balance in southwestern ponderosa pine forests and grasslands

    Science.gov (United States)

    Kolb, Thomas; Dore, Sabina; Montes-Helu, Mario

    2013-03-01

    We assessed the impacts of extreme late-summer drought on carbon balance in a semi-arid forest region in Arizona. To understand drought impacts over extremes of forest cover, we measured net ecosystem production (NEP), gross primary production (GPP), and total ecosystem respiration (TER) with eddy covariance over five years (2006-10) at an undisturbed ponderosa pine (Pinus ponderosa) forest and at a former forest converted to grassland by intense burning. Drought shifted annual NEP from a weak source of carbon to the atmosphere to a neutral carbon balance at the burned site and from a carbon sink to neutral at the undisturbed site. Carbon fluxes were particularly sensitive to drought in August. Drought shifted August NEP at the undisturbed site from sink to source because the reduction of GPP (70%) exceeded the reduction of TER (35%). At the burned site drought shifted August NEP from weak source to neutral because the reduction of TER (40%) exceeded the reduction of GPP (20%). These results show that the lack of forest recovery after burning and the exposure of undisturbed forests to late-summer drought reduce carbon sink strength and illustrate the high vulnerability of forest carbon sink strength in the southwest US to predicted increases in intense burning and precipitation variability.

  12. Mistletoe (Viscum album) infestation in the Scots pine stimulates drought-dependent oxidative damage in summer.

    Science.gov (United States)

    Mutlu, Salih; Ilhan, Veli; Turkoglu, Halil Ibrahim

    2016-04-01

    This study sought to contribute to the understanding of the detrimental effect of the mistletoe (Viscum albumL.), a hemiparasitic plant, on the mortality of the Scots pine (Pinus sylvestrisL.). Fieldwork was conducted in the town of Kelkit (Gumushane province, Turkey) from April to October in 2013. Pine needles of similar ages were removed from the branches of mistletoe-infested and noninfested Scots pine plants, then transported to the laboratory and used as research materials. The effects of the mistletoe on the Scots pine during infestation were evaluated by determining the levels of water, electrolyte leakage (EL), malondialdehyde (MDA, being a product of lipid peroxidation) and reactive oxygen species (ROS) such as superoxide anion (O2 (-•)), hydrogen peroxide (H2O2) and hydroxyl radical ((•)OH). In addition, the activities of antioxidative enzymes such as superoxide dismutase (SOD), catalase (CAT) and peroxidase (POX) were measured in the same samples. The highest level of drought stress was found in summer (especially in August) as a result of the lowest water content in the soil and the highest average temperature occurring in these months. The drought stress induced by mistletoe infestation caused a regular decrease in water content, while it increased the levels of EL, MDA and ROS (H2O2, O2 (-•)and(•)OH). The infestation also stimulated the activities of CAT and POX, with the exception of SOD. On the other hand, in August, when the drought conditions were the harshest, the levels of EL and MDA, which are two of the most important indicator parameters for oxidative stress, as well as the levels of H2O2and(•)OH, which are two of the ROS leading to oxidative stress, reached the highest values in both infested and noninfested needles, whereas the O2 (-•)level decreased. For the same period and needles, CAT activity increased, while SOD activity decreased. Peroxidase activity, however, did not exhibit a significant change. Our findings indicate

  13. Two different strategies of Mediterranean macchia plants to avoid photoinhibitory damage by excessive radiation levels during summer drought

    Science.gov (United States)

    Werner, Christiane; Correia, Otilia; Beyschlag, Wolfram

    1999-02-01

    The adaptive strategies to high radiation and water stress of the drought tolerant evergreen sclerophylls Quercus coccifera and Arbutus unedo are compared to those of the semi-deciduous Cistus spp. ( C. albidus and C. monspeliensis). Cistus spp. partially avoided drought by a marked reduction of their transpirational surface through leaf abscission during summer, when predawn water potential declined below -5.5 MPa. Chlorophyll fluorescence measurements revealed a reversible diurnal decrease of maximum photochemical efficiency of PSII (F v/F m), which became more accentuated during summer drought in all species. An important strategy to avoid damage by excessive radiation levels in Cistus spp. was the structural regulation of light interception through leaf angle changes, from a more horizontal orientation in spring ( 70°). Horizontal orientated leaves were highly susceptible to photoinhibition, and excessive radiation often resulted in irreversible photodamage followed by leaf abscission during summer, whereas vertical leaf orientation appeared to protect the leaf from severe photoinhibition. Still, these mechanisms were not fully successful in avoiding chronic photoinhibition, and predawn F v/F m values remained low in Cistus spp. during summer (only exhibiting a partial overnight recovery). Evergreen sclerophylls were less susceptible to photoinhibition, and the diurnal decline in F v/F m remained fully reversible during drought. Structural regulation of light interception was not found to be an important strategy in these species, and only small, though significant changes in leaf angle occurred. The ecological importance of the adaptive strategies of each functional group is discussed.

  14. Effects of climate-induced increases in summer drought on riparian plant species : a meta-analysis

    NARCIS (Netherlands)

    Garssen, Annemarie G.; Verhoeven, Jos T. A.; Soons, Merel B.

    Frequency and duration of summer droughts are predicted to increase in the near future in many parts of the world, with considerable anticipated effects on riparian plant community composition and species richness. Riparian plant communities along lowland streams are characterised by high species

  15. Redox proteomics and physiological responses in Cistus albidus shrubs subjected to long-term summer drought followed by recovery.

    Science.gov (United States)

    Brossa, Ricard; Pintó-Marijuan, Marta; Francisco, Rita; López-Carbonell, Marta; Chaves, Maria Manuela; Alegre, Leonor

    2015-04-01

    The interaction between enzymatic and non-enzymatic antioxidants, endogenous levels of ABA and ABA-GE, the rapid recuperation of photosynthetic proteins under re-watering as well the high level of antioxidant proteins in previously drought-stressed plants under re-watering conditions, will contribute to drought resistance in plants subjected to a long-term drought stress under Mediterranean field conditions. This work provides an overview of the mechanisms of Cistus albidus acclimation to long-term summer drought followed by re-watering in Mediterranean field conditions. To better understand the molecular mechanisms of drought resistance in these plants, a proteomic study using 2-DE and MALDI-TOF/TOF MS/MS was performed on leaves from these shrubs. The analysis identified 57 differentially expressed proteins in water-stressed plants when contrasted to well watered. Water-stressed plants showed an increase, both qualitatively and quantitatively, in HSPs, and downregulation of photosynthesis and carbon metabolism enzymes. Under drought conditions, there was considerable upregulation of enzymes related to redox homeostasis, DHA reductase, Glyoxalase, SOD and isoflavone reductase. However, upregulation of catalase was not observed until after re-watering was carried out. Drought treatment caused an enhancement in antioxidant defense responses that can be modulated by ABA, and its catabolites, ABA-GE, as well as JA. Furthermore, quantification of protein carbonylation was shown to be a useful marker of the relationship between water and oxidative stress, and showed that there was only moderate oxidative stress in C. albidus plants subjected to water stress. After re-watering plants recovered although the levels of ABA-GE and antioxidant enzymes still remain higher than in well-watered plants. We expect that our results will provide new data on summer acclimation to drought stress in Mediterranean shrubs.

  16. Response of water use efficiency to summer drought in a boreal Scots pine forest in Finland

    Directory of Open Access Journals (Sweden)

    Y. Gao

    2017-09-01

    Full Text Available The influence of drought on plant functioning has received considerable attention in recent years, however our understanding of the response of carbon and water coupling to drought in terrestrial ecosystems still needs to be improved. A severe soil moisture drought occurred in southern Finland in the late summer of 2006. In this study, we investigated the response of water use efficiency to summer drought in a boreal Scots pine forest (Pinus sylvestris on the daily time scale mainly using eddy covariance flux data from the Hyytiälä (southern Finland flux site. In addition, simulation results from the JSBACH land surface model were evaluated against the observed results. Based on observed data, the ecosystem level water use efficiency (EWUE; the ratio of gross primary production, GPP, to evapotranspiration, ET showed a decrease during the severe soil moisture drought, while the inherent water use efficiency (IWUE; a quantity defined as EWUE multiplied with mean daytime vapour pressure deficit, VPD increased and the underlying water use efficiency (uWUE, a metric based on IWUE and a simple stomatal model, is the ratio of GPP multiplied with a square root of VPD to ET was unchanged during the drought. The decrease in EWUE was due to the stronger decline in GPP than in ET. The increase in IWUE was because of the decreased stomatal conductance under increased VPD. The unchanged uWUE indicates that the trade-off between carbon assimilation and transpiration of the boreal Scots pine forest was not disturbed by this drought event at the site. The JSBACH simulation showed declines of both GPP and ET under the severe soil moisture drought, but to a smaller extent compared to the observed GPP and ET. Simulated GPP and ET led to a smaller decrease in EWUE but a larger increase in IWUE because of the severe soil moisture drought in comparison to observations. As in the observations, the simulated uWUE showed no changes in the drought event. The

  17. The role of transients in the Mid Summer Drought over the Tropical Americas

    Science.gov (United States)

    Herrera, E.; Magaña Rueda, V.; Caetano, E.

    2013-05-01

    The Mid Summer Drought (MSD) has raised the interested of those interested in regional climate dynamics since it appears to be a unique characteristic of the tropical Americas climate. The MSD corresponds to a relative minimum in summer precipitation between July and August in the Mesoamerican region. Several theories have been posed to explain its origin including the annual cycle march of the ITCZ, a teleconnection from the Asian monsoon region, or an air sea interaction process that relates the warm pools over the eastern Pacific and the Caribbean Sea. However, none of them has addressed the various characteristics of the MSD described by Magaña et al (1999) and Magaña and Caetano (2005). In the present paper, the role of the transient mean flow interaction over the Caribbean Sea is explored. The Caribbean Low Level Jet (CLLJ) and the transients interact in such a way that the CLLJ reaches maximum intensity when the MSD occurs. This is a period of minimum Perturbation Kinetic Energy in the region, suggesting that a CLLJ stronger than approximately 15 m/s tends to inhibit the amplification of eddies. Transients are crucial dynamic elements to produce precipitation over the Mexico and Central American region. Over the eastern Pacific warm pool, tropical convection and sea surface temperature are related by a sort of Clausius Clapeyron exponential equation. However, there are two branches for the relationship, one for the first maximum in tropical convection during June, and a second one during September, with a relative minimum corresponding to the MSD in July - August. The most interesting aspect of such patterns is that while the June exponential curves occurs at SST larger than 28°C, the curve corresponding to September takes place at lower SSTs, suggesting that transient activity in this period is necessary to enhance tropical convective activity during the latter part of the summer rains in the region. This is exactly the period when PKE increases over the

  18. Water-use strategies of six co-existing Mediterranean woody species during a summer drought

    NARCIS (Netherlands)

    Quero, J.L.; Sterck, F.J.; Martínez-Vilalta, J.; Villar, R.

    2011-01-01

    Drought stress is known to limit plant performance in Mediterranean-type ecosystems. We have investigated the dynamics of the hydraulics, gas exchange and morphology of six co-existing Mediterranean woody species growing under natural field conditions during a drought that continued during the

  19. Spring-summer droughts in the Czech Land in 1805–2012 and their forcings

    Czech Academy of Sciences Publication Activity Database

    Brázdil, Rudolf; Trnka, Miroslav; Mikšovský, Jiří; Řezníčková, Ladislava; Dobrovolný, Petr

    2015-01-01

    Roč. 35, č. 7 (2015), s. 1405-1421 ISSN 0899-8418 R&D Projects: GA MŠk(CZ) EE2.3.20.0248 Institutional support: RVO:67179843 Keywords : drought * drought indices * fluctuation * trend * forcing * Czech Lands Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 3.609, year: 2015

  20. Antagonism between elevated CO2, nighttime warming, and summer drought reduces the robustness of PSII performance to freezing events

    DEFF Research Database (Denmark)

    Albert, Kristian Rost; Boesgaard, Kristine Stove; Ro-Poulsen, Helge

    2013-01-01

    yield in light, Fv′/Fm′, using the pulse amplitude methodology, and the total performance index, PItotal, which integrate changes of the chlorophyll-a fluorescence transient including the maximal quantum yield in darkness, Fv/Fm.Decreasing temperature during autumn linearly reduced PItotal, both...... in the wavy hair-grass, Deschampsia flexuosa, and in the evergreen dwarf shrub common heather, Calluna vulgaris, and following freezing events the PItotal and Fv′/Fm′ were reduced even more. Contrary to expected, indirect effects of the previous summer drought reduced PSII performance before freezing events...

  1. The inter-decadal correlation between summer arctic oscillation and summer drought and moist characteristic of northwest China

    Science.gov (United States)

    Wang, Pengxiang; Zheng, Youfei; Sun, Landong; Ren, Zhenhe; He, Jinhai; Zhang, Qiang

    2007-09-01

    In the context of 1960~2003 summertime rainfall and small-sized pan evaporations from 131 stations distributed over NW China covering Xinjiang, Qinghai, Gansu, Ningxia, Shaanxi as well as western Nei Mongolia, and Arctic Oscillation Indices (AOI) we define a homogenized index for aridity or wetness feature, with which to examine the relations between AOI and NW China aridity-wetness regime, indicating their noticeable relations on an interdecadal basis. It is found that during the decade of summer Arctic oscillation stronger than mean, the sea level pressure field shows positive (negative) anomalies over Asian landmass, a stronger anticyclonic anomaly circulation appears at 700 hPa over Lake Baikal and to the south, westerly (northerly) departure emerges in the westerly (monsoon) portion of NW China, as well as over NW China there appears a structure with a low in the west and a high in the east at the 500 hPa height field, suggestive of east-Asian summer monsoon weaker than normal such that westerly flows prevail in the westerly zone of NW China, leading to rainfall more than mean for a wetter climate while in its monsoon area the northerly winds are dominant, with precipitation less than normal, resulting in a climate drier in comparison to mean and v.v. for the decade with summer AO weaker than normal.

  2. Role of sea surface temperature anomalies in the tropical Indo-Pacific region in the northeast Asia severe drought in summer 2014: month-to-month perspective

    Science.gov (United States)

    Xu, Zhiqing; Fan, Ke; Wang, HuiJun

    2017-09-01

    The severe drought over northeast Asia in summer 2014 and the contribution to it by sea surface temperature (SST) anomalies in the tropical Indo-Pacific region were investigated from the month-to-month perspective. The severe drought was accompanied by weak lower-level summer monsoon flow and featured an obvious northward movement during summer. The mid-latitude Asian summer (MAS) pattern and East Asia/Pacific teleconnection (EAP) pattern, induced by the Indian summer monsoon (ISM) and western North Pacific summer monsoon (WNPSM) rainfall anomalies respectively, were two main bridges between the SST anomalies in the tropical Indo-Pacific region and the severe drought. Warming in the Arabian Sea induced reduced rainfall over northeast India and then triggered a negative MAS pattern favoring the severe drought in June 2014. In July 2014, warming in the tropical western North Pacific led to a strong WNPSM and increased rainfall over the Philippine Sea, triggering a positive EAP pattern. The equatorial eastern Pacific and local warming resulted in increased rainfall over the off-equatorial western Pacific and triggered an EAP-like pattern. The EAP pattern and EAP-like pattern contributed to the severe drought in July 2014. A negative Indian Ocean dipole induced an anomalous meridional circulation, and warming in the equatorial eastern Pacific induced an anomalous zonal circulation, in August 2014. The two anomalous cells led to a weak ISM and WNPSM, triggering the negative MAS and EAP patterns responsible for the severe drought. Two possible reasons for the northward movement of the drought were also proposed.

  3. Drought

    NARCIS (Netherlands)

    Quevauviller, P.; Lanen, Van Henny A.J.

    2014-01-01

    Drought is one of the most extreme weather-related natural hazards. It differs from other hydrometeorological extremes in several ways. It develops gradually and usually over large areas (transnational), mostly resulting from a prolonged period (from months to years) of below-normal

  4. Diurnal regulation of photosynthesis in Jatropha curcas under drought during summer in a semi-arid region

    International Nuclear Information System (INIS)

    Tominaga, Jun; Inafuku, Sayuri; Coetzee, Tidimalo; Kawamitsu, Yoshinobu

    2014-01-01

    The diurnal photosynthetic responses to drought in Jatropha curcas have not been well assessed under field conditions in harsh semi-arid habitats. To illustrate this, diurnal changes in chlorophyll fluorescence and gas exchange rates were measured in field-grown Jatropha with or without a short (13 days) water recovery treatment under drought conditions during hot summer in a semi-arid. Sensitive stomatal closure coordinated with a drying atmosphere strictly limited a net CO 2 assimilation rate with a predominant morning peak, eventually turning negative during the day. Even though the risk of excess excitation energy which potentially causes photodamage increased with the extremely low capacity for CO 2 fixation, Jatropha preserved the integrity of PSII. Quantitative analysis of quenching partitioning revealed that regulated thermal energy dissipation accounted a large fraction of both instantaneous and daily absorbed energy by up to 80 and 72%, respectively, under the drought condition. Water recovery treatment more than doubled daily CO 2 uptake via mitigating diurnal stomatal closure. The regulated thermal dissipation flexibly adjusted PSII quantum efficiency to capacity of CO 2 fixation. In addition, downregulation of PSII quantum efficiency via sustained regulated thermal dissipation was observed and thought to be an additional photoprotective function. It is clear that Jatropha strongly rely upon the regulated thermal dissipation under drought condition, which must be critically important for this strict water conserving species, especially under a climate with high solar radiation loads as is seen in semi-arid regions. - Highlights: • Diurnal gas exchange and the fate of absorbed energy were assessed in Jatropha. • The dynamic stomatal closure was the predominant restriction under water stress. • The PSII integrity was preserved even under severe water stress. • The regulated thermal dissipation accounted by up to 72% of daily absorbed energy.

  5. The Influence of Drought and Flood Disasters on Rice NDVI in Summer

    International Nuclear Information System (INIS)

    Piao, Meihua; Hongyan, Zhang; Zhao, Jianjun; Guo, Xiaoyi

    2014-01-01

    During the period from 1995 to 2010, flooding and drought occurred frequently in North Korea. This greatly affected agriculture. The precipitation data was the main factor evaluated in flood and drought monitoring. In this study, the Z index method was used to estimate the change in precipitation, calculated from TRMM (Tropical Rainfall Measuring Mission) data. The Z index and the NDVI were combined with the map of distribution of rice to analyze the relationship between the Z index and NDVI during the growing months of rice in recent 12 years. The results revealed that the Z index is a good indicator to study the relative changes of precipitation in North Korea, and that the relationship between the Z index and NDVI in a quadratic function

  6. Heat waves, intense droughts and desertification. summer 1994 in Southeast of Spain; Olas de calor, sequias intensas y desertificacion, durante el verano 1994 en el Sureste espanol (Murcia)

    Energy Technology Data Exchange (ETDEWEB)

    Avila, F.

    2009-07-01

    The South-East of spain, which has semiarid climate, is one of the hottest and dries areas in Europe. This region is specialized in irrigated agricultures and citrus fruits (lemons). the drought can last a long period, sometimes two or three years. The lack of water is becoming the biggest problem, especially since the development of irrigated cultures. Drought and heat waves are the major climatic risks and they cause most of the economic losses in agricultural activity. 1994 summer was exceptional in this region of Spain: heat waves and drought. A major disaster that revealed a crisis that began many years ago. The need of water is growing while the volume of available water tends to go down. 1994 summer and its disasters (fire, burnt crops by heat) generated social and politic tensions. Desertification is threatening the region. This situation is not new the drought is a normal phenomenon in a semiarid area, but the accumulation of drought, aridity and human actions worsening desertification. After 1994, new droughts and heat waves increased the lack of water because agriculture needs more and more water. Nonetheless this cultural method is compacting soil by the reduction of organic matter and by the heavy falls of rain. No solution has been found yet, they have to find new resources of water or change agricultural irrigation methods to save water and build up a sustainable development of this semiarid area. (Author) 12 refs.

  7. The response of mulberry trees after seedling hardening to summer drought in the hydro-fluctuation belt of Three Gorges Reservoir Areas.

    Science.gov (United States)

    Huang, Xiaohui; Liu, Yun; Li, Jiaxing; Xiong, Xingzheng; Chen, Yang; Yin, Xiaohua; Feng, Dalan

    2013-10-01

    Interest has developed in the potential of mulberry (Morus alba), a woody perennial, for revegetating the hydro-fluctuation belt of the Three Gorges Reservoir due to its resistance to water-logging stress. To be useful, the trees must also be able to withstand dry conditions in summer when temperatures can be very high and droughts become severe quickly. Here, we report a study in which mulberry seedlings were grown in a greenhouse under a variety of simulated soil water conditions reflecting potential summer scenarios in the hydro-fluctuation belt of the Three Gorges Reservoir Area. We compared the responses of two pretreatment groups of mulberry seedlings to different levels of drought stress. The pretreatment groups differed with respect to drought hardening: the daily-managed (DM) group had relative soil moisture held constant in the range 70-80 %, while the drought-hardened (DH) group had relative soil moisture held constant at 40-50 %. Following the month-long pretreatment of seedlings, the two groups of young trees (DM and DH) were then respectively subjected to three levels of drought stress for a month: normal watering, moderate drought stress, and severe drought stress. A series of measurements comparing the physiological status of the plants in the two groups were then made, and the following results were obtained: (1) As drought stress increased, the heights, base diameters, root surface areas, photosynthetic rates (Pn), stomatal conductances (Gs), and transpiration rates (Tr) of the mulberry trees in both groups (DM and DH) decreased significantly, while the specific root area and abscisic acid (ABA) contents had increasing trends. Root activity and instantaneous water use efficiency of mulberry trees in both groups (DM and DH) were all raised under drought stress conditions than under normal watering, but the root/shoot ratio and leaf water potential were lowered. (2) At the same level of soil water content, the heights, base diameters, root

  8. Soil acidification occurs under ambient conditions but is retarded by repeated drought: Results of a field-scale climate manipulation experiment

    Energy Technology Data Exchange (ETDEWEB)

    Kopittke, G.R.; Tietema, A., E-mail: A.Tietema@uva.nl; Verstraten, J.M.

    2012-11-15

    Acid atmospheric emissions within Europe and North America have decreased strongly since 1985 and most recent acidification studies have focused on the changes occurring within ecosystems as a result of this decreased deposition. This current study documents a soil acidification trend under ambient N deposition conditions over a 13 year period, suggesting that acidification continues to be a process of concern at this Calluna vulgaris dominated heathland with an acidic sandy soil. The annual manipulation of climatic conditions on this heathland simulated the predicted summer rainfall reduction (drought) and resulted in a long term retardation of the soil acidification trend. The pH of the soil solution significantly decreased over the course of the trial for both treatments, however, in the final 2 years the decline continued only in the Control treatment. This retardation is primarily associated with the reduction in rainfall leading to lower drainage rates, reduced loss of cations and therefore reduced lowering of the soil acid neutralizing capacity (ANC). However, a change in the underlying mechanisms also indicated that N transformations became less important in the Drought treatment. This change corresponded to an increase in groundcover of an air-pollution tolerant moss species and it is hypothesized that this increasing moss cover filtered an increasing quantity of deposited N, thus reducing the N available for transformation. A soil acidification lag time is expected to increase between the two treatments due to the cumulative disparity in cation retention and rates of proton formation. To the authors' knowledge, this is the first study in which such acidification trends have been demonstrated in a field-scale climate manipulation experiment. -- Highlights: Black-Right-Pointing-Pointer A unique investigation of acidification on a field-scale climate manipulation trial. Black-Right-Pointing-Pointer Soil acidification occurred over 13 years of ambient N

  9. Decreased summer drought affects plant productivity and soil carbon dynamics in a Mediterranean woodland

    Science.gov (United States)

    Cotrufo, M. F.; Alberti, G.; Inglima, I.; Marjanović, H.; Lecain, D.; Zaldei, A.; Peressotti, A.; Miglietta, F.

    2011-09-01

    Precipitation patterns are expected to change in the Mediterranean region within the next decades, with projected decreases in total rainfall and increases in extreme events. We manipulated precipitation patterns in a Mediterranean woodland, dominated by Arbutus unedo L., to study the effects of changing precipitation regimes on above-ground net primary production (ANPP) and soil C dynamics, specifically plant-derived C input to soil and soil respiration (SR). Experimental plots were exposed to either a 20 % reduction of throughfall or to water addition targeted at maintaining soil water content above a minimum of 10 % v/v. Treatments were compared to control plots which received ambient precipitation. Enhanced soil moisture during summer months highly stimulated annual stem primary production, litter fall, SR and net annual plant-derived C input to soil which on average increased by 130 %, 26 %, 58 % and 220 %, respectively, as compared to the control. In contrast, the 20 % reduction in throughfall (equivalent to 10 % reduction in precipitation) did not significantly change soil moisture at the site, and therefore did not significantly affect ANPP or SR. We conclude that minor changes (around 10 % reduction) in precipitation amount are not likely to significantly affect ANPP or soil C dynamics in Mediterranean woodlands. However, if summer rain increases, C cycling will significantly accelerate but soil C stocks are not likely to be changed in the short-term. More studies involving modelling of long-term C dynamics are needed to predict if the estimated increases in soil C input under wet conditions is going to be sustained and if labile C is being substituted to stable C, with a negative effect on long-term soil C stocks.

  10. Decreased summer drought affects plant productivity and soil carbon dynamics in a Mediterranean woodland

    Directory of Open Access Journals (Sweden)

    M. F. Cotrufo

    2011-09-01

    Full Text Available Precipitation patterns are expected to change in the Mediterranean region within the next decades, with projected decreases in total rainfall and increases in extreme events. We manipulated precipitation patterns in a Mediterranean woodland, dominated by Arbutus unedo L., to study the effects of changing precipitation regimes on above-ground net primary production (ANPP and soil C dynamics, specifically plant-derived C input to soil and soil respiration (SR. Experimental plots were exposed to either a 20 % reduction of throughfall or to water addition targeted at maintaining soil water content above a minimum of 10 % v/v. Treatments were compared to control plots which received ambient precipitation. Enhanced soil moisture during summer months highly stimulated annual stem primary production, litter fall, SR and net annual plant-derived C input to soil which on average increased by 130 %, 26 %, 58 % and 220 %, respectively, as compared to the control. In contrast, the 20 % reduction in throughfall (equivalent to 10 % reduction in precipitation did not significantly change soil moisture at the site, and therefore did not significantly affect ANPP or SR. We conclude that minor changes (around 10 % reduction in precipitation amount are not likely to significantly affect ANPP or soil C dynamics in Mediterranean woodlands. However, if summer rain increases, C cycling will significantly accelerate but soil C stocks are not likely to be changed in the short-term. More studies involving modelling of long-term C dynamics are needed to predict if the estimated increases in soil C input under wet conditions is going to be sustained and if labile C is being substituted to stable C, with a negative effect on long-term soil C stocks.

  11. Decreased summer drought affects plant productivity and soil carbon dynamics in Mediterranean woodland

    Science.gov (United States)

    Cotrufo, M. F.; Alberti, G.; Inglima, I.; Marjanović, H.; Lecain, D.; Zaldei, A.; Peressotti, A.; Miglietta, F.

    2011-06-01

    Precipitation patterns are expected to change in the Mediterranean region within the next decades, with projected decreases in total rainfall and increases in extreme events. We manipulated precipitation patterns in a Mediterranean woodland, dominated by Arbutus unedo L., to study the effects of changing precipitation regimes on above-ground net primary production (ANPP) and soil C dynamics, specifically plant-derived C input to soil and soil respiration (SR). Experimental plots were exposed to either a 20 % reduction of throughfall or to water addition targeted at maintaining soil water content above a minimum of 10 % v/v. Treatments were compared to control plots which received ambient precipitation. The throughfall manipulation experiment started in 2004 and we report data up to the 2009 growing season. Enhanced soil moisture during summer months highly stimulated annual stem primary production, litter fall, SR and net annual plant-derived C input to soil which on average increased by 130 %, 26 %, 50 % and 220 %, respectively, as compared to control. In contrast, the 20 % reduction in throughfall (equivalent to 10 % reduction of precipitation) did not significantly change soil moisture at the site, and therefore did not significantly affect ANPP or SR. We conclude that minor changes (around 10 % reduction) in precipitation amount are not likely to significantly affect ANPP or soil C dynamics in Mediterranean woodland. However, if summer rain increases, C cycling will significantly accelerate but soil C stocks are not likely to be changed in the short-term. More studies involving modelling of long term C dynamics are needed to predict if the estimated increases in soil C input under wet conditions is going to be sustained and if labile C is being substituted to stable C, with a negative effect on long term soil C stocks.

  12. No carbon “bet hedging” in pine seedlings under prolonged summer drought and elevated CO2

    NARCIS (Netherlands)

    Bachofen, Christoph; Moser, Barbara; Hoch, Günter; Ghazoul, Jaboury; Wohlgemuth, Thomas

    2018-01-01

    © 2017 The Authors. Journal of Ecology © 2017 British Ecological Society More frequent drought episodes are expected to cause higher mortality in isohydric tree species such as pines, because individuals close their stomata early during drought in order to maintain constant needle water potentials.

  13. Water sources and controls on water-loss rates of epigeous ectomycorrhizal fungal sporocarps during summer drought

    Science.gov (United States)

    Erik A. Lilleskov; Thomas D. Bruns; Todd E. Dawson; Francisco J. Camacho

    2009-01-01

    Access to deeper soil water and water-conserving traits should reduce water stress for ectomycorrhizal fungi, permitting function during drought. Here, we explored whether epigeous fruiting of ectomycorrhizal fungi during drought was facilitated by access to deep soil water, how much water was lost from sporocarps, and how sporocarp surface to volume ratios affected...

  14. Responses of plant water use to a severe summer drought for two subtropical tree species in the central southern China

    Directory of Open Access Journals (Sweden)

    Zidong Luo

    2016-12-01

    New hydrological insights: The results show that a decrease in water use during the drought for both two species is closely associated with an increase in vapor pressure deficit and a decrease in stem water potential. The two species appear to be anisohydric, but to a different degree in response to the drought. The hydrodynamic water potential gradient (Δψ maintains relatively constant with an average value of 0.59 MPa for C. camphora, and 1.59 MPa for O. fragrans. O. fragrans is less sensitive to drought than C. camphora, while C. camphora shows an effective survival mechanism via leaf shedding and dieback of shoots.

  15. Coastal fog during summer drought improves the water status of sapling trees more than adult trees in a California pine forest.

    Science.gov (United States)

    Baguskas, Sara A; Still, Christopher J; Fischer, Douglas T; D'Antonio, Carla M; King, Jennifer Y

    2016-05-01

    Fog water inputs can offset seasonal drought in the Mediterranean climate of coastal California and may be critical to the persistence of many endemic plant species. The ability to predict plant species response to potential changes in the fog regime hinges on understanding the ways that fog can impact plant physiological function across life stages. Our study uses a direct metric of water status, namely plant water potential, to understand differential responses of adult versus sapling trees to seasonal drought and fog water inputs. We place these measurements within a water balance framework that incorporates the varying climatic and soil property impacts on water budgets and deficit. We conducted our study at a coastal and an inland site within the largest stand of the regionally endemic bishop pine (Pinus muricata D. Don) on Santa Cruz Island. Our results show conclusively that summer drought negatively affects the water status of sapling more than adult trees and that sapling trees are also more responsive to changes in shallow soil moisture inputs from fog water deposition. Moreover, between the beginning and end of a large, late-season fog drip event, water status increased more for saplings than for adults. Relative to non-foggy conditions, we found that fog water reduces modeled peak water deficit by 80 and 70 % at the inland and coastal sites, respectively. Results from our study inform mechanistically based predictions of how population dynamics of this and other coastal species may be affected by a warmer, drier, and potentially less foggy future.

  16. Effect of repeated spring drought and summer heavy rain on managed grassland biomass production and CO2 efflux

    Czech Academy of Sciences Publication Activity Database

    Dařenová, Eva; Holub, Petr; Krupková, Lenka; Pavelka, Marian

    2017-01-01

    Roč. 10, č. 3 (2017), s. 475-485 ISSN 1752-9921 R&D Projects: GA MŠk(CZ) LO1415 Institutional support: RVO:86652079 Keywords : above-ground biomass * Beskydy Mountains * rainfall manipulation * respiration * rainout shelters * root biomass Subject RIV: EF - Botanics OBOR OECD: Plant sciences, botany Impact factor: 1.754, year: 2016

  17. Enhanced UV-B radiation alleviates the adverse effects of summer drought in two Mediterranean pines under field conditions [ozone depletion

    International Nuclear Information System (INIS)

    Petropoulou, Y.; Kyparissis, A.; Nikolopoulos, D.; Manetas, Y.

    1995-01-01

    The effects of enhanced UV-B (290-320 nm) radiation on two native Mediterranean pines (Pinus pinea L., Pinus halepensis Mill.) were recorded during a one-year field study. Plants received ambient or ambient plus supplemental UV-B radiation (simulating a 15% stratospheric ozone depletion over Patras. Greece, 38.3°N. 29.1°E) and only natural precipitation, i.e. they were simultaneously exposed to other natural stresses. particularly water stress during summer. Supplemental UV-B irradiation started in early February, 1993 and up to late June, no effects were observed on growth and photochemical efficiency of photosystem II, as measured by chlorophy II fluorescence induction. Water stress during the summer was manifested in the control plants as a decline in the ratio of variable to maximum fluorescence (F v /F m ), the apparent photon yield for oxygen evolution (φ I ) and the photosynthetic capacity at 5% CO 2 (P m ). In addition, a partial needle loss was evident. Under supplemental UV-B radiation, however, the decreases in F v /F m , φ i , and P m . as well as needle losses were significantly less. Soon after the first heavy autumn rains. photosynthetic parameters in both control and UV-B treated plants recovered to similar values. but the transient summer superiority of UV-B irradiated plants resulted in a significant increase in their dry weight measured at plant harvest. during late January. 1994. Plant height. UV-B absorbing compounds, photosynthetic pigments and relative water content measured at late spring. late summer and at plant harvest, were not significantly affected by supplemental UV-B radiation. The results indicate that enhanced UV-B radiation may be beneficial for Mediterranean pines through a partial alleviation of the adverse effects of summer drought. (author)

  18. Close and distant: Contrasting the metabolism of two closely related subspecies of Scots pine under the effects of folivory and summer drought

    Energy Technology Data Exchange (ETDEWEB)

    Rivas-Ubach, Albert; Sardans, J.; Hodar, Jose A.; Garcia-Porta, Joan; Guenther, Alex B.; Pasa Tolic, Ljiljana; Oravec, Michal; Urban, Otmar; Penuelas, Josep

    2017-09-25

    The metabolome, the chemical phenotype of an organism, should be shaped by evolution. Metabolomes depend on genetic composition and expression, which can be sources of evolutionary inertia, so most aspects of metabolomes should be similar in closely related sympatric species. We examined the metabolomes of two sympatric subspecies of Pinus sylvestris in Sierra Nevada (southern Iberian Peninsula), one introduced (ssp. iberica) and one autochthonous (ssp. nevadensis), in summer and winter and exposed to folivory by the pine processionary moth. The overall metabolomes differed between the subspecies but both tended to respond more similarly to folivory. The metabolomes of the subspecies were more dissimilar in summer than in winter, and iberica trees had higher concentrations of metabolites directly related to drought stress. Our results suggest that certain plant metabolic responses associated with folivory have been conserved throughout evolutionary history. The larger divergence between subspecies metabolomes in summer is likely due to the warmer and drier conditions that the northern iberica subspecies experience in Sierra Nevada. Our results provide crucial insights into how iberica populations would respond to the predicted conditions of climate change under an increased defoliation, two recent severe issues in the Mediterranean Basin.

  19. Monoterpene emissions in response to long-term night-time warming, elevated CO2 and extended summer drought in a temperate heath ecosystem

    DEFF Research Database (Denmark)

    Tiiva, Päivi; Tang, Jing; Michelsen, Anders

    2017-01-01

    Monoterpenes emitted from plants have an important role in atmospheric chemistry through changing atmospheric oxidative capacity, forming new particles and secondary organic aerosols. The emission rates and patterns can be affected by changing climate. In this study, emission responses to six years...... of climatic manipulations (elevated CO2, extended summer drought and night-time warming) were investigated in a temperate semi-natural heath ecosystem. Samples for monoterpene analysis were collected in seven campaigns during an entire growing season (April-November, 2011). The results showed...... that the temperate heath ecosystem was a considerable source of monoterpenes to the atmosphere, with the emission averaged over the 8month measurement period of 21.7±6.8μgm(-2)groundareah(-1) for the untreated heath. Altogether, 16 monoterpenes were detected, of which the most abundant were α-pinene, δ-3-carene...

  20. Effects of elevated atmospheric CO2, prolonged summer drought and temperature increase on N2O and CH4 fluxes in a temperate heathland

    DEFF Research Database (Denmark)

    Carter, Mette Sustmann; Ambus, Per; Albert, Kristian Rost

    2011-01-01

    In temperate regions, climate change is predicted to increase annual mean temperature and intensify the duration and frequency of summer droughts, which together with elevated atmospheric carbon dioxide (CO2) concentrations, may affect the exchange of nitrous oxide (N2O) and methane (CH4) between...... terrestrial ecosystems and the atmosphere. We report results from the CLIMAITE experiment, where the effects of these three climate change parameters were investigated solely and in all combinations in a temperate heathland. Field measurements of N2O and CH4 fluxes took place 1–2 years after the climate...... change manipulations were initiated. The soil was generally a net sink for atmospheric CH4. Elevated temperature (T) increased the CH4 uptake by on average 10 μg C m−2 h−1, corresponding to a rise in the uptake rate of about 20%. However, during winter elevated CO2 (CO2) reduced the CH4 uptake, which...

  1. Diagnosing the Atmospheric/Oceanic Phenomena Associated with the Onset, Demise and Mid-Summer Drought of the Rainy Season in Mesoamerica

    Science.gov (United States)

    Groenen, D.; Bourassa, M. A.

    2017-12-01

    The rainfall in Mesoamerica (Mexico and Central America) has influences from two bodies of water, interesting topography, and complex wind patterns, which complicates weather forecasting. Knowing the approximate onset and demise of the rainy season is critical for the optimal growth and development of key crops in this region such as coffee, bananas, rice, and maize. This study compares three methods to calculate the onset/demise dates of the individual years' rainy season, using area-averaged rainfall data (7-28 °N/77-109 °W) from two datasets. After these onset/demise dates are obtained using rainfall data, the atmospheric and oceanic phenomena associated with the timing is analyzed using MERRA-2 reanalysis data. The objective is to link the large-scale phenomena to the individual years' onset/demise dates, as well as link the weather phenomena to the interannual variability of the onset/demise dates. In addition, the broad scale rainy season will be connected with regional onset/demise dates on the scale of 400km. Linking the broad scale rainfall regimes to the regional regimes will allow a more cohesive view of the dynamics related to rainfall variability in the Mesoamerican region. A smoothing method will be used to analyze the timing and intensity of the mid-summer drought (MSD), a minimum in rainfall typically occurring during July and August. The goal of this research is to link the physical and dynamical mechanisms that cause the Mesoamerican rainy season and mid-summer drought (MSD) in order to better understand the predictability of Mesoamerican rainfall and ensure the health and safety of key crops.

  2. Using intra annual density fluctuations and d13C to assess the impact of summer drought on Mediterranean ecosystem

    Science.gov (United States)

    Battipaglia, G.; Brand, W. A.; Linke, P.; Schaefer, I.; Noetzli, M.; Cherubini, P.

    2009-04-01

    Tree- ring growth and wood density have been used extensively as indicators of climate change, and tree-ring has been commonly applied as a proxy estimate for seasonal integration of temperatures and precipitation with annual resolution (Hughes 2002). While these relationships have been well established in temperate ecosystems (Fritts, 1976; Schweingruber, 1988, Briffa et al., 1998, 2004), in Mediterranean region dendrochronological studies are still scarce (Cherubini et al, 2003). In Mediterranean environment, trees may form intra-annual density fluctuations, also called "false rings" or "double rings" (Tingley 1937; Schulman 1938). They are usually induced by sudden drought events, occurring during the vegetative period, and, allowing intra-annual resolution, they may provide detailed information at a seasonal level, as well as species-specific sensitivity to drought. We investigated the variability of tree- ring width and carbon stable isotopes of a Mediterranean species, Arbutus unedo L., sampled on Elba island, (Tuscany, Italy). The samples were taken at two different sites, one characterized by wet and one by dry conditions. d13C was measured using Laser- Ablation- Combustion -GC-IRMS. Here, we present first results showing the impact of drought on tree growth and on false ring formation at the different sites and we underline the importance of using Laser Ablation to infer drought impact at the intra -annual level. Briffa KR, Schweingruber FH, Jones PD, Osborn TJ, Harris IC, Shiyatov SG, Vaganov EA, Grudd H (1998) Trees tell of past climates: but are they speaking less clearly today? Phil Transact Royal Soc London 353:65-73 Briffa KR, Osborn TJ, Schweingruber FH (2004) Large-scale temperature inferences from tree rings: a review. Glob Panet Change 40:11-26 Cherubini, P., B.L. Gartner, R. Tognetti, O.U. Bräker, W. Schoch & J.L. Innes. 2003. Identification, measurement and interpretation of tree rings in woody species from Mediterranean climates. Biol. Rev

  3. Soil respiration is stimulated by elevated CO2 and reduced by summer drought: three years of measurements in a multifactor ecosystem manipulation experiment in a temperate heathland (CLIMAITE)

    DEFF Research Database (Denmark)

    Selsted, Merete Bang; van der Linden, Leon; Ibrom, Andreas

    2012-01-01

    This study investigated the impact of predicted future climatic and atmospheric conditions on soil respiration (RS) in a Danish Calluna‐Deschampsia‐heathland. A fully factorial in situ experiment with treatments of elevated atmospheric CO2 (+130 ppm), raised soil temperature (+0.4 °C) and extended...... summer drought (5–8% precipitation exclusion) was established in 2005. The average RS, observed in the control over 3 years of measurements (1.7 μmol CO2 m−2 sec−1), increased 38% under elevated CO2, irrespective of combination with the drought or temperature treatments. In contrast, extended summer...... due to reduced plant growth or changes in soil water holding capacity. An empirical model that predicts RS from soil temperature, soil moisture and plant biomass was developed and accounted for 55% of the observed variability in RS. The model predicted annual sums of RS in 2006 and 2007...

  4. Sap flux density and stomatal conductance of European beech and common oak trees in pure and mixed stands during the summer drought of 2003

    Science.gov (United States)

    Jonard, F.; André, F.; Ponette, Q.; Vincke, C.; Jonard, M.

    2011-10-01

    SummarySap flux density of European beech and common oak trees was determined from sap flow measurements in pure and mixed stands during the summer drought of 2003. Eight trees per species and per stand were equipped with sap flow sensors. Soil water content was monitored in each stand at different depths by using time-domain reflectometry (TDR). Leaf area index and vertical root distribution were also investigated during the growing season. From sap flux density ( SFD) data, mean stomatal conductance of individual trees ( G s) was calculated by inverting the Penman-Monteith equation. Linear mixed models were developed to analyse the effects of species and stand type (pure vs. mixed) on SFD and G s and on their sensitivity to environmental variables (vapour pressure deficit ( D), incoming solar radiation ( R G), and relative extractable water ( REW)). For reference environmental conditions, we did not find any tree species or stand type effects on SFD. The sensitivity of SFD to D was higher for oak than for beech in the pure stands ( P sapwood-to-leaf area ratio compared to oak. The sensitivity of G s to REW was higher for beech than for oak and was ascribed to a higher vulnerability of beech to air embolism and to a more sensitive stomatal regulation. The sensitivity of beech G s to REW was lower in the mixed than in the pure stand, which could be explained by a better sharing of the resources in the mixture, by facilitation processes (hydraulic lift), and by a rainfall partitioning in favour of beech.

  5. The Effect of Heat Waves and Drought on Surface Wind Circulations in the Northeast of the Iberian Peninsula during the Summer of 2003

    NARCIS (Netherlands)

    Jiménez, P.A.; Vilà-Guerau de Arellano, J.; González-Rouco, J.F.; Navarro, J.; Montávez, J.P.; García-Bustamante, E.; Dudhia, J.

    2011-01-01

    Variations in the diurnal wind pattern associated with heat waves and drought conditions are investigated climatologically at a regional level (northeast of the Iberian Peninsula). The study, based on high-density observational evidence and fine spatial-scale mesoscale modeling for the 1992–2004

  6. The response of dissolved organic carbon (DOC) and the ecosystem carbon balance to experimental drought in a temperate shrubland

    DEFF Research Database (Denmark)

    Sowerby, A.; Emmett, B.A.; Williams, D.

    2010-01-01

    in northeast Wales, we have carried out an annual drought treatment for 8 years, reducing levels of annual rainfall by 23% on average (1999–2007) through the use of automated roofs, which prevent rain falling on experimental plots between June and September annually. Following 5 years of repeated summer...... drainage of water from the drought-treated soils resulted in an overall decrease of 9% in total DOC export. Calculating the carbon (C) balance for the below-ground component of the ecosystem reveals that DOC represents 3% of gross C export. Previous studies at the site have demonstrated large increases...... in soil respiration resulting from the repeated drought treatment. By including data presented here with other C fluxes and pool measurements from the site, we demonstrate that soil carbon is accumulating by 126 g C m−2 year−1 in the control plots, but decreasing by 18 g C m2 year−1 in the drought plots...

  7. Close and distant: Contrasting the metabolism of two closely related subspecies of Scots pine under the effects of folivory and summer drought

    Czech Academy of Sciences Publication Activity Database

    Rivas-Ubach, A.; Sardans, J.; Hódar, J. A.; Garcia-Porta, J.; Guenther, A.; Paša-Tolic, L.; Oravec, Michal; Urban, Otmar; Peňuelas, J.

    2017-01-01

    Roč. 7, č. 21 (2017), s. 8976-8988 ISSN 2045-7758 R&D Projects: GA MŠk(CZ) LO1415; GA MŠk EE2.3.20.0246; GA MŠk(CZ) LM2015061 Grant - others:Akademie věd České Republiky(CZ) M200871201 Institutional support: RVO:67179843 Keywords : drought * evolutionary processes * folivory * herbivorous attack * metabolomics * Pinus sylvestris * processionary moth * sympatric subspecies Subject RIV: EH - Ecology, Behaviour OBOR OECD: Environmental sciences (social aspects to be 5.7) Impact factor: 2.440, year: 2016

  8. Drought Risk Identification: Early Warning System of Seasonal Agrometeorological Drought

    Science.gov (United States)

    Dalecios, Nicolas; Spyropoulos, Nicos V.; Tarquis, Ana M.

    2014-05-01

    By considering drought as a hazard, drought types are classified into three categories, namely meteorological or climatological, agrometeorological or agricultural and hydrological drought and as a fourth class the socioeconomic impacts can be considered. This paper addresses agrometeorological drought affecting agriculture within the risk management framework. Risk management consists of risk assessment, as well as a feedback on the adopted risk reduction measures. And risk assessment comprises three distinct steps, namely risk identification, risk estimation and risk evaluation. This paper deals with the quantification and monitoring of agrometeorological drought, which constitute part of risk identification. For the quantitative assessment of agrometeorological or agricultural drought, as well as the computation of spatiotemporal features, one of the most reliable and widely used indices is applied, namely the Vegetation Health Index (VHI). The computation of VHI is based on satellite data of temperature and the Normalized Difference Vegetation Index (NDVI). The spatiotemporal features of drought, which are extracted from VHI are: areal extent, onset and end time, duration and severity. In this paper, a 20-year (1981-2001) time series of NOAA/AVHRR satellite data is used, where monthly images of VHI are extracted. Application is implemented in Thessaly, which is the major agricultural region of Greece characterized by vulnerable and drought-prone agriculture. The results show that every year there is a seasonal agrometeorological drought with a gradual increase in the areal extent and severity with peaks appearing usually during the summer. Drought monitoring is conducted by monthly remotely sensed VHI images. Drought early warning is developed using empirical relationships of severity and areal extent. In particular, two second-order polynomials are fitted, one for low and the other for high severity drought, respectively. The two fitted curves offer a seasonal

  9. Drought occurence

    Science.gov (United States)

    John W. Coulston

    2007-01-01

    Why Is Drought Important? Drought is an important forest disturbance that occurs regularly in the Western United States and irregularly in the Eastern United States (Dale and others 2001). Moderate drought stress tends to slow plant growth while severedrought stress can also reduce photosynthesis (Kareiva and others 1993). Drought can also interact with...

  10. Spatial patterns of drought persistence in East China

    Science.gov (United States)

    Meng, L.; Ford, T.

    2017-12-01

    East China has experienced a number of severe droughts in recent decades. Understanding the characteristics of droughts and their persistence will provide operational guidelines for water resource management and agricultural production. This study uses a logistic regression model to measure the probability of drought occurrence in the current season given the previous season's Standardized Precipitation Index (SPI) and Southern Oscillation Index (SOI) as well as drought persistence. Results reveal large spatial and seasonal variations in the relationship between the previous season's SPI and the drought occurrence probability in a given season. The drought persistence averaged over the entire study area for all the four seasons is approximately 34% with large variations from season to season and from region to region. The East and Northeast regions have the largest summer drought persistence ( 40%) and lowest fall drought persistence ( 28%). The spatial pattern in winter and spring drought persistence is dissimilar with stronger winter and weaker spring drought persistence in the Southwest and Northeast relative to other regions. Logistic regression analysis indicates a stronger negative relationship in summer-to-fall (or between fall drought occurrence and summer SPI) than other inter-season relationships. This study demonstrates that the impact of previous season SPI and SOI on current season drought varies substantially from region to region and from season to season. This study also shows stronger drought persistence in summer than in other seasons. In other words, the probability of fall drought occurrence is closely related to summer moisture conditions in the East China.

  11. Root growth and N dynamics in response to multi-year experimental warming, summer drought and elevated CO2 in a mixed heathland-grass ecosystem

    DEFF Research Database (Denmark)

    Arndal, M. F.; Schmidt, I. K.; Kongstad, J.

    2013-01-01

    growth would be matched by an increase in root nutrient uptake of NH4+-N and NO3- -N. Root growth was significantly increased by elevated CO2. The roots, however, did not fully compensate for the higher growth with a similar increase in nitrogen uptake per unit of root mass. Hence the nitrogen...... concentration in roots was decreased in elevated CO2, whereas the biomass N pool was unchanged or even increased. The higher net root production in elevated CO2 might be a strategy for the plants to cope with increased nutrient demand leading to a long-term increase in N uptake on a whole-plant basis. Drought...... reduced grass root biomass and N uptake, especially when combined with warming, but CO2 was the most pronounced main factor effect. Several significant interactions of the treatments were found, which indicates that the responses were nonadditive and that changes to multiple environmental changes cannot...

  12. Drought Tip: Irrigating Citrus with Limited Water

    OpenAIRE

    Faber, Ben

    2015-01-01

    As an evergreen in California's Mediterranean climate, with wet winters and dry summers, citrus requires some water all year long. Depending on the cultivar and rootstock, citrus can sustain certain levels of drought stress.

  13. Exceptional Drought and Unconventional Energy Production

    Directory of Open Access Journals (Sweden)

    Reid B. Stevens

    2018-04-01

    Full Text Available The hydraulic fracturing boom in Texas required massive water flows. Beginning in the summer of 2011, water became scarce as a prolonged heat wave and subsequent severe drought spread across the state. Oil and gas producers working in drought areas needed to purchase expensive local water or transport water from a non-drought county far from the drill site. In response to decreased water availability in drought areas, these producers completed fewer wells and completed wells that used less water. This decrease in well-level water use had a measurable effect on the amount of oil and gas produced by wells completed during exceptional conditions.

  14. The impact of the 2003 summer drought on the intra-annual growth pattern of beech (Fagus sylvatica l.) and oak (Quercus robur L.) on a dry site in the Netherlands

    NARCIS (Netherlands)

    Werf, van der G.W.; Sass-Klaassen, U.; Mohren, G.M.J.

    2007-01-01

    Climate change is expected to result in more extreme weather conditions over large parts of Europe, such as the prolonged drought of 2003. As water supply is critical for tree growth on many sites in North-Western Europe, such droughts will affect growth, species competition, and forest dynamics. To

  15. The 2010 spring drought reduced primary productivity in southwestern China

    International Nuclear Information System (INIS)

    Zhang Li; Li Jing; Xiao Jingfeng; Wang Kun; Lei Liping; Guo Huadong

    2012-01-01

    Many parts of the world experience frequent and severe droughts. Summer drought can significantly reduce primary productivity and carbon sequestration capacity. The impacts of spring droughts, however, have received much less attention. A severe and sustained spring drought occurred in southwestern China in 2010. Here we examine the influence of this spring drought on the primary productivity of terrestrial ecosystems using data on climate, vegetation greenness and productivity. We first assess the spatial extent, duration and severity of the drought using precipitation data and the Palmer drought severity index. We then examine the impacts of the drought on terrestrial ecosystems using satellite data for the period 2000–2010. Our results show that the spring drought substantially reduced the enhanced vegetation index (EVI) and gross primary productivity (GPP) during spring 2010 (March–May). Both EVI and GPP also substantially declined in the summer and did not fully recover from the drought stress until August. The drought reduced regional annual GPP and net primary productivity (NPP) in 2010 by 65 and 46 Tg C yr −1 , respectively. Both annual GPP and NPP in 2010 were the lowest over the period 2000–2010. The negative effects of the drought on annual primary productivity were partly offset by the remarkably high productivity in August and September caused by the exceptionally wet conditions in late summer and early fall and the farming practices adopted to mitigate drought effects. Our results show that, like summer droughts, spring droughts can also have significant impacts on vegetation productivity and terrestrial carbon cycling. (letter)

  16. 2003 hydrological drought - natural disaster

    International Nuclear Information System (INIS)

    Trninic, Dusan; Bosnjak, Tomislava

    2004-01-01

    An exceptionally dry and warm period from February to early October 2003 resulted in hydrological drought with attributes of a natural disaster in most of the Croatian regions. The paper presents hydrological analysis of the Sava River near Zupanja for the period 1945-2003 (N=59 years). In defining maximum annual volumes of isolated waves below the reference discharges, the following reference discharges were used:Q 30,95% = 202m 3 s -1 - minimum mean 30-day discharge, 95 % probability, Q 30,80% = 254m 3 s -1 - minimum mean 30-day discharge, 80 % probability, Q 95% = 297m 3 s -1 - (H = -17cm minimum navigation level = 95 % of water level duration from average duration curve). The analysis results have shown that the hydrological drought recorded during the current year belongs to the most thoroughly studied droughts in 59 years. For example, hydrological analysis of the reference discharge of 297m 3 s -1 has shown that this year drought comes second, immediately after the driest year 1946. However, this year hydrological drought hit the record duration of 103 days, unlike the one from 1946, which lasted 98 days. It is interesting that the hydrological droughts affect the Sava River usually in autumn and summer, rarely in winter, and it has never been recorded in spring (referring to the analysed 1945-2003 period). In conclusion, some recommendations are given for increase in low streamflows and on possible impacts of climate changes on these flows.(Author)

  17. Did a skillful prediction of sea surface temperatures help or hinder forecasting of the 2012 Midwestern US drought?

    International Nuclear Information System (INIS)

    Kam, Jonghun; Sheffield, Justin; Yuan, Xing; Wood, Eric F

    2014-01-01

    The latest drought to hit the Midwestern (MW) US region, in 2012, was driven by the least summer precipitation for the last three decades with $20 billion in agriculture losses. For 2012, the summer forecast skill for Pacific and Atlantic sea surface temperature (SST) anomalies and low MW precipitation is remarkably good for some National Multi-Model Ensemble (NMME) models, but this is not generally repeated for other drought years, with some models predicting extreme wet anomalies, despite skill in predicting Pacific and Atlantic SST anomalies. In order to diagnose the origins of the limited skill of the NMME models, we use singular value decomposition (SVD) for global SSTs and continental US (CONUS) precipitation from observational data and NMME hindcasts (1982–2012). Observational data indicate that there is an insignificant coupling between global SSTs and MW precipitation during summer over the last 30 years. However, the NMME climate forecast models show strong coupling and therefore predicted the 2012 drought fortuitously for the wrong reason (a strong pan-Pacific El Niño–Southern Oscillation (ENSO)-like pattern). The observational data indicate that the strength of ENSO teleconnections with CONUS precipitation has weakened and the precipitation footprint has shifted over the past decades, suggesting that the transient nature of teleconnections may play a role in poor model skill. (paper)

  18. EFFECT OF DROUGHT ON STRESS IN PLANTS

    Directory of Open Access Journals (Sweden)

    Jelena Marković

    2015-07-01

    Full Text Available Drought occurs due to lack of water in the soil, as well as due to disturbances in the circulation of the atmosphere. The duration of the drought may be different, and droughts not only the lack of rainfall, but also erratic distribution of rainfall throughout the year. The intensity of droughts amplified high temperatures, low relative humidity and dry, hot winds. The drought in many areas of common occurrence that repeats without a discernible regularity. Although it can be found in almost all parts of the world, its characteristics vary from region to region. Defining drought is therefore difficult and depends on regional differences and needs, but also from the perspective from which to observe this phenomenon. In the broadest sense, the drought is due to the lack of precipitation over an extended period of time, leading to water shortages for some activities, group activities or an entire sector of the environment. Drought can not be viewed solely as a physical phenomenon. The occurrence of drought, because of the weather, a lot of influences and reflects on the plants and agricultural production.

  19. Synergy of a warm spring and dry summer

    Science.gov (United States)

    Yude Pan; David. Schimel

    2016-01-01

    An analysis suggests that high carbon uptake by US land ecosystems during the warm spring of 2012 offset the carbon loss that resulted from severe drought over the summer — and hints that the warm spring could have worsened the drought.

  20. Summer Appendicitis

    African Journals Online (AJOL)

    hanumantp

    The increasing number of “fast food” restaurants where mainly high‑carbohydrate ... factors, food culture and the effect of migration for touristic purposes during the summer. .... Lal A, Hales S, French N, Baker MG. Seasonality in human.

  1. Legacies from extreme drought increase ecosystem sensitivity to future extremes

    Science.gov (United States)

    Smith, M. D.; Knapp, A.; Hoover, D. L.; Avolio, M. L.; Felton, A. J.; Wilcox, K. R.

    2016-12-01

    Climate extremes, such as drought, are increasing in frequency and intensity, and the ecological consequences of these extreme events can be substantial and widespread. Although there is still much to be learned about how ecosystems will respond to an intensification of drought, even less is known about the factors that determine post-drought recovery of ecosystem function. Such knowledge is particularly important because post-drought recovery periods can be protracted depending on the extent to which key plant populations, community structure and biogeochemical processes are affected. These drought legacies may alter ecosystem function for many years post-drought and may impact future sensitivity to climate extremes. We experimentally imposed two extreme growing season droughts in a central US grassland to assess the impacts of repeated droughts on ecosystem resistance (response) and resilience (recovery). We found that this grassland was not resistant to the first extreme drought due to reduced productivity and differential sensitivity of the co-dominant C4 grass (Andropogon gerardii) and C3 forb (Solidago canadensis) species. This differential sensitivity led to a reordering of species abundances within the plant community. Yet, despite this large shift in plant community composition, which persisted post-drought, the grassland was highly resilient post-drought, due to increased abundance of the dominant C4 grass. Because of this shift to increased C4 grass dominance, we expected that previously-droughted grassland would be more resistant to a second extreme drought. However, contrary to these expectations, previously droughted grassland was more sensitive to drought than grassland that had not experienced drought. Thus, our result suggest that legacies of drought (shift in community composition) may increase ecosystem sensitivity to future extreme events.

  2. Drought and coastal ecosystems: an assessment of decision maker needs for information

    Science.gov (United States)

    Kirsten Lackstrom; Amanda Brennan; Kirstin Dow

    2016-01-01

    The National Integrated Drought Information System (NIDIS) is in the process of developing drought early warning systems in areas of the U.S. where the development and coordination of drought information is needed. In summer 2012, NIDIS launched a pilot program in North and South Carolina, addressing the uniqueness of drought impacts on coastal ecosystems.

  3. Temporal and Spatial Variability of Droughts in Southwest China from 1961 to 2012

    Directory of Open Access Journals (Sweden)

    Yaohuan Huang

    2015-10-01

    Full Text Available Southwest China (SC has suffered a series of super extreme droughts in the last decade. This study analyzed the temporal and spatial variations of drought in SC from 1961 to 2012. Based on precipitation anomaly index (PAI that was derived from 1 km gridded precipitation data, three time scales (month, year and decade for the drought frequency (DF and drought area were applied to estimate the spatio-temporal structure of droughts. A time-series analysis showed that winter droughts and spring droughts occurred frequently for almost half of the year from November to March. Summer droughts occasionally occurred in severe drought decades: the 1960s, 1980s and 2000s. During the period of observation, the percent of drought area in SC increased from the 1960s (<5% to the 2000s (>25%. A total of 57% of the area was affected by drought in 2011, when the area experienced its most severe drought both in terms of area and severity. The spatial analysis, which benefitted from the gridded data, detailed that all of SC is at drought risk except for the central Sichuan Basin. The area at high risk for severe and extreme droughts was localized in the mountains of the junction of Sichuan and Yunnan. The temporal and spatial variability can be prerequisites for drought resistance planning and drought risk management of SC.

  4. Drought priming effects on alleviating later damages of heat and drought stress in different wheat cultivars

    DEFF Research Database (Denmark)

    Mendanha, Thayna; Hyldgaard, Benita; Ottosen, Carl-Otto

    The ongoing change is climate; in particular the increase of drought and heat waves episodes are a major challenge in the prospect of food safety. Under many field conditions, plants are usually exposed to mild intermittent stress episodes rather than a terminal stress event. Previous, but limited...... studies suggest that plants subjected to early stress (primed) can be more resistant to future stress exposure than those not stressed during seedling stage. In our experiment we aimed to test if repeated mild drought stresses could improve heat and drought tolerance during anthesis heat and drought...... stresses in wheat cultivars. Two wheat cultivars, Gladius and Paragon, were grown in a fully controlled gravimetric platform and subjected to either no stress (control) or two (P) drought cycles during seedling stage, at three and five complete developed leaves. Each cycle consisted of withholding water...

  5. a Probability Model for Drought Prediction Using Fusion of Markov Chain and SAX Methods

    Science.gov (United States)

    Jouybari-Moghaddam, Y.; Saradjian, M. R.; Forati, A. M.

    2017-09-01

    Drought is one of the most powerful natural disasters which are affected on different aspects of the environment. Most of the time this phenomenon is immense in the arid and semi-arid area. Monitoring and prediction the severity of the drought can be useful in the management of the natural disaster caused by drought. Many indices were used in predicting droughts such as SPI, VCI, and TVX. In this paper, based on three data sets (rainfall, NDVI, and land surface temperature) which are acquired from MODIS satellite imagery, time series of SPI, VCI, and TVX in time limited between winters 2000 to summer 2015 for the east region of Isfahan province were created. Using these indices and fusion of symbolic aggregation approximation and hidden Markov chain drought was predicted for fall 2015. For this purpose, at first, each time series was transformed into the set of quality data based on the state of drought (5 group) by using SAX algorithm then the probability matrix for the future state was created by using Markov hidden chain. The fall drought severity was predicted by fusion the probability matrix and state of drought severity in summer 2015. The prediction based on the likelihood for each state of drought includes severe drought, middle drought, normal drought, severe wet and middle wet. The analysis and experimental result from proposed algorithm show that the product of this algorithm is acceptable and the proposed algorithm is appropriate and efficient for predicting drought using remote sensor data.

  6. The current California drought through EDDI's eyes: early warning and monitoring of agricultural and hydrologic drought with the new Evaporative Demand Drought Index.

    Science.gov (United States)

    Hobbins, M.; McEvoy, D.; Huntington, J. L.; Wood, A. W.; Morton, C.; Verdin, J. P.

    2015-12-01

    hydrologic droughts, with correlations to water-year streamflow that are highest at the 9- to 12-month aggregation periods, and during the summer. EDDI shows significant promise as a leading indicator of drought, thereby providing a valuable planning window for growers and water resource managers.

  7. Bacterial mediated amelioration of drought stress in drought tolerant ...

    African Journals Online (AJOL)

    Bacterial mediated amelioration of drought stress in drought tolerant and susceptible cultivars of rice ( Oryza sativa L.) ... and IR-64 (drought sensitive) cultivars of rice (Oryza sativa L.) under different level of drought stress. ... from 32 Countries:.

  8. Climatological aspects of drought in Ohio

    International Nuclear Information System (INIS)

    Rogers, J.C.

    1993-01-01

    Precipitation and Palmer hydrological drought index (PHDI) data have been used to identify past occurrences of Ohio drought, to illustrate the temporal variability occurring statewide within dry periods, and to compare some of the key dry spells to those of 1987-88 and 1991-92. Periods of hydrologic drought and low precipitation generally persist for 2 to 5 years and tend to cluster in time, such as occurred from 1930-1966. It is not uncommon for precipitation to return to normal or near normal conditions while short-term drought persists in terms of streamflow, ground water supply, and runoff, as measured by the PHDI. The period April 1930 to March 1931 is the driest on record in Ohio although longer periods of low precipitation have occurred from 1893-1896, 1952-1955, and 1963-1965. The temporal clusters of droughts are separated by prolonged wet periods, including those extending roughly from 1875-1893, 1905-1924, and 1966-1987. Correlations between Ohio monthly precipitation and mean air temperature suggest that drought is linked to unusually high summer temperatures through mechanisms such as increased evapotranspiration, leading to increased fluxes of sensible heat from dry soil surfaces. In winter, warm conditions tend to favor higher precipitation, soil recharge, and runoff. Variations in mean temperature and atmospheric circulation may also be linked to other observed climatic features such as long-term trends in soil-water recharge season (October-March) precipitation

  9. Regional signatures of plant response to drought and elevated temperature across a desert ecosystem

    Science.gov (United States)

    Munson, Seth M.; Muldavin, Esteban H.; Belnap, Jayne; Peters, Debra P.C.; Anderson, John P.; Reiser, M. Hildegard; Gallo, Kirsten; Melgoza-Castillo, Alicia; Herrick, Jeffrey E.; Christiansen, Tim A.

    2013-01-01

    The performance of many desert plant species in North America may decline with the warmer and drier conditions predicted by climate change models, thereby accelerating land degradation and reducing ecosystem productivity. We paired repeat measurements of plant canopy cover with climate at multiple sites across the Chihuahuan Desert over the last century to determine which plant species and functional types may be the most sensitive to climate change. We found that the dominant perennial grass, Bouteloua eriopoda, and species richness had nonlinear responses to summer precipitation, decreasing more in dry summers than increasing with wet summers. Dominant shrub species responded differently to the seasonality of precipitation and drought, but winter precipitation best explained changes in the cover of woody vegetation in upland grasslands and may contribute to woody-plant encroachment that is widespread throughout the southwestern United States and northern Mexico. Temperature explained additional variability of changes in cover of dominant and subdominant plant species. Using a novel empirically based approach we identified ‘‘climate pivot points’’ that were indicative of shifts from increasing to decreasing plant cover over a range of climatic conditions. Reductions in cover of annual and several perennial plant species, in addition to declines in species richness below the long-term summer precipitation mean across plant communities, indicate a decrease in the productivity for all but the most drought-tolerant perennial grasses and shrubs in the Chihuahuan Desert. Overall, our regional synthesis of long-term data provides a robust foundation for forecasting future shifts in the composition and structure of plant assemblages in the largest North American warm desert.

  10. Drought assessment by evapotranspiration mapping in Twente

    Science.gov (United States)

    Eden, U.; Timmermans, J.; van der Velde, R.; Su, Z.

    2012-04-01

    Drought is a reoccurring worldwide problem with impacts ranging from food production to infrastructure. Droughts are different from other natural hazards (floods, hurricanes, and earthquakes) because the effects can only be witnessed slowly and with a time delay. Effects of droughts are diverse, like famine and migration of people. Droughts are caused by natural causes but also by interaction between the natural events and water demand. Not only typical dry regions, like the Horn of Africa, are affected, but even semi-humid environments, like Europe. Temperature rise and precipitation deficit in the summers of 2003 and 2006 caused substantial crop losses in the agricultural sector in the Netherlands. In addition increased river water temperatures and low water levels caused cooling problems for power plants. Heat waves and prolonged absence of precipitation is expected to increase due to climate change. Therefore assessing and monitoring drought in the Netherlands is thus very important. Various drought indices are available to assess the severity, duration and spatial extend of the drought. Some of the commonly indices used are Standardized precipitation index (SPI) and the Palmer Drought Severity Index (PDSI). However each of these indices do not take into account the actual state of the land surface in respect to the dryness. By analysing drought through actual evapotranspiration (ET) estimations from remote sensing this can be circumvented. The severity of the droughts was quantified by ET-mapping from 2003-2010. The assessment was based on the spatial and temporal distribution of ET using the Evapotranspiration Deficit Index (ETDI) drought index. Surface energy fluxes, like ET, were estimated using WACMOS methodology. The input data consisted of remote sensing products like land surface temperature, LAI, and albedo from MODIS; and meteorological data like air-temperature, humidity and wind speed from the European Centre for Medium weather forecast (ECMWF

  11. The Drought Monitor.

    Science.gov (United States)

    Svoboda, Mark; Lecomte, Doug; Hayes, Mike; Heim, Richard; Gleason, Karin; Angel, Jim; Rippey, Brad; Tinker, Rich; Palecki, Mike; Stooksbury, David; Miskus, David; Stephens, Scott

    2002-08-01

    information about drought and to receive regional and local input that is in turn incorporated into the product. This paper describes the Drought Monitor and the interactive process through which it is created.

  12. Hydrological Drought in the Anthropocene: Impacts of Local Water Extraction and Reservoir Regulation in the U.S.: Hydrological Drought in the Anthropocene

    Energy Technology Data Exchange (ETDEWEB)

    Wan, Wenhua [State Key Laboratory of Hydro-science and Engineering, Department of Hydraulic Engineering, Tsinghua University, Beijing China; Pacific Northwest National Laboratory, Richland WA USA; Zhao, Jianshi [State Key Laboratory of Hydro-science and Engineering, Department of Hydraulic Engineering, Tsinghua University, Beijing China; Li, Hong-Yi [Pacific Northwest National Laboratory, Richland WA USA; Now at Department of Land Resources and Environmental Sciences and Institute on Ecosystems, Montana State University, Bozeman MT USA; Mishra, Ashok [Glenn Department of Civil Engineering, Clemson University, Clemson SC USA; Ruby Leung, L. [Pacific Northwest National Laboratory, Richland WA USA; Hejazi, Mohamad [Pacific Northwest National Laboratory, Richland WA USA; Wang, Wei [The Ministry of Education Key Laboratory for Earth System Modeling, and Center for Earth System Science, Tsinghua University, Beijing China; Lu, Hui [The Ministry of Education Key Laboratory for Earth System Modeling, and Center for Earth System Science, Tsinghua University, Beijing China; Deng, Zhiqun [Pacific Northwest National Laboratory, Richland WA USA; Demissisie, Yonas [Department of Civil and Environmental Engineering, Washington State University, Pullman WA USA; Wang, Hao [State Key Laboratory of Hydro-science and Engineering, Department of Hydraulic Engineering, Tsinghua University, Beijing China; State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Hydropower and Water Resources, Beijing China

    2017-11-03

    Hydrological drought is a substantial negative deviation from normal hydrologic conditions and is influenced by climate and human activities such as water management. By perturbing the streamflow regime, climate change and water management may significantly alter drought characteristics in the future. Here we utilize a high-resolution integrated modeling framework that represents water management in terms of both local surface water extraction and reservoir regulation, and use the Standardized Streamflow Index (SSI) to quantify hydrological drought. We explore the impacts of water management on hydrological drought over the contiguous US in a warming climate with and without emissions mitigation. Despite the uncertainty of climate change impacts, local surface water extraction consistently intensifies drought that dominates at the regional to national scale. However, reservoir regulation alleviates drought by enhancing summer flow downstream of reservoirs. The relative dominance of drought intensification or relief is largely determined by the water demand, with drought intensification dominating in regions with intense water demand such as the Great Plains and California, while drought relief dominates in regions with low water demand. At the national level, water management increases the spatial extent of extreme drought despite some alleviations of moderate to severe drought. In an emissions mitigation scenario with increased irrigation demand for bioenergy production, water management intensifies drought more than the business-as-usual scenario at the national level, so the impacts of emissions mitigation must be evaluated by considering its benefit in reducing warming and evapotranspiration against its effects on increasing water demand and intensifying drought.

  13. Summer Students

    CERN Multimedia

    2005-01-01

    SUMMER STUDENT LECTURE PROGRAMME Main Auditorium, bldg. 500 DATE TIME LECTURER TITLE Wednesday 6 July 09:15 - 10:00 F. CERUTTI (CERN) Presentation of the Summer Student Programme D. Heagerty (CERN) Computer rules O. ULLALAND (CERN) Workshops presentation 10:15 - 11:00 D. SCHLATTER (CERN) Introduction to CERN 11:15 Film on CERN Thursday 7 July 09:15 - 11:00 L. Di Lella (CERN) Introduction to Particle Physics (1-2/4) 11:15 - 12:00 P. Chomaz (GANIL / CERN) Introduction to Nuclear Physics (1/3) 12:00 Discussion Session 14:00 - 14:45 M. Lindroos (CERN) ISOLDE Facility 15:00 M. Lindroos (CERN) ISOLDE Visit Friday 8 July 09:15 - 10:00 L. Di Lella (CERN) Introduction to Particle Physics (3/4) 10:15 - 11:00 P. Chomaz (GANIL / CERN) Introduction to Nuclear Physics (2/3) 11:15 - 12:00 G. ROLANDI (CERN) How an experiment is designed (1/2) 12:00 Discussion Session Monday 11 July 09:15 - 10:00 L. Di Lella (CERN) Introduction to Particle Physi...

  14. Deployment Repeatability

    Science.gov (United States)

    2016-04-01

    evaluating the deployment repeatability builds upon the testing or analysis of deployment kinematics (Chapter 6) and adds repetition. Introduction...material yield or failure during a test. For the purposes of this chapter, zero shift will refer to permanent changes in the structure, while reversible ...the content of other chapters in this book: Gravity Compensation (Chapter 4) and Deployment Kinematics and Dynamics (Chapter 6). Repeating the

  15. Summer 2011

    Directory of Open Access Journals (Sweden)

    Eric G. Strauss

    2011-01-01

    Full Text Available Cities and the Environment Editor, Eric Strauss, provides an introduction to the Summer 2011 issue. He discusses the journal's transition to its new home at Loyola Marymount University and the creation of the Center for Urban Resilience and Ecological Solution, while underscoring highlights of the special topics section on Urban Predators. The contributors to this section participated in the International Symposium on Urban Wildlife and the Environment hosted by the Wildlife Society at the University of Massachusetts Amherst in June of 2009. Finally, Dr. Strauss notes the breadth of our issue by mentioning the additional articles' focus on rain gardens, water quality, arthropod diversity, green roofs, and socio-ecological dynamics.

  16. Risk identification of agricultural drought for sustainable Agroecosystems

    Science.gov (United States)

    Dalezios, N. R.; Blanta, A.; Spyropoulos, N. V.; Tarquis, A. M.

    2014-09-01

    Drought is considered as one of the major natural hazards with a significant impact on agriculture, environment, society and economy. Droughts affect sustainability of agriculture and may result in environmental degradation of a region, which is one of the factors contributing to the vulnerability of agriculture. This paper addresses agrometeorological or agricultural drought within the risk management framework. Risk management consists of risk assessment, as well as a feedback on the adopted risk reduction measures. And risk assessment comprises three distinct steps, namely risk identification, risk estimation and risk evaluation. This paper deals with risk identification of agricultural drought, which involves drought quantification and monitoring, as well as statistical inference. For the quantitative assessment of agricultural drought, as well as the computation of spatiotemporal features, one of the most reliable and widely used indices is applied, namely the vegetation health index (VHI). The computation of VHI is based on satellite data of temperature and the normalized difference vegetation index (NDVI). The spatiotemporal features of drought, which are extracted from VHI, are areal extent, onset and end time, duration and severity. In this paper, a 20-year (1981-2001) time series of the National Oceanic and Atmospheric Administration/advanced very high resolution radiometer (NOAA/AVHRR) satellite data is used, where monthly images of VHI are extracted. Application is implemented in Thessaly, which is the major agricultural drought-prone region of Greece, characterized by vulnerable agriculture. The results show that agricultural drought appears every year during the warm season in the region. The severity of drought is increasing from mild to extreme throughout the warm season, with peaks appearing in the summer. Similarly, the areal extent of drought is also increasing during the warm season, whereas the number of extreme drought pixels is much less than

  17. Temperature impacts on the water year 2014 drought in California

    Science.gov (United States)

    Shukla, Shraddhanand; Safeeq, Mohammad; AghaKouchak, Amir; Guan, Kaiyu; Funk, Christopher C.

    2015-01-01

    California is experiencing one of the worst droughts on record. Here we use a hydrological model and risk assessment framework to understand the influence of temperature on the water year (WY) 2014 drought in California and examine the probability that this drought would have been less severe if temperatures resembled the historical climatology. Our results indicate that temperature played an important role in exacerbating the WY 2014 drought severity. We found that if WY 2014 temperatures resembled the 1916–2012 climatology, there would have been at least an 86% chance that winter snow water equivalent and spring-summer soil moisture and runoff deficits would have been less severe than the observed conditions. We also report that the temperature forecast skill in California for the important seasons of winter and spring is negligible, beyond a lead-time of one month, which we postulate might hinder skillful drought prediction in California.

  18. The paleoclimate context and future trajectory of extreme summer hydroclimate in eastern Australia

    Science.gov (United States)

    Cook, Benjamin I; Palmer, Jonathan G; Cook, Edward R; Turney, Chris S M; Allen, Kathryn; Fenwick, Pavla; O’Donnell, Alison; Lough, Janice M; Grierson, Pauline F; Ho, Michelle; Baker, Patrick J

    2018-01-01

    Eastern Australia recently experienced an intense drought (Millennium Drought, 2003–2009) and record-breaking rainfall and flooding (austral summer 2010–2011). There is some limited evidence for a climate change contribution to these events, but such analyses are hampered by the paucity of information on long-term natural variability. Analyzing a new reconstruction of summer (December–January–February) Palmer Drought Severity Index (the Australia–New Zealand Drought Atlas; ANZDA, 1500–2012 CE), we find moisture deficits during the Millennium Drought fall within the range of the last 500 years of natural hydroclimate variability. This variability includes periods of multi-decadal drought in the 1500s more persistent than any event in the historical record. However, the severity of the Millennium Drought, which was caused by autumn (March–April–May) precipitation declines, may be underestimated in the ANZDA because the reconstruction is biased towards summer and antecedent spring (September-October-November) precipitation. The pluvial in 2011, however, which was characterized by extreme summer rainfall faithfully captured by the ANZDA, is likely the wettest year in the reconstruction for Coastal Queensland. Climate projections (RCP 8.5 scenario) suggest that eastern Australia will experience long-term drying during the 21st century. While the contribution of anthropogenic forcing to recent extremes remains an open question, these projections indicate an amplified risk of multi-year drought anomalies matching or exceeding the intensity of the Millennium Drought. PMID:29780675

  19. The European Drought Observatory (EDO): Current State and Future Directions

    Science.gov (United States)

    Vogt, Jürgen; Sepulcre, Guadalupe; Magni, Diego; Valentini, Luana; Singleton, Andrew; Micale, Fabio; Barbosa, Paulo

    2013-04-01

    Europe has repeatedly been affected by droughts, resulting in considerable ecological and economic damage and climate change studies indicate a trend towards increasing climate variability most likely resulting in more frequent drought occurrences also in Europe. Against this background, the European Commission's Joint Research Centre (JRC) is developing methods and tools for assessing, monitoring and forecasting droughts in Europe and develops a European Drought Observatory (EDO) to complement and integrate national activities with a European view. At the core of the European Drought Observatory (EDO) is a portal, including a map server, a metadata catalogue, a media-monitor and analysis tools. The map server presents Europe-wide up-to-date information on the occurrence and severity of droughts, which is complemented by more detailed information provided by regional, national and local observatories through OGC compliant web mapping and web coverage services. In addition, time series of historical maps as well as graphs of the temporal evolution of drought indices for individual grid cells and administrative regions in Europe can be retrieved and analysed. Current work is focusing on validating the available products, developing combined indicators, improving the functionalities, extending the linkage to additional national and regional drought information systems and testing options for medium-range probabilistic drought forecasting across Europe. Longer-term goals include the development of long-range drought forecasting products, the analysis of drought hazard and risk, the monitoring of drought impact and the integration of EDO in a global drought information system. The talk will provide an overview on the development and state of EDO, the different products, and the ways to include a wide range of stakeholders (i.e. European, national river basin, and local authorities) in the development of the system as well as an outlook on the future developments.

  20. A global evaluation of streamflow drought characteristics

    Directory of Open Access Journals (Sweden)

    A. K. Fleig

    2006-01-01

    Full Text Available How drought is characterised depends on the purpose and region of the study and the available data. In case of regional applications or global comparison a standardisation of the methodology to characterise drought is preferable. In this study the threshold level method in combination with three common pooling procedures is applied to daily streamflow series from a wide range of hydrological regimes. Drought deficit characteristics, such as drought duration and deficit volume, are derived, and the methods are evaluated for their applicability for regional studies. Three different pooling procedures are evaluated: the moving-average procedure (MA-procedure, the inter-event time method (IT-method, and the sequent peak algorithm (SPA. The MA-procedure proved to be a flexible approach for the different series, and its parameter, the averaging interval, can easily be optimised for each stream. However, it modifies the discharge series and might introduce dependency between drought events. For the IT-method it is more difficult to find an optimal value for its parameter, the length of the excess period, in particular for flashy streams. The SPA can only be recommended as pooling procedure for the selection of annual maximum series of deficit characteristics and for very low threshold levels to ensure that events occurring shortly after major events are recognized. Furthermore, a frequency analysis of deficit volume and duration is conducted based on partial duration series of drought events. According to extreme value theory, excesses over a certain limit are Generalized Pareto (GP distributed. It was found that this model indeed performed better than or equally to other distribution models. In general, the GP-model could be used for streams of all regime types. However, for intermittent streams, zero-flow periods should be treated as censored data. For catchments with frost during the winter season, summer and winter droughts have to be analysed

  1. Indian Summer

    Energy Technology Data Exchange (ETDEWEB)

    Galindo, E. [Sho-Ban High School, Fort Hall, ID (United States)

    1997-08-01

    This paper focuses on preserving and strengthening two resources culturally and socially important to the Shoshone-Bannock Indian Tribe on the Fort Hall Reservation in Idaho; their young people and the Pacific-Northwest Salmon. After learning that salmon were not returning in significant numbers to ancestral fishing waters at headwater spawning sites, tribal youth wanted to know why. As a result, the Indian Summer project was conceived to give Shoshone-Bannock High School students the opportunity to develop hands-on, workable solutions to improve future Indian fishing and help make the river healthy again. The project goals were to increase the number of fry introduced into the streams, teach the Shoshone-Bannock students how to use scientific methodologies, and get students, parents, community members, and Indian and non-Indian mentors excited about learning. The students chose an egg incubation experiment to help increase self-sustaining, natural production of steelhead trout, and formulated and carried out a three step plan to increase the hatch-rate of steelhead trout in Idaho waters. With the help of local companies, governmental agencies, scientists, and mentors students have been able to meet their project goals, and at the same time, have learned how to use scientific methods to solve real life problems, how to return what they have used to the water and land, and how to have fun and enjoy life while learning.

  2. Summer Students

    CERN Multimedia

    2005-01-01

    SUMMER STUDENT LECTURE PROGRAMME Main Auditorium, bldg. 500 Monday 8 August 09:15 - 10:00 A. Höcker CP Violation (3/4) 10:15 - 12:00 J-J. GOMEZ-CADENAS Neutrino Physics (1-2/4) 12:00 Discussion Session Tuesday 9 August 09:15 - 10:00 A. Höcker CP Violation (4/4) 10:15 - 11:00 J-J. GOMEZ-CADENAS Neutrino Physics (3/4) 11:15 - 12:00 F. GREY The GRID 12:00 Discussion Session 14:15 - 17:00 Student Sessions Wednesday 10 August 09:15 - 10:00 J-J. GOMEZ-CADENAS Neutrino Physics (4/4) 10:15 - 12:00 J. LESGOURGUES Introduction to Cosmology (1-2/5) 12:00 Discussion Session 14:15 - 17:00 Student Sessions Thursday 11 August 09:15 - 11:00 J. LESGOURGUES Introduction to Cosmology (3-4/5) 11:15 - 12:00 G. KALMUS The ILC Story 12:00 Discussion Session Friday 12 August 09:15 - 10:00 J. LESGOURGUES Introduction to Cosmology (5/5) 10:15 - 11:00 G. VENEZIANO String theory: has Einstein's dream come true? 11:00  Discussion...

  3. Summer Students

    CERN Multimedia

    2005-01-01

    SUMMER STUDENT LECTURE PROGRAMME Main Auditorium, bldg. 500 DATE TIME LECTURER TITLE Monday 1 August 09:15 - 10:00 P. WELLS The Higgs Saga at LEP 10:15 - 11:00 E. KIRITSIS Beyond the Standard Model (1/4) 11:15 - 12:00 G. COWAN Introduction to Statistics (1/3) 12:00 Discussion Session Tuesday 2 August 09:15 - 11:00 E. KIRITSIS Beyond the Standard Model (2-3/4) 11:15 - 12:00 G. COWAN Introduction to Statistics (2/3) 12:00 Discussion Session Wednesday 3 August 09:15 - 10:00 G. COWAN Introduction to Statistics (3/3) 10:15 - 11:00 E. KIRITSIS Beyond the Standard Model (4/4) 11:15 - 12:00 K. JAKOBS Physics at Hadronic Colliders (1/4) 12:00 Discussion Session Thursday 4 August 09:15 - 11:00 K. JAKOBS Physics at Hadronic Colliders (2-3/4) 11:15 - 12:00 A. WEINSTEIN Gravitation Waves 12:00 Discussion Session 16:30 - 18:00 Poster Session Friday 5 August 09:15 - 11:00 A. Höcker CP Violation (1-2/4) 11:15 - 12:00 K. JA...

  4. Summer Students

    CERN Multimedia

    2005-01-01

    SUMMER STUDENT LECTURE PROGRAMME Main Auditorium, bldg. 500 DATE TIME LECTURER TITLE Monday 18 July 09:15 - 11:00 G. ROSS Fundamental concepts in Particle Physics (1-2/6) 11:15 - 12:00 N. PALANQUE-DELABROUILLE Astroparticle Physics (1/3) 12:00 Discussion Session Tuesday 19 July 09:15 - 10:00 G. ROSS Fundamental concepts in Particle Physics (3/6) 10:15 - 12:00 N. PALANQUE-DELABROUILLE Astroparticle Physics (2-3/3) 12:00 Discussion Session Wednesday 20 July 09:15 - 10:00 G. ROSS Fundamental concepts in Particle Physics (4/6) 10:15 - 11:00 F. RADEMAKERS ROOT 11:15 - 12:00 L. ROSSI Super-conducting magnet technology for particle accelerators and detectors 12:00 Discussion Session Thursday 21 July 09:15 - 10:00 G. ROSS Fundamental concepts in Particle Physics (5/6) 10:15 - 12:00 C. DE LA TAILLE Introduction to Electronics (1-2/3) 12:00 Discussion Session Friday 22 July 09:15 - 10:00 C. DE LA TAILLE Introduction to Electronics (3/3) 10:15 -...

  5. Summer Students

    CERN Multimedia

    2005-01-01

    SUMMER STUDENT LECTURE PROGRAMME Main Auditorium, bldg. 500 DATE TIME LECTURER TITLE Monday 25 July 09:15 - 11:00 A. PICH The Standard Model (2-3/8) 11:15 - 12:00 J. STACHEL Quark Gluon Plasma Physics (1/3) 12:00 Discussion Session Tuesday 26 July 09:15 - 10:00 A. PICH The Standard Model (4/8) 10:15 - 12:00 J. STACHEL Quark Gluon Plasma Physics (2-3/3) 12:00 Discussion Session Wednesday 27 July 09:15 - 11:00 A. PICH The Standard Model (5-6/8) 11:15 - 12:00 J-P. DELAHAYE The CLIC Concept and Technology for an e+e-Collider at the Energy Frontier 11:15 - 12:00 Discussion Session Thursday 28 July 09:15 - 10:00 A. PICH The Standard Model (7/8) 10:15 - 11:00 P. SPHICAS Data Acquisition Systems (1/2) 11:15 - 12:00 R. JACOBSEN From Raw data to Physics Results (1/2) 12:00 Discussion Session Friday 29 July 09:15 - 10:00 A. PICH The Standard Model (8/8) 10:15 - 11:00 P. SPHICAS Data Acquisition Systems (2/2) 11:15 - 12:00 R. JACOBSEN Fr...

  6. Summer Students

    CERN Multimedia

    2005-01-01

    SUMMER STUDENT LECTURE PROGRAMME Main Auditorium, bldg. 500 DATE TIME LECTURER TITLE Monday 11 July 09:15 - 10:00 L. Di Lella (CERN) Introduction to Particle Physics (4/4) 10:15 - 11:00 P. Chomaz (GANIL / CERN) Introduction to Nuclear Physics (3/3) 11:15 - 12:00 G. ROLANDI (CERN) How an experiment is designed (2/2) 12:00 Discussion Session Tuesday 12 July  09:15 - 11:00 O. BrÜning (CERN) Accelerators (1-2/5) 11:15 - 12:00 O. ULLALAND (CERN) Detectors (1/5) 12:00 Discussion Session Wednesday 13 July 09:15 - 10:00 O. BrÜning (CERN) Accelerators (3/5) 10:15 - 11:00 R. LANDUA (CERN) Antimatter in the Lab (1/2) 11:15 - 12:00 O. ULLALAND (CERN) Detectors (2/5) 12:00 Discussion Session Thursday 14 July 09:15 - 10:00 O. ULLALAND (CERN) Detectors (3/5) 10:15 - 11:00 G. ROLANDI (CERN) Antimatter in the Lab (2/2) 11:15 - 12:00 O. BrÜning (CERN) Accelerators (4/5) 12:00 Discussion Session Friday 1...

  7. Drought resistance of Pinus sylvestris seedlings conferred by plastic root architecture rather than ectomycorrhizal colonisation

    OpenAIRE

    Moser , Barbara; Kipfer , Tabea; Richter , Sarah; Egli , Simon; Wohlgemuth , Thomas

    2015-01-01

    International audience; Abstract ContextIncreased summer drought is considered as a threat to the regeneration of Pinus sylvestris in the Central Alps. To a certain degree, seedlings are able to mitigate negative effects of drought by altering root/shoot ratios. But, seedlings may also enhance access to water and nutrients by cooperation with ectomycorrhizal fungi. AimsWe tested the importance of both mechanisms for drought resistance of P. sylvestris seedlings during early establishment and ...

  8. Dzuds, droughts, and livestock mortality in Mongolia

    Science.gov (United States)

    Palat Rao, Mukund; Davi, Nicole K.; D'Arrigo, Rosanne D.; Skees, Jerry; Nachin, Baatarbileg; Leland, Caroline; Lyon, Bradfield; Wang, Shih-Yu; Byambasuren, Oyunsanaa

    2015-07-01

    Recent incidences of mass livestock mortality, known as dzud, have called into question the sustainability of pastoral nomadic herding, the cornerstone of Mongolian culture. A total of 20 million head of livestock perished in the mortality events of 2000-2002, and 2009-2010. To mitigate the effects of such events on the lives of herders, international agencies such as the World Bank are taking increasing interest in developing tailored market-based solutions like index-insurance. Their ultimate success depends on understanding the historical context and underlying causes of mortality. In this paper we examine mortality in 21 Mongolian aimags (provinces) between 1955 and 2013 in order to explain its density independent cause(s) related to climate variability. We show that livestock mortality is most strongly linked to winter (November-February) temperatures, with incidences of mass mortality being most likely to occur because of an anomalously cold winter. Additionally, we find prior summer (July-September) drought and precipitation deficit to be important triggers for mortality that intensifies the effect of upcoming winter temperatures on livestock. Our density independent mortality model based on winter temperature, summer drought, summer precipitation, and summer potential evaporanspiration explains 48.4% of the total variability in the mortality dataset. The Mongolian index based livestock insurance program uses a threshold of 6% mortality to trigger payouts. We find that on average for Mongolia, the probability of exceedance of 6% mortality in any given year is 26% over the 59 year period between 1955 and 2013.

  9. Drought and groundwater management

    DEFF Research Database (Denmark)

    Amundsen, Eirik S; Jensen, Frank

    This paper considers the problem of a water management authority faced with the threat of a drought that hits at an uncertain date. Three management policies are investigated: i) a laissez-faire (open-access) policy of automatic adjustment through a zero marginal private net benefit condition, ii......-drought steady-state equilibrium stock size of water under policy iii) is smaller than under policy ii) and, hence, a precautionary stock size should not be built up prior to the drought....

  10. Drought in Africa 2

    Energy Technology Data Exchange (ETDEWEB)

    Dalby, D; Harrison-Church, R J; Berzaz, F [eds.

    1977-01-01

    The second edition of Drought in Africa is reviewed. The book, which has been greatly expanded, looks at the Sahelian and Ethiopian droughts from a long-term perspective. Among the subjects included are: a description of the meteorological aspects of the drought; changes in animal and human populations; overpopulation of areas of nomadic pastoralism and of crop-producing areas; and mechanisms by which people survived. Cash crops, taxes, the market economy and over-centralized planning receive much of the blame for the effects of the drought.

  11. Impact of drought on wildfires in Iberia

    Science.gov (United States)

    Russo, Ana; Gouveia, Célia M.; DaCamara, Carlos; Sousa, Pedro; Trigo, Ricardo M.

    2015-04-01

    Southern European countries, and the Iberian Peninsula (IP) in particular, have been vastly affected by summer wildfires (Trigo et al., 2013). This condition is hampered by the frequent warm and dry meteorological conditions found in summer which play a significant role in the triggering and spreading of wildfires. These meteorological conditions are also particularly important for the onset and end of drought periods, a phenomenon that has recurrently affected the IP (Gouveia et al., 2012). Moreover, the IP corresponds to one of the most sensitive areas to current and future climate change, and recent and future trends towards a dryer and warmer Mediterranean climate (Sousa et al., 2014) will tend to exacerbate these problems. The main scope of this study was to investigate the impact of drought on wildfires' burned areas in the IP. The objective was to examine the correlation between drought, as expressed by both the Standardized Precipitation Index (SPI) and the Standardized Precipitation Evapotranspiration Index (SPEI) (Vicente-Serrano et al., 2010), and wildfire burned areas. The SPI and SPEI were both calculated for 4 large regions (Northwestern, Northern, Southwestern and Eastern) whose spatial patterns and seasonal fire regimes were shown to be related with constraining factors such as topography, vegetation cover and climate conditions (Trigo et al., 2013). In this study, the drought indices were determined for the time scales of 3 and 6 months for August and for 12 months in September, thus representing the summer and annual drought. The correlation between drought and burned areas during July and August was particularly significant for the 3 months SPEI and SPI relatively to the 6 and 12 time scales, which indicates that drought and fires relation is a small-size scale process. Moreover, the correlation between drought and burned areas during July and August was particularly significant for the Northern and Southwestern regions both for SPEI for 3 and 6

  12. The European 2015 drought from a hydrological perspective

    Directory of Open Access Journals (Sweden)

    G. Laaha

    2017-06-01

    Full Text Available In 2015 large parts of Europe were affected by drought. In this paper, we analyze the hydrological footprint (dynamic development over space and time of the drought of 2015 in terms of both severity (magnitude and spatial extent and compare it to the extreme drought of 2003. Analyses are based on a range of low flow and hydrological drought indices derived for about 800 streamflow records across Europe, collected in a community effort based on a common protocol. We compare the hydrological footprints of both events with the meteorological footprints, in order to learn from similarities and differences of both perspectives and to draw conclusions for drought management. The region affected by hydrological drought in 2015 differed somewhat from the drought of 2003, with its center located more towards eastern Europe. In terms of low flow magnitude, a region surrounding the Czech Republic was the most affected, with summer low flows that exhibited return intervals of 100 years and more. In terms of deficit volumes, the geographical center of the event was in southern Germany, where the drought lasted a particularly long time. A detailed spatial and temporal assessment of the 2015 event showed that the particular behavior in these regions was partly a result of diverging wetness preconditions in the studied catchments. Extreme droughts emerged where preconditions were particularly dry. In regions with wet preconditions, low flow events developed later and tended to be less severe. For both the 2003 and 2015 events, the onset of the hydrological drought was well correlated with the lowest flow recorded during the event (low flow magnitude, pointing towards a potential for early warning of the severity of streamflow drought. Time series of monthly drought indices (both streamflow- and climate-based indices showed that meteorological and hydrological events developed differently in space and time, both in terms of extent and severity

  13. Repeating Marx

    DEFF Research Database (Denmark)

    Fuchs, Christian; Monticelli, Lara

    2018-01-01

    This introduction sets out the context of the special issue “Karl Marx @ 200: Debating Capitalism & Perspectives for the Future of Radical Theory”, which was published on the occasion of Marx’s bicentenary on 5 May 2018. First, we give a brief overview of contemporary capitalism’s development...... and its crises. Second, we argue that it is important to repeat Marx today. Third, we reflect on lessons learned from 200 years of struggles for alternatives to capitalism. Fourth, we give an overview of the contributions in this special issue. Taken together, the contributions in this special issue show...... that Marx’s theory and politics remain key inspirations for understanding exploitation and domination in 21st-century society and for struggles that aim to overcome these phenomena and establishing a just and fair society. We need to repeat Marx today....

  14. Extreme wildfire events are linked to global-change-type droughts in the northern Mediterranean

    Science.gov (United States)

    Ruffault, Julien; Curt, Thomas; Martin-StPaul, Nicolas K.; Moron, Vincent; Trigo, Ricardo M.

    2018-03-01

    Increasing drought conditions under global warming are expected to alter the frequency and distribution of large and high-intensity wildfires. However, our understanding of the impact of increasing drought on extreme wildfires events remains incomplete. Here, we analyzed the weather conditions associated with the extreme wildfires events that occurred in Mediterranean France during the exceptionally dry summers of 2003 and 2016. We identified that these fires were related to two distinct shifts in the fire weather space towards fire weather conditions that had not been explored before and resulting from specific interactions between different types of drought and different fire weather types. In 2016, a long-lasting press drought intensified wind-driven fires. In 2003, a hot drought combining a heat wave with a press drought intensified heat-induced fires. Our findings highlight that increasing drought conditions projected by climate change scenarios might affect the dryness of fuel compartments and lead to a higher frequency of extremes wildfires events.

  15. Deployment Repeatability

    Science.gov (United States)

    2016-08-31

    large cohort of trials to spot unusual cases. However, deployment repeatability is inherently a nonlinear phenomenon, which makes modeling difficult...and GEMS tip position were both tracked during ground testing by a laser target tracking system. Earlier SAILMAST testing in 2005 [8] used...recalls the strategy used by SRTM, where a constellation of lights was installed at the tip of the boom and a modified star tracker was used to track tip

  16. Tree responses to drought

    Science.gov (United States)

    Michael G. Ryan

    2011-01-01

    With global climate change, drought may become more common in the future (IPCC 2007). Several factors will promote more frequent droughts: earlier snowmelt, higher temperatures and higher variability in precipitation. For ecosystems where the water cycle is dominated by snowmelt, warmer temperatures bring earlier melt (Stewart et al. 2005) and longer, drier snow-free...

  17. USGS integrated drought science

    Science.gov (United States)

    Ostroff, Andrea C.; Muhlfeld, Clint C.; Lambert, Patrick M.; Booth, Nathaniel L.; Carter, Shawn L.; Stoker, Jason M.; Focazio, Michael J.

    2017-06-05

    Project Need and OverviewDrought poses a serious threat to the resilience of human communities and ecosystems in the United States (Easterling and others, 2000). Over the past several years, many regions have experienced extreme drought conditions, fueled by prolonged periods of reduced precipitation and exceptionally warm temperatures. Extreme drought has far-reaching impacts on water supplies, ecosystems, agricultural production, critical infrastructure, energy costs, human health, and local economies (Milly and others, 2005; Wihlite, 2005; Vörösmarty and others, 2010; Choat and others, 2012; Ledger and others, 2013). As global temperatures continue to increase, the frequency, severity, extent, and duration of droughts are expected to increase across North America, affecting both humans and natural ecosystems (Parry and others, 2007).The U.S. Geological Survey (USGS) has a long, proven history of delivering science and tools to help decision-makers manage and mitigate effects of drought. That said, there is substantial capacity for improved integration and coordination in the ways that the USGS provides drought science. A USGS Drought Team was formed in August 2016 to work across USGS Mission Areas to identify current USGS drought-related research and core capabilities. This information has been used to initiate the development of an integrated science effort that will bring the full USGS capacity to bear on this national crisis.

  18. 12 years of irrigation in a drought stressed pine forest speeds up carbon cycling and alters the soil biome but has negligible effects on soil organic matter storage

    Science.gov (United States)

    Hagedorn, Frank; Hartmann, Martin; Brunner, Ivano; Rigling, Andreas; Herzog, Claude; Schaub, Marcus; Frey, Beat

    2017-04-01

    Inneralpine valleys are experiencing repeated summer droughts, which have caused a die-back of pine forests since the 1990s. Drought limits the metabolic activity and hence C cycling in the plant and soil system. The net effects of drought on soil organic matter (SOM) storage is, however, ambiguous as drought affects both C inputs and outputs. Moreover, in the long-term, water limitation is also altering above- and belowground diversity due to species-dependent resistance and adaptation to drought. In our study, we explored how ten years of irrigation of a water-limited pine forest in the central European Alps altered above- and belowground diversity and C cycling in the plant and soil systems. The decadal long irrigation during summer time strongly increased ecosystem productivity with litter fall and fine root biomass being increased by +50 and +40%, respectively. At the same time, soil CO2 efflux was stimulated by 60%, indicating that the removal of water limitation enhanced both the inputs and outputs of C into soils. The accelerated C cycling was also mirrored by compositional shifts in the soil microbiome. 454-pyrosequencing of ribosomal marker genes indicated that irrigation promoted bacteria and fungi with more copiotrophic life style strategies, that are typical for nutrient-rich conditions associated with a higher decomposition. Determination of SOM pools revealed a C loss in the organic layer under irrigation (-900 gC m-2) but a C gain in the mineral soil (+970 gC m-2), resulting in a negligible net effect. The likely mechanisms for the altered vertical SOM distribution might be (1) an accelerated mineralization of litter in conjunction with higher C inputs from the rhizosphere and/or (2) an increased incorporation of litter in the mineral soil as suggested by a litter bag experiment showing a stimulated activity of the macrofauna with a 5-fold increase of the earthworm density. In summary, our long-term irrigation experiment revealed that the removal of

  19. Anomalous behaviour of the Indian summer monsoon 2009

    Indian Academy of Sciences (India)

    The Indian subcontinent witnessed a severe monsoon drought in the year 2009. India as a whole received. 77% of its long period average during summer monsoon season (1 June to 30 September) of 2009, which is the third highest deficient all India monsoon season rainfall year during the period 1901–2009. Therefore,.

  20. Decreased summer water table depth affects peatland vegetation

    NARCIS (Netherlands)

    Breeuwer, A.J.G.; Robroek, B.J.M.; Limpens, J.; Heijmans, M.M.P.D.; Schouten, M.G.C.; Berendse, F.

    2009-01-01

    Climate change can be expected to increase the frequency of summer droughts and associated low water tables in ombrotrophic peatlands. We studied the effects of periodic water table drawdown in a mesocosm experiment. Mesocosms were collected in Southern Sweden, and subsequently brought to an

  1. Drought variability and change across the Iberian Peninsula

    Science.gov (United States)

    Coll, J. R.; Aguilar, E.; Ashcroft, L.

    2017-11-01

    Drought variability and change was assessed across the Iberian Peninsula over more than 100 years expanding through the twentieth century and the first decade of the twenty-first century. Daily temperature and precipitation data from 24 Iberian time series were quality controlled and homogenized to create the Monthly Iberian Temperature and Precipitation Series (MITPS) for the period 1906-2010. The Standardized Precipitation Index (SPI), driven only by precipitation, and the Standardized Precipitation Evapotranspiration Index (SPEI), based on the difference between the precipitation and the reference evapotranspiration (ET0), were computed at annual and seasonal scale to describe the evolution of droughts across time. The results confirmed that a clear temperature increase has occurred over the entire Iberian Peninsula at the annual and seasonal scale, but no significant changes in precipitation accumulated amounts were found. Similar drought variability was provided by the SPI and SPEI, although the SPEI showed greater drought severity and larger surface area affected by drought than SPI from 1980s to 2010 due to the increase in atmospheric evaporative demand caused by increased temperatures. Moreover, a clear drying trend was found by the SPEI for most of the Iberian Peninsula at annual scale and also for spring and summer, although the SPI did not experience significant changes in drought conditions. From the drying trend identified for most of the Iberian Peninsula along the twentieth century, an increase in drought conditions can also be expected for this region in the twenty-first century according to future climate change projections and scenarios.

  2. Monitoring and Assessing the 2012 Drought in the Great Plains: Analyzing Satellite-Retrieved Solar-Induced Chlorophyll Fluorescence, Drought Indices, and Gross Primary Production

    Directory of Open Access Journals (Sweden)

    Siheng Wang

    2016-01-01

    Full Text Available We examined the relationship between satellite measurements of solar-induced chlorophyll fluorescence (SIF and several meteorological drought indices, including the multi-time-scale standard precipitation index (SPI and the Palmer drought severity index (PDSI, to evaluate the potential of using SIF to monitor and assess drought. We found significant positive relationships between SIF and drought indices during the growing season (from June to September. SIF was found to be more sensitive to short-term SPIs (one or two months and less sensitive to long-term SPI (three months than were the normalized difference vegetation index (NDVI or the normalized difference water index (NDWI. Significant correlations were found between SIF and PDSI during the growing season for the Great Plains. We found good consistency between SIF and flux-estimated gross primary production (GPP for the years studied, and synchronous declines of SIF and GPP in an extreme drought year (2012. We used SIF to monitor and assess the drought that occurred in the Great Plains during the summer of 2012, and found that although a meteorological drought was experienced throughout the Great Plains from June to September, the western area experienced more agricultural drought than the eastern area. Meanwhile, SIF declined more significantly than NDVI during the peak growing season. Yet for senescence, during which time the reduction of NDVI still went on, the reduction of SIF was eased. Our work provides an alternative to traditional reflectance-based vegetation or drought indices for monitoring and assessing agricultural drought.

  3. Comprehensive Analysis of Drought Persistence, Hazard, and Recovery across the CONUS

    Science.gov (United States)

    Zarekarizi, M.; Ahmadi, B.; Moradkhani, H.

    2017-12-01

    Drought is a creeping intertwined natural hazard affecting society more than any other natural disaster and causing enormous damages on economy and ecosystems. Better understanding of potential drought hazard can help water managers and stakeholders devising mitigation plans to minimize the adverse effects of droughts. In this study, soil moisture, simulated by the Variable Infiltration Capacity (VIC) land surface model, is used to analyze the probability of agricultural drought with different severities across the CONUS. Due to the persistence of soil moisture, a drought episode at a particular time is affected by its earlier status; therefore, this study has utilized a Copula function to model the selected hydrologic variable over the time. The probability of drought intensity for each unit is presented spatially. If the unit remains in the drought condition at the same or lower intensity, drought persists and if it improves above a pre-defined threshold, the unit recovers. Results show that the west of US is more vulnerable to drought persistence in summer and spring while the Midwest and Northeast of US are experiencing drought persistence in fall and winter. In addition, the analysis reveals that as the intensity of drought in a given season decreases the following season has higher chance of recovery.

  4. Dynamics of meteorological and hydrological droughts in the Neman river basin

    International Nuclear Information System (INIS)

    Rimkus, Egidijus; Stonevičius, Edvinas; Kažys, Justas; Valiuškevičius, Gintaras; Korneev, Vladimir; Pakhomau, Aliaksandr

    2013-01-01

    The analysis of drought dynamics in the Neman river basin allows an assessment of extreme regional climate changes. Meteorological and hydrological warm period droughts were analyzed in this study. Meteorological droughts were identified using the standardized precipitation index, and hydrological droughts using the streamflow drought index. The whole river basin was analyzed over the period from 1961 to 2010. Precipitation data from Vilnius meteorological station (from 1887) and discharge data from Smalininkai (Neman) hydrological station (from 1811) were used for an evaluation of meteorological and hydrological drought recurrence over a long-term period. It was found that the total area dryness has decreased over the last 50 years. A statistically significant increase in standardized precipitation index values was observed in some river sub-basins. An analysis of drought recurrence dynamics showed that there was no indication that the number of dangerous drought was increased. It was determined that the standardized precipitation index cannot successfully identify the hydrological summer droughts in an area where the spring snowmelt forms a large part of the annual flow. In particular, the weak relationship between the indices was recorded in the first half of the summer, when a large part of the river runoff depends on accumulated water during the spring thaw. (letter)

  5. Impact of drought on the temporal dynamics of wood formation in Pinus sylvestris.

    Science.gov (United States)

    Gruber, Andreas; Strobl, Stefan; Veit, Barbara; Oberhuber, Walter

    2010-04-01

    We determined the temporal dynamics of cambial activity and xylem cell differentiation of Scots pine (Pinus sylvestris L.) within a dry inner Alpine valley (750 m a.s.l., Tyrol, Austria), where radial growth is strongly limited by drought in spring. Repeated micro-sampling of the developing tree ring of mature trees was carried out during two contrasting years at two study plots that differ in soil water availability (xeric and dry-mesic sites). In 2007, when air temperature at the beginning of the growing season in April exceeded the long-term mean by 6.4 degrees C, cambial cell division started in early April at both study plots. A delayed onset of cambial activity of c. 2 weeks was found in 2008, when average climate conditions prevailed in spring, indicating that resumption of cambial cell division after winter dormancy is temperature controlled. Cambial cell division consistently ended about the end of June/early July in both study years. Radial enlargement of tracheids started almost 3 weeks earlier in 2007 compared with 2008 at both study plots. At the xeric site, the maximum rate of tracheid production in 2007 and 2008 was reached in early and mid-May, respectively, and c. 2 weeks later at the dry-mesic site. Since in both study years more favorable growing conditions (i.e., an increase in soil water content) were recorded during summer, we suggest a strong sink competition for carbohydrates to mycorrhizal root and shoot growth. Wood formation stopped c. 4 weeks earlier at the xeric compared with the dry-mesic site in both years, indicating a strong influence of drought stress on cell differentiation. This is supported by radial widths of earlywood cells, which were found to be significantly narrower at the xeric than at the dry-mesic site (P drought is strongly influenced by water availability, the onset of cambial activity and cell differentiation is controlled by temperature.

  6. Climate and drought

    Science.gov (United States)

    McNab, Alan L.

    Drought is a complex phenomenon that can be defined from several perspectives [Wilhite and Glantz, 1987]. The common characteristic and central idea of these perspectives is the straightforward notion of a water deficit. Complexity arises because of the need to specify the part of the hydrologic cycle experiencing the deficit and the associated time period. For example, a long-term deficit in deep groundwater storage can occur simultaneously with a short-term surplus of root zone soil water.Figure 1 [Changnon, 1987] illustrates how the definitions of drought are related to specific components of the hydrologic cycle. The dashed lines indicate the delayed translation of two hypothetical precipitation deficits with respect to runoff, soil moisture, streamflow and groundwater. From this perspective, precipitation can be considered as the carrier of the drought signal, and hydrological processes are among the final indicators that reveal the presence of drought [Hare, 1987; Klemes, 1987].

  7. Palmer Drought Severity Index

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — PDSI from the Dai dataset. The Palmer Drought Severity Index (PDSI) is devised by Palmer (1965) to represent the severity of dry and wet spells over the U.S. based...

  8. Hydrological Drought in the Anthropocene: Impacts of Local Water Extraction and Reservoir Regulation in the U.S.

    Science.gov (United States)

    Wan, Wenhua; Zhao, Jianshi; Li, Hong-Yi; Mishra, Ashok; Ruby Leung, L.; Hejazi, Mohamad; Wang, Wei; Lu, Hui; Deng, Zhiqun; Demissisie, Yonas; Wang, Hao

    2017-11-01

    Hydrological drought is a substantial negative deviation from normal hydrologic conditions and is influenced by climate and human activities such as water management. By perturbing the streamflow regime, climate change and water management may significantly alter drought characteristics in the future. Here we utilize a high-resolution integrated modeling framework that represents water management in terms of both local surface water extraction and reservoir regulation and use the Standardized Streamflow Index to quantify hydrological drought. We explore the impacts of water management on hydrological drought over the contiguous U.S. in a warming climate with and without emissions mitigation. Despite the uncertainty of climate change impacts, local surface water extraction consistently intensifies drought that dominates at the regional to national scale. However, reservoir regulation alleviates drought by enhancing summer flow downstream of reservoirs. The relative dominance of drought intensification or relief is largely determined by the water demand, with drought intensification dominating in regions with intense water demand such as the Great Plains and California, while drought relief dominates in regions with low water demand. At the national level, water management increases the spatial extent of extreme drought despite some alleviations of moderate to severe drought. In an emissions mitigation scenario with increased irrigation demand for bioenergy production, water management intensifies drought more than the business-as-usual scenario at the national level, so the impacts of emissions mitigation must be evaluated by considering its benefit in reducing warming and evapotranspiration against its effects on increasing water demand and intensifying drought.

  9. The Summer Monsoon of 1987.

    Science.gov (United States)

    Krishnamurti, T. N.; Bedi, H. S.; Subramaniam, M.

    1989-04-01

    In this paper we have examined the evolution of a number of parameters we believe were important for our understanding of the drought over India during the summer of 1987. The list of parameters includes monthly means or anomalies of the following fields: sea surface temperatures, divergent circulations, outgoing longwave radiation, streamfunction of the lower and upper troposphere, and monthly precipitation (expressed as a percentage departure from a long-term mean). The El Niño related warm sea surface temperature anomaly and a weaker warm sea surface temperature anomaly over the equatorial Indian Ocean provide sustained convection, as reflected by the negative values of the outgoing longwave radiation. With the seasonal heating, a pronounced planetary-scale divergent circulation evolved with a center along the western Pacific Ocean. The monsoonal divergent circulation merged with that related to the El Niño, maintaining most of the heavy rainfall activity between the equatorial Pacific Ocean and east Asia. Persistent convective activity continued south of India during the entire monsoon season. Strong Hadley type overturnings with rising motions over these warm SST anomaly regions and descent roughly near 20° to 25°S was evident as early as April 1987. The subtropical high pressure areas near 20° to 25°S showed stronger than normal circulations. This was revealed by the presence of a counterclockwise streamfunction anomaly at 850 mb during April 1987. With the seasonal heating, this anomaly moved northwards and was located over the Arabian Sea and India. This countermonsoon circulation anomaly at the low levels was associated with a weaker than normal Somali jet and Arabian Sea circulation throughout this summer. The monsoon remained active along northeast India, Bangladesh, northern lndochina, and central China during the summer monsoon season. This was related to the eastward shift of the divergent circulation. An eastward shift of the upper tropospheric

  10. Global patterns of drought recovery

    Energy Technology Data Exchange (ETDEWEB)

    Schwalm, Christopher R.; Anderegg, William R. L.; Michalak, Anna M.; Fisher, Joshua B.; Biondi, Franco; Koch, George; Litvak, Marcy; Ogle, Kiona; Shaw, John D.; Wolf, Adam; Huntzinger, Deborah N.; Schaefer, Kevin; Cook, Robert; Wei, Yaxing; Fang, Yuanyuan; Hayes, Daniel; Huang, Maoyi; Jain, Atul; Tian, Hanqin

    2017-08-09

    Drought is a recurring multi-factor phenomenon with major impacts on natural and human systems1-3. Drought is especially important for land carbon sink variability, influencing climate regulation of the terrestrial biosphere4. While 20th Century trends in drought regime are ambiguous, “more extreme extremes” as well as more frequent and severe droughts3,7 are expected in the 21st Century. Recovery time, the length of time an ecosystem requires to revert to its pre-drought functional state, is a critical metric of drought impact. Yet the spatiotemporal patterning and controls of drought recovery are largely unknown. Here we use three distinct global datasets of gross primary productivity to show that across diverse terrestrial ecosystems drought recovery times are driven by biological productivity and biodiversity, with drought length and severity of secondary importance. Recovery time, especially for extreme droughts, and the areal extent of ecosystems in recovery from drought generally increase over the 20th Century, supporting an increase globally in drought impact8. Our results indicate that if future Anthropocene droughts become more widespread as expected, that droughts will become more frequent relative to recovery time. This increases the risk of entering a new regime where vegetation never recovers to its original state and widespread degradation of the land carbon sink ensues.

  11. Summer Meal Capacity Builder

    Data.gov (United States)

    Department of Agriculture — Allows users to search for summer meal sites from the previous summer by zip code, adding “layers” of information, such as free and reduced-price lunch participation...

  12. Characterizing Drought Risk Management and Assessing the Robustness of Snowpack-based Drought Indicators in the Upper Colorado River Basin.

    Science.gov (United States)

    Livneh, B.; Badger, A.; Lukas, J.; Dilling, L.; Page, R.

    2017-12-01

    Drought conditions over the past two decades have arisen during a time of increasing water demands in the Upper Colorado River Basin. The Basin's highly allocated and diverse water systems raise the question of how drought-based information, such as snowpack, streamflow, and reservoir conditions, can be used to inform drought risk management. Like most of the western U.S., snow-water equivalent (SWE) at key dates during the year (e.g., April 1) is routinely used in water resource planning because it is often the highest observed value during the season and it embodies stored water to be released, through melt, during critical periods later in the summer. This presentation will first focus on how water managers on Colorado's Western Slope (a) perceive drought-related risk, (b) use and access drought information, and (c) respond to drought. Preliminary findings will be presented from in-person interviews, document analysis, observations of planning meetings, and other interactions with seven water-management entities across the Western Slope. The second part of the presentation will focus on how the predictive power of snowpack-based drought indicators—identified as the most useful and reliable drought indicator by regional water stakeholders—are expected change in a warmer world, i.e. where expectations are for more rain versus snow, smaller snowpacks, and earlier snowmelt and peak runoff. We will present results from hydrologic simulations using climate projection to examine how a warming climate will affect the robustness of these snowpack-based drought indicators by mid-century.

  13. Evaluation of drought propagation in an ensemble mean of large-scale hydrological models

    Directory of Open Access Journals (Sweden)

    A. F. Van Loon

    2012-11-01

    Full Text Available Hydrological drought is increasingly studied using large-scale models. It is, however, not sure whether large-scale models reproduce the development of hydrological drought correctly. The pressing question is how well do large-scale models simulate the propagation from meteorological to hydrological drought? To answer this question, we evaluated the simulation of drought propagation in an ensemble mean of ten large-scale models, both land-surface models and global hydrological models, that participated in the model intercomparison project of WATCH (WaterMIP. For a selection of case study areas, we studied drought characteristics (number of droughts, duration, severity, drought propagation features (pooling, attenuation, lag, lengthening, and hydrological drought typology (classical rainfall deficit drought, rain-to-snow-season drought, wet-to-dry-season drought, cold snow season drought, warm snow season drought, composite drought.

    Drought characteristics simulated by large-scale models clearly reflected drought propagation; i.e. drought events became fewer and longer when moving through the hydrological cycle. However, more differentiation was expected between fast and slowly responding systems, with slowly responding systems having fewer and longer droughts in runoff than fast responding systems. This was not found using large-scale models. Drought propagation features were poorly reproduced by the large-scale models, because runoff reacted immediately to precipitation, in all case study areas. This fast reaction to precipitation, even in cold climates in winter and in semi-arid climates in summer, also greatly influenced the hydrological drought typology as identified by the large-scale models. In general, the large-scale models had the correct representation of drought types, but the percentages of occurrence had some important mismatches, e.g. an overestimation of classical rainfall deficit droughts, and an

  14. Coping With Droughts

    Science.gov (United States)

    Zaporozec, Alexander

    This book is a collection of selected papers from the NATO Advanced Study Institute on Droughts entitled “Drought Impact Control Technology,” held at the National Laboratory of Civil Engineering in Lisbon, Portugal, in June 1980. The editors of the book have chosen a nontraditional but successful approach to presenting the papers. Instead of including a verbatim proceedings of the institute, they assembled 21 papers presented by 14 of the institute's lecturers, reshaped and synthesized them, and supplemented them by five new papers that cover obvious gaps in topics. The result is enlightening reading and a more or less complete presentation of the subject. The edited material in the book was arranged around three central themes related to efforts needed to cope with or manage the droughts. In the process, the identity of individual contributors has been preserved.

  15. Drought in the Emerald City

    International Nuclear Information System (INIS)

    Babcock, S.D.

    1993-01-01

    This paper discusses a drought preparedness study being conducted for the Cedar River and Green River basins in western Washington state. The study is one of four regional case studies being managed by the U.S. Army Corps of Engineers as part of the National Study of Water Management During Drought. The overriding objective of the drought preparedness study is to leave the region better prepared for drought, through demonstration and test of drought preparedness tools and strategies. The study has served as a vehicle to promote a greater regional focus on drought related water supply problem solving. The 1992 drought in the Seattle/Tacoma metropolitan area provided a unique opportunity for the study team to demonstrate approaches to drought management being researched and tested as part of the study

  16. Low flow and drought spatial analysis

    International Nuclear Information System (INIS)

    Dakova, Snejana

    2004-01-01

    The hydrological characteristics of Bulgarian rivers reflect to the climate variability. Nearly all precipitation is received during the spring and/or winter months, with negligible precipitations in summer. Thus, peak flows occur in spring and/or winter, and during the summer, the flow is significant lower with many rivers being ephemeral. Therefore, 2210 reservoirs for satisfaction the water needs have been constructed during the last sixty years. In spit of that, Bulgaria is facing to a new insufficiency of water. The recent climate change investigations and climate scenarios determine the area of Balkan Peninsula as territories with decreasing of rainfalls and increasing of air temperature. In view of that, research the low flow in the light of climate changing together with the water management is required. In this study the definitions of low flow and drought are developed using available data obtained in Bulgarian area, which has semiarid zone conditions. The difference between the terms of drought and low flow is describing and clarified also. The low flow and drought variables are investigated on two levels: first on long-year's variability using annual data and than monthly and seasonal data series-for enabling the within-year effects to be determined. The relationship between the probability of river's dry up and mean annual and seasonal rainfalls is quantified using multiple regressions applied to logarithmic- transformed data. This paper presets also analyses of minimum flow series with zero values. The exceed probability above which stream flow is zero and conditional probability of non-zero flow (non-zero-duration curve) is obtained by the principals of total probability. A different kind of adjusting duration curves are proposed depending of the number of zero values in the series.(Author)

  17. Introduction 'Governance for Drought Resilience'

    NARCIS (Netherlands)

    Bressers, Nanny; Bressers, Johannes T.A.; Larrue, Corinne; Bressers, Hans; Bressers, Nanny; Larrue, Corinne

    2016-01-01

    This book is about governance for drought resilience. But that simple sentence alone might rouse several questions. Because what do we mean with drought, and how does that relate to water scarcity? And what do we mean with resilience, and why is resilience needed for tackling drought? And how does

  18. Estimating drought risk across Europe from reported drought impacts, drought indices, and vulnerability factors

    Science.gov (United States)

    Blauhut, Veit; Stahl, Kerstin; Stagge, James Howard; Tallaksen, Lena M.; De Stefano, Lucia; Vogt, Jürgen

    2016-07-01

    Drought is one of the most costly natural hazards in Europe. Due to its complexity, drought risk, meant as the combination of the natural hazard and societal vulnerability, is difficult to define and challenging to detect and predict, as the impacts of drought are very diverse, covering the breadth of socioeconomic and environmental systems. Pan-European maps of drought risk could inform the elaboration of guidelines and policies to address its documented severity and impact across borders. This work tests the capability of commonly applied drought indices and vulnerability factors to predict annual drought impact occurrence for different sectors and macro regions in Europe and combines information on past drought impacts, drought indices, and vulnerability factors into estimates of drought risk at the pan-European scale. This hybrid approach bridges the gap between traditional vulnerability assessment and probabilistic impact prediction in a statistical modelling framework. Multivariable logistic regression was applied to predict the likelihood of impact occurrence on an annual basis for particular impact categories and European macro regions. The results indicate sector- and macro-region-specific sensitivities of drought indices, with the Standardized Precipitation Evapotranspiration Index (SPEI) for a 12-month accumulation period as the overall best hazard predictor. Vulnerability factors have only limited ability to predict drought impacts as single predictors, with information about land use and water resources being the best vulnerability-based predictors. The application of the hybrid approach revealed strong regional and sector-specific differences in drought risk across Europe. The majority of the best predictor combinations rely on a combination of SPEI for shorter and longer accumulation periods, and a combination of information on land use and water resources. The added value of integrating regional vulnerability information with drought risk prediction

  19. Analysis of Droughts of Northwest of Iran Using the Reconnaissance Drought Index

    Directory of Open Access Journals (Sweden)

    behrouz hosseini

    2016-02-01

    second stage, the 64 candidate statistical distributions were fitted for the mentioned RDI’s of each station. The best statistical distribution was selected among the 64 candidate distributions. The best fitted distribution was identified by the chi-square criterion. The parameters of the distribution were estimated by the Maximum Likelihood Estimation (MLE scheme. Then 500 synthetic time series (each of them have the same number of observed data were generated employing the parent population parameters. The three main drought characteristics (namely duration, severity and magnitude were obtained for each of the mentioned artificial time series. The maximum values for each of the mentioned drought characteristic were selected for each year. Then, a new time series having the 500 elements were obtained by collecting the chosen values for each station. Once again the best distribution was selected for each series. Drought characteristics for different return periods (2, 10, 25, 50, 100 and 200 years were estimated for each station. Results and Discussion: Preliminary results indicated that a negative trend existed in annual rainfall time series for almost all of the stations. On the other hand, the pattern of monthly PET histograms were more or less similar for all of the selected stations. The peak of the PET was mainly observed in the hottest month of year, whereas the lowest value of the monthly PET belonged to the coldest month of year. The results showed that the amount of annual rainfall time series decreases sharply, after the year 1991. However, PET values significantly increase for all of the selected stations. After calculation of RDI values, the histogram of annual RDI’s was plotted against the year. This is repeated for all of the selected stations. Figure. 6 shows the mentioned diagram for Tabriz station as an example. In the mentioned Figure, negative values of RDI (shown by red bars indicated the drought years. A critical prolonged drought with a sixteen

  20. A Groundwater Resource Index (GRI) for drought monitoring and forecasting in a mediterranean climate

    Science.gov (United States)

    Mendicino, Giuseppe; Senatore, Alfonso; Versace, Pasquale

    2008-08-01

    SummaryDrought indices are essential elements of an efficient drought watching system, aimed at providing a concise overall picture of drought conditions. Owing to its simplicity, time-flexibility and standardization, the Standardized Precipitation Index (SPI) has become a very widely used meteorological index, even if it is not able to account for effects of aquifers, soil, land use characteristics, canopy growth and temperature anomalies. Many other drought indices have been developed over the years, with monitoring and forecasting purposes, also with the purpose of taking advantage of the opportunities offered by remote sensing and improved general circulation models (GCMs). Moreover, some aggregated indices aimed at capturing the different features of drought have been proposed, but very few drought indices are focused on the groundwater resource status. In this paper a novel Groundwater Resource Index (GRI) is presented as a reliable tool useful in a multi-analysis approach for monitoring and forecasting drought conditions. The GRI is derived from a simple distributed water balance model, and has been tested in a Mediterranean region, characterized by different geo-lithological conditions mainly affecting the summer hydrologic response of the catchments to winter precipitation. The analysis of the GRI characteristics shows a high spatial variability and, compared to the SPI through spectral analysis, a significant sensitivity to the lithological characterization of the analyzed region. Furthermore, the GRI shows a very high auto-correlation during summer months, useful for forecasting purposes. The capability of the proposed index in forecasting summer droughts was tested analyzing the correlation of the GRI April values with the mean summer runoff values of some river basins (obtaining a mean correlation value of 0.60) and with the summer NDVI values of several forested areas, where correlation values greater than 0.77 were achieved. Moreover, its performance

  1. Physical mechanisms of spring and summertime drought related with the global warming over the northern America

    Science.gov (United States)

    Choi, W.; Kim, K. Y.

    2017-12-01

    Drought during the growing season (spring through summer) is severe natural hazard in the large cropland over the northern America. It is important to understand how the drought is related with the global warming and how it will change in the future. This study aims to investigate the physical mechanism of global warming impact on the spring and summertime drought over the northern America using Cyclostationary Empirical Orthogonal Function (CSEOF) analysis. The Northern Hemisphere surface warming, the most dominant mode of the surface air temperature, has resulted in decreased relative humidity and precipitation over the mid-latitude region of North America. For the viewpoint of atmospheric water demand, soil moisture and evaporation have also decreased significantly, exacerbating vulnerability of drought. These consistent features of changes in water demand and supply related with the global warming can provide a possibility of credible insight for future drought change.

  2. The combined effects of a long-term experimental drought and an extreme drought on the use of plant-water sources in a Mediterranean forest.

    Science.gov (United States)

    Barbeta, Adrià; Mejía-Chang, Monica; Ogaya, Romà; Voltas, Jordi; Dawson, Todd E; Peñuelas, Josep

    2015-03-01

    Vegetation in water-limited ecosystems relies strongly on access to deep water reserves to withstand dry periods. Most of these ecosystems have shallow soils over deep groundwater reserves. Understanding the functioning and functional plasticity of species-specific root systems and the patterns of or differences in the use of water sources under more frequent or intense droughts is therefore necessary to properly predict the responses of seasonally dry ecosystems to future climate. We used stable isotopes to investigate the seasonal patterns of water uptake by a sclerophyll forest on sloped terrain with shallow soils. We assessed the effect of a long-term experimental drought (12 years) and the added impact of an extreme natural drought that produced widespread tree mortality and crown defoliation. The dominant species, Quercus ilex, Arbutus unedo and Phillyrea latifolia, all have dimorphic root systems enabling them to access different water sources in space and time. The plants extracted water mainly from the soil in the cold and wet seasons but increased their use of groundwater during the summer drought. Interestingly, the plants subjected to the long-term experimental drought shifted water uptake toward deeper (10-35 cm) soil layers during the wet season and reduced groundwater uptake in summer, indicating plasticity in the functional distribution of fine roots that dampened the effect of our experimental drought over the long term. An extreme drought in 2011, however, further reduced the contribution of deep soil layers and groundwater to transpiration, which resulted in greater crown defoliation in the drought-affected plants. This study suggests that extreme droughts aggravate moderate but persistent drier conditions (simulated by our manipulation) and may lead to the depletion of water from groundwater reservoirs and weathered bedrock, threatening the preservation of these Mediterranean ecosystems in their current structures and compositions. © 2014

  3. Long range forecasting of summer monsoon rainfall from SST in the central equatorial Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Sadhuram, Y; Murthy, T.V.R.

    of summer monsoon rainfall from SST in the central equatorial Indian ocean Y. Sadhuram and T. V. Ramana Murthy National Institute of Oceanography, Regional Centre, 176, Lawson's Bay Colony, . Visakhapatnam-530017 ABSTRACT Severalprediction tedmiques have... and droughts associated with strong and weak monsoons greatly influence the economy of the country. Most of the droughts and floods are associated with EI-Nino and La- Nina respectively (Webster andYang3 and krishna Kumar et al\\. The relationship between ENSO...

  4. Spatial and temporal characteristics of droughts in Luanhe River basin, China

    Science.gov (United States)

    Wang, Yixuan; Zhang, Ting; Chen, Xu; Li, Jianzhu; Feng, Ping

    2018-02-01

    The spatial and temporal characteristics of drought are investigated for Luanhe River basin, using monthly precipitation data from 26 stations covering the common period of 1958-2011. The spatial pattern of drought was assessed by applying principal component analysis (PCA) to the Standardized Precipitation Index (SPI) computed on 3- and 12-month time scales. In addition, annual SPI and seasonal SPIs (including spring SPI, summer SPI, autumn SPI, and winter SPI) were also defined and considered in this study to characterize seasonal and annual drought conditions, respectively. For all seven SPI cases, three distinctive sub-regions with different temporal evolutions of droughts are well identified, respectively, representing the southeast, middle, and northwest of the Luanhe River basin. The Mann-Kendall (MK) trend test with a trend-free pre-whitening (TFPW) procedure and Sen's method were used to determine the temporal trends in the annual and seasonal SPI time series. The continuous wavelet transform (CWT) was employed for further detecting the periodical features of drought condition in each sub-region. Results of MK and Sen's tests show a general tendency of intensification in summer drought over the entire basin, while a significant mitigating trend in spring drought. On the whole, an aggravating trend of inter-annual drought is discovered across the basin. Based on the CWT, the drought variability in the basin is generally dominated by 16- to 64-month cycles, and the 2- to 6-year cycles appear to be obvious when concerned with annual and seasonal droughts. Furthermore, a cross wavelet analysis was performed to examine the possible links between the drought conditions and large-scale climate patterns. The teleconnections of ENSO, NAO, PDO, and AMO show significant influences on the regional droughts principally concentrated in the 16- to 64-month period, maybe responsible for the physical causes of the cyclical behavior of drought occurrences. PDO and AMO also

  5. Joint pattern of seasonal hydrological droughts and floods alternation in China's Huai River Basin using the multivariate L-moments

    Science.gov (United States)

    Wu, ShaoFei; Zhang, Xiang; She, DunXian

    2017-06-01

    Under the current condition of climate change, droughts and floods occur more frequently, and events in which flooding occurs after a prolonged drought or a drought occurs after an extreme flood may have a more severe impact on natural systems and human lives. This challenges the traditional approach wherein droughts and floods are considered separately, which may largely underestimate the risk of the disasters. In our study, the sudden alternation of droughts and flood events (ADFEs) between adjacent seasons is studied using the multivariate L-moments theory and the bivariate copula functions in the Huai River Basin (HRB) of China with monthly streamflow data at 32 hydrological stations from 1956 to 2012. The dry and wet conditions are characterized by the standardized streamflow index (SSI) at a 3-month time scale. The results show that: (1) The summer streamflow makes the largest contribution to the annual streamflow, followed by the autumn streamflow and spring streamflow. (2) The entire study area can be divided into five homogeneous sub-regions using the multivariate regional homogeneity test. The generalized logistic distribution (GLO) and log-normal distribution (LN3) are acceptable to be the optimal marginal distributions under most conditions, and the Frank copula is more appropriate for spring-summer and summer-autumn SSI series. Continuous flood events dominate at most sites both in spring-summer and summer-autumn (with an average frequency of 13.78% and 17.06%, respectively), while continuous drought events come second (with an average frequency of 11.27% and 13.79%, respectively). Moreover, seasonal ADFEs most probably occurred near the mainstream of HRB, and drought and flood events are more likely to occur in summer-autumn than in spring-summer.

  6. Your Best Summer Ever

    Science.gov (United States)

    Cleaver, Samantha

    2012-01-01

    "It must be nice to have summers off." Only other teachers know just how short summer is, with much of August devoted to planning for the new school year. This article offers 17 fresh ideas for exploring, making money, and preparing for next year. Plus, a reading list that hits all the marks!

  7. Indian Summer Arts Festival


    OpenAIRE

    Martel, Yann; Tabu; Tejpal, Tarun; Kunzru, Hari

    2011-01-01

    The SFU Woodward's Cultural Unit partnered with the Indian Summer Festival Society to kick off the inaugural Indian Summer Festival. Held at the Goldcorp Centre for the Arts, it included an interactive Literature Series with notable authors from both India and Canada, including special guests Yann Martel, Bollywood superstar Tabu, journalist Tarun Tejpal, writer Hari Kunzru, and many others.

  8. Impacts of drought on grape yields in Western Cape, South Africa

    Science.gov (United States)

    Araujo, Julio A.; Abiodun, Babatunde J.; Crespo, Olivier

    2016-01-01

    Droughts remain a threat to grape yields in South Africa. Previous studies on the impacts of climate on grape yield in the country have focussed on the impact of rainfall and temperature separately; meanwhile, grape yields are affected by drought, which is a combination of rainfall and temperature influences. The present study investigates the impacts of drought on grape yields in the Western Cape (South Africa) at district and farm scales. The study used a new drought index that is based on simple water balance (Standardized Precipitation Evapotranspiration Index; hereafter, SPEI) to identify drought events and used a correlation analysis to identify the relationship between drought and grape yields. A crop simulation model (Agricultural Production Systems sIMulator, APSIM) was applied at the farm scale to investigate the role of irrigation in mitigating the impacts of drought on grape yield. The model gives a realistic simulation of grape yields. The Western Cape has experienced a series of severe droughts in the past few decades. The severe droughts occurred when a decrease in rainfall occurred simultaneously with an increase in temperature. El Niño Southern Oscillation (ENSO) appears to be an important driver of drought severity in the Western Cape, because most of the severe droughts occurred in El Niño years. At the district scale, the correlation between drought index and grape yield is weak ( r≈-0.5), but at the farm scale, it is strong ( r≈-0.9). This suggests that many farmers are able to mitigate the impacts of drought on grape yields through irrigation management. At the farm scale, where the impact of drought on grape yields is high, poor yield years coincide with moderate or severe drought periods. The APSIM simulation, which gives a realistic simulation of grape yields at the farm scale, suggests that grape yields become more sensitive to spring and summer droughts in the absence of irrigation. Results of this study may guide decision-making on

  9. Could the 2012 Drought in Central U.S. Have Been Anticipated? A Review of NASA Working Group Research

    Science.gov (United States)

    Wang, S.-Y. Simon; Barandiaran, Danny; Hilburn, Kyle; Houser, Paul; Oglesby, Bob; Pan, Ming; Pinker, Rachel; Santanello, Joe; Schubert, Siegfried; Wang, Hailan; hide

    2015-01-01

    This paper summarizes research related to the 2012 record drought in the central United States conducted by members of the NASA Energy and Water cycle Study (NEWS) Working Group. Past drought patterns were analyzed for signal coherency with latest drought and the contribution of long-term trends in the Great Plains low-level jet, an important regional circulation feature of the spring rainy season in the Great Palins. Long-term changes in the seasonal transition from rainy spring into dry summer were also examined. Potential external forcing from radiative processes, soil-air interactions, and ocean teleconnections were assessed as contributors to the intensity of the drought. The atmospheric Rossby wave activity was found to be a potential source of predictability for the onset of drought. A probabilistic model was introduced and evaluated for its performance in predicting drought recovery in the Great Plains.

  10. Spatiotemporal Drought Analysis and Drought Indices Comparison in India

    Science.gov (United States)

    Janardhanan, A.

    2017-12-01

    Droughts and floods are an ever-occurring phenomenon that has been wreaking havoc on humans since the start of time. As droughts are on a very large scale, studying them within a regional context can minimize confounding factors such as climate change. Droughts and floods are extremely erratic and very difficult to predict and therefore necessitate modeling through advanced statistics. The SPI (Standard Precipitation Index) and the SPEI (Standard Precipitation Evapotranspiration Index) are two ways to temporally model drought and flood patterns across each metrological sub basin in India over a variety of different time scales. SPI only accounts for precipitation values, while the SPEI accounts for both precipitation and temperature and is commonly regarded as a more reliable drought index. Using monthly rainfall and temperature data from 1871-2016, these two indices were calculated. The results depict the drought and flood severity index, length of drought, and average SPI or SPEI value for each meteorological sub region in India. A Wilcox Ranksum test was then conducted to determine whether these two indices differed over the long term for drought analysis. The drought return periods were analyzed to determine if the population mean differed between the SPI and SPEI values. Our analysis found no statistical difference between SPI and SPEI with regards to long-term drought analysis. This indicates that temperature is not needed when modeling drought on a long-term time scale and that SPI is just as effective as SPEI, which has the potential to save a lot of time and resources on calculating drought indices.

  11. Developing drought impact functions for drought risk management

    Directory of Open Access Journals (Sweden)

    S. Bachmair

    2017-11-01

    Full Text Available Drought management frameworks are dependent on methods for monitoring and prediction, but quantifying the hazard alone is arguably not sufficient; the negative consequences that may arise from a lack of precipitation must also be predicted if droughts are to be better managed. However, the link between drought intensity, expressed by some hydrometeorological indicator, and the occurrence of drought impacts has only recently begun to be addressed. One challenge is the paucity of information on ecological and socioeconomic consequences of drought. This study tests the potential for developing empirical drought impact functions based on drought indicators (Standardized Precipitation and Standardized Precipitation Evaporation Index as predictors and text-based reports on drought impacts as a surrogate variable for drought damage. While there have been studies exploiting textual evidence of drought impacts, a systematic assessment of the effect of impact quantification method and different functional relationships for modeling drought impacts is missing. Using Southeast England as a case study we tested the potential of three different data-driven models for predicting drought impacts quantified from text-based reports: logistic regression, zero-altered negative binomial regression (hurdle model, and an ensemble regression tree approach (random forest. The logistic regression model can only be applied to a binary impact/no impact time series, whereas the other two models can additionally predict the full counts of impact occurrence at each time point. While modeling binary data results in the lowest prediction uncertainty, modeling the full counts has the advantage of also providing a measure of impact severity, and the counts were found to be reasonably predictable. However, there were noticeable differences in skill between modeling methodologies. For binary data the logistic regression and the random forest model performed similarly well based on

  12. UAV remote sensing for phenotyping drought tolerance in peanuts

    Science.gov (United States)

    Balota, Maria; Oakes, Joseph

    2017-05-01

    Farmers can benefit from growing drought tolerant peanut (Arachis hypogaea L.) cultivars with improved yield when rainfall is sporadic. In the Virginia-Carolina (VC) region, drought is magnified by hot summers and usually occurs in July and Aug when pod and seed growth are intense. At these growth stages, weekly supply of 50 to 75 mm of water is needed to ensure profitability. Irrigation can supplement crop water needs, but only 10% of the peanut farms are irrigated. In this frame, drought tolerant varieties can be profitable, but breeding for cultivars with improved drought tolerance requires fast yet accurate phenotyping. Our objective was to evaluate the potential of UAV remote sensing technologies for drought tolerance selection in peanut. In this study, we examined the effect of drought on leaf wilting, pod yield, grading characteristics, and crop value of 23 peanut cultivars (Virginia, Runner, and Valencia type). These varieties were arranged in a factorial design, with four replications drought stressed and two replications well-watered. Drought was imposed by covering the drought stressed plots with rainout shelters on July 19; they remained covered until August 29 and only received 38 mm irrigation in mid Aug. The well-watered plots continued to receive rain and supplemental irrigation as needed. During this time, Canopy Temperature Depression (CT) and Normalized Differential Vegetative Index (NDVI) were collected from the ground on all plots at weekly intervals. After the shelters were removed, these measurements were collected daily for approximately 2 weeks. At the same time, Red-Green-Blue (RGB), near-infrared (NIR), and infrared (IR) images taken from an UAV platform were also collected. Vegetation indices derived from the ground and aerial data were compared with leaf wilting, pod yield and crop value. Wilting, which is a common water stress symptom, was best estimated by NDVI and RGB, and least by CT; but CT was best in estimating yield, SMK and

  13. Understanding the land-atmospheric interaction in drought forecast from CFSv2 for the 2011 Texas and 2012 Upper Midwest US droughts

    Science.gov (United States)

    Zhang, Y.; Roundy, J. K.; Ek, M. B.; Wood, E. F.

    2015-12-01

    Prediction and thus preparedness in advance of hydrological extremes, such as drought and flood events, is crucial for proactively reducing their social and economic impacts. In the summers of 2011 Texas, and 2012 the Upper Midwest, experienced intense droughts that affected crops and the food market in the US. It is expected that seasonal forecasts with sufficient skill would reduce the negative impacts through planning and preparation. However, the forecast skill from models such as Climate Forecast System Version 2 (CFSv2) from National Centers for Environmental Prediction (NCEP) is low over the US, especially during the warm season (Jun - Sep), which restricts their practical use for drought prediction. This study analyzes the processes that lead to premature termination of 2011 and 2012 US summer droughts in CFSv2 forecast resulting in its low forecast skill. Using the North American Land Data Assimilation System version 2 (NLDAS2) and Climate Forecast System Reanalysis (CFSR) as references, this study investigates the forecast skills of CFSv2 initialized at 00, 06, 12, 18z from May 15 - 31 (leads out to September) for each event in terms of land-atmosphere interaction, through a recently developed Coupling Drought Index (CDI), which is based on the Convective Triggering Potential-Humidity Index-soil moisture (CTP-HI-SM) classification of four climate regimes: wet coupling, dry coupling, transitional and atmospherically controlled. A recycling model is used to trace the moisture sources in the CFSv2 forecasts of anomalous precipitation, which lead to the breakdown of drought conditions and a lack of drought forecasting skills. This is then compared with tracing the moisture source in CFSR with the same recycling model, which is used as the verification for the same periods. This helps to identify the parameterization that triggered precipitation in CFSv2 during 2011 and 2012 summer in the US thus has the potential to improve the forecast skill of CSFv2.

  14. Climatic limits on foliar growth during major droughts in the southwestern USA

    Science.gov (United States)

    Weiss, Jeremy L.; Betancourt, Julio L.; Overpeck, Jonathan T.

    2012-09-01

    Pronounced droughts during the 1950s and 2000s in the American Southwest provide an opportunity to compare mesoscale ecosystem responses to anomalously dry conditions before and during the regional warming that started in the late 1970s. This year-round warming has produced fewer cool season freezes, losses in regional snowpack, an 8-10 day advance in spring onset, and hotter summers, all of which should affect vegetation differently across seasons and elevations. Here, we examine indices that represent climatic limits on foliar growth for both drought periods and evaluate these indices for areas that experienced tree mortality during the 2000s drought. Relative to the 1950s drought, warmer conditions during the 2000s drought decreased the occurrence of temperatures too low for foliar growth at lower elevations in winter and higher elevations in summer. Higher vapor pressure deficits (VPDs), largely driven by warmer temperatures in the more recent drought, were more limiting to foliar growth from spring through summer at lower and middle elevations. At many locations where tree mortality occurred during the 2000s drought, low-temperature constraints on foliar growth were extremely unlimiting, whereas VPD constraints were extremely limiting from early spring through late autumn. Our analysis shows that in physiographically complex regions such as the Southwest, seasonality and elevational gradients are important for understanding vegetative responses to warming. It also suggests that continued warming will both increase the degree to which VPD limits foliar growth during future droughts and expand its reach to higher elevations and other seasons.

  15. Registration Summer Camp 2016

    CERN Multimedia

    2016-01-01

    Reminder: registration for the CERN Staff Association Summer Camp is now open for children from 4 to 6 years old.   More information on the website: http://nurseryschool.web.cern.ch/. The summer camp is open to all children. The proposed cost is 480.-CHF/week, lunch included. The camp will be open weeks 27, 28, 29 and 30, from 8:30 a.m. to 5:30 p.m. For further questions, you are welcome to contact us by email at Summer.Camp@cern.ch. CERN Staff Association

  16. Drought-induced weakening of growth-temperature associations in high-elevation Iberian pines

    Czech Academy of Sciences Publication Activity Database

    Diego Galvan, J.; Büntgen, Ulf; Ginzler, Ch.; Grudd, H.; Gutierrez, E.; Labuhn, I.; Julio Camarero, J.

    2015-01-01

    Roč. 124, JAN (2015), s. 95-106 ISSN 0921-8181 Institutional support: RVO:67179843 Keywords : tree-ring chronologies * regional curve standardization * pinus-uncinata * european alps * spatial variability * summer temperatures * divergence problem * spanish pyrenees * fagus-sylvatica * large-scale * Climate change * Drought * Growth response * High-elevation forest * Pyrenees * Summer temperature Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 3.548, year: 2015

  17. Contrasting impacts of continuous moderate drought and episodic severe droughts on the aboveground-biomass increment and litterfall of three coexisting Mediterranean woody species.

    Science.gov (United States)

    Liu, Daijun; Ogaya, Romà; Barbeta, Adrià; Yang, Xiaohong; Peñuelas, Josep

    2015-11-01

    Climate change is predicted to increase the aridity in the Mediterranean Basin and severely affect forest productivity and composition. The responses of forests to different timescales of drought, however, are still poorly understood because extreme and persistent moderate droughts can produce nonlinear responses in plants. We conducted a rainfall-manipulation experiment in a Mediterranean forest dominated by Quercus ilex, Phillyrea latifolia, and Arbutus unedo in the Prades Mountains in southern Catalonia from 1999 to 2014. The experimental drought significantly decreased forest aboveground-biomass increment (ABI), tended to increase the litterfall, and decreased aboveground net primary production throughout the 15 years of the study. The responses to the experimental drought were highly species-specific. A. unedo suffered a significant reduction in ABI, Q. ilex experienced a decrease during the early experiment (1999-2003) and in the extreme droughts of 2005-2006 and 2011-2012, and P. latifolia was unaffected by the treatment. The drought treatment significantly increased branch litterfall, especially in the extremely dry year of 2011, and also increased overall leaf litterfall. The drought treatment reduced the fruit production of Q. ilex, which affected seedling recruitment. The ABIs of all species were highly correlated with SPEI in early spring, whereas the branch litterfalls were better correlated with summer SPEIs and the leaf and fruit litterfalls were better correlated with autumn SPEIs. These species-specific responses indicated that the dominant species (Q. ilex) could be partially replaced by the drought-resistant species (P. latifolia). However, the results of this long-term study also suggest that the effect of drought treatment has been dampened over time, probably due to a combination of demographic compensation, morphological and physiological acclimation, and epigenetic changes. However, the structure of community (e.g., species composition

  18. Analysis of Drought in North Darfur Region of Sudan: Application of the DPSIR Framework on Long Term Data

    Science.gov (United States)

    Mohmmed, Alnail; Zhange, Ke; Makomere, Reuben; Twecan, Dalson; Mohamme, Mustafa

    2017-04-01

    Darfur region in western Sudan is located in one of the world's most inhospitable environments, adjacent to the Sahara desert, conflicts and drought have severely degraded this fragile area, devastating the environment, livestock and people. Northern Darfur is bedeviled with frequent drought due to insufficient water resources, high summer temperatures, and poor precipitation. Monitoring drought and providing timely seasonal predictions is important for integrated drought risk reduction in the region. This paper evaluates drought conditions in North Darfur by applying meteorological, remote sensing and crop production data, as well as the Driving force-Pressure-State-Impacts-Response (DPSIR) assessment framework. Interviews, group discussions and participant observations were conducted in order to understand the DPSIR framework indicators. The relationship between the Reconnaissance Drought Index (RDI), Vegetation Condition Index (VCI) and Soil Moisture Content Index (SMCI) were evaluated utilizing data from all five North Darfur counties during 10 growing seasons (2004-2013). Our results showed a strong correlation between RDI, VCI, and SMAI. Also, a significant agreement was noticed between Yield Anomaly Index (YAI) and Rainfall Anomaly Index (RAI). Generally, a high correlation coefficient was obtained between the meteorology drought index and remote sensing indices, which demonstrates the effectiveness of the above indices for evaluating agricultural drought in the sub-Saharan area. Keywords: Drought; Vegetation Condition Index; Reconnaissance Drought Index; Soil Moisture Content Index; North Darfur.

  19. 2003 SOLAS Summer School

    National Research Council Canada - National Science Library

    McGillis, Wade R

    2003-01-01

    In 2003, the United States provided support for the participation of 18 students, three research assistants, and seven lecturers in the first Surface Ocean Lower Atmosphere Study (SOLAS) Summer School...

  20. Summer Meal Sites

    Data.gov (United States)

    Allegheny County / City of Pittsburgh / Western PA Regional Data Center — Information pertaining to Summer Meal Sites, as collected by Citiparks in the City of Pittsburgh Department of Parks and Recreation. This dataset includes the...

  1. Legacy effects of drought on plant growth and the soil food web

    DEFF Research Database (Denmark)

    de Vries, Franciska; Liiri, Mira; Strandmark, Lisa Bjørnlund

    2012-01-01

    the potential to feed back on each other's performance. In a greenhouse experiment, we compared legacy effects of repeated drought on plant growth and the soil food web in two contrasting land-use systems: extensively managed grassland, rich in C and with a fungal-based food web, and intensively managed wheat...... lower in C and with a bacterial-based food web. Moreover, we assessed the effect of plant presence on the recovery of the soil food web after drought. Drought legacy effects increased plant growth in both systems, and a plant strongly reduced N leaching. Fungi, bacteria, and their predators were more...... resilient after drought in the grassland soil than in the wheat soil. The presence of a plant strongly affected the composition of the soil food web, and alleviated the effects of drought for most trophic groups, regardless of the system. This effect was stronger for the bottom trophic levels, whose...

  2. Summer Steelhead Distribution [ds341

    Data.gov (United States)

    California Natural Resource Agency — Summer Steelhead Distribution October 2009 Version This dataset depicts observation-based stream-level geographic distribution of anadromous summer-run steelhead...

  3. Drought-induced weakening of growth-temperature associations in high-elevation Iberian pines

    Science.gov (United States)

    Diego Galván, J.; Büntgen, Ulf; Ginzler, Christian; Grudd, Håkan; Gutiérrez, Emilia; Labuhn, Inga; Julio Camarero, J.

    2015-01-01

    The growth/climate relationship of theoretically temperature-controlled high-elevation forests has been demonstrated to weaken over recent decades. This is likely due to new tree growth limiting factors, such as an increasing drought risk for ecosystem functioning and productivity across the Mediterranean Basin. In addition, declining tree growth sensitivity to spring temperature may emerge in response to increasing drought stress. Here, we evaluate these ideas by assessing the growth/climate sensitivity of 1500 tree-ring width (TRW) and 102 maximum density (MXD) measurement series from 711 and 74 Pinus uncinata trees, respectively, sampled at 28 high-elevation forest sites across the Pyrenees and two relict populations of the Iberian System. Different dendroclimatological standardization and split period approaches were used to assess the high- to low-frequency behavior of 20th century tree growth in response to temperature means, precipitation totals and drought indices. Long-term variations in TRW track summer temperatures until about 1970 but diverge afterwards, whereas MXD captures the recent temperature increase in the low-frequency domain fairly well. On the other hand summer drought has increasingly driven TRW along the 20th century. Our results suggest fading temperature sensitivity of Iberian high-elevation P. uncinata forest growth, and reveal the importance of summer drought that is becoming the emergent limiting factor of tree ring width formation in many parts of the Mediterranean Basin.

  4. A phenological timetable of oak growth under experimental drought and air warming.

    Directory of Open Access Journals (Sweden)

    Thomas M Kuster

    Full Text Available Climate change is expected to increase temperature and decrease summer precipitation in Central Europe. Little is known about how warming and drought will affect phenological patterns of oaks, which are considered to possess excellent adaptability to these climatic changes. Here, we investigated bud burst and intra-annual shoot growth of Quercus robur, Q. petraea and Q. pubescens grown on two different forest soils and exposed to air warming and drought. Phenological development was assessed over the course of three growing seasons. Warming advanced bud burst by 1-3 days °C⁻¹ and led to an earlier start of intra-annual shoot growth. Despite this phenological shift, total time span of annual growth and shoot biomass were not affected. Drought changed the frequency and intensity of intra-annual shoot growth and advanced bud burst in the subsequent spring of a severe summer drought by 1-2 days. After re-wetting, shoot growth recovered within a few days, demonstrating the superior drought tolerance of this tree genus. Our findings show that phenological patterns of oaks are modified by warming and drought but also suggest that ontogenetic factors and/or limitations of water and nutrients counteract warming effects on the biomass and the entire span of annual shoot growth.

  5. Climate Change Decouples Drought from Early Wine Grape Harvests in France

    Science.gov (United States)

    Cook, Benjamin I.; Wolkovich, Elizabeth M.

    2016-01-01

    Across the world, wine grape phenology has advanced in recent decades, in step with climate-change-induced trends in temperature - the main driver of fruit maturation - and drought. Fully understanding how climate change contributes to changes in harvest dates, however, requires analysing wine grape phenology and its relationship to climate over a longer-term context, including data predating anthropogenic interference in the climate system. Here, we investigate the climatic controls of wine grape harvest dates from 1600-2007 in France and Switzerland using historical harvest and climate data. Early harvests occur with warmer temperatures (minus 6 days per degree Centigrade) and are delayed by wet conditions (plus 0.07 days per millimeter; plus 1.68 days per PDSI (Palmer drought severity index)) during spring and summer. In recent decades (1981-2007), however, the relationship between harvest timing and drought has broken down. Historically, high summer temperatures in Western Europe, which would hasten fruit maturation, required drought conditions to generate extreme heat. The relationship between drought and temperature in this region, however, has weakened in recent decades and enhanced warming from anthropogenic greenhouse gases can generate the high temperatures needed for early harvests without drought. Our results suggest that climate change has fundamentally altered the climatic drivers of early wine grape harvests in France, with possible ramifications for viticulture management and wine quality.

  6. Tolerance to multiple climate stressors: A case study of Douglas-fir drought and cold hardiness

    Science.gov (United States)

    Bansal, Sheel; Harrington, Constance A; St. Clair, John Bradley

    2016-01-01

    Summary: 1. Drought and freeze events are two of the most common forms of climate extremes which result in tree damage or death, and the frequency and intensity of both stressors may increase with climate change. Few studies have examined natural covariation in stress tolerance traits to cope with multiple stressors among wild plant populations. 2. We assessed the capacity of coastal Douglas-fir (Pseudotsuga menziesii var. menziesii), an ecologically and economically important species in the northwestern USA, to tolerate both drought and cold stress on 35 populations grown in common gardens. We used principal components analysis to combine drought and cold hardiness trait data into generalized stress hardiness traits to model geographic variation in hardiness as a function of climate across the Douglas-fir range. 3. Drought and cold hardiness converged among populations along winter temperature gradients and diverged along summer precipitation gradients. Populations originating in regions with cold winters had relatively high tolerance to both drought and cold stress, which is likely due to overlapping adaptations for coping with winter desiccation. Populations from regions with dry summers had increased drought hardiness but reduced cold hardiness, suggesting a trade-off in tolerance mechanisms. 4. Our findings highlight the necessity to look beyond bivariate trait–climate relationships and instead consider multiple traits and climate variables to effectively model and manage for the impacts of climate change on widespread species.

  7. Drought, nutrition and food security

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. Drought associated with climate change may lead to food and water shortage. Drought associated with climate change may lead to food and water shortage. Greater vulnerability to infectious diseases. Population displacements and mass migrations with all ...

  8. Drought and ecosystem carbon cycling

    NARCIS (Netherlands)

    Molen, M.K. van der; Dolman, A.J.; Ciais, P.; Eglin, T.; Gobron, N.; Law, B.E.; Meir, P.; Peters, P.; Philips, O.L.; Reichstein, M.; Chen, T.; Dekker, S.C.; Doubkova, M.; Friedl, M.A.; Jung, M.; Hurk, B.J.J.M. van den; Jeu, R.A.M. de; Kruijt, B.; Ohta, T.; Rebel, K.T.; Plummer, S.; Seneviratne, S.I.; Sitch, S.; Teuling, A.J.; Werf, G.R. van der; Wang, G.

    2011-01-01

    Drought as an intermittent disturbance of the water cycle interacts with the carbon cycle differently than the ‘gradual’ climate change. During drought plants respond physiologically and structurally to prevent excessive water loss according to species-specific water use strategies. This has

  9. A European Drought Reference Database: Design and Online Implementation

    NARCIS (Netherlands)

    Stagge, J.H.; Tallaksen, L.M.; Kohn, I.; Stahl, K.; Loon, van A.

    2013-01-01

    This report presents the structure and status of the online European Drought Reference (EDR) database. This website provides detailed historical information regarding major historical European drought events. Each drought event is summarized using climatological drought indices, hydrological drought

  10. Predicting forest dieback in Maine, USA: a simple model based on soil frost and drought

    Science.gov (United States)

    Allan N.D. Auclair; Warren E. Heilman; Blondel. Brinkman

    2010-01-01

    Tree roots of northern hardwoods are shallow rooted, winter active, and minimally frost hardened; dieback is a winter freezing injury to roots incited by frost penetration in the absence of adequate snow cover and exacerbated by drought in summer. High soil water content greatly increases conductivity of frost. We develop a model based on the sum of z-scores of soil...

  11. Legume ground covers alter defoliation response of black walnut saplings to drought and anthracnose

    Science.gov (United States)

    J. W. Van Sambeek

    2003-01-01

    Growth and premature defoliation of black walnut saplings underplanted 5 or 6 years earlier with six different ground covers were quantified in response to a summer drought or anthracnose. Walnut saplings growing with ground covers of hairy vetch, crownvetch, and to a lesser extent sericea lespedeza continued to have more rapid height and diameter growth than saplings...

  12. Water Storage, Mixing and Transit Times During a Multiyear Drought.

    Science.gov (United States)

    Van der Velde, Y.; Visser, A.; Thaw, M.; Safeeq, M.

    2017-12-01

    From 2012 to 2016, a five year intensive drought occurred in the Californian Sierra Nevada. We use this drought period as an opportunity to investigate how catchment water storage, mixing and transit times changes from wet to dry conditions using long term datasets of river discharge, evapotranspiration, water quality, and multiple cosmogenic radioactive isotopes. Characteristic features of the test catchment (4.6 km2 , altitude 1660-2117 m) include a thick (>5m) unsaturated zone in deeply weathered granite mountain soils, snow melt and events of high intensity rainfall, dry summers and numerous wetland meadows along the stream. Our data and model analysis suggest that under drought conditions, river flow predominantly consist of deep groundwater tapped by deeply incised sections of the stream, while the wetlands hold on to their water just below the root system of its shallow rooting vegetation. In contrast, during wet periods, most runoff is generated on the flat riparian wetland meadows, while the regional groundwater system slowly refills itself as water makes its way through the thick unsaturated zones. Antecedent wet or dry years play an crucial role as antecedent wet years cause a substantial regional groundwater flow towards the riparian wetlands, filling up the riparian wetlands and yielding a much stronger discharge response of the wetlands to rainfall events than under antecedent dry years This interaction between the regional groundwater system and the local wetland systems weakens as the drought progresses and regional groundwater flow to the wetlands lessens. Although, due to the wet events in 2016-2017, the catchment fills up rapidly to pre-drought conditions, we show that water transit times and therefore likely the water quality will contain drought signs for several years to come. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS- XXXXXX

  13. Methods for estimating drought streamflow probabilities for Virginia streams

    Science.gov (United States)

    Austin, Samuel H.

    2014-01-01

    Maximum likelihood logistic regression model equations used to estimate drought flow probabilities for Virginia streams are presented for 259 hydrologic basins in Virginia. Winter streamflows were used to estimate the likelihood of streamflows during the subsequent drought-prone summer months. The maximum likelihood logistic regression models identify probable streamflows from 5 to 8 months in advance. More than 5 million streamflow daily values collected over the period of record (January 1, 1900 through May 16, 2012) were compiled and analyzed over a minimum 10-year (maximum 112-year) period of record. The analysis yielded the 46,704 equations with statistically significant fit statistics and parameter ranges published in two tables in this report. These model equations produce summer month (July, August, and September) drought flow threshold probabilities as a function of streamflows during the previous winter months (November, December, January, and February). Example calculations are provided, demonstrating how to use the equations to estimate probable streamflows as much as 8 months in advance.

  14. Drought as a natural disaster

    Energy Technology Data Exchange (ETDEWEB)

    Maybank, J. [Agvironics Consulting, SK (Canada); Bonsal, B. [Saskatchewan Univ., Saskatoon, SK (Canada). Dept. of Geography; Jones, K. [Environment Canada, Downsview, ON (Canada). Canadian Climate Centre; Lawford, R. [Canadian Climate Centre, Saskatoon, SK (Canada). National Hydrology Research Centre; O`Brien, E.G. [Agriculture Canada, Ottawa, ON (Canada). Energy Analysis and Policy Div.; Ripley, E.A. [Saskatchewan Univ., Saskatoon, SK (Canada). Dept. of Soil Science; Wheaton, E. [Saskatchewan Research Council, Saskatoon, SK (Canada)

    1995-12-31

    A discussion of droughts as a major natural disaster in dry areas such as the Canadian Prairies where precipitation patterns are seasonal, was presented. Environmental damages include soil degradation and erosion, vegetation damage, slough and lake deterioration and wildlife loss. The development and application of specific soil moisture and drought indices based on cumulative precipitation deficits have enhanced drought monitoring programs. The identification of precursor conditions raises the possibility that the likelihood of a drought occurring in a particular year or growing season might be predictable. The ability to forecast seasonal temperature and precipitation anomalies is potentially feasible using a suitable merging of precursor parameters and modelling methodologies. Research activity to identify and evaluate new mitigative measure should be increased to keep pace with the prospects of drought predictability. 90 refs., 1 tab., 7 figs.

  15. An underestimated role of precipitation frequency in regulating summer soil moisture

    International Nuclear Information System (INIS)

    Wu Chaoyang; Chen, Jing M; Pumpanen, Jukka; Cescatti, Alessandro; Marcolla, Barbara; Blanken, Peter D; Ardö, Jonas; Tang, Yanhong; Magliulo, Vincenzo; Georgiadis, Teodoro; Soegaard, Henrik; Cook, David R; Harding, Richard J

    2012-01-01

    Soil moisture induced droughts are expected to become more frequent under future global climate change. Precipitation has been previously assumed to be mainly responsible for variability in summer soil moisture. However, little is known about the impacts of precipitation frequency on summer soil moisture, either interannually or spatially. To better understand the temporal and spatial drivers of summer drought, 415 site yr measurements observed at 75 flux sites world wide were used to analyze the temporal and spatial relationships between summer soil water content (SWC) and the precipitation frequencies at various temporal scales, i.e., from half-hourly, 3, 6, 12 and 24 h measurements. Summer precipitation was found to be an indicator of interannual SWC variability with r of 0.49 (p < 0.001) for the overall dataset. However, interannual variability in summer SWC was also significantly correlated with the five precipitation frequencies and the sub-daily precipitation frequencies seemed to explain the interannual SWC variability better than the total of precipitation. Spatially, all these precipitation frequencies were better indicators of summer SWC than precipitation totals, but these better performances were only observed in non-forest ecosystems. Our results demonstrate that precipitation frequency may play an important role in regulating both interannual and spatial variations of summer SWC, which has probably been overlooked or underestimated. However, the spatial interpretation should carefully consider other factors, such as the plant functional types and soil characteristics of diverse ecoregions. (letter)

  16. Spatio-temporal seasonal drought patterns in Europe from 1950 to 2015

    Science.gov (United States)

    Spinoni, Jonathan; Naumann, Gustavo; Vogt, Jürgen

    2016-04-01

    Drought is one of the natural disasters with severe impacts in Europe, not only in areas which frequently experience water scarcity such as the Mediterranean, but also in temperate or continental climates such as Central and Eastern Europe and even in cold regions such as Scandinavia and Iceland. In this study the spatio-temporal patterns of seasonal meteorological droughts in Europe between 1950 and 2015 are investigated using the Standardized Precipitation Index (SPI) and the Standardized Precipitation-Evapotranspiration Index (SPEI). Since the focus is on the analysis of seasonal drought trends, indicators were calculated for 3 monthly accumulation periods. The input variables of precipitation and temperature were derived from E-OBS grids (v11-v12) at a spatial resolution of 0.25°x0.25°. Seasonal trends of drought frequency and severity were analyzed for moderate (SPI or SPEI 2.0) events during the periods 1950-2015 and 1981-2015. For the moderate events, results of the SPI analysis (precipitation driven) demonstrate a significant tendency towards less frequent and severe droughts in Northern Europe and Russia, especially in winter and spring; oppositely, an increasing trend is visible in Southern Europe, mainly in spring and summer. According to the SPEI analysis (precipitation and temperature driven) Northern Europe shows wetting patterns, while Southern and Eastern Europe show a more remarkable drying tendency, especially in summer and autumn for drought frequency and in every season for drought severity. The evolution towards drier conditions is more relevant from 1981 onwards, both in terms of frequency and severity. This is especially true for Central Europe in spring, for the Mediterranean in summer, and for Eastern Europe in autumn. Extreme events follow similar patterns, but in autumn no spatially coherent trend can be found.

  17. Is Managed Wildfire Protecting Yosemite National Park from Drought?

    Science.gov (United States)

    Boisrame, G. F. S.; Thompson, S. E.; Stephens, S.; Collins, B.; Kelly, M.; Tague, N.

    2016-12-01

    Fire suppression in many dry forest types has left a legacy of dense, homogeneous forests. Such landscapes have high water demands and fuel loads, and when burned can result in catastrophically large fires. These characteristics are undesirable in the face of projected warming and drying in the Western US. This project explores the potential of managed wildfire - a forest management strategy in which fires caused by lightning are allowed to burn naturally as long as certain safety parameters are met - to reverse the effects of fire suppression. The Illilouette Creek Basin in Yosemite National Park has experienced 40 years of managed wildfire, reducing forest cover and increasing meadow and shrubland areas. We have collected evidence from field measurements and remote sensing which suggest that managed wildfire increases landscape and hydrologic heterogeneity, and likely improves resilience to disturbances such as fire and drought. Vegetation maps created from aerial photos show an increase in landscape heterogeneity following the introduction of managed wildfire. Soil moisture observations during the drought years of 2013-2016 suggest that transitions from dense forest to shrublands or meadows can increase summer soil moisture. In the winter of 2015-2016, snow depth measurements showed deeper spring snowpacks in burned areas compared to dense forests. Our study provides a unique view of relatively long-term effects of managed wildfire on vegetation change, ecohydrology, and drought resistance. Understanding these effects is increasingly important as the use of managed wildfire becomes more widely accepted, and as the likelihood of both drought and wildfire increases.

  18. Drought effects on large fire activity in Canadian and Alaskan forests

    International Nuclear Information System (INIS)

    Xiao Jingfeng; Zhuang Qianlai

    2007-01-01

    Fire is the dominant disturbance in forest ecosystems across Canada and Alaska, and has important implications for forest ecosystems, terrestrial carbon dioxide emissions and the forestry industry. Large fire activity had increased in Canadian and Alaskan forests during the last four decades of the 20th century. Here we combined the Palmer Drought Severity Index and historical large fire databases to demonstrate that Canada and Alaska forest regions experienced summer drying over this time period, and drought during the fire season significantly affected forest fire activity in these regions. Climatic warming, positive geopotential height anomalies and ocean circulation patterns were spatially and temporally convolved in causing drought conditions, which in turn enhanced fuel flammability and thereby indirectly affected fire activity. Future fire regimes will likely depend on drought patterns under global climate change scenarios

  19. Summer Camp Registrations 2018

    CERN Multimedia

    Staff Association

    2018-01-01

    Registration for the CERN SA Summer camp, for children from 4 to 6 years old, is now open. The general conditions are available on the EVE and School website: http://nurseryschool.web.cern.ch For further questions, please contact us by email at  Summer.Camp@cern.ch An inscription per week is proposed, for 450.-CHF/week, lunch included. The camp will be open on weeks 27, 28, 29 and 30, from 8:30 am to 5:30 pm. This year the theme will be Vivaldi’s Four Seasons.

  20. Spatiotemporal Distribution of Droughts in the Xijiang River Basin, China and Its Responses to Global Climatic Events

    Directory of Open Access Journals (Sweden)

    Jizhong Qiu

    2017-04-01

    Full Text Available The Xijiang River is a main branch of the Pearl River, the largest river in South China. Droughts in this area have seriously influenced local water resource utilization, and socio-economic development. The spatiotemporal distribution of droughts and its responses to global climatic events are of critical significance for the assessment and early warning of drought disasters. In this paper, the spatiotemporal patterns of droughts characterized by Rotated Empirical Orthogonal Function/Rotated Principal Components (REOF/RPC in the Xijiang River Basin, China were evaluated using the Self-calibrated Palmer Drought Severity Index (Sc-PDSI. The drought responses to El Niño/Southern Oscillation (ENSO, Pacific Decadal Oscillation (PDO, India Ocean Dipole (IOD, and North Atlantic Oscillation (NAO were analysed by Pearson correlation and multiple stepwise regression. The results showed that one year earlier NAO was the dominant factor impacting the droughts in the Xijiang Basin. Its contribution for the RPC2s of the annual, the first and second half years, winter, summer, autumn, and February were −0.556, −0.419, 0.597, −0.447, 0.542, 0.600, and −0.327, respectively. Besides the two adjacent Pacific and India oceans, the droughts seem be influenced by distant Atlantic climatic events. These results offer new reference insights into the early warning of droughts as well as the planning and management of water resources in the study area.

  1. Dampening effects of long-term experimental drought on growth and mortality rates of a Holm oak forest.

    Science.gov (United States)

    Barbeta, Adrià; Ogaya, Romà; Peñuelas, Josep

    2013-10-01

    Forests respond to increasing intensities and frequencies of drought by reducing growth and with higher tree mortality rates. Little is known, however, about the long-term consequences of generally drier conditions and more frequent extreme droughts. A Holm oak forest was exposed to experimental rainfall manipulation for 13 years to study the effect of increasing drought on growth and mortality of the dominant species Quercus ilex, Phillyrea latifolia, and Arbutus unedo. The drought treatment reduced stem growth of A. unedo (-66.5%) and Q. ilex (-17.5%), whereas P. latifolia remained unaffected. Higher stem mortality rates were noticeable in Q. ilex (+42.3%), but not in the other two species. Stem growth was a function of the drought index of early spring in the three species. Stem mortality rates depended on the drought index of winter and spring for Q. ilex and in spring and summer for P. latifolia, but showed no relation to climate in A. unedo. Following a long and intense drought (2005-2006), stem growth of Q. ilex and P. latifolia increased, whereas it decreased in A. unedo. Q. ilex also enhanced its survival after this period. Furthermore, the effect of drought treatment on stem growth in Q. ilex and A. unedo was attenuated as the study progressed. These results highlight the different vulnerabilities of Mediterranean species to more frequent and intense droughts, which may lead to partial species substitution and changes in forest structure and thus in carbon uptake. The response to drought, however, changed over time. Decreased intra- and interspecific competition after extreme events with high mortality, together with probable morphological and physiological acclimation to drought during the study period, may, at least in the short term, buffer forests against drier conditions. The long-term effects of drought consequently deserve more attention, because the ecosystemic responses are unlikely to be stable over time.Nontechnical summaryIn this study, we

  2. Quercitol and osmotic adaptation of field-grown Eucalyptus under seasonal drought stress.

    Science.gov (United States)

    Arndt, Stefan K; Livesley, Stephen J; Merchant, Andrew; Bleby, Timothy M; Grierson, Pauline F

    2008-07-01

    This study investigated the role of quercitol in osmotic adjustment in field-grown Eucalyptus astringens Maiden subject to seasonal drought stress over the course of 1 year. The trees grew in a native woodland and a farm plantation in the semi-arid wheatbelt region of south Western Australia. Plantation trees allocated relatively more biomass to leaves than woodland trees, but they suffered greater drought stress over summer, as indicated by lower water potentials, CO(2)assimilation rates and stomatal conductances. In contrast, woodland trees had relatively fewer leaves and suffered less drought stress. Plantation trees under drought stress engaged in osmotic adjustment, but woodland trees did not. Quercitol made a significant contribution to osmotic adjustment in drought-stressed trees (25% of total solutes), and substantially more quercitol was measured in the leaves of plantation trees (5% dry matter) than in the leaves of woodland trees (2% dry matter). We found no evidence that quercitol was used as a carbon storage compound while starch reserves were depleted under drought stress. Differences in stomatal conductance, biomass allocation and quercitol production clearly indicate that E. astringens is both morphologically and physiologically 'plastic' in response to growth environment, and that osmotic adjustment is only one part of a complex strategy employed by this species to tolerate drought.

  3. Politics and drought planning: Friends or foes?

    International Nuclear Information System (INIS)

    McDowell, B.D.; Blomquist, W.

    1993-01-01

    Nothing frustrates the average drought planner more than politics. Yet, droughts cannot be prepared for realistically without reliable political partners, smoothly cooperating government agencies, and strong public support. This paper suggests six rules for linking technical drought planning processes to the political processes and institutions that can implement drought plans

  4. Economics and societal considerations of drought

    Science.gov (United States)

    Jeff Prestemon; Linda Kruger; Karen L. Abt; Michael Bowker; Consuelo Brandeis; Dave Calkin; Geoffrey H. Donovan; Charlotte Ham; Thomas P. Holmes; Jeffrey Kline; Travis Warziniack

    2016-01-01

    The economic and social effects of drought are diverse and related to physical characteristics of drought, including spatial extent, severity, duration, and frequency that combine to determine drought’s overall effects on society. Most of the attention given to economic and social impacts of drought focuses on adverse consequences, but technology, public...

  5. Genetic dissection of drought tolerance in potato

    NARCIS (Netherlands)

    Anithakumari, A.M.

    2011-01-01

    Drought is the most important cause of crop and yield loss around the world. Breeding for

    drought tolerance is not straightforward, as drought is a complex trait. A better understanding

    of the expression of drought traits, the genes underlying the traits and the way these

  6. Drought Tip: Keeping Plants Alive under Drought or Water Restrictions

    OpenAIRE

    Hartin, Janet; Oki, Loren; Fujino, Dave; Faber, Ben

    2015-01-01

    Plants that don't receive enough water eventually show signs of water stress. During a drought or under water restrictions aimed at water conservation, keeping plants alive can be particularly difficult.

  7. ASHRAE Summer Meeting 1998

    DEFF Research Database (Denmark)

    Rudbeck, Claus Christian

    1998-01-01

    ASHRAE's (American Society for Heating, Refrigerating and Air- Condition Engineering) summer meeting was visited in June in Toronto. ASHRAE is an American organization dealing with American problems in HVAC, but many results can be used under Danish conditions. It is therefore essential that Danish...

  8. Summer of history

    NARCIS (Netherlands)

    Burman, Jeremy Trevelyan

    2017-01-01

    This summer, the University of Groningen will host three events—yes, three—that will be of special interest to the historically- and theoretically-inclined. The meeting of the International Society for the History of Philosophy of Science (HOPOS) will be held on July 9-12, a workshop exploring the

  9. Books for Summer Reading.

    Science.gov (United States)

    Phi Delta Kappan, 1992

    1992-01-01

    Advises administrators to use their summers to relax and recharge their intellectual batteries. Reading suggestions include Edith Wharton's "House of Mirth," Charlotte Perkins Gilman's "The Yellow Wallpaper," Amy Tan's "Joy Luck Club," China Achebe's "Things Fall Apart," Paule Marshall's "The Chosen…

  10. Future Drought Projections over the Iberian Peninsula using Drought Indices

    Science.gov (United States)

    Garcia-Valdecasas Ojeda, M.; Yeste Donaire, P.; Góngora García, T. M.; Gámiz-Fortis, S. R.; Castro-Diez, Y.; Esteban-Parra, M. J.

    2017-12-01

    Currently, drought events are the cause of numerous annual economic losses. In a context of climate change, it is expected an increase in the severity and the frequency of drought occurrences, especially in areas such as the Mediterranean region. This study makes use of two drought indices in order to analyze the potential changes on future drought events and their effects at different time scales over a vulnerable region, the Iberian Peninsula. The indices selected were the Standardized Precipitation Evapotranspiration Index (SPEI), which takes into account the global warming through the temperature, and the Standardized Precipitation Index (SPI), based solely on precipitation data, at a spatial resolution of 0.088º ( 10 km). For their computation, current (1980-2014) and future (2021-2050 and 2071-2100) high resolution simulations were carried out using the Weather Research and Forecasting (WRF) model over a domain centered in the Iberian Peninsula, and nested in the 0.44 EUROCORDEX region. WRF simulations were driven by two different global bias-corrected climate models: the version 1 of NCAR's Community Earth System Model (CESM1) and the Max Planck Institute's Earth System Model (MPI-ESM-LR), and under two different Representative Concentration Pathway (RCP) scenarios: RCP 4.5 and RCP 8.5. Future projections were analyzed regarding to changes in mean, median and variance of drought indices with respect to the historical distribution, as well as changes in the frequency and duration of moderate and severe drought events. In general, results suggest an increase in frequency and severity of drought, especially for 2071-2100 period in the RCP 8.5 scenario. Results also shown an increase of drought phenomena more evident using the SPEI. Conclusions from this study could provide a valuable contribution to the understanding of how the increase of the temperature would affect the drought variability in the Mediterranean regions which is necessary for a suitable

  11. Improving Federal Response to Drought.

    Science.gov (United States)

    Wilhite, Donald A.; Rosenberg, Norman J.; Glantz, Michael H.

    1986-03-01

    Severe and widespread drought occurred over a large portion of the United States between 1974 and 1977. Impacts on agriculture and other industries, as well as local water supplies, were substantial. The federal government responded with forty assistance programs administered by sixteen federal agencies. Assistance was provided primarily in the form of loans and grants to people, businesses and governments experiencing hardship caused by drought. The total cost of the program is estimated at $7-8 billion.Federal response to the mid-1970s drought was largely untimely, ineffective and poorly coordinated. Four recommendations are offered that, if implemented, would improve future drought assessment and response efforts: 1) reliable and timely informational products and dissemination plans; 2) improved impact assessment techniques, especially in the agricultural sector, for use by government to identify periods of enhanced risk and to trigger assistance measures; 3) administratively centralized drought declaration procedures that are well publicized and consistently applied; and 4) standby assistance measures that encourage appropriate levels of risk management by producers and that are equitable, consistent and predictable. The development of a national drought plan that incorporates these four items is recommended. Atmospheric scientists have an important role to play in the collection and interpretation of near-real time weather data for use by government decision makers.

  12. Hydrologic drought of water year 2011 compared to four major drought periods of the 20th century in Oklahoma

    Science.gov (United States)

    Shivers, Molly J.; Andrews, William J.

    2013-01-01

    Water year 2011 (October 1, 2010, through September 30, 2011) was a year of hydrologic drought (based on streamflow) in Oklahoma and the second-driest year to date (based on precipitation) since 1925. Drought conditions worsened substantially in the summer, with the highest monthly average temperature record for all States being broken by Oklahoma in July (89.1 degrees Fahrenheit), June being the second hottest and August being the hottest on record for those months for the State since 1895. Drought conditions continued into the fall, with all of the State continuing to be in severe to exceptional drought through the end of September. In addition to effects on streamflow and reservoirs, the 2011 drought increased damage from wildfires, led to declarations of states of emergency, water-use restrictions, and outdoor burning bans; caused at least $2 billion of losses in the agricultural sector and higher prices for food and other agricultural products; caused losses of tourism and wildlife; reduced hydropower generation; and lowered groundwater levels in State aquifers. The U.S. Geological Survey, in cooperation with the Oklahoma Water Resources Board, conducted an investigation to compare the severity of the 2011 drought with four previous major hydrologic drought periods during the 20th century – water years 1929–41, 1952–56, 1961–72, and 1976–81. The period of water years 1925–2011 was selected as the period of record because few continuous record streamflow-gaging stations existed before 1925, and gaps in time existed where no streamflow-gaging stations were operated before 1925. In water year 2011, statewide annual precipitation was the 2d lowest, statewide annual streamflow was 16th lowest, and statewide annual runoff was 42d lowest of those 87 years of record. Annual area-averaged precipitation totals by the nine National Weather Service climate divisions from water year 2011 were compared to those during four previous major hydrologic drought

  13. Summer 2014 Pathways Report

    Science.gov (United States)

    Hand, Zachary

    2014-01-01

    Over the summer I had the exciting opportunity to work for NASA at the Kennedy Space Center as a Mission Assurance Engineering intern. When I was offered a position in mission assurance for the Safety and Mission Assurance directorate's Launch Services Division, I didn't really know what I would be doing, but I knew it would be an excellent opportunity to learn and grow professionally. In this report I will provide some background information on the Launch Services Division, as well as detail my duties and accomplishments during my time as an intern. Additionally, I will relate the significance of my work experience to my current academic work and future career goals. This report contains background information on Mission Assurance Engineering, a description of my duties and accomplishments over the summer of 2014, and relates the significance of my work experience to my school work and future career goals. It is a required document for the Pathways program.

  14. Drought effect on selection of conservation reserve program grasslands by white-tailed deer on the Northern Great Plains

    Science.gov (United States)

    Grovenburg, T.W.; Jacques, C.N.; Klaver, R.W.; Jenks, J.A.

    2011-01-01

    Limited information exists regarding summer resource selection of white-tailed deer (Odocoileus virginianus) in grassland regions of the Northern Great Plains. During summers 2005-2006, we analyzed habitat selection of adult female white-tailed deer in north-central South Dakota. We collected 1905 summer locations and used 21 and 30 home ranges during 2005 and 2006, respectively, to estimate habitat selection. Results indicated that selection occurred at the population (P rural development areas containing permanent water sources during extreme drought conditions during 2006. Deer likely selected for fields of CRP grasslands during early summer for cover and natural forages, such as clover (Trifolium sp.), prior to the period when agricultural crops become available. Drought conditions occurring in semiarid prairie grassland regions may reduce food and water availability and contribute to subsequent changes in deer habitat selection across the range of the species.

  15. Summer season | Cafeteria closures

    CERN Multimedia

    2013-01-01

    Please note the following cafeteria closures over the summer season: Bldg. 54 closed from 29/07/2013 to 06/09/2013. Bldg. 13: closed from 13/07/2013 to 06/09/2013. Restaurant No. 2, table service (brasserie and restaurant): closed from 01/08/2013 to 06/09/2013. Bldg. 864: closed from 29/07/2013 to 06/09/2013. Bldg. 865: closed from 29/07/2013 to 06/09/2013.

  16. Summer and Autumn activities

    CERN Multimedia

    Staff Association

    2013-01-01

    Time to recharge the batteries, and much more… The summer holidays are an ideal opportunity to spend more time with the family, to discover new countries, make new friends, in other words to take time away from the daily grind. This recharging is essential to your work-life balance, and CERN, as a modern and socially responsible employer, has recognized this as a central part of its human resources policy.Nevertheless we should not forget that, while many of you enjoy a well-deserved summer break, some of our colleagues are hard at work making LS1 (first Long Shutdown) a success in order to guarantee that at the beginning of 2015 the LHC will be able to start physics in an energy range never before reached by mankind. Preparing the questionnaire and the elections to the Staff Council During this summer your delegates in the Staff Council are hard at work preparing for the upcoming five-yearly review whose content will be decided by CERN Council in June 2014. Therefore, as every five years, to ...

  17. Controls on summer low flow

    Science.gov (United States)

    Graham, C. B.; McNamara, J. P.

    2012-12-01

    Summer low flow has significant impacts on aquatic flora and fauna, municipal water use, and power generation. However, the controls on the minimum annual summer discharge are complex, including a combination of snowmelt dynamics, summer evapotranspiration demand, and spring, summer precipitation patterns and surface - groundwater interactions. This is especially true in the Rocky Mountain West of the United States, where snowpack provides the majority of water available for spring runoff and groundwater replenishment. In this study, we look at summer low flow conditions at four snow dominated catchments (26 km2 - 2200 km2) in South-central Idaho currently feeling the effects of climate change. Measures of snowmelt dynamics, summer evapotranspiration demand and spring and summer precipitation are used to determine the dominant controls on late summer low flow magnitude, timing and duration. These analyses show that the controls vary between watersheds, with significant implications for the impacts of climate change in snow dominated areas of the Rocky Mountain West.

  18. Allegheny County Summer Food Sites

    Data.gov (United States)

    Allegheny County / City of Pittsburgh / Western PA Regional Data Center — This data set shows the Summer Food Sites located within Allegheny County for children (18 years and younger) for breakfast and lunch during summer recess. OPEN...

  19. Precipitation, temperature, and teleconnection signals across the combined North American, Monsoon Asia, and Old World Drought Atlases

    Science.gov (United States)

    Smerdon, J. E.; Baek, S. H.; Coats, S.; Williams, P.; Cook, B.; Cook, E. R.; Seager, R.

    2017-12-01

    The tree-ring-based North American Drought Atlas (NADA), Monsoon Asia Drought Atlas (MADA), and Old World Drought Atlas (OWDA) collectively yield a near-hemispheric gridded reconstruction of hydroclimate variability over the last millennium. To test the robustness of the large-scale representation of hydroclimate variability across the drought atlases, the joint expression of seasonal climate variability and teleconnections in the NADA, MADA, and OWDA are compared against two global, observation-based PDSI products. Predominantly positive (negative) correlations are determined between seasonal precipitation (surface air temperature) and collocated tree-ring-based PDSI, with average Pearson's correlation coefficients increasing in magnitude from boreal winter to summer. For precipitation, these correlations tend to be stronger in the boreal winter and summer when calculated for the observed PDSI record, while remaining similar for temperature. Notwithstanding these differences, the drought atlases robustly express teleconnection patterns associated with the El Niño-Southern Oscillation (ENSO), North Atlantic Oscillation (NAO), Pacific Decadal Oscillation (PDO), and Atlantic Multidecadal Oscillation (AMO). These expressions exist in the drought atlas estimates of boreal summer PDSI despite the fact that these modes of climate variability are dominant in boreal winter, with the exception of the Atlantic Multidecadal Oscillation. ENSO and NAO teleconnection patterns in the drought atlases are particularly consistent with their well-known dominant expressions in boreal winter and over the OWDA domain, respectively. Collectively, our findings confirm that the joint Northern Hemisphere drought atlases robustly reflect large-scale patterns of hydroclimate variability on seasonal to multidecadal timescales over the 20th century and are likely to provide similarly robust estimates of hydroclimate variability prior to the existence of widespread instrumental data.

  20. Adding the human dimension to drought: an example from Chile

    Science.gov (United States)

    Rangecroft, Sally; Van Loon, Anne; Maureira, Héctor; Rojas, Pablo; Alejandro Gutiérrez Valdés, Sergio; Verbist, Koen

    2016-04-01

    , regulations and therefore interpretation of the data and results. We will repeat the analysis done in Chile in a diverse series of case studies across the world to reflect different natural and human influences on the water cycle. This will enable an increased understanding of our influence on water resources and the feedbacks involved, which may be both positive and negative. Ultimately, this research will develop a methodology for identifying and quantifying human activities and use this information in combination with water management modeling and forecasting for effective drought early warning and risk management.

  1. Diverging Drought Resistance of Scots Pine Provenances Revealed by Infrared Thermography

    Directory of Open Access Journals (Sweden)

    Hannes Seidel

    2016-08-01

    Full Text Available With recent climate changes, Scots pine (Pinus sylvestris L. forests have been affected by die-off events. Assisted migration of adapted provenances mitigates drought impacts and promotes forest regeneration. Although suitable provenances are difficult to identify by traditional ecophysiological techniques, which are time consuming and invasive, plant water status can be easily assessed by infrared thermography. Thus, we examined the stress responses of 2-year-old potted Scots pine seedlings from six provenances (Bulgaria, France, Germany, Italy, Poland, and Spain based on two thermal indices (crop water stress index and stomatal conductance index. Both indices were derived from infrared images during a six-week drought/control treatment in a greenhouse in the summer of 2013. The pines were monitored during the stress and subsequent recovery period. After controlling for fluctuating environmental conditions, soil moisture or treatment-specific water supply was the most important driver of drought stress. The stress magnitude and response to soil water deficit depended on provenance. Under moderate drought conditions, pines from western and eastern Mediterranean provenances (Bulgaria, France, and Spain expressed lower stress levels than those from both continental provenances (Germany and Poland. In pines from the Spanish and Bulgarian provenances, the stress level differences were significantly lower than in continental pines. Moreover, pines from continental provenances were less resilient (showed less recovery after the stress period than Mediterranean pines. Under extreme drought, all provenances were equally stressed with almost no significant differences in their thermal indices. Provenance-specific differences in drought resistance, which are associated with factors such as summer precipitation at the origin of Scots pine seedlings, may offer promising tracks of adaptation to future drought risks.

  2. Spatial differences in drought vulnerability

    Science.gov (United States)

    Perčec Tadić, M.; Cindić, K.; Gajić-Čapka, M.; Zaninović, K.

    2012-04-01

    Drought causes the highest economic losses among all hydro-meteorological events in Croatia. It is the most frequent hazard, which produces the highest damages in the agricultural sector. The climate assessment in Croatia according to the aridity index (defined as the ratio of precipitation and potential evapotranspiration) shows that the susceptibility to desertification is present in the warm part of the year and it is mostly pronounced in the Adriatic region and the eastern Croatia lowland. The evidence of more frequent extreme drought events in the last decade is apparent. These facts were motivation to study the drought risk assessment in Croatia. One step in this issue is the construction of the vulnerability map. This map is a complex combination of the geomorphologic and climatological inputs (maps) that are presumed to be natural factors which modify the amount of moisture in the soil. In this study, the first version of the vulnerability map is followed by the updated one that additionally includes the soil types and the land use classes. The first input considered is the geomorphologic slope angle calculated from the digital elevation model (DEM). The SRTM DEM of 100 m resolution is used. The steeper slopes are more likely to lose water and to become dryer. The second climatological parameter, the solar irradiation map, gives for the territory of Croatia the maximum irradiation on the coast. The next meteorological parameter that influences the drought vulnerability is precipitation which is in this assessment included through the precipitation variability expressed by the coefficient of variation. Larger precipitation variability is related with the higher drought vulnerability. The preliminary results for Croatia, according to the recommended procedure in the framework of Drought Management Centre for Southeastern Europe (DMCSEE project), show the most sensitive areas to drought in the southern Adriatic coast and eastern continental lowland.

  3. Proteomic responses of drought-tolerant and drought-sensitive cotton varieties to drought stress.

    Science.gov (United States)

    Zhang, Haiyan; Ni, Zhiyong; Chen, Quanjia; Guo, Zhongjun; Gao, Wenwei; Su, Xiujuan; Qu, Yanying

    2016-06-01

    Drought, one of the most widespread factors reducing agricultural crop productivity, affects biological processes such as development, architecture, flowering and senescence. Although protein analysis techniques and genome sequencing have made facilitated the proteomic study of cotton, information on genetic differences associated with proteomic changes in response to drought between different cotton genotypes is lacking. To determine the effects of drought stress on cotton seedlings, we used two-dimensional polyacrylamide gel electrophoresis (2-DE) and matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry to comparatively analyze proteome of drought-responsive proteins during the seedling stage in two cotton (Gossypium hirsutum L.) cultivars, drought-tolerant KK1543 and drought-sensitive Xinluzao26. A total of 110 protein spots were detected on 2-DE maps, of which 56 were identified by MALDI-TOF and MALDI-TOF/TOF mass spectrometry. The identified proteins were mainly associated with metabolism (46.4 %), antioxidants (14.2 %), and transport and cellular structure (23.2 %). Some key proteins had significantly different expression patterns between the two genotypes. In particular, 5-methyltetrahydropteroyltriglutamate-homocysteine methyltransferase, UDP-D-glucose pyrophosphorylase and ascorbate peroxidase were up-regulated in KK1543 compared with Xinluzao26. Under drought stress conditions, the vacuolar H(+)-ATPase catalytic subunit, a 14-3-3g protein, translation initiation factor 5A and pathogenesis-related protein 10 were up-regulated in KK1543, whereas ribosomal protein S12, actin, cytosolic copper/zinc superoxide dismutase, protein disulfide isomerase, S-adenosylmethionine synthase and cysteine synthase were down-regulated in Xinluzao26. This work represents the first characterization of proteomic changes that occur in response to drought in roots of cotton plants. These differentially expressed proteins may be related to

  4. Comprehensive drought characteristics analysis based on a nonlinear multivariate drought index

    Science.gov (United States)

    Yang, Jie; Chang, Jianxia; Wang, Yimin; Li, Yunyun; Hu, Hui; Chen, Yutong; Huang, Qiang; Yao, Jun

    2018-02-01

    It is vital to identify drought events and to evaluate multivariate drought characteristics based on a composite drought index for better drought risk assessment and sustainable development of water resources. However, most composite drought indices are constructed by the linear combination, principal component analysis and entropy weight method assuming a linear relationship among different drought indices. In this study, the multidimensional copulas function was applied to construct a nonlinear multivariate drought index (NMDI) to solve the complicated and nonlinear relationship due to its dependence structure and flexibility. The NMDI was constructed by combining meteorological, hydrological, and agricultural variables (precipitation, runoff, and soil moisture) to better reflect the multivariate variables simultaneously. Based on the constructed NMDI and runs theory, drought events for a particular area regarding three drought characteristics: duration, peak, and severity were identified. Finally, multivariate drought risk was analyzed as a tool for providing reliable support in drought decision-making. The results indicate that: (1) multidimensional copulas can effectively solve the complicated and nonlinear relationship among multivariate variables; (2) compared with single and other composite drought indices, the NMDI is slightly more sensitive in capturing recorded drought events; and (3) drought risk shows a spatial variation; out of the five partitions studied, the Jing River Basin as well as the upstream and midstream of the Wei River Basin are characterized by a higher multivariate drought risk. In general, multidimensional copulas provides a reliable way to solve the nonlinear relationship when constructing a comprehensive drought index and evaluating multivariate drought characteristics.

  5. Evaluation of Drought Implications on Ecosystem Services: Freshwater Provisioning and Food Provisioning in the Upper Mississippi River Basin.

    Science.gov (United States)

    Li, Ping; Omani, Nina; Chaubey, Indrajeet; Wei, Xiaomei

    2017-05-08

    Drought is one of the most widespread extreme climate events with a potential to alter freshwater availability and related ecosystem services. Given the interconnectedness between freshwater availability and many ecosystem services, including food provisioning, it is important to evaluate the drought implications on freshwater provisioning and food provisioning services. Studies about drought implications on streamflow, nutrient loads, and crop yields have been increased and these variables are all process-based model outputs that could represent ecosystem functions that contribute to the ecosystem services. However, few studies evaluate drought effects on ecosystem services such as freshwater and food provisioning and quantify these services using an index-based ecosystem service approach. In this study, the drought implications on freshwater and food provisioning services were evaluated for 14 four-digit HUC (Hydrological Unit Codes) subbasins in the Upper Mississippi River Basin (UMRB), using three drought indices: standardized precipitation index ( SPI ), standardized soil water content index ( SSWI ), and standardized streamflow index ( SSI ). The results showed that the seasonal freshwater provisioning was highly affected by the precipitation deficits and/or surpluses in summer and autumn. A greater importance of hydrological drought than meteorological drought implications on freshwater provisioning was evident for the majority of the subbasins, as evidenced by higher correlations between freshwater provisioning and SSI 12 than SPI 12. Food provisioning was substantially affected by the precipitation and soil water deficits during summer and early autumn, with relatively less effect observed in winter. A greater importance of agricultural drought effects on food provisioning was evident for most of the subbasins during crop reproductive stages. Results from this study may provide insights to help make effective land management decisions in responding to

  6. Revisiting the TALE repeat.

    Science.gov (United States)

    Deng, Dong; Yan, Chuangye; Wu, Jianping; Pan, Xiaojing; Yan, Nieng

    2014-04-01

    Transcription activator-like (TAL) effectors specifically bind to double stranded (ds) DNA through a central domain of tandem repeats. Each TAL effector (TALE) repeat comprises 33-35 amino acids and recognizes one specific DNA base through a highly variable residue at a fixed position in the repeat. Structural studies have revealed the molecular basis of DNA recognition by TALE repeats. Examination of the overall structure reveals that the basic building block of TALE protein, namely a helical hairpin, is one-helix shifted from the previously defined TALE motif. Here we wish to suggest a structure-based re-demarcation of the TALE repeat which starts with the residues that bind to the DNA backbone phosphate and concludes with the base-recognition hyper-variable residue. This new numbering system is consistent with the α-solenoid superfamily to which TALE belongs, and reflects the structural integrity of TAL effectors. In addition, it confers integral number of TALE repeats that matches the number of bound DNA bases. We then present fifteen crystal structures of engineered dHax3 variants in complex with target DNA molecules, which elucidate the structural basis for the recognition of bases adenine (A) and guanine (G) by reported or uncharacterized TALE codes. Finally, we analyzed the sequence-structure correlation of the amino acid residues within a TALE repeat. The structural analyses reported here may advance the mechanistic understanding of TALE proteins and facilitate the design of TALEN with improved affinity and specificity.

  7. Reconfigurable multiport EPON repeater

    Science.gov (United States)

    Oishi, Masayuki; Inohara, Ryo; Agata, Akira; Horiuchi, Yukio

    2009-11-01

    An extended reach EPON repeater is one of the solutions to effectively expand FTTH service areas. In this paper, we propose a reconfigurable multi-port EPON repeater for effective accommodation of multiple ODNs with a single OLT line card. The proposed repeater, which has multi-ports in both OLT and ODN sides, consists of TRs, BTRs with the CDR function and a reconfigurable electrical matrix switch, can accommodate multiple ODNs to a single OLT line card by controlling the connection of the matrix switch. Although conventional EPON repeaters require full OLT line cards to accommodate subscribers from the initial installation stage, the proposed repeater can dramatically reduce the number of required line cards especially when the number of subscribers is less than a half of the maximum registerable users per OLT. Numerical calculation results show that the extended reach EPON system with the proposed EPON repeater can save 17.5% of the initial installation cost compared with a conventional repeater, and can be less expensive than conventional systems up to the maximum subscribers especially when the percentage of ODNs in lightly-populated areas is higher.

  8. Next Generation Summer School

    Science.gov (United States)

    Eugenia, Marcu

    2013-04-01

    On 21.06.2010 the "Next Generation" Summer School has opened the doors for its first students. They were introduced in the astronomy world by astronomical observations, astronomy and radio-astronomy lectures, laboratory projects meant to initiate them into modern radio astronomy and radio communications. The didactic programme was structure as fallowing: 1) Astronomical elements from the visible spectrum (lectures + practical projects) 2) Radio astronomy elements (lectures + practical projects) 3) Radio communication base (didactic- recreative games) The students and professors accommodation was at the Agroturistic Pension "Popasul Iancului" situated at 800m from the Marisel Observatory. First day (summer solstice day) began with a practical activity: determination of the meridian by measurements of the shadow (the direction of one vertical alignment, when it has the smallest length). The experiment is very instructive and interesting because combines notions of physics, spatial geometry and basic astronomy elements. Next day the activities took place in four stages: the students processed the experimental data obtained on first day (on sheets of millimetre paper they represented the length of the shadow alignments according the time), each team realised its own sun quadrant, point were given considering the design and functionality of these quadrant, the four teams had to mimic important constellations on carton boards with phosphorescent sticky stars and the students, accompanied by the professors took a hiking trip to the surroundings, marking the interest point coordinates, using a GPS to establish the geographical coronations and at the end of the day the students realised a small map of central Marisel area based on the GPS data. On the third day, the students were introduced to basic notions of radio astronomy, the principal categories of artificial Earth satellites: low orbit satellites (LEO), Medium orbit satellites (MEO) and geostationary satellites (GEO

  9. Quantum repeated games revisited

    International Nuclear Information System (INIS)

    Frąckiewicz, Piotr

    2012-01-01

    We present a scheme for playing quantum repeated 2 × 2 games based on Marinatto and Weber’s approach to quantum games. As a potential application, we study the twice repeated Prisoner’s Dilemma game. We show that results not available in the classical game can be obtained when the game is played in the quantum way. Before we present our idea, we comment on the previous scheme of playing quantum repeated games proposed by Iqbal and Toor. We point out the drawbacks that make their results unacceptable. (paper)

  10. Patterns of Tamarix water use during a record drought.

    Science.gov (United States)

    Nippert, Jesse B; Butler, James J; Kluitenberg, Gerard J; Whittemore, Donald O; Arnold, Dave; Spal, Scott E; Ward, Joy K

    2010-02-01

    During a record drought (2006) in southwest Kansas, USA, we assessed groundwater dynamics in a shallow, unconfined aquifer, along with plant water sources and physiological responses of the invasive riparian shrub Tamarix ramosissima. In early May, diel water table fluctuations indicated evapotranspirative consumption of groundwater by vegetation. During the summer drought, the water table elevation dropped past the lowest position previously recorded. Concurrent with this drop, water table fluctuations abruptly diminished at all wells at which they had previously been observed despite increasing evapotranspirative demand. Following reductions in groundwater fluctuations, volumetric water content declined corresponding to the well-specific depths of the capillary fringe in early May, suggesting a switch from primary dependence on groundwater to vadose-zone water. In at least one well, the fluctuations appear to re-intensify in August, suggesting increased groundwater uptake by Tamarix or other non-senesced species from a deeper water table later in the growing season. Our data suggest that Tamarix can rapidly shift water sources in response to declines in the water table. The use of multiple water sources by Tamarix minimized leaf-level water stress during drought periods. This study illustrates the importance of the previous hydrologic conditions experienced by site vegetation for controlling root establishment at depth and demonstrates the utility of data from high-frequency hydrologic monitoring in the interpretation of plant water sources using isotopic methods.

  11. Abrupt change of the mid-summer climate in central east China by the influence of atmospheric pollution

    International Nuclear Information System (INIS)

    Qun Xu

    2001-01-01

    Following the great flooding of summer 1998, the mid-lower Yangtze Basin further suffered from another large flooding in summer 1999. Successive droughts through three recent summers (1997-1999) appeared in north China in addition, leading to an abnormal summer climate pattern of ''north drought with south flooding''. Such southward move of the summer monsoon rainy belt in east China started in the late 1970s-early 1980s. Its main cause may not be a purely natural climate change, but the acceleration of industrialization in east China could play a major role by emitting large volumes of SO 2 , especially from the rapidly growing rural factories of east China. The annual release of SO 2 in China exceeded 20Tg during 1992-1998, so dense sulfate aerosols covered the central east China which significantly reduced the sunlight. Although present estimates for the changes of clear sky global solar radiation may include some error, they show that the negative radiative forcing of sulfate aerosols in central east China by far exceeds the effect of greenhouse warming in summer. Hence the mid-summer monsoon rainy belt of east China has a trend moving southward in 21 recent years (1979-1999), showing the very sensitive characteristic of the summer monsoon system to the change in heat equilibrium of the land surface. The occurrence rate of summer climate pattern of ''north drought with south flooding'' in east China during 21 recent years is the largest since AD 950; such anomalous climate has brought large losses to China. The only possible way to reverse this southward trend of summer monsoon rainy belt is to significantly reduce air pollution by using more clean energy. Recently, the PRC has paid serious attention to this problem by adopting a series of countermeasures. (author)

  12. Global Drought Proportional Economic Loss Risk Deciles

    Data.gov (United States)

    National Aeronautics and Space Administration — Global Drought Proportional Economic Loss Risk Deciles is a 2.5 minute grid of drought hazard economic loss as proportions of Gross Domestic Product (GDP) per...

  13. Global Drought Total Economic Loss Risk Deciles

    Data.gov (United States)

    National Aeronautics and Space Administration — Global Drought Total Economic Loss Risk Deciles is a 2.5 minute grid of global drought total economic loss risks. A process of spatially allocating Gross Domestic...

  14. Drought Resilience and Water Conservation Technical Brief

    Science.gov (United States)

    In many areas of the US, the frequency, intensity, and duration of drought events are increasing, this brief highlights EPA drought and conservation activities across the nation and includes links to additional materials and reference documents.

  15. A hot future for European droughts

    Science.gov (United States)

    Teuling, Adriaan J.

    2018-05-01

    Low soil moisture conditions can induce drought but also elevate temperatures. Detailed modelling of the drought-temperature link now shows that rising global temperature will bring drier soils and higher heatwave temperatures in Europe.

  16. Drought and submergence tolerance in plants

    Energy Technology Data Exchange (ETDEWEB)

    Du, Hewei; Zhou, Yufan; Oksenberg, Nir; Ronald, Pamela

    2017-11-14

    The invention provides methods of genetically modified plants to increase tolerance to drought and/or submergence. The invention additionally provides plants having increased drought and/or submergence tolerance engineered using such methods.

  17. Global Drought Mortality Risks and Distribution

    Data.gov (United States)

    National Aeronautics and Space Administration — Global Drought Mortality Risks and Distribution is a 2.5 minute grid of global drought mortality risks. Gridded Population of the World, Version 3 (GPWv3) data...

  18. Summer Camp, July 2016

    CERN Multimedia

    Staff Association

    2016-01-01

    During the month of July, the Staff Association’s Children’s Day-Care Centre and School EVEE held a summer camp for 4- to 6-year-olds. 24 children altogether joined in on the adventures. On the summer camp, the children got to “travel” to a different continent of the world every week. Day after day, they would pass through make-believe Customs upon arrival and get their passports stamped by a “customs officer”. For the first week, we went on a trip to Africa. In the spirit of the theme, the children got to do plenty of crafts and coloring, make their own little bindles and play various games. They even had the chance to visit the Museum of Ethnography in Geneva (MEG), learn to play the balafon and make musical instruments with Sterrenlab. For the second week, we set off to discover the Americas, exploring both the South and the North. Alongside different workshops (singing, dancing, storytelling, crafts), the children could enjoy several special ac...

  19. On the propagation of drought : how climate and catchment characteristics influence hydrological drought development and recovery

    NARCIS (Netherlands)

    Loon, van A.F.

    2013-01-01

    Drought is a severe natural disaster resulting in high economic loss and huge ecological and societal impacts. In this thesis drought is defined as a period of below-normal water availability in precipitation (meteorological drought), soil moisture (soil moisture drought), or groundwater and

  20. The effect of severe drought and management after drought on the ...

    African Journals Online (AJOL)

    The False Thornveld of the Eastern Cape experienced a particularly intense drought during the 1982/1983 growing season. Extensive grass mortality took place during the drought. After the drought, recovery was particularly sensitive to the post-drought management treatment applied. Veld that was grazed immediately ...

  1. Drought-related tree mortality in drought-resistant semi-arid Aleppo pine forest

    Science.gov (United States)

    Preisler, Yakir; Grünzweig, José M.; Rotenberg, Eyal; Rohatyn, Shani; Yakir, Dan

    2014-05-01

    The frequency and intensity of drought events are expected to increase as part of global climate change. In fact, drought related tree mortality had become a widespread phenomenon in forests around the globe in the past decades. This study was conducted at the Yatir FLUXNET site, located in a 45 years old Pinus halepensis dominated forest that successfully sustained low mean annual precipitation (276mm) and extended seasonal droughts (up to 340 days between rain events). However, five recent non-consecutive drought years led to enhanced tree mortality in 2010 (5-10% of the forest population, which was not observed hitherto). The Tree mortality was characterized by patchiness, showing forest zones with either >80% mortality or no mortality at all. Areas of healthy trees were associated with deeper root distribution and increased stoniness (soil pockets & cracks). To help identify possible causes of the increased mortality and its patterns, four tree stress levels were identified based on visual appearance, and studied in more detail. This included examining from spring 2011 to summer 2013 the local trees density, root distribution, annual growth rings, needle length and chlorophyll content, rates of leaf gas exchange, and branch predawn water potential. Tree phenotypic stress level correlated with the leaf predawn water potential (-1.8 and -3.0 in healthy and stressed trees, respectively), which likely reflected tree-scale water availability. These below ground characteristics were also associated, in turn, with higher rate of assimilation (3.5 and 0.8 μmol CO2 m-2s1 in healthy and stress trees, respectively), longer needles (8.2cm and 3.4 cm in healthy and stressed trees, respectively). Annual ring widths showed differences between stress classes, with stressed trees showing 30% narrower rings on average than unstressed trees. Notably, decline in annual ring widths could be identified in currently dead or severely stressed trees 15-20 years prior to mortality or

  2. Evaluation of drought tolerance indices for the selection of Iranian ...

    African Journals Online (AJOL)

    Drought is an important factor limiting crop production in arid and semi-arid conditions. Drought indices which provide a measure of drought based on yield loss under drought condition in comparison to normal condition was used for screening drought-tolerant genotypes. This study was conducted to determine drought ...

  3. Repeat migration and disappointment.

    Science.gov (United States)

    Grant, E K; Vanderkamp, J

    1986-01-01

    This article investigates the determinants of repeat migration among the 44 regions of Canada, using information from a large micro-database which spans the period 1968 to 1971. The explanation of repeat migration probabilities is a difficult task, and this attempt is only partly successful. May of the explanatory variables are not significant, and the overall explanatory power of the equations is not high. In the area of personal characteristics, the variables related to age, sex, and marital status are generally significant and with expected signs. The distance variable has a strongly positive effect on onward move probabilities. Variables related to prior migration experience have an important impact that differs between return and onward probabilities. In particular, the occurrence of prior moves has a striking effect on the probability of onward migration. The variable representing disappointment, or relative success of the initial move, plays a significant role in explaining repeat migration probabilities. The disappointment variable represents the ratio of actural versus expected wage income in the year after the initial move, and its effect on both repeat migration probabilities is always negative and almost always highly significant. The repeat probabilities diminish after a year's stay in the destination region, but disappointment in the most recent year still has a bearing on the delayed repeat probabilities. While the quantitative impact of the disappointment variable is not large, it is difficult to draw comparisons since similar estimates are not available elsewhere.

  4. Soil solution chemistry and element fluxes in three European heathlands and their responses to warming and drought

    DEFF Research Database (Denmark)

    Schmidt, I.K.; Tietema, A.; Williams, D.

    2004-01-01

    Soil water chemistry and element budgets were studied at three northwestern European Calluna vulgaris heathland sites in Denmark (DK), The Netherlands (NL), and Wales (UK). Responses to experimental nighttime warming and early summer drought were followed during a two-year period. Soil solution...

  5. Bacterial mediated amelioration of drought stress in drought tolerant ...

    African Journals Online (AJOL)

    yogendra

    2015-02-23

    Feb 23, 2015 ... for a beneficial effect of PGPRs application in enhancing drought tolerance of rice under water deficit conditions. ..... involvement of PGPRs in ROS metabolism in rice plants. ... osmoregulatory solute in plants (Kumar et al., 2011). ..... Pseudomonas fluorescens mediated saline resistance in groundnut.

  6. Forest biogeochemistry in response to drought

    Science.gov (United States)

    William H. Schlesinger; Michael C. Dietze; Robert B. Jackson; Richard P. Phillips; Charles C. Rhoades; Lindsey E. Rustad; James M. Vose

    2015-01-01

    Trees alter their use and allocation of nutrients in response to drought, and changes in soil nutrient cycling and trace gas flux (N2O and CH4) are observed when experimental drought is imposed on forests. In extreme droughts, trees are increasingly susceptible to attack by pests and pathogens, which can lead to major changes in nutrient flux to the soil....

  7. Diversity of seedling responses to drought

    NARCIS (Netherlands)

    Slot, M.; Poorter, L.

    2007-01-01

    Drought is an important seedling mortality agent in dry and moist tropical forests, and more severe and frequent droughts are predicted in the future. The effect of drought on leaf gas exchange and seedling survival was tested in a dry-down experiment with four tree species from dry and moist

  8. The bioeconomic implications of various drought management ...

    African Journals Online (AJOL)

    Keywords: Drought management strategies; Herd structures; KwaZulu/Natal; Labour costs; Net present values; Simulation modelling; drought; drought management; management strategy; cattle; semi-arid; savanna; south africa; net present value; simulation model; domestic stock; economics. African Journal of Range ...

  9. (SSR) markers for drought tolerance in maize

    African Journals Online (AJOL)

    Maize is moderately sensitive to drought. Drought affects virtually all aspects of maize growth in varying degrees at all stages, from germination to maturity. Tolerance to drought is genetically and physiologically complicated and inherited quantitatively. Application of molecular-marker aided selection technique for ...

  10. European Drought and Water Scarcity Policies

    NARCIS (Netherlands)

    Özerol, Gül; Stein, Ulf; Troeltzsch, Jenny; Landgrebe, Ruta; Szendrenyi, Anna; Vidaurre, Rodrigo; Bressers, Hans; Bressers, Nanny; Larrue, Corinne

    2016-01-01

    Over the last decade, Europe’s drought management and policy has been characterized by a predominantly crisis-oriented approach. However, the widening gap between the impacts of drought episodes and the ability to prepare, manage and mitigate such droughts has motivated the European Union (EU) to

  11. Forest resilience to drought varies across biomes.

    Science.gov (United States)

    Gazol, Antonio; Camarero, Jesus Julio; Vicente-Serrano, Sergio M; Sánchez-Salguero, Raúl; Gutiérrez, Emilia; de Luis, Martin; Sangüesa-Barreda, Gabriel; Novak, Klemen; Rozas, Vicente; Tíscar, Pedro A; Linares, Juan C; Martín-Hernández, Natalia; Martínez Del Castillo, Edurne; Ribas, Montse; García-González, Ignacio; Silla, Fernando; Camisón, Alvaro; Génova, Mar; Olano, José M; Longares, Luis A; Hevia, Andrea; Tomás-Burguera, Miquel; Galván, J Diego

    2018-05-01

    Forecasted increase drought frequency and severity may drive worldwide declines in forest productivity. Species-level responses to a drier world are likely to be influenced by their functional traits. Here, we analyse forest resilience to drought using an extensive network of tree-ring width data and satellite imagery. We compiled proxies of forest growth and productivity (TRWi, absolutely dated ring-width indices; NDVI, Normalized Difference Vegetation Index) for 11 tree species and 502 forests in Spain corresponding to Mediterranean, temperate, and continental biomes. Four different components of forest resilience to drought were calculated based on TRWi and NDVI data before, during, and after four major droughts (1986, 1994-1995, 1999, and 2005), and pointed out that TRWi data were more sensitive metrics of forest resilience to drought than NDVI data. Resilience was related to both drought severity and forest composition. Evergreen gymnosperms dominating semi-arid Mediterranean forests showed the lowest resistance to drought, but higher recovery than deciduous angiosperms dominating humid temperate forests. Moreover, semi-arid gymnosperm forests presented a negative temporal trend in the resistance to drought, but this pattern was absent in continental and temperate forests. Although gymnosperms in dry Mediterranean forests showed a faster recovery after drought, their recovery potential could be constrained if droughts become more frequent. Conversely, angiosperms and gymnosperms inhabiting temperate and continental sites might have problems to recover after more intense droughts since they resist drought but are less able to recover afterwards. © 2018 John Wiley & Sons Ltd.

  12. Effects of drought on avian community structure

    Science.gov (United States)

    Thomas P. Albright; Anna M. Pidgeon; Chadwick D. Rittenhouse; Murray K. Clayton; Curtis H. Flather; Patrick D. Culbert; Brian D. Wardlow; Volker C. Radeloff

    2010-01-01

    Droughts are expected to become more frequent under global climate change. Avifauna depend on precipitation for hydration, cover, and food. While there are indications that avian communities respond negatively to drought, little is known about the response of birds with differing functional and behavioural traits, what time periods and indicators of drought are most...

  13. Comparative Analysis of Drought Indices for Drought Zone Scheme of Northern Khorasan Province of Iran

    OpenAIRE

    Ehsan EYSHI REZAEI; Azade MOHAMMADIAN; Mansoreh KOOHI; Mohammad BANNAYAN

    2011-01-01

    Drought is one of the natural disasters which deeply influenced agricultural production. Drought monitoring programs could help to forecast and mitigate the impacts of drought. In this study occurrence, severity, and duration of drought were evaluated by monthly rainfall data (1986-2005) that were recorded at all meteorological stations in north Khorasan province of Iran. Drought indices include Standard Rainfall Index (SPI), Decades Index (DI) and Percent of Normal (PNI) calculated and compa...

  14. Historical droughts in northern Vietnam captured by variability in speleothem δ18O

    Science.gov (United States)

    Hardt, B. F.; McGee, D.; Burns, S. J.; Hieu, N.; Hieu, D. T.

    2015-12-01

    Speleothem records overlapping with the historical period offer valuable comparisons of documentary evidence with speleothem proxy data. These records provide opportunities to 'ground-truth' the paleo-record, fill in gaps in the historical record, and more confidently extent the paleo-record into deeper time. Here we present isotopic results from a stalagmite collected in northern Vietnam spanning 1200 to 1950 CE, a period with a rich historical record in Vietnam. This sample adds significantly to the relatively sparse paleoclimate record from Southeast Asia. The record includes several multi-decadal positive excursions of ≥1 per mille in calcite δ18O. A preliminary age model, based on six U/Th ages, suggests possible correspondence to noted droughts from the historical record, including the Angkor Droughts, the Ming Dynasty Drought, the Strange Parallels Drought, and the Victorian Holocaust Drought. As modeling studies indicate a strong correlation between rainfall δ18O and both the intensity of summer monsoon winds and summer rainfall over northern Vietnam (e.g., Liu et al., 2014), these excursions are consistent with a decrease in regional precipitation. The Vietnam record shows an overall negative trend during the Little Ice Age. The study site is located well south of the westerly wind belt, ruling out a shift between monsoonal and mid-latitude circulation systems as a likely explanation for the northern Vietnam record. We explore the correspondence between our record and other proxy data from Southeast Asia and suggest possible implications of the differences between Vietnamese and Chinese speleothem records during the Little Ice Age. References cited: Liu Z., Wen X., Brady E. C., Otto-Bliesner B., Yu G., Lu H., Cheng H., Wang Y., Zheng W., Ding Y., Edwards R. L., Cheng J., Liu W. and Yang H. (2014) Chinese cave records and the East Asia Summer Monsoon. Quaternary Science Reviews 83, 115-128.

  15. Drought resistance in durum wheat

    NARCIS (Netherlands)

    Simane, B.

    1993-01-01

    Durum wheat is widely grown as a rainfed crop in the semi-arid tropics. Its production is low and variable from season to season due to frequent drought-stress. Characterization of target environment and employing both analytical and empirical breeding approaches would speed up progress in

  16. Contrasting physiological responses of two co-occurring eucalypts to seasonal drought at restored bauxite mine sites.

    Science.gov (United States)

    Szota, Christopher; Farrell, Claire; Koch, John M; Lambers, Hans; Veneklaas, Erik J

    2011-10-01

    This study describes the physiological response of two co-occurring tree species (Eucalyptus marginata and Corymbia calophylla) to seasonal drought at low- and high-quality restored bauxite mine sites in south-western Australia. Seasonal changes in photosynthesis (A), stomatal conductance (g(s)), leaf water potential (ψ), leaf osmotic potential (ψ), leaf relative water content (RWC) and pressure-volume analysis were captured over an 18-month field study to (i) determine the nature and severity of physiological stress in relation to site quality and (ii) identify any physiological differences between the two species. Root system restriction at the low-quality site reduced maximum rates of gas exchange (g(s) and A) and increased water stress (midday ψ and daily RWC) in both species during drought. Both species showed high stomatal sensitivity during drought; however, E. marginata demonstrated a higher dehydration tolerance where ψ and RWC fell to -3.2 MPa and 73% compared with -2.4 MPa and 80% for C. calophylla. Corymbia calophylla showed lower g(s) and higher ψ and RWC during drought, indicating higher drought tolerance. Pressure-volume curves showed that cell-wall elasticity of E. marginata leaves increased in response to drought, while C. calophylla leaves showed lower osmotic potential at zero turgor in summer than in winter, indicating osmotic adjustment. Both species are clearly able to tolerate seasonal drought at hostile sites; however, by C. calophylla closing stomata earlier in the drought cycle, maintaining a higher water status during drought and having the additional mechanism of osmotic adjustment, it may have a greater capacity to survive extended periods of drought.

  17. US Drought-Heat Wave Relationships in Past Versus Current Climates

    Science.gov (United States)

    Cheng, L.; Hoerling, M. P.; Eischeid, J.; Liu, Z.

    2017-12-01

    This study explores the relationship between droughts and heat waves over various regions of the contiguous United States that are distinguished by so-called energy-limited versus water-limited climatologies. We first examine the regional sensitivity of heat waves to soil moisture variability under 19th century climate conditions, and then compare to sensitivities under current climate that has been subjected to human-induced change. Our approach involves application of the conditional statistical framework of vine copula. Vine copula is known for its flexibility in reproducing various dependence structures exhibited by climate variables. Here we highlight its feature for evaluating the importance of conditional relationships between variables and processes that capture underlying physical factors involved in their interdependence during drought/heat waves. Of particular interest is identifying changes in coupling strength between heat waves and land surface conditions that may yield more extreme events as a result of land surface feedbacks. We diagnose two equilibrium experiments a coupled climate model (CESM1), one subjected to Year-1850 external forcing and the other to Year-2000 radiative forcing. We calculate joint heat wave/drought relationships for each climate state, and also calculate their change as a result of external radiative forcing changes across this 150-yr period. Our results reveal no material change in the dependency between heat waves and droughts, aside from small increases in coupling strength over the Great Plains. Overall, hot U.S. summer droughts of 1850-vintage do not become hotter in the current climate -- aside from the warming contribution of long-term climate change, in CESM1. The detectability of changes in hotter droughts as a consequence of anthropogenic forced changes in this single effect, i.e. coupling strength between soil moisture and hot summer temperature, is judged to be low at this time.

  18. Drought in a human-modified world: reframing drought definitions, understanding, and analysis approaches

    Science.gov (United States)

    Van Loon, Anne F.; Stahl, Kerstin; Di Baldassarre, Giuliano; Clark, Julian; Rangecroft, Sally; Wanders, Niko; Gleeson, Tom; Van Dijk, Albert I. J. M.; Tallaksen, Lena M.; Hannaford, Jamie; Uijlenhoet, Remko; Teuling, Adriaan J.; Hannah, David M.; Sheffield, Justin; Svoboda, Mark; Verbeiren, Boud; Wagener, Thorsten; Van Lanen, Henny A. J.

    2016-09-01

    In the current human-modified world, or Anthropocene, the state of water stores and fluxes has become dependent on human as well as natural processes. Water deficits (or droughts) are the result of a complex interaction between meteorological anomalies, land surface processes, and human inflows, outflows, and storage changes. Our current inability to adequately analyse and manage drought in many places points to gaps in our understanding and to inadequate data and tools. The Anthropocene requires a new framework for drought definitions and research. Drought definitions need to be revisited to explicitly include human processes driving and modifying soil moisture drought and hydrological drought development. We give recommendations for robust drought definitions to clarify timescales of drought and prevent confusion with related terms such as water scarcity and overexploitation. Additionally, our understanding and analysis of drought need to move from single driver to multiple drivers and from uni-directional to multi-directional. We identify research gaps and propose analysis approaches on (1) drivers, (2) modifiers, (3) impacts, (4) feedbacks, and (5) changing the baseline of drought in the Anthropocene. The most pressing research questions are related to the attribution of drought to its causes, to linking drought impacts to drought characteristics, and to societal adaptation and responses to drought. Example questions include (i) What are the dominant drivers of drought in different parts of the world? (ii) How do human modifications of drought enhance or alleviate drought severity? (iii) How do impacts of drought depend on the physical characteristics of drought vs. the vulnerability of people or the environment? (iv) To what extent are physical and human drought processes coupled, and can feedback loops be identified and altered to lessen or mitigate drought? (v) How should we adapt our drought analysis to accommodate changes in the normal situation (i.e. what

  19. Performance and carcass characteristics of steers fed with two levels of metabolizable energy intake during summer and winter season.

    Science.gov (United States)

    Arias, R A; Keim, J P; Gandarillas, M; Velásquez, A; Alvarado-Gilis, C; Mader, T L

    2018-05-22

    Climate change is producing an increase on extreme weather events around the world such as flooding, drought and extreme ambient temperatures impacting animal production and animal welfare. At present, there is a lack of studies addressing the effects of climatic conditions associated with energy intake in finishing cattle in South American feed yards. Therefore, two experiments were conducted to assess the effects of environmental variables and level of metabolizable energy intake above maintenance requirements (MEI) on performance and carcass quality of steers. In each experiment (winter and summer), steers were fed with 1.85 or 2.72 times of their requirements of metabolizable energy of maintenance. A total of 24 crossbred steers per experiment were used and located in four pens (26.25 m2/head) equipped with a Calan Broadbent Feeding System. Animals were fed with the same diet within each season, varying the amount offered to adjust the MEI treatments. Mud depth, mud scores, tympanic temperature (TT), environmental variables, average daily gain, respiration rates and carcass characteristics plus three thermal comfort indices were collected. Data analysis considered a factorial arrangement (Season and MEI). In addition, a repeated measures analysis was performed for TT and respiration rate. Mean values of ambient temperature, solar radiation and comfort thermal indices were greater in the summer experiment as expected (Pcarcass characteristics were affected by season but not by the level of MEI. Finally, due to the high variability of data as well as the small number of animals assessed in these experiments, more studies on carcass characteristics under similar conditions are required.

  20. Asia’s glaciers are a regionally important buffer against drought

    Science.gov (United States)

    Pritchard, Hamish D.

    2017-05-01

    The high mountains of Asia—encompassing the Himalayas, the Hindu Kush, Karakoram, Pamir Alai, Kunlun Shan, and Tian Shan mountains—have the highest concentration of glaciers globally, and 800 million people depend in part on meltwater from them. Water stress makes this region vulnerable economically and socially to drought, but glaciers are a uniquely drought-resilient source of water. Here I show that these glaciers provide summer meltwater to rivers and aquifers that is sufficient for the basic needs of 136 million people, or most of the annual municipal and industrial needs of Pakistan, Tajikistan, Turkmenistan, Uzbekistan and Kyrgyzstan. During drought summers, meltwater dominates water inputs to the upper Indus and Aral river basins. Uncertainties in mountain precipitation are poorly known, but, given the magnitude of this water supply, predicted glacier loss would add considerably to drought-related water stress. Such additional water stress increases the risk of social instability, conflict and sudden, uncontrolled population migrations triggered by water scarcity, which is already associated with the large and rapidly growing populations and hydro-economies of these basins.

  1. Research NoteEffect of drought and fires on the quality of water in Lithuanian rivers

    OpenAIRE

    Sakalauskiene, G.; Ignatavicius, G.

    2003-01-01

    In August and September 2002, concentrations of heavy metals (copper, lead, and zinc) were 21-74% more than in previous years in Lithuanian rivers. Such a sudden increase in heavy metal pollution reduces the value of any water body for fishing or recreation and poses a potential risk to the environment and to human health. Droughts in the summer of 2002 led to forest and peat bog fires all over Lithuania and may have caused the increase ...

  2. The Pentapeptide Repeat Proteins

    OpenAIRE

    Vetting, Matthew W.; Hegde, Subray S.; Fajardo, J. Eduardo; Fiser, Andras; Roderick, Steven L.; Takiff, Howard E.; Blanchard, John S.

    2006-01-01

    The Pentapeptide Repeat Protein (PRP) family has over 500 members in the prokaryotic and eukaryotic kingdoms. These proteins are composed of, or contain domains composed of, tandemly repeated amino acid sequences with a consensus sequence of [S,T,A,V][D,N][L,F]-[S,T,R][G]. The biochemical function of the vast majority of PRP family members is unknown. The three-dimensional structure of the first member of the PRP family was determined for the fluoroquinolone resistance protein (MfpA) from Myc...

  3. California's Drought - Stress test for the future

    Science.gov (United States)

    Lund, J. R.

    2014-12-01

    The current California drought is in its third dry years, with this year being the third driest years in a 106-year record. This drought occurs at a time when urban, agricultural, and environmental water demands have never been greater. This drought has revealed the importance of more quantitative evaluation and methods for water assessment and management. All areas of water and environmental management are likely to become increasingly stressed, and have essentially drought-like conditions, in the future, as California's urban, agricultural, and environmental demands continue to expand and as the climate changes. In the historical past, droughts have pre-viewed stresses developing in the future and helped focus policy-makers, the public, and stakeholders on preparing for these developing future conditions. Multi-decade water management strategies are often galvinized by drought. Irrigation was galvanized by California droughts in the 1800s, reservoir systems by the 1928-32 drought, urban water conservation by the 1976-77 drought, and water markets by the 1988-92 drought. With each drought, demands for tighter accounting, rights, and management have increased. This talk reviews the prospects and challenges for increased development and use of water data and systems analysis in the service of human and environmental water demands in California's highly decentralized water management system, and the prospects if these challenges are not more successfully addressed.

  4. Description of future drought indices in Virginia

    Directory of Open Access Journals (Sweden)

    Hyunwoo Kang

    2017-10-01

    Full Text Available This article presents projected future drought occurrences in five river basins in Virginia. The Soil and Water Assessment Tool (SWAT and the Coupled Model Intercomparison Project Phase 5 (CMIP5 climate models were used to derive input variables of multiple drought indices, such as the Standardized Soil Moisture index (SSI, the Multivariate Standardized Drought Index (MSDI, and the Modified Palmer Drought Severity Index (MPDSI for both historic and future periods. The results of SSI indicate that there was an overall increase in agricultural drought occurrences and that these were caused by increases in evapotranspiration and runoff. However, the results of the MSDI and MPDSI projected a decrease in drought occurrences in future periods due to a greater increase in precipitation in the future. Furthermore, GCM-downscaled products (precipitation and temperature were verified using comparisons with historic observations, and the results of uncertainty analyses suggest that the lower and upper bounds of future drought projections agree with historic conditions.

  5. Status of Drought and Desertification in Kenya

    International Nuclear Information System (INIS)

    Mutiso, S.K

    2001-01-01

    The author defined drought in three points of view, viz: agricultural, meteorological and hydrological. All categories of drought are important in the understanding of the society's vulnerability to drought and adjustment mechanisms. Agricultural and hydrological droughts have been shown to have far greater socio-economic and political impacts to people living in the dry lands. methods of predicting drought have been highlighted. Early warning systems should be put in places at District level. Mitigation and rehabilitation of people suffering drought and attendant famine should involve both short term and long term strategies. Rain-harvesting techniques, soil and water conservation, crop water requirement and drought risk forecasting should be carried out along with other measures to combat desrtification

  6. Development of DArT-based PCR markers for selecting drought-tolerant spring barley.

    Science.gov (United States)

    Fiust, Anna; Rapacz, Marcin; Wójcik-Jagła, Magdalena; Tyrka, Mirosław

    2015-08-01

    The tolerance of spring barley (Hordeum vulgare L.) cultivars to spring drought is an important agronomic trait affecting crop yield and quality in Poland. Therefore, breeders require new molecular markers to select plants with lower spring drought susceptibility. With the advent of genomic selection technology, simple molecular tools may still be applicable to screen material for markers of the most important traits and in-depth genome scanning. In previous studies, diversity arrays technology (DArT)-based genetic maps were constructed for F2 populations of Polish fodder and malt barley elite breeding lines, and 15 and 18 quantitative trait loci (QTLs) related to spring drought tolerance were identified, respectively. In this paper, we show the results of a conversion of 30 DArT markers corresponding to 11 QTLs into simple sequence repeat (SSR) and sequence tagged site (STS) markers. Twenty-two polymorphic markers were obtained, including 13 DArT-based SSRs. Additionally, 31 SSR markers, located in close proximity to the DArT markers, were selected from the GrainGenes database and tested. Further analyses of 24 advanced breeding lines with different drought tolerances confirmed that five out of the 30 converted markers, as well as three out of the 31 additional SSR markers, were effective in marker-assisted selection for drought tolerance. The possible function of clones related to these markers in drought tolerance is discussed.

  7. Responses of enchytraeids to increased temperature, drought and atmospheric CO2: Results of an eight-year field experiment in dry heathland

    DEFF Research Database (Denmark)

    Holmstrup, Martin; Schmelz, Rüdiger M.; Carrera, Noela

    2015-01-01

    In a long-term field trial we investigated the responses of enchytraeids to simulated future climatic conditions predicted for Denmark. At a semi-natural Danish heathland site we exposed 9.1 m2 plots to elevated atmospheric CO2 concentration (510 ppm), extended summer drought and passive night...... in spring 2013, perhaps indicating that warming stimulates fragmentation (reproduction) rates at this time of the year. Increased drought in MayeJune 2012 did not have lasting effects on abundance or biomass 3 months after the termination of drought treatment. However, comparison with earlier assessments...... of enchytraeids in the CLIMAITE experiment shows that the severity of drought and the time elapsed since the last drought is the best predictor of the biovolume (or biomass) of enchytraeids. Moreover, species richness was significantly impacted by the average soil water content experienced by enchytraeids during...

  8. Drought, Agriculture, and Labor: Understanding Drought Impacts and Vulnerability in California

    Science.gov (United States)

    Greene, C.

    2015-12-01

    Hazardous drought impacts are a product of not only the physical intensity of drought, but also the economic, social, and environmental characteristics of the region exposed to drought. Drought risk management requires understanding the complex links between the physical and human dimensions of drought. Yet, there is a research gap in identifying and explaining the socio-economic complexities of drought in the context of the first world, especially for economic and socially marginal groups who rely on seasonal and temporary jobs. This research uses the current drought in California as a case study to identify the socioeconomic impacts of drought on farmworker communities in California's San Joaquin Valley, with a specific focus on the relationship between drought and agricultural labor. Through both a narrative analysis of drought coverage in newspaper media, drought policy documents, and interviews with farmworkers, farmers, community based organizations, and government officials in the San Joaquin Valley, this research aims to highlight the different understandings and experiences of the human impacts of drought and drought vulnerability in order to better inform drought risk planning and policy.

  9. Repeated Causal Decision Making

    Science.gov (United States)

    Hagmayer, York; Meder, Bjorn

    2013-01-01

    Many of our decisions refer to actions that have a causal impact on the external environment. Such actions may not only allow for the mere learning of expected values or utilities but also for acquiring knowledge about the causal structure of our world. We used a repeated decision-making paradigm to examine what kind of knowledge people acquire in…

  10. simple sequence repeat (SSR)

    African Journals Online (AJOL)

    In the present study, 78 mapped simple sequence repeat (SSR) markers representing 11 linkage groups of adzuki bean were evaluated for transferability to mungbean and related Vigna spp. 41 markers amplified characteristic bands in at least one Vigna species. The transferability percentage across the genotypes ranged ...

  11. Regional tree growth and inferred summer climate in the Winnipeg River basin, Canada, since AD 1783

    Science.gov (United States)

    St. George, Scott; Meko, David M.; Evans, Michael N.

    2008-09-01

    A network of 54 ring-width chronologies is used to estimate changes in summer climate within the Winnipeg River basin, Canada, since AD 1783. The basin drains parts of northwestern Ontario, northern Minnesota and southeastern Manitoba, and is a key area for hydroelectric power production. Most chronologies were developed from Pinus resinosa and P. strobus, with a limited number of Thuja occidentalis, Picea glauca and Pinus banksiana. The dominant pattern of regional tree growth can be recovered using only the nine longest chronologies, and is not affected by the method used to remove variability related to age or stand dynamics from individual trees. Tree growth is significantly, but weakly, correlated with both temperature (negatively) and precipitation (positively) during summer. Simulated ring-width chronologies produced by a process model of tree-ring growth exhibit similar relationships with summer climate. High and low growth across the region is associated with cool/wet and warm/dry summers, respectively; this relationship is supported by comparisons with archival records from early 19th century fur-trading posts. The tree-ring record indicates that summer droughts were more persistent in the 19th and late 18th century, but there is no evidence that drought was more extreme prior to the onset of direct monitoring.

  12. Evaluation of Summer Bridge Programs

    Science.gov (United States)

    Garcia, Lisa D.; Paz, Chiara C.

    2009-01-01

    Many colleges and universities in the United States offer summer programs for their incoming students. While programs are structured and administered in a variety of ways and target various student populations, the most common type of summer bridge program aims to serve historically underrepresented students and students of low socioeconomic…

  13. Drought impacts on vegetation dynamics in the Mediterranean based on remote sensing and multi-scale drought indices

    Science.gov (United States)

    Trigo, Ricardo; Gouveia, Celia M.; Beguería, Santiago; Vicente-Serrano, Sergio

    2015-04-01

    A number of recent studies have identified a significant increase in the frequency of drought events in the Mediterranean basin (e.g. Trigo et al., 2013, Vicente-Serrano et al., 2014). In the Mediterranean region, large drought episodes are responsible for the most negative impacts on the vegetation including significant losses of crop yield, increasing risk of forest fires (e.g. Gouveia et al., 2012) and even forest decline. The aim of the present work is to analyze in detail the impacts of drought episodes on vegetation in the Mediterranean basin behavior using NDVI data from (from GIMMS) for entire Mediterranean basin (1982-2006) and the multi-scale drought index (the Standardised Precipitation-Evapotranspiration Index (SPEI). Correlation maps between fields of monthly NDVI and SPEI for at different time scales (1-24 months) were computed in order to identify the regions and seasons most affected by droughts. Affected vegetation presents high spatial and seasonal variability, with a maximum in summer and a minimum in winter. During February 50% of the affected pixels corresponded to a time scale of 6 months, while in November the most frequent time scale corresponded to 3 months, representing more than 40% of the affected region. Around 20% of grid points corresponded to the longer time scales (18 and 24 months), persisting fairly constant along the year. In all seasons the wetter clusters present higher NDVI values which indicates that aridity holds a key role to explain the spatial differences in the NDVI values along the year. Despite the localization of these clusters in areas with higher values of monthly water balance, the strongest control of drought on vegetation activity are observed for the drier classes located over regions with smaller absolute values of water balance. Gouveia C.M., Bastos A., Trigo R.M., DaCamara C.C. (2012) "Drought impacts on vegetation in the pre and post-fire events over Iberian Peninsula". Natural Hazards and Earth System

  14. SUMMER STUDENT LECTURE PROGRAMME

    CERN Multimedia

    Françoise Benz

    2002-01-01

    SUMMER STUDENT LECTURE PROGRAMME Main Auditorium, bldg. 500   DATE TIME LECTURER TITLE Monday 29 July 09:15 - 10:00 R. RATTAZZI Beyond the Standard Model (3/3) 10:15 - 11:00 P. WELLS Experimental test of the SM - LEP (3/3) 11:15 - 12:00 P. WELLS Discussion Session 14:00 - 16:00 R. ASSMANN The CLIC Concept for a Future Particle Collider at the Energy Frontier Tuesday 30 July 09:15 - 10:00 F. ANTINORI Heavy Ions (1/2) 10:15 - 12:00 F. DYDAK Neutrino Physics (1&2/4) Wednesday 31 July  09:15 - 10:00 F. ANTINORI Heavy Ions (2/2) 10:15 - 11:00 F. DYDAK Neutrino Physics (3/4) 11:15 - 12:00 F. DYDAK / F. ANTINORI Discussion Session Thursday 1 August 09:15 - 10:00 T. NAKADA CP Violation (1/4) 10:15 - 11:00 F. DYDAK Neutrino Physics (4/4) 11:15 - 12:00 F. BEDESCHI Experimental test of the SM Tevatron (1/2) Friday 2 August 09:15 - 10:00 T. NAKADA CP Violation (2/4) 10:15 ? 11:00 F. BEDESCHI Experimental test of the SM Tevatron (2/2) 11:15 ? 12:00 F. BEDESCHI / T. NAKADA Di...

  15. Summer music festivals

    CERN Document Server

    2008-01-01

    Although July is set to be a crucial time in the working life of the Laboratory, the CERN clubs have organised musical events to make sure that there’s also a chance to chill out and relax. The group Blend at the 2007 Hardronic Festival. From left to right (on stage): Eric Pfirsch, Stephan Petit, Frédéric Lejal, Niklaus Hirt, Paulo Dos Santos with Laurent Tarrano filming.If you have a strong appetite for music the ‘Monts Jura Jazz Festival’, might tempt you this summer. Sponsored by both the CERN Administration and the Staff Association, it is an established highlight of the local arts calendar and will this year be held on 4 and 5 July in Crozet, France. For the third year running established musicians, stars of the jazz scene, and rising talent from France, Switzerland and Brazil will be joining forces to perform an exiting mixture of jazz music. A ‘master class’ in improvisation methods will also be held on Saturda...

  16. Summer student final report

    CERN Document Server

    Guzik, Jakub

    2013-01-01

    During my time spent at CERN I worked under the Technology Department of CERN, in the Machine Protection and Electrical Integrity (MPE) Group. The MPE Group supports LHC operations and maintains state of the art technology for magnet circuit protection and interlock systems for the present and future accelerators, magnet test facilities and CERN hosted experiments[1]. As a member of Magnet Powering Interlocks & Software (TE-MPE-MS) section I was involved in three different projects and used not only CERN developed tools like FESA Framework, but also open source C++ frameworks, Google Test and Google Mock. I had a chance to work with Programmable Logic Controllers and real-time devices known as Front End Computers. I was part of a software developer team, and familiarized myself with the Scrum agile software development methodology. The description and results of my work are presented in three parts of this report. Each part describes a separate project created during my participation in the CERN Summer St...

  17. Summer Student Programme

    CERN Multimedia

    2006-01-01

    Date Time Title Speaker 05/07/2006 09:15 - 10:00 Presentation of the Summer Student Programme F. CERUTTI Information on Computing Rules D. HEAGERTY Workshops presentation O. ULLALAND 10:15 - 11:00 Introduction to CERN J. ENGELEN 11:15 Film on CERN 11:00 Introduction to Particle Physics F. CLOSE 11:15 - 12:00 Accelerators (1/5) S. GILARDONI / E. METRAL 12:00 Discussion Session 7/07/2006 09:15 - 11:00 Introduction to Particle Physics F. CLOSE 11:15 - 12:00 Accelerators (2/5) S. GILARDONI / E. METRAL 12:00 Discussion Session 09:15 - 10:00 Accelerators (3/5) S. GILARDONI / E. METRAL 10:15 - 12:00 Detectors (1-2/5) O. ULLALAND 12:00 Discussion Session 11/07/2006 09:15 - 10:00 Accelerators (4/5) S. GILARDONI / E. METRAL 10:15 - 11:00 Detectors (3/5) O. ULLALAND 11:15 - 12:00 Introduction to Nuclear Physics (1/4) P. CHOMAZ P. CHOMAZ 10:15 - 11:00 Accelerators (5/5) S. GILARDONI / E. METRAL 11:15 - 12:00 Detectors (4/5) O. ULLALAND 12:00 Discus...

  18. Summer School on Spintronics

    CERN Document Server

    Wolf, Stuart; Idzerda, Yves

    2003-01-01

    Stuart Wolf This book originated as a series of lectures that were given as part of a Summer School on Spintronics in the end of August, 1998 at Lake Tahoe, Nevada. It has taken some time to get these lectures in a form suitable for this book and so the process has been an iterative one to provide current information on the topics that are covered. There are some topics that have developed in the intervening years and we have tried to at least alert the readers to them in the Introduction where a rather complete set of references is provided to the current state of the art. The field of magnetism, once thought to be dead or dying, has seen a remarkable rebirth in the last decade and promises to get even more important as we enter the new millennium. This rebirth is due to some very new insight into how the spin degree of freedom of both electrons and nucleons can play a role in a new type of electronics that utilizes the spin in addition to or in place of the charge. For this new field to mature and prosper, ...

  19. A comparative analysis of surface winds in the Mid-Continental United States of America during severe droughts in the 1950s and 2010s.

    Science.gov (United States)

    McCarter, R.; Kohfeld, K. E.; Schepanski, K.; Gill, T. E.

    2016-12-01

    In 2011 the Mid-Continental United States of America experienced its worst drought since the 1930s `Dust Bowl` and subsequent 1950s Southwest drought. Both the 1950s and 2010s droughts have had negative ecological and economic impacts the Mid-Continental US (i.e. crops, livestock, fuel, and transportation). Drought distribution, severity, and duration in North America are influenced by large-scale ocean-atmosphere climate variability as well as mesoscale land-surface forcing. Intense surface heating during a drought's summer months promotes dry convection and convergence thereby indirectly increasing dust emissions through increased surface-winds. Thus, drought years are frequently linked with increased dust storms and overall dust production that can affect visibility, crop production, and human health. Another important aspect that influences dust production is the potential change in behavior of surface winds during different drought and non-drought regimes over the past 60 years. This investigation compares historic and modern surface winds to determine if the wind-driven drought and dust producing conditions have changed. We examine hourly wind speed data from 79 meteorological stations distributed over the mid-continental USA (25° to 49°N,-116° to -93°W) for two drought periods (1954-1956, 2011-2013), and two relatively wet time periods (1983-1987, 1992-1998), as determined using the Palmer-Drought Severity Index. Our preliminary examination of annual and seasonal distributions of wind speed and show that wind speeds were statistically higher during the 1950s compared with the 2010s drought and wind speeds were also greater during the spring months compared to other seasons. Characterizing these winds is a first step in identifying if these changes are a result of land surface changes, general circulation changes associated with atmospheric anomalies, and/or climate change.

  20. Species Diversity of Oak Stands and Its Significance for Drought Resistance

    Directory of Open Access Journals (Sweden)

    Jan Kotlarz

    2018-03-01

    Full Text Available Drought periods have an adverse impact on the condition of oak stands. Research on different types of ecosystems has confirmed a correlation between plant species diversity and the adverse effects of droughts. The purpose of this study was to investigate the changes that occurred in an oak stand (Krotoszyn Plateau, Poland under the impact of the summer drought in 2015. We used a method based on remote sensing indices from satellite images in order to detect changes in the vegetation in 2014 and 2015. A positive difference was interpreted as an improvement, whereas a negative one was treated as a deterioration of the stand condition. The Shannon-Wiener species diversity was estimated using an iterative principal component analysis (PCA algorithm based on aerial images. We observed a relationship between the species indices of the individual forest divisions and their response to drought. The highest correlation between the index differences and the Shannon-Wiener indices was found for the Green Normalized Difference Vegetation Index (GNDVI index (+0.74. In addition, correlations were observed between the mean index difference and the percentage shares in the forest divisions of species such as Pinus sylvestris L. (P. sylvestris (+0.67 ± 0.08 and Quercus robur L. (Q. robur (−0.65 ± 0.10. Our results lead us to infer that forest management based on highly diverse habitats is more suitable to meet the challenges in the context of global climatic changes, characterized by increasingly frequent droughts.

  1. The Hunger Stones: a new source for more objective identification of historical droughts

    Science.gov (United States)

    Elleder, Libor

    2016-04-01

    Extreme droughts recorded recently more frequently in different parts of the world represent the most serious environmental problem. Our contribution identifies periods of hydrological drought. The extreme drought period in summer 2015 enabled the levelling of historical watermarks on the „Hunger Stone" (Hungerstein) in the Elbe in Czech town of Děčín. The comparison of the obtained levels of earlier palaeographic records with systematic measurements in the Děčín profile confirmed the hypothesis that the old watermarks represent the minimal water levels. Moreover, we present a review of so far known Hunger Stones in the Elbe River with their low-level watermarks. For identification of the drought period duration we used the oldest water level records from the Czech Hydrometeorological Institute (CHMI) database archive: Magdeburg (since 1727), Dresden (since 1801), Prague (since 1825) and Decin (since 1851) time-series. We obtained more objective and complex information on all historical droughts between 1727 and 2015. The low water-marks on Hunger Stones give us a possibility for augmentation of systematic records and extended our knowledge's back to 1616. The Hunger Stones in the Elbe River with old watermarks are unique testimony for studying of hydrological extremes, and last but not least also of anthropogenic changes in the riverbed of the Elbe.

  2. South American Monsoon: Recent Droughts in the Context of Changing Global Circulation.

    Science.gov (United States)

    Seth, A.; Fernandes, K.; Camargo, S. J.

    2016-12-01

    The 2013-2015 drought in Southeast Brazil led to water shortages in São Paulo, the country's most populous city. The observed drought during austral summers of 2013/2014 and 2014/2015 and related large-scale dynamics are examined. The 2013-2014 precipitation deficits were more concentrated in the state of São Paulo, while in 2014-2015 moderate deficits were seen throughout the region. We find that a persistent warm sea surface temperature (SST) anomaly in the western tropical Pacific Ocean was an important driver of drought via atmospheric teleconnection in the two December-February seasons. The warm SST and associated convective heating initiated a wave train across the South Pacific. The resulting anticyclonic geopotential height anomaly over the southwest Atlantic expanded the westward margin of the South Atlantic high and prevented low-pressure systems from entering southeast Brazil from midlatitudes. This mechanism suggests a hemispheric symmetry to that proposed for the recent California drought. A first look at CMIP5 model projections to examine the role of large scale circulation changes to drought in the Sao Paulo region will be presented.

  3. Drought early warning and risk management in a changing environment

    Science.gov (United States)

    Pulwarty, R. S.

    2011-12-01

    Drought has long been recognized as falling into the category of incremental but long-term and cumulative environmental changes, also termed slow-onset or creeping events. These event types would include: air and water quality decline, desertification processes, deforestation and forest fragmentation, loss of biodiversity and habitats, and nitrogen overloading, among others. Climate scientists continue to struggle with recognizing the onset of drought and scientists and policy makers continue to debate the basis (i.e., criteria) for declaring an end to a drought. Risk-based management approaches to drought planning at the national and regional levels have been recommended repeatedly over the years but their prototyping, testing and operational implementation have been limited. This presentation will outline two avenues for disaster risk reduction in the context of drought (1) integrated early warning information systems, and (2) linking disaster risk reduction to climate change adaptation strategies. Adaptation involves not only using operational facilities and infrastructure to cope with the immediate problems but also leaving slack or reserve for coping with multiple stress problems that produce extreme impacts and surprise. Increasing the 'anticipatability' of an event, involves both monitoring of key indicators from appropriate baseline data, and observing early warning signs that assumptions in risk management plans are failing and critical transitions are occurring. Illustrative cases will be drawn from the IPCC Special Report on Managing the Risks of Extreme Events and Disasters (2011), the UN Global Assessment of Disaster Risk Reduction (2011) and implementation activities in which the author has been engaged. Most drought early warning systems have tended to focus on the development and use of physical system indicators and forecasts of trends and thresholds. We show that successful early warning systems that meet expectations of risk management also have

  4. The impact of the resolution of meteorological datasets on catchment-scale drought studies

    Science.gov (United States)

    Hellwig, Jost; Stahl, Kerstin

    2017-04-01

    Gridded meteorological datasets provide the basis to study drought at a range of scales, including catchment scale drought studies in hydrology. They are readily available to study past weather conditions and often serve real time monitoring as well. As these datasets differ in spatial/temporal coverage and spatial/temporal resolution, for most studies there is a tradeoff between these features. Our investigation examines whether biases occur when studying drought on catchment scale with low resolution input data. For that, a comparison among the datasets HYRAS (covering Central Europe, 1x1 km grid, daily data, 1951 - 2005), E-OBS (Europe, 0.25° grid, daily data, 1950-2015) and GPCC (whole world, 0.5° grid, monthly data, 1901 - 2013) is carried out. Generally, biases in precipitation increase with decreasing resolution. Most important variations are found during summer. In low mountain range of Central Europe the datasets of sparse resolution (E-OBS, GPCC) overestimate dry days and underestimate total precipitation since they are not able to describe high spatial variability. However, relative measures like the correlation coefficient reveal good consistencies of dry and wet periods, both for absolute precipitation values and standardized indices like the Standardized Precipitation Index (SPI) or Standardized Precipitation Evaporation Index (SPEI). Particularly the most severe droughts derived from the different datasets match very well. These results indicate that absolute values of sparse resolution datasets applied to catchment scale might be critical to use for an assessment of the hydrological drought at catchment scale, whereas relative measures for determining periods of drought are more trustworthy. Therefore, studies on drought, that downscale meteorological data, should carefully consider their data needs and focus on relative measures for dry periods if sufficient for the task.

  5. Human water consumption intensifies hydrological drought worldwide

    International Nuclear Information System (INIS)

    Wada, Yoshihide; Van Beek, Ludovicus P H; Wanders, Niko; Bierkens, Marc F P

    2013-01-01

    Over the past 50 years, human water use has more than doubled and affected streamflow over various regions of the world. However, it remains unclear to what degree human water consumption intensifies hydrological drought (the occurrence of anomalously low streamflow). Here, we quantify over the period 1960–2010 the impact of human water consumption on the intensity and frequency of hydrological drought worldwide. The results show that human water consumption substantially reduced local and downstream streamflow over Europe, North America and Asia, and subsequently intensified the magnitude of hydrological droughts by 10–500%, occurring during nation- and continent-wide drought events. Also, human water consumption alone increased global drought frequency by 27 (±6)%. The intensification of drought frequency is most severe over Asia (35 ± 7%), but also substantial over North America (25 ± 6%) and Europe (20 ± 5%). Importantly, the severe drought conditions are driven primarily by human water consumption over many parts of these regions. Irrigation is responsible for the intensification of hydrological droughts over the western and central US, southern Europe and Asia, whereas the impact of industrial and households’ consumption on the intensification is considerably larger over the eastern US and western and central Europe. Our findings reveal that human water consumption is one of the more important mechanisms intensifying hydrological drought, and is likely to remain as a major factor affecting drought intensity and frequency in the coming decades. (letter)

  6. Response of surface and groundwater on meteorological drought in Topla River catchment, Slovakia

    Science.gov (United States)

    Fendekova, Miriam; Fendek, Marian; Vrablikova, Dana; Blaskovicova, Lotta; Slivova, Valeria; Horvat, Oliver

    2016-04-01

    upper gauging station in Bardejov lasts usually longer than in Hanusovce nad Toplou station being located downstream. Higher number of short-term droughts was estimated for groundwater head in one monitoring well with the smallest depth of groundwater head below the surface. In this case, the influence of evapotranspiration could be the reason. More long-term droughts were estimated by TLM method for groundwater heads in other seven monitoring wells. Those droughts lasted for tens of weeks since summer until the spring of the next year. No regularity in temporal groundwater head drought propagation downstream the Topla River was discovered. However, results of the cluster analysis showed some common features of long-term drought periods (more than 100 days) occurrence for two groups of wells. Different hydrogeological conditions in two evaluated wells were also reflected in drought periods number and severity. The research was financially supported by APVV-0089-12 project (principal investigator Miriam Fendekova).

  7. Drought Tolerance in Modern and Wild Wheat

    Science.gov (United States)

    Budak, Hikmet; Kantar, Melda; Yucebilgili Kurtoglu, Kuaybe

    2013-01-01

    The genus Triticum includes bread (Triticum aestivum) and durum wheat (Triticum durum) and constitutes a major source for human food consumption. Drought is currently the leading threat on world's food supply, limiting crop yield, and is complicated since drought tolerance is a quantitative trait with a complex phenotype affected by the plant's developmental stage. Drought tolerance is crucial to stabilize and increase food production since domestication has limited the genetic diversity of crops including wild wheat, leading to cultivated species, adapted to artificial environments, and lost tolerance to drought stress. Improvement for drought tolerance can be achieved by the introduction of drought-grelated genes and QTLs to modern wheat cultivars. Therefore, identification of candidate molecules or loci involved in drought tolerance is necessary, which is undertaken by “omics” studies and QTL mapping. In this sense, wild counterparts of modern varieties, specifically wild emmer wheat (T. dicoccoides), which are highly tolerant to drought, hold a great potential. Prior to their introgression to modern wheat cultivars, drought related candidate genes are first characterized at the molecular level, and their function is confirmed via transgenic studies. After integration of the tolerance loci, specific environment targeted field trials are performed coupled with extensive analysis of morphological and physiological characteristics of developed cultivars, to assess their performance under drought conditions and their possible contributions to yield in certain regions. This paper focuses on recent advances on drought related gene/QTL identification, studies on drought related molecular pathways, and current efforts on improvement of wheat cultivars for drought tolerance. PMID:23766697

  8. Drought Tolerance in Modern and Wild Wheat

    Directory of Open Access Journals (Sweden)

    Hikmet Budak

    2013-01-01

    Full Text Available The genus Triticum includes bread (Triticum aestivum and durum wheat (Triticum durum and constitutes a major source for human food consumption. Drought is currently the leading threat on world's food supply, limiting crop yield, and is complicated since drought tolerance is a quantitative trait with a complex phenotype affected by the plant's developmental stage. Drought tolerance is crucial to stabilize and increase food production since domestication has limited the genetic diversity of crops including wild wheat, leading to cultivated species, adapted to artificial environments, and lost tolerance to drought stress. Improvement for drought tolerance can be achieved by the introduction of drought-grelated genes and QTLs to modern wheat cultivars. Therefore, identification of candidate molecules or loci involved in drought tolerance is necessary, which is undertaken by “omics” studies and QTL mapping. In this sense, wild counterparts of modern varieties, specifically wild emmer wheat (T. dicoccoides, which are highly tolerant to drought, hold a great potential. Prior to their introgression to modern wheat cultivars, drought related candidate genes are first characterized at the molecular level, and their function is confirmed via transgenic studies. After integration of the tolerance loci, specific environment targeted field trials are performed coupled with extensive analysis of morphological and physiological characteristics of developed cultivars, to assess their performance under drought conditions and their possible contributions to yield in certain regions. This paper focuses on recent advances on drought related gene/QTL identification, studies on drought related molecular pathways, and current efforts on improvement of wheat cultivars for drought tolerance.

  9. Variability of East Asian summer monsoon precipitation during the Holocene and possible forcing mechanisms

    Science.gov (United States)

    Lu, Fuzhi; Ma, Chunmei; Zhu, Cheng; Lu, Huayu; Zhang, Xiaojian; Huang, Kangyou; Guo, Tianhong; Li, Kaifeng; Li, Lan; Li, Bing; Zhang, Wenqing

    2018-03-01

    Projecting how the East Asian summer monsoon (EASM) rainfall will change with global warming is essential for human sustainability. Reconstructing Holocene climate can provide critical insight into its forcing and future variability. However, quantitative reconstructions of Holocene summer precipitation are lacking for tropical and subtropical China, which is the core region of the EASM influence. Here we present high-resolution annual and summer rainfall reconstructions covering the whole Holocene based on the pollen record at Xinjie site from the lower Yangtze region. Summer rainfall was less seasonal and 30% higher than modern values at 10-6 cal kyr BP and gradually declined thereafter, which broadly followed the Northern Hemisphere summer insolation. Over the last two millennia, however, the summer rainfall has deviated from the downward trend of summer insolation. We argue that greenhouse gas forcing might have offset summer insolation forcing and contributed to the late Holocene rainfall anomaly, which is supported by the TraCE-21 ka transient simulation. Besides, tropical sea-surface temperatures could modulate summer rainfall by affecting evaporation of seawater. The rainfall pattern concurs with stalagmite and other proxy records from southern China but differs from mid-Holocene rainfall maximum recorded in arid/semiarid northern China. Summer rainfall in northern China was strongly suppressed by high-northern-latitude ice volume forcing during the early Holocene in spite of high summer insolation. In addition, the El Niño/Southern Oscillation might be responsible for droughts of northern China and floods of southern China during the late Holocene. Furthermore, quantitative rainfall reconstructions indicate that the Paleoclimate Modeling Intercomparison Project (PMIP) simulations underestimate the magnitude of Holocene precipitation changes. Our results highlight the spatial and temporal variability of the Holocene EASM precipitation and potential forcing

  10. Development of SSR Markers Based on Transcriptome Sequencing and Association Analysis with Drought Tolerance in Perennial Grass Miscanthus from China

    Directory of Open Access Journals (Sweden)

    Gang Nie

    2017-05-01

    Full Text Available Drought has become a critical environmental stress affecting on plant in temperate area. As one of the promising bio-energy crops to sustainable biomass production, the genus Miscanthus has been widely studied around the world. However, the most widely used hybrid cultivar among this genus, Miscanthus × giganteus is proved poor drought tolerance compared to some parental species. Here we mainly focused on Miscanthus sinensis, which is one of the progenitors of M. × giganteus providing a comparable yield and well abiotic stress tolerance in some places. The main objectives were to characterize the physiological and photosynthetic respond to drought stress and to develop simple sequence repeats (SSRs markers associated with drought tolerance by transcriptome sequencing within an originally collection of 44 Miscanthus genotypes from southwest China. Significant phenotypic differences were observed among genotypes, and the average of leaf relative water content (RWC were severely affected by drought stress decreasing from 88.27 to 43.21%, which could well contribute to separating the drought resistant and drought sensitive genotype of Miscanthus. Furthermore, a total of 16,566 gene-associated SSRs markers were identified based on Illumina RNA sequencing under drought conditions, and 93 of them were randomly selected to validate. In total, 70 (75.3% SSRs were successfully amplified and the generated loci from 30 polymorphic SSRs were used to estimate the genetic differentiation and population structure. Finally, two optimum subgroups of the population were determined by structure analysis and based on association analysis, seven significant associations were identified including two markers with leaf RWC and five markers with photosynthetic traits. With the rich sequencing resources annotation, such associations would serve an efficient tool for Miscanthus drought response mechanism study and facilitate genetic improvement of drought resistant for

  11. A two millennium-long hot drought in the southwestern United States driven by Arctic sea-ice retreat

    Science.gov (United States)

    Lachniet, M. S.; Asmerom, Y.; Polyak, V. J.; Denniston, R. F.

    2017-12-01

    The Great Basin and lower Colorado River Basin are susceptible to sustained droughts that impact water resources and economic activity for millions of residents of the southwestern United States. The causes of past droughts in the basin remain debated. Herein, we document a strong Arctic to mid-latitude teleconnection during the Holocene that resulted in an extreme `hot drought' persisting for more than two millennia in the southwestern United States, based on a continuous growth rate and new high-resolution carbon and oxygen isotopic time series from a precisely-dated stalagmite from Leviathan Cave, Nevada. Between 9850-7670 yr B2k, highest Holocene oxygen isotope values indicate warm temperatures and moisture-sensitive proxies of high carbon isotope values and low stalagmite growth rate and minimal soil productivity and aquifer recharge. We refer to this period as the Altithermal Hot Drought. A second interval (6770 to 5310 yr B2k) indicates a warm drought. The two Altithermal droughts exceed in severity and duration any droughts observed in the modern and tree-ring records. Further, we show that Altithermal hot droughts were widespread in the southwestern United States, at a time when human populations in the Great Basin were low. The droughts show strong similarities to proxies for Arctic paleoclimate and we suggest that insolation-driven changes in sea ice and snow cover extent in the high latitudes drove atmospheric circulation anomalies in the Great Basin. Because rising greenhouse gas concentrations are projected to increase global and Arctic temperatures with a possible loss of summer sea by the end of the 21st century, our record suggests that a return to prolonged hotter and drier conditions in the southern Great Basin and lower Colorado River Basin is possible within coming centuries.

  12. Genetic studies towards elucidation of drought tolerance of potato

    NARCIS (Netherlands)

    Tessema, Biructa Bekele

    2017-01-01

    Drought is a major threat to agricultural production, which makes drought tolerance a prime target for breeding approaches towards crop improvement. Drought is a complex polygenic trait and poses a challenge for drought tolerance breeding. Improving crops for drought tolerance at least requires

  13. Fostering drought research and science-policy interfacing

    NARCIS (Netherlands)

    Lanen, van Henny A.J.; Tallaksen, Lena M.; Assimacopoulos, Dionysis; Stahl, Kerstin; Wolters, Wouter; Andreu, Joaquin; Seneviratne, Sonia I.; Stefano, De Lucia; Seidl, Irmi; Rego, Francisco Castro; Massarutto, Antonio; Garnier, Emmanuel

    2015-01-01

    The DROUGHT-R&SPI project adopted a transdisciplinary approach that combined drought analyses for six selected Case Studies across Europe with drought analyses at the pan-European scale both for past and future climates. Achievements on drought as natural hazard, drought impacts, responses

  14. Hydrological drought severity explained by climate and catchment characteristics

    NARCIS (Netherlands)

    Loon, Van A.F.; Laaha, G.

    2015-01-01

    Impacts of a drought are generally dependent on the severity of the hydrological drought event, which can be expressed by streamflow drought duration or deficit volume. For prediction and the selection of drought sensitive regions, it is crucial to know how streamflow drought severity relates to

  15. Post-Fire Seedling Recruitment and Morpho-Ecophysiological Responses to Induced Drought and Salvage Logging in Pinus halepensis Mill. Stands

    Directory of Open Access Journals (Sweden)

    Daniel Moya

    2015-05-01

    Full Text Available Salvage logging is the commonest post-fire emergency action, but has unclear ecological effects. In the Mediterranean Basin, drought periods and fire regimes are changing and forest management should be adapted. In summer 2009, a mid-high severity fire burned 968 ha of Aleppo pine (Pinus halepensis Mill. forest in southeast Spain, which was submitted to salvage logging six months later. In spring 2010, plots were set in untreated and logged areas to monitor the recruitment and survival of the main tree species and three companion species: Stipa tenacissima L. (resprouter, Cistus clusii Dunal and Rosmarinus officinalis L. (obligate seeders. We evaluated responses to different scenarios in relation to intensification of summer droughts and forest management to obtain differences in water stress, growth, and gas exchange to cope with summer drought. Drought was induced by using rain-exclusion shelters and recorded ecophysiological characteristics were obtained with a portable gas exchange system. The main tree species recruitment was poor, but companion species showed a high survival ratio. Lower water stress was found for obligate seeder seedlings, which was higher in logged areas with induced drought. The initial post-fire stage was similar for the studied areas. However, after two drought periods (2010 and 2011, significant differences were found in the morphological and ecophysiological responses. In the unmanaged area, the biggest size of individuals due to the most marked increases in height and coverage were observed mainly in resprouter S. tenacissima. In the area submitted to salvage logging, the growth ratios in plots with induced drought were lower, mainly for seeders. Greater productivity was related to higher transpiration, stomatal conductance, and net photosynthetic ratio, but lower water use efficiency was found in obligate seeders with no drought induction, and S. tenacissima obtained higher values in untreated areas. Our results

  16. Climate signals in a multispecies tree-ring network from central and southern Italy and reconstruction of the late summer temperatures since the early 1700s

    Science.gov (United States)

    Leonelli, Giovanni; Coppola, Anna; Salvatore, Maria Cristina; Baroni, Carlo; Battipaglia, Giovanna; Gentilesca, Tiziana; Ripullone, Francesco; Borghetti, Marco; Conte, Emanuele; Tognetti, Roberto; Marchetti, Marco; Lombardi, Fabio; Brunetti, Michele; Maugeri, Maurizio; Pelfini, Manuela; Cherubini, Paolo; Provenzale, Antonello; Maggi, Valter

    2017-11-01

    A first assessment of the main climatic drivers that modulate the tree-ring width (RW) and maximum latewood density (MXD) along the Italian Peninsula and northeastern Sicily was performed using 27 forest sites, which include conifers (RW and MXD) and broadleaves (only RW). Tree-ring data were compared using the correlation analysis of the monthly and seasonal variables of temperature, precipitation and standardized precipitation index (SPI, used to characterize meteorological droughts) against each species-specific site chronology and against the highly sensitive to climate (HSTC) chronologies (based on selected indexed individual series). We find that climate signals in conifer MXD are stronger and more stable over time than those in conifer and broadleaf RW. In particular, conifer MXD variability is directly influenced by the late summer (August, September) temperature and is inversely influenced by the summer precipitation and droughts (SPI at a timescale of 3 months). The MXD sensitivity to August-September (AS) temperature and to summer drought is mainly driven by the latitudinal gradient of summer precipitation amounts, with sites in the northern Apennines showing stronger climate signals than sites in the south. Conifer RW is influenced by the temperature and drought of the previous summer, whereas broadleaf RW is more influenced by summer precipitation and drought of the current growing season. The reconstruction of the late summer temperatures for the Italian Peninsula for the past 300 years, based on the HSTC chronology of conifer MXD, shows a stable model performance that underlines periods of climatic cooling (and likely also wetter conditions) in 1699, 1740, 1814, 1914 and 1938, and follows well the variability of the instrumental record and of other tree-ring-based reconstructions in the region. Considering a 20-year low-pass-filtered series, the reconstructed temperature record consistently deviates divergence may also be due to the precipitation

  17. Climate signals in a multispecies tree-ring network from central and southern Italy and reconstruction of the late summer temperatures since the early 1700s

    Directory of Open Access Journals (Sweden)

    G. Leonelli

    2017-11-01

    Full Text Available A first assessment of the main climatic drivers that modulate the tree-ring width (RW and maximum latewood density (MXD along the Italian Peninsula and northeastern Sicily was performed using 27 forest sites, which include conifers (RW and MXD and broadleaves (only RW. Tree-ring data were compared using the correlation analysis of the monthly and seasonal variables of temperature, precipitation and standardized precipitation index (SPI, used to characterize meteorological droughts against each species-specific site chronology and against the highly sensitive to climate (HSTC chronologies (based on selected indexed individual series. We find that climate signals in conifer MXD are stronger and more stable over time than those in conifer and broadleaf RW. In particular, conifer MXD variability is directly influenced by the late summer (August, September temperature and is inversely influenced by the summer precipitation and droughts (SPI at a timescale of 3 months. The MXD sensitivity to August–September (AS temperature and to summer drought is mainly driven by the latitudinal gradient of summer precipitation amounts, with sites in the northern Apennines showing stronger climate signals than sites in the south. Conifer RW is influenced by the temperature and drought of the previous summer, whereas broadleaf RW is more influenced by summer precipitation and drought of the current growing season. The reconstruction of the late summer temperatures for the Italian Peninsula for the past 300 years, based on the HSTC chronology of conifer MXD, shows a stable model performance that underlines periods of climatic cooling (and likely also wetter conditions in 1699, 1740, 1814, 1914 and 1938, and follows well the variability of the instrumental record and of other tree-ring-based reconstructions in the region. Considering a 20-year low-pass-filtered series, the reconstructed temperature record consistently deviates < 1 °C from the instrumental

  18. Automated Monitoring of Carbon Fluxes in a Northern Rocky Mountain Forest Indicates Above-Average Net Primary Productivity During the 2015 Western U.S. Drought

    Science.gov (United States)

    Stenzel, J.; Hudiburg, T. W.

    2016-12-01

    As global temperatures rise in the 21st century, "hotter" droughts will become more intense and persistent, particularly in areas which already experience seasonal drought. Because forests represent a large and persistent terrestrial carbon sink which has previously offset a significant proportion of anthropogenic carbon emissions, forest carbon cycle responses to drought have become a prominent research concern. However, robust mechanistic modeling of carbon balance responses to projected drought effects requires improved observation-driven representations of carbon cycle processes; many such component processes are rarely monitored in complex terrain, are modeled or unrepresented quantities at eddy covariance sites, or are monitored at course temporal scales that are not conducive to elucidating process responses at process time scales. In the present study, we demonstrate the use of newly available and affordable automated dendrometers for the estimation of intra-seasonal Net Primary Productivity (NPP) in a Northern Rocky Mountain conifer forest which is impacted by seasonal drought. Results from our pilot study suggest that NPP was restricted by mid-summer moisture deficit under the extraordinary 2015 Western U.S. drought, with greater than 90% off stand growth occurring prior to August. Examination of growth on an inter-annual scale, however, suggests that the study site experienced above-average NPP during this exceptionally hot year. Taken together, these findings indicate that intensifying mid-summer drought in regional forests has affected the timing but has not diminished the magnitude of this carbon flux. By employing automated instrumentation for the intra-annual assessment of NPP, we reveal that annual NPP in regional forests is largely determined before mid-summer and is therefore surprisingly resilient to intensities of seasonal drought that exceed normal conditions of the 20th century.

  19. NEWS: AAPT Summer Meeting

    Science.gov (United States)

    Mellema, Steve

    2000-11-01

    The 2000 Summer Meeting of the American Association of Physics Teachers (AAPT) was held from 28~July-2~August at the University of Guelph in Ontario, Canada. Despite somewhat rainy weather throughout the week, the annual gathering was an enjoyable one, filled with interesting talks on the state of physics education in North America. Using a new scheduling format for the summer meeting, all of the paid workshops and tutorials were held on Saturday and Sunday 29-30 July. The invited and contributed papers for the main AAPT meeting were then presented on Monday, Tuesday and Wednesday. As had been done in 1999 in San Antonio, a two-day tandem meeting dedicated to Physics Education Research (PER) was held on Wednesday and Thursday 2-3 August, immediately after the main AAPT meeting. Over the three days of the main meeting, 60 sessions were held under the sponsorship of various AAPT committees. These included sessions (numbers in parentheses) organized by the committees on Apparatus (1), Astronomy Education (3), Awards (2), Computers (5), Graduate Education (2), High Schools (1), History and Philosophy (1), Instructional Media (3), International Education (1), Laboratories (2), Pre-High School Education (2), Programs (4), Professional Concerns (6), Research in Physics Education (8), Science Education for the Public (2), Two-Year Colleges (5), Undergraduate Education (7) and Women in Physics (4). Figure 1. Guelph Church of Our Lady. The main meeting opened on Sunday evening with an invited lecture by Dr John J Simpson from the host institution, the University of Guelph, describing the Sudbury Neutrino Observatory. At the ceremonial session that began the activities on Monday morning, recognition was given to Clifford Swartz for his almost 30 years of service as Editor of the AAPT journal, The Physics Teacher. This was followed by an invited talk by Jim Nelson from Seminole County Public School in Florida, who received the Excellence in Pre-College Teaching Award. The

  20. Drought and Winter Drying (Pest Alert)

    Science.gov (United States)

    USDA Forest Service

    Drought and winter drying have periodically caused major damage to trees. Drought reduces the amount of water available in the soil. In the case of winter drying, the water may be in the soil, but freezing of the soil makes the water unavailable to the tree. In both cases, more water is lost through transpiration than is available to the plant. Symptoms of drought and...

  1. Experimental droughts: Are precipitation variability and methodological trends hindering our understanding of ecological sensitivities to drought?

    Science.gov (United States)

    Hoover, D. L.; Wilcox, K.; Young, K. E.

    2017-12-01

    Droughts are projected to increase in frequency and intensity with climate change, which may have dramatic and prolonged effects on ecosystem structure and function. There are currently hundreds of published, ongoing, and new drought experiments worldwide aimed to assess ecosystem sensitivities to drought and identify the mechanisms governing ecological resistance and resilience. However, to date, the results from these experiments have varied widely, and thus patterns of drought sensitivities have been difficult to discern. This lack of consensus at the field scale, limits the abilities of experiments to help improve land surface models, which often fail to realistically simulate ecological responses to extreme events. This is unfortunate because models offer an alternative, yet complementary approach to increase the spatial and temporal assessment of ecological sensitivities to drought that are not possible in the field due to logistical and financial constraints. Here we examined 89 published drought experiments, along with their associated historical precipitation records to (1) identify where and how drought experiments have been imposed, (2) determine the extremity of drought treatments in the context of historical climate, and (3) assess the influence of precipitation variability on drought experiments. We found an overall bias in drought experiments towards short-term, extreme experiments in water-limited ecosystems. When placed in the context of local historical precipitation, most experimental droughts were extreme, with 61% below the 5th, and 43% below the 1st percentile. Furthermore, we found that interannual precipitation variability had a large and potentially underappreciated effect on drought experiments due to the co-varying nature of control and drought treatments. Thus detecting ecological effects in experimental droughts is strongly influenced by the interaction between drought treatment magnitude, precipitation variability, and key

  2. Influence of repeated prescribed fire on tree growth and mortality in Pinus resinosa forests, northern Minnesota

    Science.gov (United States)

    Bottero, Alessandra; D'Amato, Anthony W.; Palik, Brian J.; Kern, Christel C.; Bradford, John B.; Scherer, Sawyer S.

    2017-01-01

    Prescribed fire is widely used for ecological restoration and fuel reduction in fire-dependent ecosystems, most of which are also prone to drought. Despite the importance of drought in fire-adapted forests, little is known about cumulative effects of repeated prescribed burning on tree growth and related response to drought. Using dendrochronological data in red pine (Pinus resinosa Ait.)-dominated forests in northern Minnesota, USA, we examined growth responses before and after understory prescribed fires between 1960 and 1970, to assess whether repeated burning influences growth responses of overstory trees and vulnerability of overstory tree growth to drought. We found no difference in tree-level growth vulnerability to drought, expressed as growth resistance, resilience, and recovery, between areas receiving prescribed fire treatments and untreated forests. Annual mortality rates during the period of active burning were also low (less than 2%) in all treatments. These findings indicate that prescribed fire can be effectively integrated into management plans and climate change adaptation strategies for red pine forest ecosystems without significant short- or long-term negative consequences for growth or mortality rates of overstory trees.

  3. Characteristics and drivers of drought in Europe-a summary of the DROUGHT-R&SPI project

    NARCIS (Netherlands)

    Tallaksen, Lena M.; Stagge, James H.; Stahl, Kerstin; Gudmundsson, Lukas; Orth, Rene; Seneviratne, Sonia I.; Loon, van Anne F.; Lanen, van Henny A.J.

    2015-01-01

    A prerequisite to mitigate the wide range of drought impacts is to establish a good understanding of the drought generating mechanisms from their initiation as a meteorological drought through to their development as soil moisture and hydrological drought. The DROUGHT-R&SPI project has

  4. Reduced Drought Tolerance by CRISPR/Cas9-Mediated SlMAPK3 Mutagenesis in Tomato Plants.

    Science.gov (United States)

    Wang, Liu; Chen, Lin; Li, Rui; Zhao, Ruirui; Yang, Meijing; Sheng, Jiping; Shen, Lin

    2017-10-04

    Drought stress is one of the most destructive environmental factors that affect tomato plants adversely. Mitogen-activated protein kinases (MAPKs) are important signaling molecules that respond to drought stress. In this study, SlMAPK3 was induced by drought stress, and the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (CRISPR/Cas9) system was utilized to generate slmapk3 mutants. Two independent T1 transgenic lines and wild-type (WT) tomato plants were used for analysis of drought tolerance. Compared with WT plants, slmapk3 mutants exhibited more severe wilting symptom, higher hydrogen peroxide content, lower antioxidant enzymes activities, and suffered more membrane damage under drought stress. Furthermore, knockout of SlMAPK3 led to up- or down-regulated expressions of drought stress-responsive genes including SlLOX, SlGST, and SlDREB. The results suggest that SlMAPK3 is involved in drought response in tomato plants by protecting cell membranes from oxidative damage and modulating transcription of stress-related genes.

  5. Enhancing drought tolerance in C(4) crops.

    Science.gov (United States)

    Lopes, Marta S; Araus, Jose Luis; van Heerden, Philippus D R; Foyer, Christine H

    2011-05-01

    Adaptation to abiotic stresses is a quantitative trait controlled by many different genes. Enhancing the tolerance of crop plants to abiotic stresses such as drought has therefore proved to be somewhat elusive in terms of plant breeding. While many C(4) species have significant agronomic importance, most of the research effort on improving drought tolerance has focused on maize. Ideally, drought tolerance has to be achieved without penalties in yield potential. Possibilities for success in this regard are highlighted by studies on maize hybrids performed over the last 70 years that have demonstrated that yield potential and enhanced stress tolerance are associated traits. However, while our understanding of the molecular mechanisms that enable plants to tolerate drought has increased considerably in recent years, there have been relatively few applications of DNA marker technologies in practical C(4) breeding programmes for improved stress tolerance. Moreover, until recently, targeted approaches to drought tolerance have concentrated largely on shoot parameters, particularly those associated with photosynthesis and stay green phenotypes, rather than on root traits such as soil moisture capture for transpiration, root architecture, and improvement of effective use of water. These root traits are now increasingly considered as important targets for yield improvement in C(4) plants under drought stress. Similarly, the molecular mechanisms underpinning heterosis have considerable potential for exploitation in enhancing drought stress tolerance. While current evidence points to the crucial importance of root traits in drought tolerance in C(4) plants, shoot traits may also be important in maintaining high yields during drought.

  6. Drought Persistence Errors in Global Climate Models

    Science.gov (United States)

    Moon, H.; Gudmundsson, L.; Seneviratne, S. I.

    2018-04-01

    The persistence of drought events largely determines the severity of socioeconomic and ecological impacts, but the capability of current global climate models (GCMs) to simulate such events is subject to large uncertainties. In this study, the representation of drought persistence in GCMs is assessed by comparing state-of-the-art GCM model simulations to observation-based data sets. For doing so, we consider dry-to-dry transition probabilities at monthly and annual scales as estimates for drought persistence, where a dry status is defined as negative precipitation anomaly. Though there is a substantial spread in the drought persistence bias, most of the simulations show systematic underestimation of drought persistence at global scale. Subsequently, we analyzed to which degree (i) inaccurate observations, (ii) differences among models, (iii) internal climate variability, and (iv) uncertainty of the employed statistical methods contribute to the spread in drought persistence errors using an analysis of variance approach. The results show that at monthly scale, model uncertainty and observational uncertainty dominate, while the contribution from internal variability is small in most cases. At annual scale, the spread of the drought persistence error is dominated by the statistical estimation error of drought persistence, indicating that the partitioning of the error is impaired by the limited number of considered time steps. These findings reveal systematic errors in the representation of drought persistence in current GCMs and suggest directions for further model improvement.

  7. Drought impact on vegetation growth and mortality

    Science.gov (United States)

    Xu, C.; Wang, M.; Allen, C. D.; McDowell, N. G.; Middleton, R. S.

    2017-12-01

    Vegetation is a key regulator of the global carbon cycle via CO2 absorption through photosynthesis and subsequent growth; however, low water availability, heat stress, and disturbances associated with droughts could substantially reduce vegetation growth and increase vegetation mortality. As far as we know, there are few studies have assessed the drought impact on vegetation growth and mortality at regional and global scales. In this study, we analyzed 13 Earth System models (ESMs) to quantify the impact of drought on GPP and linked the remote-sensing based tree mortality to observed drought indices to assess the drought impact on tree mortality in continental US (CONUS). Our analysis of 13 Earth System models (ESMs) shows that the average global gross primary production (GPP) reduction per year associated with extreme droughts over years 2075-2099 is predicted to be 3-5 times larger than that over years 1850-1999. The annual drought-associated reduction in GPP over years 2075-2099 could be 52 and 74 % of annual fossil fuel carbon emission during years 2000-2007. Increasing drought impacts on GPP are driven primarily by the increasing drought frequency. The risks of drought-associated GPP reduction are particularly high for temperate and tropical regions. The consistent prediction of higher drought-associated reduction in NPP across 13 ESMs suggests increasing impacts of drought on the global carbon cycle with atmospheric warming. Our analysis of drought impact on tree mortality showed that drought-associated carbon loss accounts for 12% of forest carbon loss in CONUS for 2000-2014, which is about one-fifth of that resulting from timber harvesting and 1.35 % of average annual fossil fuel emissions in the U.S. for the same period. The carbon stock loss from natural disturbances for 2000-2014 is approximately 75% of the total carbon loss from anthropogenic disturbance (timber harvesting), suggesting that natural disturbances play a very important role on forest

  8. Variability and trends in global drought

    Science.gov (United States)

    McCabe, Gregory J.; Wolock, David M.

    2015-01-01

    Monthly precipitation (P) and potential evapotranspiration (PET) from the CRUTS3.1 data set are used to compute monthly P minus PET (PMPE) for the land areas of the globe. The percent of the global land area with annual sums of PMPE less than zero are used as an index of global drought (%drought) for 1901 through 2009. Results indicate that for the past century %drought has not changed, even though global PET and temperature (T) have increased. Although annual global PET and T have increased, annual global P also has increased and has mitigated the effects of increased PET on %drought.

  9. Drought-induced defoliation and long periods of near-zero gas exchange play a key role in accentuating metabolic decline of Scots pine.

    Science.gov (United States)

    Poyatos, Rafael; Aguadé, David; Galiano, Lucía; Mencuccini, Maurizio; Martínez-Vilalta, Jordi

    2013-10-01

    Drought-induced defoliation has recently been associated with the depletion of carbon reserves and increased mortality risk in Scots pine (Pinus sylvestris). We hypothesize that defoliated individuals are more sensitive to drought, implying that potentially higher gas exchange (per unit of leaf area) during wet periods may not compensate for their reduced photosynthetic area. We measured sap flow, needle water potentials and whole-tree hydraulic conductance to analyse the drought responses of co-occurring defoliated and nondefoliated Scots pines in northeast Spain during typical (2010) and extreme (2011) drought conditions. Defoliated Scots pines showed higher sap flow per unit leaf area during spring, but were more sensitive to summer drought, relative to nondefoliated pines. This pattern was associated with a steeper decline in soil-to-leaf hydraulic conductance with drought and an enhanced sensitivity of canopy conductance to soil water availability. Near-homeostasis in midday water potentials was observed across years and defoliation classes, with minimum values of -2.5 MPa. Enhanced sensitivity to drought and prolonged periods of near-zero gas exchange were consistent with low levels of carbohydrate reserves in defoliated trees. Our results support the critical links between defoliation, water and carbon availability, and their key roles in determining tree survival and recovery under drought. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

  10. CERN Summer Student Project Report

    CERN Document Server

    Parton, Thomas

    2015-01-01

    My Summer Student project was divided between two areas: work on Thin Gap Chamber (TGC) Level-1 muon triggers for the ATLAS experiment, and data acquisition (DAQ) for an RPC muon detector at the Gamma Irradiation Facility (GIF++)

  11. The year without a summer

    Science.gov (United States)

    Luterbacher, J.; Pfister, C.

    2015-04-01

    The 1815 eruption of Tambora caused an unusually cold summer in much of Europe in 1816. The extreme weather led to poor harvests and malnutrition, but also demonstrated the capability of humans to adapt and help others in worse conditions.

  12. Summer Student Report - AV Workflow

    CERN Document Server

    Abramson, Jessie

    2014-01-01

    The AV Workflow is web application which allows cern users to publish, update and delete videos from cds. During my summer internship I implemented the backend of the new version of the AV Worklow in python using the django framework.

  13. Winter/Summer Monsoon Experiment

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Winter/Summer Monsoon Experiment (MONEX) was conducted during the First Global GARP (Global Atmospheric Research Program) Experiment (FGGE). An international...

  14. Summer Research Fellowship Programme–2015

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 19; Issue 12. Summer Research Fellowship Programme - 2015. Information and Announcements Volume 19 Issue 12 December 2014 pp 1199-1199. Fulltext. Click here to view fulltext PDF. Permanent link:

  15. Comparative Analysis of Drought Indices for Drought Zone Scheme of Northern Khorasan Province of Iran

    Directory of Open Access Journals (Sweden)

    Ehsan EYSHI REZAEI

    2011-08-01

    Full Text Available Drought is one of the natural disasters which deeply influenced agricultural production. Drought monitoring programs could help to forecast and mitigate the impacts of drought. In this study occurrence, severity, and duration of drought were evaluated by monthly rainfall data (1986-2005 that were recorded at all meteorological stations in north Khorasan province of Iran. Drought indices include Standard Rainfall Index (SPI, Decades Index (DI and Percent of Normal (PNI calculated and compared to determine drought severity, duration and drought occurrence for all stations. In addition, drought maps were prepared by Inverse Distance Weighted (IDW method, for each study zone. Based on these indices, the most extensive drought occurred in 1989, 1990, 1995, 1996, 2000, and 2001 years. The longest duration of drought based on SPI happened in 1994 and 1997 years. Furthermore, the extreme drought occurred in 1990 and 2001 in all stations. In conclusion, Central part of this province was more exposed to extreme drought during study period than other parts of this region.

  16. The effect of reservoir networks on drought propagation

    NARCIS (Netherlands)

    Oel, van P.R.; Martins, E.S.P.R.; Costa, A.C.

    2017-01-01

    Human interventions in response to drought can both alleviate and enhance drought. Developments of infrastructure for freshwater storage, groundwater abstraction and irrigation have proved to be effective in overcoming meteorological and agricultural drought in many locations worldwide. At the same

  17. NAC transcription factor JUNGBRUNNEN1 enhances drought tolerance in tomato

    KAUST Repository

    Thirumalaikumar, Venkatesh P.; Devkar, Vikas; Mehterov, Nikolay; Ali, Shawkat; Ozgur, Rengin; Turkan, Ismail; Mueller-Roeber, Bernd; Balazadeh, Salma

    2017-01-01

    Water deficit (drought stress) massively restricts plant growth and the yield of crops; reducing the deleterious effects of drought is therefore of high agricultural relevance. Drought triggers diverse cellular processes including the inhibition

  18. Influence of soil drought stress on photosynthesis, carbohydrates ...

    African Journals Online (AJOL)

    USER

    2010-08-16

    Aug 16, 2010 ... and the ability of plant to adapt to drought stress. (Bulbotko, 1973; Atkinson et ... drought stress. In general, little is known about the effects of soil drought ..... fluorescence, water relations, and leaf abscisic acid. Plant Physiol.

  19. How climate seasonality modifies drought duration and deficit

    NARCIS (Netherlands)

    Loon, van A.F.; Tijdeman, E.; Wanders, N.; Lanen, van H.A.J.; Teuling, A.J.; Uijlenhoet, R.

    2014-01-01

    Drought propagation through the terrestrial hydrological cycle is associated with a change in drought characteristics (duration and deficit), moving from precipitation via soil moisture to discharge. Here we investigate climate controls on drought propagation with a modeling experiment in 1271

  20. Summer Final Report

    Science.gov (United States)

    Makidi, Nitou

    2012-01-01

    The summer of 2012 has been filled with many memorable events and activities. As an intern, I had responsibilities that had to be fulfilled. My tour of duty was completed as an administrative student trainee in the Information Technology and Communications Services Business Office (IT-A). In accordance with the Business Objectives and Agreement of the Business Office and my performance plan, I was to provide business office support, improve business, project management, and technical work processes. With this being stated, I supported a project called "The Big Move Project" (TBMP), which will take course over the next several years. The Big Move Project is the planning of the Information Technology (IT) Directorate's relocation to various buildings in the course of upcoming years, when designs and the building of Central Campus have been completed. Working directly with my supervisor and the project manager, I was responsible for gathering both administrative and operational area requirements for the Information Technology (IT) Directorate, along with its outsourced support and contractors, such as IMCS, NICS, and ACES. My first action was to create rubrics that will serve as a guideline for the information that should be given by each branch of IT. After receiving that information via a few KAITS actions, I was able to start the consolidation process, and begin working on a presentation. A SharePoint was created shortly after for others to view the progression of the project, which I managed. During the consolidation ofthis information, I would occasionally present to the IT Deputy Director and IT Chiefs. The draft of this presentation was shown to employees of Center Operations (T A) and stakeholders-IT Chief Officers and contractor managers-in the relocation of IT to make them aware of what requirements must be met that will enable IT to be accommodated appropriately in the design of Central Campus Phase 11-the time in which IT and its contractors are scheduled

  1. A case for multi-model and multi-approach based event attribution: The 2015 European drought

    Science.gov (United States)

    Hauser, Mathias; Gudmundsson, Lukas; Orth, René; Jézéquel, Aglaé; Haustein, Karsten; Seneviratne, Sonia Isabelle

    2017-04-01

    Science on the role of anthropogenic influence on extreme weather events such as heat waves or droughts has evolved rapidly over the past years. The approach of "event attribution" compares the occurrence probability of an event in the present, factual world with the probability of the same event in a hypothetical, counterfactual world without human-induced climate change. Every such analysis necessarily faces multiple methodological choices including, but not limited to: the event definition, climate model configuration, and the design of the counterfactual world. Here, we explore the role of such choices for an attribution analysis of the 2015 European summer drought (Hauser et al., in preparation). While some GCMs suggest that anthropogenic forcing made the 2015 drought more likely, others suggest no impact, or even a decrease in the event probability. These results additionally differ for single GCMs, depending on the reference used for the counterfactual world. Observational results do not suggest a historical tendency towards more drying, but the record may be too short to provide robust assessments because of the large interannual variability of drought occurrence. These results highlight the need for a multi-model and multi-approach framework in event attribution research. This is especially important for events with low signal to noise ratio and high model dependency such as regional droughts. Hauser, M., L. Gudmundsson, R. Orth, A. Jézéquel, K. Haustein, S.I. Seneviratne, in preparation. A case for multi-model and multi-approach based event attribution: The 2015 European drought.

  2. Evaporative demand and water requirements of the principal crops of the Guadalentin valley (SE Spain) in drought periods

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Toribio, M. I.; Garcia-Marin, R.; Conesa-Garcia, C.; Lopez-Bermudez, F.

    2010-07-01

    The drought periods that affect the province of Murcia, especially the Guadalentin Valley, are aggravated by an increase in evaporative demand. The aim of the present study was to characterize the increased water demand of woody and herbaceous crops during drought periods in the Guadalentin Valley, an agricultural zone with an excellent climate for specialty crops, which is of great economic importance for Murcia. After defining the drought periods of the last three decades in time and space by means of the standard index of rainfall drought (IESP), several methods were used to determine the reference evapotranspiration (ETo): the Penman-Monteith model (ASCE and FAO models for grass), the Hargreaves method (ETo-ASCE for alfalfa), and ETo using the FAO Radiation method. Finally, the crop water requirements for each to crop type and area of cultivation were estimated using monthly crop coefficients (K{sub c}) and the mean monthly evaporative demand values were obtained by the best fitting method. The increase in the evaporative demand reflected the increased water deficits that occur in the drought years, both in summer and winter (1.23 hm{sup 3} yr{sup -}1). Drought periods are also responsible for reducing the areas dedicated to horticultural crops, because of their high water demands and the additional costs involved, resulting an aggravated socioeconomic position and increased unemployment. (Author) 25 refs.

  3. Drought assessment in the Dongliao River basin: traditional approaches vs. generalized drought assessment index based on water resources systems

    Science.gov (United States)

    Weng, B. S.; Yan, D. H.; Wang, H.; Liu, J. H.; Yang, Z. Y.; Qin, T. L.; Yin, J.

    2015-08-01

    Drought is firstly a resource issue, and with its development it evolves into a disaster issue. Drought events usually occur in a determinate but a random manner. Drought has become one of the major factors to affect sustainable socioeconomic development. In this paper, we propose the generalized drought assessment index (GDAI) based on water resources systems for assessing drought events. The GDAI considers water supply and water demand using a distributed hydrological model. We demonstrate the use of the proposed index in the Dongliao River basin in northeastern China. The results simulated by the GDAI are compared to observed drought disaster records in the Dongliao River basin. In addition, the temporal distribution of drought events and the spatial distribution of drought frequency from the GDAI are compared with the traditional approaches in general (i.e., standard precipitation index, Palmer drought severity index and rate of water deficit index). Then, generalized drought times, generalized drought duration, and generalized drought severity were calculated by theory of runs. Application of said runs at various drought levels (i.e., mild drought, moderate drought, severe drought, and extreme drought) during the period 1960-2010 shows that the centers of gravity of them all distribute in the middle reaches of Dongliao River basin, and change with time. The proposed methodology may help water managers in water-stressed regions to quantify the impact of drought, and consequently, to make decisions for coping with drought.

  4. Repeatability of Cryogenic Multilayer Insulation

    Science.gov (United States)

    Johnson, W. L.; Vanderlaan, M.; Wood, J. J.; Rhys, N. O.; Guo, W.; Van Sciver, S.; Chato, D. J.

    2017-12-01

    Due to the variety of requirements across aerospace platforms, and one off projects, the repeatability of cryogenic multilayer insulation (MLI) has never been fully established. The objective of this test program is to provide a more basic understanding of the thermal performance repeatability of MLI systems that are applicable to large scale tanks. There are several different types of repeatability that can be accounted for: these include repeatability between identical blankets, repeatability of installation of the same blanket, and repeatability of a test apparatus. The focus of the work in this report is on the first two types of repeatability. Statistically, repeatability can mean many different things. In simplest form, it refers to the range of performance that a population exhibits and the average of the population. However, as more and more identical components are made (i.e. the population of concern grows), the simple range morphs into a standard deviation from an average performance. Initial repeatability testing on MLI blankets has been completed at Florida State University. Repeatability of five Glenn Research Center (GRC) provided coupons with 25 layers was shown to be +/- 8.4% whereas repeatability of repeatedly installing a single coupon was shown to be +/- 8.0%. A second group of 10 coupons has been fabricated by Yetispace and tested by Florida State University, the repeatability between coupons has been shown to be +/- 15-25%. Based on detailed statistical analysis, the data has been shown to be statistically significant.

  5. Effect of Trinexapac-ethyl on Increased Resistance to Drought Stress in Wheatgrass (Agropyron desertorum L.

    Directory of Open Access Journals (Sweden)

    mohamad hossein sheikh mohamadi

    2017-10-01

    Full Text Available Introduction: Drought is one of the most detrimental abiotic stresses for turfgrass growth across a wide range of geographic locations. Most cool-season grass species are not well adapted to extended periods of drought, particularly during summer months. Decline in turf quality caused by drought stress is a major concern in turfgrass culture. Therefore, developing management practices for improving drought resistance of turfgrasses has become essential in arid and semi-arid regions, especially during water use restriction. One strategy to improve plant drought resistance is to promote drought avoidance by reducing water loss during drought, which may be achieved by slowing growth rate of shoots and lowering leaf area canopy to reduce demand for water. Application of growth regulators is one of the methods for increasing resistance of plants to biotic and abiotic stresses. Trinexapac-ethyl (TE is one of the most widely used PGRs in the management of cool-season and warm-season turfgrass species. TE absorbed quickly by foliage and slow cell elongation through inhibiting of converting one form of gibberellic acid (GA20 to another (GA1. Most studies conducted under non-stressed conditions found that TE application increased chlorophyll content, turf quality, turf density and reduced shoot extension rate. We hypothesized that TE may influence plant tolerance to drought stress. Limited available data─ as reported in the above referred studies─ suggest that TE application may be beneficial for plant tolerance to stresses, but the effectiveness varies with turfgrass species, dose and duration of TE treatment, and type of stress. The main aim of this research is to evaluate the effect of Trinexapac-ethyl on increased resistance to drought stress in wheatgrass. Materials and Methods: Wheatgrass (Agropyron desertorum L. was used in this study. This study was conducted in field conditions at Isfahan University of Technology, Isfahan, Iran.. Wheatgrass

  6. Nonparametric Integrated Agrometeorological Drought Monitoring: Model Development and Application

    Science.gov (United States)

    Zhang, Qiang; Li, Qin; Singh, Vijay P.; Shi, Peijun; Huang, Qingzhong; Sun, Peng

    2018-01-01

    Drought is a major natural hazard that has massive impacts on the society. How to monitor drought is critical for its mitigation and early warning. This study proposed a modified version of the multivariate standardized drought index (MSDI) based on precipitation, evapotranspiration, and soil moisture, i.e., modified multivariate standardized drought index (MMSDI). This study also used nonparametric joint probability distribution analysis. Comparisons were done between standardized precipitation evapotranspiration index (SPEI), standardized soil moisture index (SSMI), MSDI, and MMSDI, and real-world observed drought regimes. Results indicated that MMSDI detected droughts that SPEI and/or SSMI failed to do. Also, MMSDI detected almost all droughts that were identified by SPEI and SSMI. Further, droughts detected by MMSDI were similar to real-world observed droughts in terms of drought intensity and drought-affected area. When compared to MMSDI, MSDI has the potential to overestimate drought intensity and drought-affected area across China, which should be attributed to exclusion of the evapotranspiration components from estimation of drought intensity. Therefore, MMSDI is proposed for drought monitoring that can detect agrometeorological droughts. Results of this study provide a framework for integrated drought monitoring in other regions of the world and can help to develop drought mitigation.

  7. Summer freezing resistance: a critical filter for plant community assemblies in Mediterranean high mountains

    Directory of Open Access Journals (Sweden)

    David Sánchez Pescador

    2016-02-01

    Full Text Available Assessing freezing community response and whether freezing resistance is related to other functional traits is essential for understanding alpine community assemblages, particularly in Mediterranean environments where plants are exposed to freezing temperatures and summer droughts. Thus, we characterized the leaf freezing resistance of 42 plant species in 38 plots at Sierra de Guadarrama (Spain by measuring their ice nucleation temperature, freezing point (FP, and low-temperature damage (LT50, as well as determining their freezing resistance mechanisms (i.e., tolerance or avoidance. The community response to freezing was estimated for each plot as community weighted means (CWMs and functional diversity, and we assessed their relative importance with altitude. We established the relationships between freezing resistance, growth forms, and four key plant functional traits (i.e., plant height, specific leaf area, leaf dry matter content, and seed mass. There was a wide range of freezing resistance responses and more than in other alpine habitats. At the community level, the CWMs of FP and LT50 responded negatively to altitude, whereas the functional diversity of both traits increased with altitude. The proportion of freezing-tolerant species also increased with altitude. The ranges of FP and LT50 varied among growth forms, and only the leaf dry matter content correlated negatively with freezing-resistance traits. Summer freezing events represent important abiotic filters for assemblies of Mediterranean high mountain communities, as suggested by the CWMs. However, a concomitant summer drought constraint may also explain the high freezing resistance of species that thrive in these areas and the lower functional diversity of freezing resistance traits at lower altitudes. Leaves with high dry matter contents may maintain turgor at lower water potential and enhance drought tolerance in parallel to freezing resistance. This adaptation to drought seems to

  8. An assessment toolkit to increase the resilience of NWE catchments to periods of drought

    Science.gov (United States)

    La Jeunesse, Isabelle; Larrue, Corinne

    2013-04-01

    In many North Western Europe (NWE) areas the balance between water demand and availability is under pressure, thus under water scarcity. In addition, NWE areas are adversely affected by changes in the hydrological cycle and precipitation patterns, thus droughts periods. Over the past thirty years, droughts have dramatically increased and NWE are not immune. The summer of 2003 caused 10 billion euro damage to agriculture. In April 2012 the South West of the UK has moved to environmental drought status. Water scarcity and drought problems in the EU are increasing: 11% of the European population and 17% of its territory have been affected to date. Climate change is likely to exacerbate these adverse impacts. 50% of the NWE area are planned to be affected in 2050. Although the problems caused by drought in NWE are currently not overwhelmingly visible early action should be taken to reduce costs and prevent damage. Adapting to drought in NWE is the transnational challenge of the DROP (governance in DROught adaPtation) project. The Commission's recent "Blue Print on European Waters" states that existing policies are good but the problem lays in implementation. So the future challenge for NWE regions is to improve the implementation, meaning both governance and measures. The problem of drought is relatively new in comparison with flooding for these Regions. This demands another approach with the interaction of different stakeholders. NWE countries have proven strategies for flood prevention; no such strategies exist for drought adaptation. To do this, DROP combines science, practitioners and decisions makers, realizing the science-policy window. Thus, the aim of the DROP project is to increase the resilience of NWE catchments to periods of drought. To tackle these issues DROP will develop a governance toolkit to be used by NWE regional water authorities and will test a few pilot measures on drought adaptation. The objectives of the project are 1) to promote the use of a

  9. Molecular regulation of drought tolerance in rice

    NARCIS (Netherlands)

    Haider, I.

    2014-01-01

    Abiotic stresses are the primary cause of crop failure worldwide, reducing average yields by more than 50%. Among the various forms of abiotic stress, drought is the most limiting factor for rice productivity. Drought affects about

  10. Statistical of the drought in Colombia

    International Nuclear Information System (INIS)

    Hurtado Moreno, Gonzalo

    1994-01-01

    The drought is evaluated by means of a standardized index of precipitation, at the same time simple and direct. It has not been guided toward a specific type of drought, but rather it has been evaluated as a phenomenon caused exclusively by the rain deficiency

  11. Drought tolerant wheat varieties developed through mutation ...

    African Journals Online (AJOL)

    In search for higher yielding drought tolerant wheat varieties, one of the Kenyan high yielding variety 'Pasa' was irradiated with gamma rays (at 150, 200, and 250gy) in 1997 so as to induce variability and select for drought tolerance. Six mutants ((KM10, KM14, KM15, KM18, KM20 and KM21) were selected at M4 for their ...

  12. Isolation of cowpea genes conferring drought tolerance ...

    African Journals Online (AJOL)

    The main objective of this study was to identify and isolate the genes conferring drought tolerance in cowpea. A cDNA library enriched for cowpea genes expressed specifically during responses to drought was constructed. A procedure called suppression subtractive hybridisation (SSH) was successfully employed to obtain ...

  13. Linkage disequilibrium and association mapping of drought ...

    African Journals Online (AJOL)

    Drought stress is a major abiotic stress that limits crop production. Molecular association mapping techniques through linkage disequilibrium (LD) can be effectively used to tag genomic regions involved in drought stress tolerance. With the association mapping approach, 90 genotypes of cotton Gossypium hirsutum, from ...

  14. (EAHB-AAA) cultivars to drought stress

    African Journals Online (AJOL)

    Banana (Musa spp.) yields are estimated at 5-30 t ha-1yr-1, lower than the potential 60 t ha-1yr-1, with the cause being drought stress. Much evidence among stakeholders shows little understanding about banana cultivar sensitivity, escape and avoidance mechanisms to drought due to un-attempted measures of retaining ...

  15. Plants' responses to drought and shade environments

    African Journals Online (AJOL)

    전병기

    Among them, drought is widely known as the main factor that limits plants' growth, productivity and development (Reddy et al., 2004; Shao et al., 2008; Li et al., 2009). Recently, drought occured frequently all over the globe due to climate changes (Khaine and Woo, 2015). Light and shade are very important environements ...

  16. Cold-season patterns of reserve and soluble carbohydrates in sugar maple and ice-damaged trees of two age classes following drought

    Science.gov (United States)

    B. L. Wong; K. L. Baggett; A. H. Rye

    2009-01-01

    This study examines the effects of summer drought on the composition and profiles of cold-season reserve and soluble carbohydrates in sugar maple (Acer saccharum Marsh.) trees (50-100 years old or ~200 years old) in which the crowns were nondamaged or damaged by the 1998 ice storm. The overall cold season reserve...

  17. Integrated Modeling of Drought-Impacted Areas using Remote Sensing and Microenvironmental Data in California

    Science.gov (United States)

    Rao, M.; Silber-coats, Z.; Lawrence, F.

    2015-12-01

    California's ongoing drought condition shriveled not just the agricultural sector, but also the natural resources sector including forestry, wildlife, and fisheries. As future predictions of drought and fire severity become more real in California, there is an increased awareness to pursue innovative and cost-effective solutions that are based on silvicultural treatments and controlled burns to improve forest health and reduce the risk of high-severity wildfires. The main goal of this study is to develop a GIS map of the drought-impacted region of northern and central California using remote sensing data for the summer period of 2014. Specifically, Landsat/NAIP imagery will be analyzed using a combination of object-oriented classification and spectral indices such as the Modified Perpendicular Drought Index (MPDI). This spectral index basically scales the line perpendicular to the soil line defined in the Red-NIR feature space in conjunction with added information about vegetative fraction derived using NDVI. The resulting output will be correlated with USGS-produced estimates of climatic water deficit (CWD) data to characterize the severity of the drought. The CWD is simulated based on hydrological tool, Basin Characterization Model (BCM) that ingests historical climate data in conjunction with soils, topography, and geological data to predict other monthly hydrological outputs including runoff, recharge, and snowpack. In addition to field data, data collected by state agencies including USFS, calforests.org will be used in the classification and accuracy assessment procedures. Visual assessment using high-resolution imagery such as NAIP will be used to further refine the spatial maps. The drought severity maps produced will greatly facilitate site-specific planning efforts aimed at implementing resource management decisions.

  18. Repeat Customer Success in Extension

    Science.gov (United States)

    Bess, Melissa M.; Traub, Sarah M.

    2013-01-01

    Four multi-session research-based programs were offered by two Extension specialist in one rural Missouri county. Eleven participants who came to multiple Extension programs could be called "repeat customers." Based on the total number of participants for all four programs, 25% could be deemed as repeat customers. Repeat customers had…

  19. 78 FR 65594 - Vehicular Repeaters

    Science.gov (United States)

    2013-11-01

    ... coordinators estimate the effect on coordination fees? Does the supposed benefit that mobile repeater stations... allow the licensing and operation of vehicular repeater systems and other mobile repeaters by public... email: [email protected] or phone: 202-418- 0530 or TTY: 202-418-0432. For detailed instructions for...

  20. Estimating drought risk across Europe from reported drought impacts, hazard indicators and vulnerability factors

    Science.gov (United States)

    Blauhut, V.; Stahl, K.; Stagge, J. H.; Tallaksen, L. M.; De Stefano, L.; Vogt, J.

    2015-12-01

    Drought is one of the most costly natural hazards in Europe. Due to its complexity, drought risk, the combination of the natural hazard and societal vulnerability, is difficult to define and challenging to detect and predict, as the impacts of drought are very diverse, covering the breadth of socioeconomic and environmental systems. Pan-European maps of drought risk could inform the elaboration of guidelines and policies to address its documented severity and impact across borders. This work (1) tests the capability of commonly applied hazard indicators and vulnerability factors to predict annual drought impact occurrence for different sectors and macro regions in Europe and (2) combines information on past drought impacts, drought hazard indicators, and vulnerability factors into estimates of drought risk at the pan-European scale. This "hybrid approach" bridges the gap between traditional vulnerability assessment and probabilistic impact forecast in a statistical modelling framework. Multivariable logistic regression was applied to predict the likelihood of impact occurrence on an annual basis for particular impact categories and European macro regions. The results indicate sector- and macro region specific sensitivities of hazard indicators, with the Standardised Precipitation Evapotranspiration Index for a twelve month aggregation period (SPEI-12) as the overall best hazard predictor. Vulnerability factors have only limited ability to predict drought impacts as single predictor, with information about landuse and water resources as best vulnerability-based predictors. (3) The application of the "hybrid approach" revealed strong regional (NUTS combo level) and sector specific differences in drought risk across Europe. The majority of best predictor combinations rely on a combination of SPEI for shorter and longer aggregation periods, and a combination of information on landuse and water resources. The added value of integrating regional vulnerability information

  1. Structural adjustment and drought in Zambia.

    Science.gov (United States)

    Mulwanda, M

    1995-06-01

    While drought is not uncommon in Zambia, the country is now facing the worst drought in history. The monetary and social costs will be enormous. Although it is too early to measure the economic and social costs of the drought on Zambia, it is obvious that the impact is catastrophic on a country whose economy is under pressure. The drought will affect the structural adjustment programme (SAP) unveiled by the new government which has embraced the market economy. The country has imported, and will continue to import, large quantities of maize and other foodstuffs, a situation likely to strain the balance of payments. Earlier targets with regard to export earnings, reductions in the budget deficit, and GDP growth as contained in the Policy Framework Paper (PFP) are no longer attainable due to the effects of the drought.

  2. Phenotyping common beans for adaptation to drought

    Science.gov (United States)

    Beebe, Stephen E.; Rao, Idupulapati M.; Blair, Matthew W.; Acosta-Gallegos, Jorge A.

    2013-01-01

    Common beans (Phaseolus vulgaris L.) originated in the New World and are the grain legume of greatest production for direct human consumption. Common bean production is subject to frequent droughts in highland Mexico, in the Pacific coast of Central America, in northeast Brazil, and in eastern and southern Africa from Ethiopia to South Africa. This article reviews efforts to improve common bean for drought tolerance, referring to genetic diversity for drought response, the physiology of drought tolerance mechanisms, and breeding strategies. Different races of common bean respond differently to drought, with race Durango of highland Mexico being a major source of genes. Sister species of P. vulgaris likewise have unique traits, especially P. acutifolius which is well adapted to dryland conditions. Diverse sources of tolerance may have different mechanisms of plant response, implying the need for different methods of phenotyping to recognize the relevant traits. Practical considerations of field management are discussed including: trial planning; water management; and field preparation. PMID:23507928

  3. Screening Pakistani cotton for drought tolerance

    International Nuclear Information System (INIS)

    Soomro, M.H.; Markhand, G.S.

    2011-01-01

    The drought is one of the biggest abiotic stresses for crop production in arid and semi-arid agriculture. Thus it is a challenge for plant scientists to screen and develop the drought tolerant cotton lines. In this study, 31 cotton genotypes/cultivars were evaluated under two irrigation regimes i. e., seven irrigations (Control) and two irrigations (Stress), using split plot design with four replications. The crop growth, yield and some physiological parameters were studied. There were high inter-varietal differences for all the parameters under control as well as drought stress. Although all the varieties for all parameters were significantly affected by drought but however, CRIS-9, MARVI, CRIS-134, CRIS-126, CRIS-337, CRIS-355 and CRIS-377 maintained highest performance for all the parameters studied under high drought conditions. (author)

  4. Rainwater harvesting for drought disaster alleviation

    International Nuclear Information System (INIS)

    Widodo, B.; Prinzand, D.; Malik, A.H.

    2005-01-01

    Too little water and too much water can be as devastating as well. Drought usually does not show up instantly like flood, but it creeps slowly. Drought that is less popular than flood has impact more serious than flood. It is difficult to be identified when it comes and when it goes away. However, it is suddenly understood when water becomes scare, or no more water is available in wells, rivers and reservoirs. Managing flood and drought has to be at an integrated basis. Rainwater harvesting (RWH) combined with water conservation methods can be developed to alleviate drought disaster as well as flood disaster in the same time. RWH and water conservation must be an integral part of integrated water resources management. Preventing drought could be automatically reducing the extent of flood that means preventing people and the environment from the disasters. (author)

  5. Rehab: Drought and famine in Ethiopia

    Energy Technology Data Exchange (ETDEWEB)

    Hussein, A.M.

    1976-01-01

    A Special Report on the two Ethiopian drought-famine crises is reviewed. The Wollo drought occurred at the same time as the West African. Although drought also hit Sudan, and thus spread from the Atlantic to the Red Sea, Ethiopia's drought seems to have been unique, for its normal rainfall pattern is different from that of the Sahel; there are two rainy seasons, linked to a wind system more complex than that in West Africa. The limited data on this is summarized in S. Betheke's chapter of Rehap. This is an important study which helps impact an understanding of the revolution provoked by the Imperial regime's handling of the northern famine, and also allows useful comparisons of the Ethiopian and West African drought crisis.

  6. What causes southeast Australia's worst droughts?

    Science.gov (United States)

    Ummenhofer, Caroline C.; England, Matthew H.; McIntosh, Peter C.; Meyers, Gary A.; Pook, Michael J.; Risbey, James S.; Gupta, Alexander Sen; Taschetto, Andréa S.

    2009-02-01

    Since 1995, a large region of Australia has been gripped by the most severe drought in living memory, the so-called ``Big Dry''. The ramifications for affected regions are dire, with acute water shortages for rural and metropolitan areas, record agricultural losses, the drying-out of two of Australia's major river systems and far-reaching ecosystem damage. Yet the drought's origins have remained elusive. For Southeast Australia, we show here that the ``Big Dry'' and other iconic 20th Century droughts, including the Federation Drought (1895-1902) and World War II drought (1937-1945), are driven by Indian Ocean variability, not Pacific Ocean conditions as traditionally assumed. Specifically, a conspicuous absence of Indian Ocean temperature conditions conducive to enhanced tropical moisture transport has deprived southeastern Australia of its normal rainfall quota. In the case of the ``Big Dry'', its unprecedented intensity is also related to recent higher temperatures.

  7. Untangling the primary drivers of pinyon monoterpene production and emissions under predicted drought

    Science.gov (United States)

    Trowbridge, A. M.; Adams, H. D.; Breshears, D. D.; Monson, R. K.

    2012-04-01

    Climate and insect herbivory have important consequences for plant function, atmospheric composition, and the functioning of ecosystems and ecological communities. Within the last decade, pinyon-juniper woodlands throughout the southwestern U.S. have suffered large-scale mortality, especially of pinyon pine, due to drought and associated insect outbreaks. While much research has focused on the primary metabolic mechanisms underlying pinyon's sensitivity to drought, there remains a gap in our knowledge concerning how the resulting shift in carbon allocation toward plant secondary compounds, particularly monoterpenes, affects atmospheric process and ecological interactions. Monoterpenes are the principal constituents of pinyon resin. Because of their large global emission rates and effect on atmospheric chemistry, particularly ozone creation, identifying controls over emissions and sensitivities to environmental change is critical for global emission models. Furthermore, monoterpenes are known to impact insect behavior and act as defense compounds against herbivores, contributing to insect population fluctuations either directly through toxicity, or indirectly by influencing parasitism susceptibility. Pinyon mortality events are thought to be exacerbated by their susceptibility to herbivores resulting from weakened secondary chemical defenses, but the impact of current and predicted drought on the chemical defense status of pinyons and subsequent atmospheric and ecological consequences remain unknown. A field study was developed to examine the impact of seasonality and climate, particularly drought, on pinyon pine physiology and chemistry in the context of tiger moth (Lophocampa ingens) herbivory in pinyon-juniper woodlands. We demonstrate the importance of geography and seasonality, particularly mid-summer drought and late summer monsoons, in driving physiology and monoterpene concentrations and emissions. Emission rates significantly decreased throughout the summer

  8. Prospects for Groundwater Drought Termination in the UK in 2017-18

    Science.gov (United States)

    Parry, S.; McKenzie, A.; Prudhomme, C.; Wilby, R.; Wood, P.

    2017-12-01

    The recovery of groundwater levels towards the end of a drought can lag behind surface water stores such as reservoirs or snowpack - as was the case for California in 2016/17. Groundwater replenishment is an important precursor to the ending of water restrictions, and an improved understanding of the range of plausible groundwater recovery scenarios would be useful for a range of stakeholders, including water managers, farmers and businesses. A method for characterising drought termination in hydrological data is applied systematically here to long time series of groundwater levels (some from the mid-1800s) for the UK. This analysis capitalises on the comprehensive perspective of post-drought recovery in the historical record to provide various outlooks of recovery in groundwater levels over seasonal to multi-year timeframes and to better understand how present conditions are likely to evolve. Rainfall deficiencies in the UK since summer 2016 limited replenishment during the 2016/17 winter recharge season. As a consequence, groundwater levels in south-east England were notably below normal in summer 2017. The possibility of an abrupt termination as occurred in 2012 can already be excluded, and extrapolating recent patterns suggests that very gradual recoveries may be underway. At many sites, normal conditions are not expected to return during 2017, and later still for sites in less responsive aquifers. This is supported by the multi-year drought durations typically found in the historical record, much more prolonged than those observed during the currently developing event. The rainfall rates that have driven historical drought termination events are also assessed for their likelihood across a range of timeframes and start months. Overall results underline the importance of the typical recharge season during the wetter winter half-year in averting multi-year groundwater drought events that would threaten water resources in the populous south-east of the UK. The

  9. Evaluation of groundwater droughts in Austria

    Science.gov (United States)

    Haas, Johannes Christoph; Birk, Steffen

    2015-04-01

    Droughts are abnormally dry periods that affect various aspects of human life on earth, ranging from negative impacts on agriculture or industry, to being the cause for conflict and loss of human life. The changing climate reinforces the importance of investigations into this phenomenon. Various methods to analyze and classify droughts have been developed. These include drought indices such as the Standard Precipitation Index SPI, the Palmer Drought Severity Index PDSI or the Crop Moisture Index CMI. These and other indices consider meteorological parameters and/or their effects on soil moisture. A depletion of soil moisture triggered by low precipitation and high evapotranspiration may also cause reduced groundwater recharge and thus decreasing groundwater levels and reduced groundwater flow to springs, streams, and wetlands. However, the existing indices were generally not designed to address such drought effects on groundwater. Thus, a Standardized Groundwater level Index has recently been proposed by Bloomfied and Marchant (2013). Yet, to our knowledge, this approach has only been applied to consolidated aquifers in the UK. This work analyzes time series of groundwater levels from various, mostly unconsolidated aquifers in Austria in order to characterize the effects of droughts on aquifers in different hydrogeologic and climatic settings as well as under different usage scenarios. In particular, comparisons are made between the water rich Alpine parts of Austria, and the dryer parts situated in the East. The time series of groundwater levels are compared to other data, such as meteorological time series and written weather records about generally accepted phenomena, such as the 2003 European drought and heat wave. Thus, valuable insight is gained into the propagation of meteorological droughts through the soil and the aquifer in different types of hydrogeologic and climatic settings, which provides a prerequisite for the assessment of the aquifers' drought

  10. Compound summer temperature and precipitation extremes over central Europe

    Science.gov (United States)

    Sedlmeier, Katrin; Feldmann, H.; Schädler, G.

    2018-02-01

    Reliable knowledge of the near-future climate change signal of extremes is important for adaptation and mitigation strategies. Especially compound extremes, like heat and drought occurring simultaneously, may have a greater impact on society than their univariate counterparts and have recently become an active field of study. In this paper, we use a 12-member ensemble of high-resolution (7 km) regional climate simulations with the regional climate model COSMO-CLM over central Europe to analyze the climate change signal and its uncertainty for compound heat and drought extremes in summer by two different measures: one describing absolute (i.e., number of exceedances of absolute thresholds like hot days), the other relative (i.e., number of exceedances of time series intrinsic thresholds) compound extreme events. Changes are assessed between a reference period (1971-2000) and a projection period (2021-2050). Our findings show an increase in the number of absolute compound events for the whole investigation area. The change signal of relative extremes is more region-dependent, but there is a strong signal change in the southern and eastern parts of Germany and the neighboring countries. Especially the Czech Republic shows strong change in absolute and relative extreme events.

  11. CERN openlab Summer Student Programme

    CERN Multimedia

    2012-01-01

    CERN openlab is currently taking applications for its summer student programme. The closing date for applications is 30 March 2012.   The openlab Summer Student Programme is open for applications from bachelor, master and PhD students in computer science and physics. Successful applicants will spend 8 weeks at CERN, during the period June to September 2012, to work with some of the latest hardware and software technologies. The programme is more than just a summer at CERN: it can lead to follow-on projects at the home institute and may even inspire the students to become entrepreneurs in cutting-edge computing technologies. A series of lectures will be given by experts in various domains of CERN related high-throughput computing. Study tours to external companies and universities as well as to CERN facilities are also part of the programme. Please visit www.cern.ch/openlab-students for more information.

  12. CERN openlab summer student programme

    CERN Multimedia

    2013-01-01

    CERN openlab is currently taking applications for its summer student programme. The closing date for applications is 31 March 2013.   The openlab summer student programme is open for applications from bachelor, master and PhD students in computer science and physics. Successful applicants will spend 9 weeks at CERN, during the period from June to September 2013, working with some of the latest hardware and software technologies. The programme is more than just a summer at CERN: it can lead to follow-on projects at the home institute and may even inspire students to become entrepreneurs in cutting-edge computing technologies. A series of lectures will be given by experts in various domains of CERN-related high-throughput computing. Study tours of external companies and universities as well as of CERN facilities are also part of the programme. Please visit the CERN openlab website for more information.

  13. Experimental design of multifactor climate change experiments with elevated CO2, warming and drought: the CLIMAITE project

    DEFF Research Database (Denmark)

    Mikkelsen, Teis Nørgaard; Beier, Claus; Jonasson, S.

    2008-01-01

    a larger set of main factors are needed. We describe a new Danish climate change-related field scale experiment, CLIMAITE, in a heath/grassland ecosystem. CLIMAITE is a full factorial combination of elevated CO2, elevated temperature and prolonged summer drought. The manipulations are intended to mimic...... anticipated major environmental changes at the site by year 2075 as closely as possible. The impacts on ecosystem processes and functioning (at ecophysiological levels, through responses by individuals and communities to ecosystem-level responses) are investigated simultaneously. The increase of [CO2] closely...... corresponds with the scenarios for year 2075, while the warming treatment is at the lower end of the predictions and seems to be the most difficult treatment to increase without unwanted side effects on the other variables. The drought treatment follows predictions of increased frequency of drought periods...

  14. Summer Schools In Nuclear Chemistry

    International Nuclear Information System (INIS)

    Clark, Sue; Herbert, Mieva; Mantica, Paul

    2006-01-01

    This the report for the 5 year activities for the ACS Summer Schools in Nuclear and Radiochemistry. The American Chemical Society's Summer Schools in Nuclear and Radiochemistry were held at Brookhaven National Laboratory (Upton, NY) and San Jose State University (San Jose, CA) during the award period February 1, 2002 to January 31, 2007. The Summer Schools are intensive, six-week program involving both a lecture component covering fundamental principles of nuclear chemistry and radiochemistry and a laboratory component allowing hands-on experience for the students to test many of the basic principles they learn about in lecture. Each site hosted 12 undergraduate students annually, and students received coursework credits towards their undergraduate degrees. Up to 7 student credit hours were earned at San Jose State University, and Brookhaven students received up to 6 college credits through BNL's management partner, SUNY Stony Brook. Funding from the award period covered travel, housing, educational expenses, and student stipends, for the 24 undergraduate participants. Furthermore, funding was also used to cover expenses for lecturers and staff to run the programs at the two facilities. The students were provided with nuclear and radiochemistry training equivalent to a three-hour upper-level undergraduate course along with a two-hour hands-on laboratory experience within the six-week summer period. Lectures were held 5 days per week. Students completed an extensive laboratory sequence, as well as radiation safety training at the start of the Summer Schools. The summer school curriculum was enhanced with a Guest Lecture series, as well as through several one-day symposia and organized field trips to nuclear-related research and applied science laboratories. This enrichment afforded an opportunity for students to see the broader impacts of nuclear science in today's world, and to experience some of the future challenges through formal and informal discussions with

  15. Southern Hemisphere bog persists as a strong carbon sink during droughts

    Science.gov (United States)

    Goodrich, Jordan P.; Campbell, David I.; Schipper, Louis A.

    2017-10-01

    Peatland ecosystems have been important global carbon sinks throughout the Holocene. Most of the research on peatland carbon budgets and effects of variable weather conditions has been done in Northern Hemisphere Sphagnum-dominated systems. Given their importance in other geographic and climatic regions, a better understanding of peatland carbon dynamics is needed across the spectrum of global peatland types. In New Zealand, much of the historic peatland area has been drained for agriculture but little is known about rates of carbon exchange and storage in unaltered peatland remnants that are dominated by the jointed wire rush, Empodisma robustum. We used eddy covariance to measure ecosystem-scale CO2 and CH4 fluxes and a water balance approach to estimate the sub-surface flux of dissolved organic carbon from the largest remaining raised peat bog in New Zealand, Kopuatai bog. The net ecosystem carbon balance (NECB) was estimated over four years, which included two drought summers, a relatively wet summer, and a meteorologically average summer. In all measurement years, the bog was a substantial sink for carbon, ranging from 134.7 to 216.9 gC m-2 yr-1, owing to the large annual net ecosystem production (161.8 to 244.9 gCO2-C m-2 yr-1). Annual methane fluxes were large relative to most Northern Hemisphere peatlands (14.2 to 21.9 gCH4-C m-2 yr-1), although summer and autumn emissions were highly sensitive to dry conditions, leading to very predictable seasonality according to water table position. The annual flux of dissolved organic carbon was similar in magnitude to methane emissions but less variable, ranging from 11.7 to 12.8 gC m-2 yr-1. Dry conditions experienced during late summer droughts led to significant reductions in annual carbon storage, which resulted nearly equally from enhanced ecosystem respiration due to lowered water tables and increased temperatures, and from reduced gross primary production due to vapor pressure deficit-related stresses to the

  16. Methods and Model Dependency of Extreme Event Attribution: The 2015 European Drought

    Science.gov (United States)

    Hauser, Mathias; Gudmundsson, Lukas; Orth, René; Jézéquel, Aglaé; Haustein, Karsten; Vautard, Robert; van Oldenborgh, Geert J.; Wilcox, Laura; Seneviratne, Sonia I.

    2017-10-01

    Science on the role of anthropogenic influence on extreme weather events, such as heatwaves or droughts, has evolved rapidly in the past years. The approach of "event attribution" compares the occurrence-probability of an event in the present, factual climate with its probability in a hypothetical, counterfactual climate without human-induced climate change. Several methods can be used for event attribution, based on climate model simulations and observations, and usually researchers only assess a subset of methods and data sources. Here, we explore the role of methodological choices for the attribution of the 2015 meteorological summer drought in Europe. We present contradicting conclusions on the relevance of human influence as a function of the chosen data source and event attribution methodology. Assessments using the maximum number of models and counterfactual climates with pre-industrial greenhouse gas concentrations point to an enhanced drought risk in Europe. However, other evaluations show contradictory evidence. These results highlight the need for a multi-model and multi-method framework in event attribution research, especially for events with a low signal-to-noise ratio and high model dependency such as regional droughts.

  17. Drought, ecological crisis and famine in late nineteenth century south-eastern Africa

    Science.gov (United States)

    Pribyl, Kathleen; Nash, David J.; Klein, Jørgen; Endfield, Georgina H.

    2017-04-01

    In the second half of the 1890s a drought-driven ecological crisis took hold in the region of modern-day Botswana, Zimbabwe and northern, central and eastern South Africa. A number of years of very late rainy seasons had severe repercussions for the rain-fed agriculture. Sowing was delayed and the young crops suffered from below average summer rainfall levels. Drawing on a wide variety of documentary sources - administrative records, writings by members of missionary societies and local newspapers - this paper outlines how the drought drove the ecological crisis and aggravated a locust infestation and the cattle plague (rinderpest). Whereas the locusts found better breeding conditions in areas that were normally too humid for them, the drought also facilitated the spread of rinderpest by reducing the number of watering holes and by forcing the cattle into an immunodepressed state due to malnutrition. The locusts contributed to the loss of grain crops, and the rinderpest decimated cattle herds by more than 90 per cent in areas where the disease coincided with the drought. As agriculture as well as the pastoral sector were hit hard, famine conditions developed in the interior of the region.

  18. On the issue of drought-tolerant ornamental woody plants the Black Sea coast (near Sochi

    Directory of Open Access Journals (Sweden)

    Karpun Yuriy Nikolaevich

    2017-12-01

    Full Text Available The summer-autumn drought, when rainfall in July - September, less than 200 mm, a significant limiting factor for ornamental woody plants of the Black Sea coast of the Caucasus. In the region under dry periods are irregular, the study of their impact on plants is problematic and delayed for many years. The last drought was in 2015, when the three months fell only 87 mm of rainfall. In the last days of the dry period were examined 501 views and intraspecific taxa belonging to 112 genera, bushy evergreen shrubs and trees, as the most vulnerable. Evaluation of drought resistance was evaluated according to our 3-point system, and the results were analyzed in the context of consolidated floristic regions. The results showed adequate drought tolerance, not less than 65 %, cultivated in the region of evergreen shrubs and bushy trees mainly from East Asia and the Mediterranean. Among the species that are recommended for mass plantings, for the pre-emptive use of landscaping and street-resistant plants 67-80 %. All this ensures stability and high decorative plants ofSochi city.

  19. Are Scots pine forest edges particularly prone to drought-induced mortality?

    Science.gov (United States)

    Buras, Allan; Schunk, Christian; Zeiträg, Claudia; Herrmann, Corinna; Kaiser, Laura; Lemme, Hannes; Straub, Christoph; Taeger, Steffen; Gößwein, Sebastian; Klemmt, Hans-Joachim; Menzel, Annette

    2018-02-01

    Climate change is expected to exacerbate the frequency of drought-induced tree mortality world-wide. To better predict the associated change of species composition and forest dynamics on various scales and develop adequate adaptation strategies, more information on the mechanisms driving the often observed patchiness of tree die-back is needed. Although forest-edge effects may play an important role within the given context, only few corresponding studies exist. Here, we investigate the regional die-back of Scots pine in Franconia, Germany, after a hot and dry summer in 2015, thereby emphasizing possible differences in mortality between forest edge and interior. By means of dendroecological investigations and close-range remote sensing, we assess long-term growth performance and current tree vitality along five different forest-edge distance gradients. Our results clearly indicate a differing growth performance between edge and interior trees, associated with a higher vulnerability to drought, increased mortality rates, and lower tree vitality at the forest edge. Prior long-lasting growth decline of dead trees compared to live trees suggests depletion of carbon reserves in course of a long-term drought persisting since the 1990s to be the cause of regional Scots pine die-back. These findings highlight the forest edge as a potential focal point of forest management adaptation strategies in the context of drought-induced mortality.

  20. Winter-to-Summer Precipitation Phasing in Southwestern North America: A Multi-Century Perspective from Paleoclimatic Model-Data Comparisons

    Science.gov (United States)

    Coats, Sloan; Smerdon, Jason E.; Seager, Richard; Griffin, Daniel; Cook, Benjamin I.

    2015-01-01

    The phasing of winter-to-summer precipitation anomalies in the North American monsoon (NAM) region 2 (113.25 deg W-107.75 deg W, 30 deg N-35.25 deg N-NAM2) of southwestern North America is analyzed in fully coupled simulations of the Last Millennium and compared to tree ring reconstructed winter and summer precipitation variability. The models simulate periods with in-phase seasonal precipitation anomalies, but the strength of this relationship is variable on multidecadal time scales, behavior that is also exhibited by the reconstructions. The models, however, are unable to simulate periods with consistently out-of-phase winter-to-summer precipitation anomalies as observed in the latter part of the instrumental interval. The periods with predominantly in-phase winter-to-summer precipitation anomalies in the models are significant against randomness, and while this result is suggestive of a potential for dual-season drought on interannual and longer time scales, models do not consistently exhibit the persistent dual-season drought seen in the dendroclimatic reconstructions. These collective findings indicate that model-derived drought risk assessments may underestimate the potential for dual-season drought in 21st century projections of hydroclimate in the American Southwest and parts of Mexico.

  1. Modeling drought impact occurrence based on climatological drought indices for four European countries

    Science.gov (United States)

    Stagge, James H.; Kohn, Irene; Tallaksen, Lena M.; Stahl, Kerstin

    2014-05-01

    The relationship between atmospheric conditions and the likelihood of a significant drought impact has, in the past, been difficult to quantify, particularly in Europe where political boundaries and language have made acquiring comprehensive drought impact information difficult. As such, the majority of studies linking meteorological drought with the occurrence or severity of drought impacts have previously focused on specific regions, very detailed impact types, or both. This study describes a new methodology to link the likelihood of drought impact occurrence with climatological drought indices across different European climatic regions and impact sectors using the newly developed European Drought Impact report Inventory (EDII), a collaborative database of drought impact information (www.geo.uio.no/edc/droughtdb/). The Standardized Precipitation Index (SPI) and Standardized Precipitation-Evapotranspiration Index (SPEI) are used as predictor variables to quantify meteorological drought severity over prior time periods (here 1, 2, 3, 6, 9, 12, and 24 months are used). The indices are derived using the gridded WATCH Forcing Datasets, covering the period 1958-2012. Analysis was performed using logistic regression to identify the climatological drought index and accumulation period, or linear combination of drought indices, that best predicts the likelihood of a documented drought impact, defined by monthly presence/absence. The analysis was carried out for a subset of four European countries (Germany, UK, Norway, Slovenia) and four of the best documented impact sectors: Public Water Supply, Agriculture and Livestock Farming, Energy and Industry, and Environmental Quality. Preliminary results show that drought impacts in these countries occur most frequently due to a combination of short-term (2-6 month) precipitation deficits and long-term (12-24 month) potential evapotranspiration anomaly, likely associated with increased temperatures. Agricultural drought impacts

  2. Recent changes and relations among drought, vegetation and wildfires in the Eastern Mediterranean: The case of Israel

    Science.gov (United States)

    Turco, Marco; Levin, Noam; Tessler, Naama; Saaroni, Hadas

    2017-04-01

    On-going changes in drought, vegetation and wildfires in Israel provide a key example of possible future evolution in transition areas at the border between Mediterranean and arid climates. Here we present multiple lines of evidence suggesting that drought conditions in Israel, representing the eastern Mediterranean, have increased during the period 1980-2014. Drought conditions were calculated using the Standardized Precipitation Evapotranspiration Index (SPEI), the Standardized Precipitation Index (SPI) and the Standardized Soil Moisture Index (SSI). A 30-year series (1982-2011) of monthly Fraction of Photosynthetically Active Radiation absorbed by vegetation (FPAR) indicates generally positive trends in winter and spring and negative ones in summer and autumn, except in the transition zone between the southern Negev desert and the Mediterranean climate region, where a statistically significant negative trend in all seasons was found. Available ground observations suggest that fire activity has decreased during the period 1987-2011. Apparent year-to-year oscillations are superposed onto these long-term trends. We show that inter-annual variability of summer fires is related to antecedent wet conditions and to above normal vegetation conditions. These relationships suggest the summer fires in Israel are mainly limited by fuel availability rather than by fuel flammability. On the other hand, the year-to-year variations of spring and autumn fires are significantly related with drought indices. Thus, the increase of drought conditions together with climate projections for further warming and drying in this region, point at a potential increase of fire risk in the intermediate seasons.

  3. Changes in field workability and drought risk from projected climate change drive spatially variable risks in Illinois cropping systems.

    Directory of Open Access Journals (Sweden)

    Bradley J Tomasek

    Full Text Available As weather patterns become more volatile and extreme, risks introduced by weather variability will become more critical to agricultural production. The availability of days suitable for field work is driven by soil temperature and moisture, both of which may be altered by climate change. We projected changes in Illinois season length, spring field workability, and summer drought risk under three different emissions scenarios (B1, A1B, and A2 down to the crop district scale. Across all scenarios, thermal time units increased in parallel with a longer frost-free season. An increase in late March and Early April field workability was consistent across scenarios, but a decline in overall April through May workable days was observed for many cases. In addition, summer drought metrics were projected to increase for most scenarios. These results highlight how the spatial and temporal variability in climate change may present unique challenges to mitigation and adaptation efforts.

  4. Blended Drought Index: Integrated Drought Hazard Assessment in the Cuvelai-Basin

    Directory of Open Access Journals (Sweden)

    Robert Luetkemeier

    2017-07-01

    Full Text Available Drought is one of the major threats to societies in Sub-Saharan Africa, as the majority of the population highly depends on rain-fed subsistence agriculture and traditional water supply systems. Hot-spot areas of potential drought impact need to be identified to reduce risk and adapt a growing population to a changing environment. This paper presents the Blended Drought Index (BDI, an integrated tool for estimating the impact of drought as a climate-induced hazard in the semi-arid Cuvelai-Basin of Angola and Namibia. It incorporates meteorological and agricultural drought characteristics that impair the population’s ability to ensure food and water security. The BDI uses a copula function to combine common standardized drought indicators that describe precipitation, evapotranspiration, soil moisture and vegetation conditions. Satellite remote sensing products were processed to analyze drought frequency, severity and duration. As the primary result, an integrated drought hazard map was built to spatially depict drought hot-spots. Temporally, the BDI correlates well with millet/sorghum yield (r = 0.51 and local water consumption (r = −0.45 and outperforms conventional indicators. In the light of a drought’s multifaceted impact on society, the BDI is a simple and transferable tool to identify areas highly threatened by drought in an integrated manner.

  5. Influence of mathematical and physical background of drought indices on their complementarity and drought recognition ability

    Science.gov (United States)

    Frank, Anna; Armenski, Tanja; Gocic, Milan; Popov, Srdjan; Popovic, Ljiljana; Trajkovic, Slavisa

    2017-09-01

    The aim of this study is to test how effective and physically correct are the mathematical approaches of operational indices used by relevant National Agencies across the globe. To do so, the following indices were analysed Standardized Precipitation Index (SPI) -1, 3, 6, 12 and 24, Standardized Precipitation - Evapotranspiration Index (SPEI) - 1, 3, 6, 12 and 24, Effective Drought Index (EDI) and Index of Drying Efficiency of Air (IDEA). To make regions more comparable to each other and follow the spatial development of drought SPI index was advised by World Meteorological Organisation to be used widely by official meteorological services. The SPI and SPEI are used for Drought Early Warning in the USA, National Drought Mitigation Center and NASA, and in the EU by the European Drought Centre (EDC) and in the Balkan Region by National Meteorological Agencies. The EDI Index has wide application in Asia. In this paper four different issues were investigated: 1) how the mathematical method used in a drought indicator's computation influence drought indices' (DI) comparative analyses; 2) the sensitivity of the DIs on any change of the length of observational period; 3) similarities between the DIs time series; 4) and how accurate DIs are when compared to historical drought records. Results suggest that it is necessary to apply a few crucial changes in the Drought Monitoring and Early Warning Systems: 1) reconsider use of SPI and SPEI family indices as a measure of quality of other indices; and for Drought Early Recognition Programs 2) switch to DIs with a solid physical background, such as EDI; 3) Adopt solid physics for modelling drought processes and define the physical measure of drought, e.g. EDI and IDEA indices; 4) investigate further the IDEA index, which, supported by our study as well, is valuable for simulation of a drought process.

  6. Examining Severe Drought-Induced Vegetation Change and its Influence on Water Resources

    Science.gov (United States)

    White, A. B.; Springer, E. P.; Vivoni, E. R.

    2007-12-01

    A "global-change-type" drought that occurred in the southwestern U.S. from 2000 to 2003, accompanied by increased temperatures and bark beetle infestations, induced large-scale woodland overstory mortality, the consequent redistribution of water, radiation, and nutrients, as well as modification of the ecosystem phenology. Our objectives in this research are to examine these vegetation changes in detail and to determine whether they translated to changes in hydrological processes. We chose the Rio Ojo Caliente, a subbasin of the Rio Grande, as a study site since a significant portion of the woodland ecosystem (piñon-juniper) was affected. Examining a remotely-sensed vegetation index (1-km AVHRR NDVI from 1989 to 2006), there is an increasing trend in the mean NDVI from 1989 to 1998 (pre-drought period), a decreasing trend from 1999 to 2003 (drought period), and a dramatic increasing trend from 2004 to 2006 (post-drought period) in which the mean NDVI rebounds to pre- drought magnitudes. Streamflow records from 1932 to 2006 show the watershed to be primarily spring snowmelt-driven, although monsoonal summer precipitation also plays a significant role. We compare the temporal variability in the streamflow to the NDVI, including the mean, anomalies from the mean, and seasonally- based duration curves, and find significant correlations (correlation coefficient ρ = -0.61) between the streamflow and NDVI at approximately a three-month lag (NDVI lagging streamflow). In analyzing the three phases of the drought, the correlation is slightly stronger during the pre-drought (ρ = -0.64) and drought (ρ = -0.65) periods, yet markedly stronger during the post-drought period (ρ = -0.74). This suggests that the coupling between vegetation water use and streamflow is tighter after the drought. This may be attributable to the reduction in the less-responsive overstory (pinñon mortality) and increase in the more-responsive understory (grasses and shrubs exploiting newly

  7. Repeated causal decision making.

    Science.gov (United States)

    Hagmayer, York; Meder, Björn

    2013-01-01

    Many of our decisions refer to actions that have a causal impact on the external environment. Such actions may not only allow for the mere learning of expected values or utilities but also for acquiring knowledge about the causal structure of our world. We used a repeated decision-making paradigm to examine what kind of knowledge people acquire in such situations and how they use their knowledge to adapt to changes in the decision context. Our studies show that decision makers' behavior is strongly contingent on their causal beliefs and that people exploit their causal knowledge to assess the consequences of changes in the decision problem. A high consistency between hypotheses about causal structure, causally expected values, and actual choices was observed. The experiments show that (a) existing causal hypotheses guide the interpretation of decision feedback, (b) consequences of decisions are used to revise existing causal beliefs, and (c) decision makers use the experienced feedback to induce a causal model of the choice situation even when they have no initial causal hypotheses, which (d) enables them to adapt their choices to changes of the decision problem. (PsycINFO Database Record (c) 2013 APA, all rights reserved).

  8. A Tri-National program for estimating the link between snow resources and hydrological droughts

    Directory of Open Access Journals (Sweden)

    M. Zappa

    2015-06-01

    Full Text Available To evaluate how summer low flows and droughts are affected by the winter snowpack, a Tri-National effort will analyse data from three catchments: Alpbach (Prealps, central Switzerland, Gudjaretis-Tskali (Little Caucasus, central Georgia, and Kamenice (Jizera Mountains, northern Czech Republic. Two GIS-based rainfall-runoff models will simulate over 10 years of runoff in streams based on rain and snowfall measurements, and further meteorological variables. The models use information on the geographical settings of the catchments together with knowledge of the hydrological processes of runoff generation from rainfall, looking particularly at the relationship between spring snowmelt and summer droughts. These processes include snow accumulation and melt, evapotranspiration, groundwater recharge in spring that contributes to (the summer runoff, and will be studied by means of the environmental isotopes 18O and 2H. Knowledge about the isotopic composition of the different water sources will allow to identify the flow paths and estimate the residence time of snow meltwater in the subsurface and its contribution to the stream. The application of the models in different nested or neighbouring catchments will explore their potential for further development and allow a better early prediction of low-flow periods in various mountainous zones across Europe. The paper presents the planned activities including a first analysis of already available dataset of environmental isotopes, discharge, snow water equivalent and modelling experiments of the (already available datasets.

  9. Assessment of the Impact of Climate Change on Drought Characteristics in the Hwanghae Plain, North Korea Using Time Series SPI and SPEI: 1981–2100

    Directory of Open Access Journals (Sweden)

    Sang-Hyun Lee

    2017-08-01

    Full Text Available North Korea is a food-deficit nation in which climate change could have a significant impact on drought. We analyzed drought characteristics in the Hwanghae Plain, North Korea using both the multiple timescales of the standardized precipitation index (SPI and the standardized precipitation evapotranspiration index (SPEI from 1981 to 2100. The probability of non-exceedance for a one-month SPEI below −1.0 was only 1.1% in the spring season of 1995 but increased to 24.4% in 2085. The SPEI for a ten-year return period varied from −0.6 to −0.9 in 1995 and decreased to −1.18 in 2025. The results indicate that severe drought is more likely to occur in future as a result of climate change. The seasonal drought conditions were also significantly influenced by climate change. The largest decrease in the SPEI occurred in late spring and early summer, both of which are important for rice growth. Drought characteristics include severity, duration, and intensity. Therefore, we applied the time series of SPIs and SPEIs to the runs theory and found that the drought intensity identified by one-month SPEIs in 1995 was at a level of 1.21, which reached 1.39 in 2085, implying that climate change will intensify drought in the future.

  10. Interspecific variation in functional traits of oak seedlings (Quercus ilex, Quercus trojana, Quercus virgiliana) grown under artificial drought and fire conditions.

    Science.gov (United States)

    Chiatante, D; Tognetti, R; Scippa, G S; Congiu, T; Baesso, B; Terzaghi, M; Montagnoli, A

    2015-07-01

    To face summer drought and wildfire in Mediterranean-type ecosystems, plants adopt different strategies that involve considerable rearrangements of biomass allocation and physiological activity. This paper analyses morphological and physiological traits in seedlings of three oak species (Quercus ilex, Quercus trojana and Quercus virgiliana) co-occurring under natural conditions. The aim of this study was to evaluate species-specific characteristics and the response of these oak seedlings to drought stress and fire treatment. Seedlings were kept in a growth chamber that mimicked natural environmental conditions. All three species showed a good degree of tolerance to drought and fire treatments. Differences in specific biomass allocation patterns and physiological traits resulted in phenotypic differences between species. In Q. ilex, drought tolerance depended upon adjustment of the allocation pattern. Q. trojana seedlings undergoing mild to severe drought presented a higher photosystem II (PSII) efficiency than control seedlings. Moreover, Q. trojana showed a very large root system, which corresponded to higher soil area exploitation, and bigger leaf midrib vascular bundles than the other two species. Morphological and physiological performances indicated Q. trojana as the most tolerant to drought and fire. These characteristics contribute to a high recruitment potential of Q. trojana seedlings, which might be the reason for the dominance of this species under natural conditions. Drought increase as a result of climate change is expected to favour Q. trojana, leading to an increase in its spatial distribution.

  11. Phenotypic Approaches to Drought in Cassava: Review

    Directory of Open Access Journals (Sweden)

    Emmanuel eOkogbenin

    2013-05-01

    Full Text Available Cassava is an important crop in Africa, Asia, Latin America and the Caribbean. Cassava can be produced adequately in drought conditions making it the ideal food security crop in marginal environments. Although cassava can tolerate drought stress, it can be genetically improved to enhance productivity in such environments. Drought adaptation studies in over three decades in cassava have identified relevant mechanisms which have been explored in conventional breeding. Drought is a quantitative trait and its multigenic nature makes it very challenging to effectively manipulate and combine genes in breeding for rapid genetic gain and selection process. Cassava has a long growth cycle of 12 - 18 months which invariably contributes to a long breeding scheme for the crop. Modern breeding using advances in genomics and improved genotyping, is facilitating the dissection and genetic analysis of complex traits including drought tolerance, thus helping to better elucidate and understand the genetic basis of such traits. A beneficial goal of new innovative breeding strategies is to shorten the breeding cycle using minimized, efficient or fast phenotyping protocols. While high throughput genotyping have been achieved, this is rarely the case for phenotyping for drought adaptation. Some of the storage root phenotyping in cassava are often done very late in the evaluation cycle making selection process very slow. This paper highlights some modified traits suitable for early-growth phase phenotyping that may be used to reduce drought phenotyping cycle in cassava. Such modified traits can significantly complement the high throughput genotyping procedures to fast track breeding of improved drought tolerant varieties. The need for metabolite profiling, improved phenomics to take advantage of next generation sequencing technologies and high throughput phenotyping are basic steps for future direction to improve genetic gain and maximize speed for drought tolerance

  12. Belowground heathland responses after 2 years of combined warming, elevated CO2 and summer drought

    DEFF Research Database (Denmark)

    Andresen, Louise C.; Michelsen, Anders; Ambus, Per

    2010-01-01

    significantly to the treatments. In the combined temperature and CO2 treatment the dissolved organic nitrogen concentration decreased and the ammonium concentration increased, but this release of nutrients was not mirrored by plant parameters. Microbial biomass carbon and microbial enrichment with 13C and 15N...

  13. Summer droughts limit tree growth across 10 temperate species on a productive forest site

    NARCIS (Netherlands)

    Weemstra, M.; Eilmann, B.; Sass-Klaassen, U.; Sterck, F.J.

    2013-01-01

    Studies on climate impacts on tree annual growth are mainly restricted to marginal sites. To date, the climate effects on annual growth of trees in favorable environments remain therefore unclear despite the importance of these sites in terms of forest productivity. Because species respond

  14. Summer Student Report - Project Kryolize

    CERN Document Server

    Drozdowski, Pawel

    2016-01-01

    The purpose of this document is to describe the work and results obtained by the author during his summer student internship at CERN. The author of this document was attached to the project Kryolize as a software developer, overtaking the job from a recently departed technical student.

  15. Joint pattern of seasonal hydrological droughts and floods ...

    Indian Academy of Sciences (India)

    Under the current condition of climate change, droughts and floods occur more frequently, and events in which flooding occurs after a prolonged drought or a drought occurs after an extreme flood may have a more severe impact on natural systems and human lives. This challenges the traditional approach wherein droughts ...

  16. Selection for drought tolerance in two tropical maize populations ...

    African Journals Online (AJOL)

    Drought is a major factor limiting maize (Zea mays L.) yield in much of the world. The need to breed maize cultivars with improved drought tolerance is apparent. This study compared two maize populations, ZM601 and ZM607 for drought tolerance during flowering, the most drought-vulnerable period for the maize plant.

  17. A process-based typology of hydrological drought

    NARCIS (Netherlands)

    Loon, van A.F.; Lanen, van H.A.J.

    2012-01-01

    Hydrological drought events have very different causes and effects. Classifying these events into distinct types can be useful for both science and management. We propose a hydrological drought typology that is based on governing drought propagation processes derived from catchment-scale drought

  18. Assessment of sorghum genetic resources for genetic diversity and drought tolerance using molecular markers and agro-morphological traits

    Energy Technology Data Exchange (ETDEWEB)

    Abu Assar, A H; Salih, M; Ali, A M [Agricultural Research Corporation (ARC), P.O. Box 126 Wad Medani (Sudan); Uptmoor, R [Institute of Vegetable and Fruit Science, University of Hannover, Herrengauser Strabe 2.30419 Hanover (Greece); Abdelmula, A A [Department of Agronomy, Faculty of Agriculture, University of Khartoum, postal code: 13314 Shambat (Sudan); Ordon, F [Institute of Eqidemiology and Resistance, Federal Centre for Breeding Research on Cultivated Plants, Theodor-Roemer-Weg 4, D-06449 Aschersleben (Greece); Wagner, C; Friedt, W [Institute of Crop Science and Plant Breedin 1, Heinrich-Buff-Ring 26-32, D-35392 Giessen (Greece)

    2009-07-01

    Forty sorghum genotype were investigated for genetic diversity and drought tolerance. Diversity parameters were estimated using 16 simple sequence repeats markers. For assessment of drought tolerance, the genotype were field evaluated under normal and drought stress condition for two seasons in three environments, in Sudan. In total, 98 SSRs alleles were detected with an average of 6.1 alleles per locus. The estimated polymorphic information contents ranged from 0.33 to 0.86. The genetic similarity ranged from 0.00 to 0.88 with a low mean of 0.32. The dendrogram, generated from the UPGMA cluster analysis, showed two main clusters differentiated into nine sub-clusters with close relationship to morphological characters and pedigree information. Mantel statistics revealed a good fit of the cophenetic values to the original data set (r= 0.88). The overall mean genetic diversity was 0.67. Significant differences were detected among genotypes under both normal and drought stressed conditions for all measured traits. Based on the relative yield, the most drought-tolerant genotypes were Arfa Gadamak, Wad Ahmed, El-Najada, Korcola, ICSR 92003 And Sham Sham. Drought five days delay in flowering, and the earliest genotypes were PI 569695, PI 570446, PI 569953, Dwarf White Milo and PI 56995. (Author)

  19. Assessment of sorghum genetic resources for genetic diversity and drought tolerance using molecular markers and agro-morphological traits

    International Nuclear Information System (INIS)

    Abu Assar, A. H.; Salih, M.; Ali, A. M.; Uptmoor, R.; Abdelmula, A. A.; Ordon, F.; Wagner, C.; Friedt, W.

    2009-01-01

    Forty sorghum genotype were investigated for genetic diversity and drought tolerance. Diversity parameters were estimated using 16 simple sequence repeats markers. For assessment of drought tolerance, the genotype were field evaluated under normal and drought stress condition for two seasons in three environments, in Sudan. In total, 98 SSRs alleles were detected with an average of 6.1 alleles per locus. The estimated polymorphic information contents ranged from 0.33 to 0.86. The genetic similarity ranged from 0.00 to 0.88 with a low mean of 0.32. The dendrogram, generated from the UPGMA cluster analysis, showed two main clusters differentiated into nine sub-clusters with close relationship to morphological characters and pedigree information. Mantel statistics revealed a good fit of the cophenetic values to the original data set (r= 0.88). The overall mean genetic diversity was 0.67. Significant differences were detected among genotypes under both normal and drought stressed conditions for all measured traits. Based on the relative yield, the most drought-tolerant genotypes were Arfa Gadamak, Wad Ahmed, El-Najada, Korcola, ICSR 92003 And Sham Sham. Drought five days delay in flowering, and the earliest genotypes were PI 569695, PI 570446, PI 569953, Dwarf White Milo and PI 56995. (Author)

  20. A Global Drought Observatory for Emergency Response

    Science.gov (United States)

    Vogt, Jürgen; de Jager, Alfred; Carrão, Hugo; Magni, Diego; Mazzeschi, Marco; Barbosa, Paulo

    2016-04-01

    Droughts are occurring on all continents and across all climates. While in developed countries they cause significant economic and environmental damages, in less developed countries they may cause major humanitarian catastrophes. The magnitude of the problem and the expected increase in drought frequency, extent and severity in many, often highly vulnerable regions of the world demand a change from the current reactive, crisis-management approach towards a more pro-active, risk management approach. Such approach needs adequate and timely information from global to local scales as well as adequate drought management plans. Drought information systems are important for continuous monitoring and forecasting of the situation in order to provide timely information on developing drought events and their potential impacts. Against this background, the Joint Research Centre (JRC) is developing a Global Drought Observatory (GDO) for the European Commission's humanitarian services, providing up-to-date information on droughts world-wide and their potential impacts. Drought monitoring is achieved by a combination of meteorological and biophysical indicators, while the societal vulnerability to droughts is assessed through the targeted analysis of a series of social, economic and infrastructural indicators. The combination of the information on the occurrence and severity of a drought, on the assets at risk and on the societal vulnerability in the drought affected areas results in a likelihood of impact, which is expressed by a Likelihood of Drought Impact (LDI) indicator. The location, extent and magnitude of the LDI is then further analyzed against the number of people and land use/land cover types affected in order to provide the decision bodies with information on the potential humanitarian and economic bearings in the affected countries or regions. All information is presented through web-mapping interfaces based on OGC standards and customized reports can be drawn by the

  1. Agricultural Productivity Forecasts for Improved Drought Monitoring

    Science.gov (United States)

    Limaye, Ashutosh; McNider, Richard; Moss, Donald; Alhamdan, Mohammad

    2010-01-01

    Water stresses on agricultural crops during critical phases of crop phenology (such as grain filling) has higher impact on the eventual yield than at other times of crop growth. Therefore farmers are more concerned about water stresses in the context of crop phenology than the meteorological droughts. However the drought estimates currently produced do not account for the crop phenology. US Department of Agriculture (USDA) and National Oceanic and Atmospheric Administration (NOAA) have developed a drought monitoring decision support tool: The U.S. Drought Monitor, which currently uses meteorological droughts to delineate and categorize drought severity. Output from the Drought Monitor is used by the States to make disaster declarations. More importantly, USDA uses the Drought Monitor to make estimates of crop yield to help the commodities market. Accurate estimation of corn yield is especially critical given the recent trend towards diversion of corn to produce ethanol. Ethanol is fast becoming a standard 10% ethanol additive to petroleum products, the largest traded commodity. Thus the impact of large-scale drought will have dramatic impact on the petroleum prices as well as on food prices. USDA's World Agricultural Outlook Board (WAOB) serves as a focal point for economic intelligence and the commodity outlook for U.S. WAOB depends on Drought Monitor and has emphatically stated that accurate and timely data are needed in operational agrometeorological services to generate reliable projections for agricultural decision makers. Thus, improvements in the prediction of drought will reflect in early and accurate assessment of crop yields, which in turn will improve commodity projections. We have developed a drought assessment tool, which accounts for the water stress in the context of crop phenology. The crop modeling component is done using various crop modules within Decision Support System for Agrotechnology Transfer (DSSAT). DSSAT is an agricultural crop

  2. Evaluation of last extreme drought events in Amazon basin using remotely sensing data

    Science.gov (United States)

    Panisset, Jéssica S.; Gouveia, Célia M.; Libonati, Renata; Peres, Leonardo; Machado-Silva, Fausto; França, Daniela A.; França, José R. A.

    2017-04-01

    Amazon basin has experienced several intense droughts among which were highlighted last recent ones in 2005 and 2010. Climate models suggest these events will be even more frequent due to higher concentration of greenhouse gases that are also driven forward by alteration in forest dynamics. Environmental and social impacts demand to identify these intense droughts and the behavior of climate parameters that affect vegetation. This present study also identifies a recent intense drought in Amazon basin during 2015. Meteorological parameters and vegetation indices suggest this event was the most severe already registered in the region. We have used land surface temperature (LST), vegetation indices, rainfall and shortwave radiation from 2000 to 2015 to analyze and compare droughts of 2005, 2010 and 2015. Our results show singularities among the three climate extreme events. The austral winter was the most affected season in 2005 and 2010, but not in 2015 when austral summer presented extreme conditions. Precipitation indicates epicenter of 2005 in west Amazon corroborating with previous studies. In 2010, the west region was strongly affected again together with the northwest and the southeast areas. However, 2015 epicenters were concentrated in the east of the basin. In 2015, shortwave radiation has exceeded the maximum values of 2005 and temperature the maximum value of 2010. Vegetation indices have shown positive and negative anomalies. Despite of heterogenous response of Amazon forest to drought, hybrid vegetation indices using NDVI (Normalized Difference Vegetation Index) and LST highlights the exceptionality of 2015 drought episode that exhibits higher vegetation water stress than the cases of 2010 and 2005. Finally, this work has shown how meteorological parameters influence droughts and the effects on vegetation in Amazon basin. Complexity of climate, ecosystem heterogeneity and high diversity of Amazon forest are response by idiosyncrasies of each drought. All

  3. Time Series MODIS and in Situ Data Analysis for Mongolia Drought

    Directory of Open Access Journals (Sweden)

    Munkhzul Dorjsuren

    2016-06-01

    Full Text Available Drought is a period of abnormally dry weather with a serious shortage of water supply. Drought indices can be an advantageous indicator to assess drought for taking further response actions. However, drought indices based on ground meteorological measurements could not completely reveal the land use effects over a regional scale. On the other hand, the satellite-derived products provide consistent, spatial and temporal comparisons of global signatures for the regional-scale drought events. This research is to investigate the drought signatures over Mongolia by using satellite remote sensing imagery. The evapotranspiration (ET, potential evapotranspiration (PET and two-band Enhanced Vegetation Index (EVI2 were extracted from MODIS data. Based on the standardized ratio of ET to PET (ET/PET and EVI2, the Modified Drought Severity Index (MDSI anomaly during the growing season from May–August for the years 2000–2013 was acquired. Fourteen-year summer monthly data for air temperature, precipitation and soil moisture content of in situ measurements from sixteen meteorological stations for four various land use areas were analyzed. We also calculated the percentage deviation of climatological variables at the sixteen stations to compare to the MDSI anomaly. Both comparisons of satellite-derived and observed anomalies and variations were analyzed by using the existing common statistical methods. The results demonstrated that the air temperature anomaly (T anomaly and the precipitation anomaly (P anomaly were negatively (correlation coefficient r = −0.66 and positively (r = 0.81 correlated with the MDSI anomaly, respectively. The MDSI anomaly distributions revealed that the wettest area occupied 57% of the study area in 2003, while the driest (drought area occurred over 54% of the total area in 2007. The results also showed very similar variations between the MDSI and T anomalies. The highest (wettest MDSI anomaly indicated the lowest T anomaly

  4. The Role of Precipitation Recycling in the Propagation and Intensification of Droughts in North America

    Science.gov (United States)

    Herrera-Estrada, J. E.; Sheffield, J.; Martinez-Agudelo, J. A.; Dominguez, F.; Wood, E. F.

    2017-12-01

    Predicting droughts allows stakeholders to mitigate some of the negative impacts of these natural disasters. However, there are still large gaps of knowledge regarding the physical drivers of drought onset, development, and recovery. These gaps have limited our ability to predict some important droughts and to understand how they may be affected by climate change. One physical mechanism that has been linked to the evolution of droughts is precipitation recycling, but its role has not been quantified in detail. Here we use a precipitation recycling model that backtracks the spatial origins of precipitation using vertically integrated moisture fluxes and evapotranspiration data. This allows us to estimate the climatology of moisture sources and sinks, and identify from where moisture fails to arrive when a given region experiences a drought. ERA-Interim data is used to drive this precipitation recycling model from 1980 to 2016 throughout North America and its surrounding oceans. The climatological analysis shows that oceans contribute around 80% of the precipitation over North America during winter, while precipitation that originates from evapotranspiration over land reaches a relative contribution of 60% in the summer. Precipitation contributions from the Pacific Ocean were found to be significantly and positively correlated with ENSO and PDO indices. Furthermore, a regression analysis showed that dry soil moisture in the US Southwest reduces moisture exports to the US Midwest, which in turn can dry soil moisture in the US Midwest. Given that up to 13% of precipitation over the US Midwest was found to be locally recycled, there is a multiplier effect whereby a 10 mm/month reduction in precipitation imports into the region leads to an additional decrease of 0.8 mm/month (on average) from reduced local precipitation recycling, causing a drought to intensify. It was also found that during extensive droughts (e.g. 2011 in Texas and 2012 in the US Midwest

  5. Local Perception of Drought Impacts in a Changing Climate: The Mega-Drought in Central Chile

    Directory of Open Access Journals (Sweden)

    Paulina Aldunce

    2017-11-01

    Full Text Available Droughts are a recurrent and complex natural hazard whose frequency and magnitude are expected to increase with climate change. Despite the advances in responding and adapting to droughts (with the development of new policies, for example, droughts continue to cause serious impacts and suffering. Developing well-targeted public policies requires further research on adaptation. Specifically, understanding the public perception of drought can help to identify drivers of and barriers to adaptation and options. This research seeks to understand the public perception of drought in central Chile in order to inform adaptation-related policies and decision-making processes. This study focused on the Mega-drought, which was a protracted dry spell afflicting central Chile since 2010.

  6. Natural recovery and leaf water potential after fire influenced by salvage logging and induced drought stress

    Directory of Open Access Journals (Sweden)

    D. Moya

    2013-01-01

    Full Text Available Salvage logging is one of the most common emergency actions in the short-term management after a fire. Several studies have been carried out and some obtained positive results which incite to carry it out but other, found negative effects on seedling establishment and regeneration. In addition, climatic changes will have large impacts on vegetation productivity and resilience since the regional models for south-eastern Spain predicts a rainfall decrease of about 20% and temperature increase of 4.5 ºC. Our aim was to determine how short-term forest management and induced drought affect the ecosystem recovery in Aleppo pine stands naturally recovered after a fire.In summer 2009, a mid-high severity fire burned 968 ha of Aleppo pine (Pinus halepensis Mill. forest in south-eastern Spain. Six months later, a salvage logging was carried out. The Aleppo pine recruitment was negligible. During summer 2010, twelve square plots (2m x 2m were set in the three scenarios: control, salvaged and drought induced. The surface cover and soil water availability for three dominant understory species were recorded in four field campaigns: Spring-2010, Fall-2010, Spring-2011 and Fall-2011.The season, management and the target species showed significant differences in growing and water stress. In general, Esparto grass showed lower water stress, mainly in Fall, a higher increase of total coverage. Both effects were showing their highest values in non-salvaged areas and no drought. Changes in leaf water potential and soil water content after the drought season influence the survival and development of individuals.Our results indicate that soil water content and ecosystem response can be modified by short-term silvicultural treatments. Therefore, management after fire could cause opposite effects to those initially foreseen, since they depend on fire severity, and type of ecosystem management response. So, their application must be evaluated and assessed before

  7. Effects of prolonged soil drought on CH4 oxidation in a temperate spruce forest

    Science.gov (United States)

    Borken, W.; Brumme, R.; Xu, Y.-J.

    2000-03-01

    Our objective was to determine potential impacts of changes in rainfall amount and distribution on soil CH4 oxidation in a temperate forest ecosystem. We constructed a roof below the canopy of a 65-year-old Norway spruce forest (Picea abies (L.) Karst.) and simulated two climate change scenarios: (1) an extensively prolonged summer drought of 172 days followed by a rewetting period of 19 days in 1993 and (2) a less intensive summer drought of 108 days followed by a rewetting period of 33 days in 1994. CH4 oxidation, soil matric potential, and soil temperature were measured hourly to daily over a 2-year period. The results showed that annual CH4 oxidation in the drought experiment increased by 102% for the climate change scenario 1 and by 41% for the climate change scenario 2, compared to those of the ambient plot (1.33 kg CH4 ha-1 in 1993 and 1.65 kg CH4 ha-1 in 1994). We tested the relationships between CH4 oxidation rates, water-filled pore space (WFPS), soil matric potential, gas diffusivity, and soil temperature. Temporal variability in the CH4 oxidation rates corresponded most closely to soil matric potential. Employing soil matric potential and soil temperature, we developed a nonlinear model for estimating CH4 oxidation rates. Modeled results were in strong agreement with the measured CH4 oxidation for the ambient (r2 = 0.80) and drought plots (r2 = 0.89) over two experimental years, suggesting that soil matric potential is a highly reliable parameter for modeling CH4 oxidation rate.

  8. Expansion of protein domain repeats.

    Directory of Open Access Journals (Sweden)

    Asa K Björklund

    2006-08-01

    Full Text Available Many proteins, especially in eukaryotes, contain tandem repeats of several domains from the same family. These repeats have a variety of binding properties and are involved in protein-protein interactions as well as binding to other ligands such as DNA and RNA. The rapid expansion of protein domain repeats is assumed to have evolved through internal tandem duplications. However, the exact mechanisms behind these tandem duplications are not well-understood. Here, we have studied the evolution, function, protein structure, gene structure, and phylogenetic distribution of domain repeats. For this purpose we have assigned Pfam-A domain families to 24 proteomes with more sensitive domain assignments in the repeat regions. These assignments confirmed previous findings that eukaryotes, and in particular vertebrates, contain a much higher fraction of proteins with repeats compared with prokaryotes. The internal sequence similarity in each protein revealed that the domain repeats are often expanded through duplications of several domains at a time, while the duplication of one domain is less common. Many of the repeats appear to have been duplicated in the middle of the repeat region. This is in strong contrast to the evolution of other proteins that mainly works through additions of single domains at either terminus. Further, we found that some domain families show distinct duplication patterns, e.g., nebulin domains have mainly been expanded with a unit of seven domains at a time, while duplications of other domain families involve varying numbers of domains. Finally, no common mechanism for the expansion of all repeats could be detected. We found that the duplication patterns show no dependence on the size of the domains. Further, repeat expansion in some families can possibly be explained by shuffling of exons. However, exon shuffling could not have created all repeats.

  9. Performing drought indices to identify the relationship between agricultural losses and drought events in Spain.

    Science.gov (United States)

    Peña Gallardo, Marina; Serrano, Sergio Martín Vicente; Portugués Santiago, Beguería; Burguera Miquel, Tomás

    2017-04-01

    Drought leads to crop failures reducing the productivity. For this reason, the need of appropriate tool for recognize dry periods and evaluate the impact of drought on crop production is important. In this study, we provide an assessment of the relationship between drought episodes and crop failures in Spain as one of the direct consequences of drought is the diminishing of crop yields. First, different drought indices [the Standardized Precipitation and Evapotranspiration Index (SPEI); the Standardized Precipitation Index (SPI); the self-calibrated Palmer Moisture Anomaly Index (Z-Index), the self-calibrated Crop Moisture Index (CMI) and the Standardized Palmer Drought Index (SPDI)] have been calculated at different time scales in order to identify the dry events occurred in Spain and determine the duration and intensity of each event. Second, the drought episodes have been correlated with crop production estimated and final crop production data provided by the Spanish Crop Insurance System for the available period from 1995 to 2014 at the municipal spatial scale, with the purpose of knowing if the characteristics of the drought episodes are reflected on the agricultural losses. The analysis has been carried out in particular for two types of crop, wheat and barley. The results indicate the existence of an agreement between the most important drought events in Spain and the response of the crop productions and the proportion of hectare insurance. Nevertheless, this agreement vary depending on the drought index applied. Authors found a higher competence of the drought indices calculated at different time scales (SPEI, SPI and SPDI) identifying the begging and end of the drought events and the correspondence with the crop failures.

  10. [Physiological responses of mycorrhizal Pinus massoniana seedlings to drought stress and drought resistance evaluation].

    Science.gov (United States)

    Wang, Yi; Ding, Gui-jie

    2013-03-01

    A greenhouse pot experiment was conducted to study the effects of inoculating Pisolithus tinctorius, Cenococcum geophilum, Cantharellus cibarius, and Suillus luteus on the physiological characteristics of Pinus massoniana seedlings under the conditions of drought stress and re-watering, with the drought resistance of the mycorrhizal seedlings evaluated. Under drought stress, the MDA content and membrane' s relative permeability of P. massoniana seedlings increased, but these two indices in the inoculated (mycorrhizal) seedlings were significantly lower than these in the un-inoculated (control) seedlings. After re-watering, the MDA content and membrane's relative permeability of mycorrhizal seedlings had a rapid decrease, as compared with the control. In the first 21 days of drought stress, the production rate of superoxide radical of the seedlings increased, and the SOD, POD and NR activities of mycorrhizal seedlings increased significantly. With the extending of drought stress, the seedlings after re-watering had different recovery ability. Under the re-watering after 14 days drought stress, the SOD, POD and NR activities recovered. The drought resistance of the mycorrhizal seedlings was in the order of Suillus luteus 1 > Suillus luteus 7 > Cantharellus cibarius > Cenococcum geophilum > Pisolithus tinctorius. The SOD and MDA activities had a greater correlation with the mycorrhizal seedlings drought resistance, being able to be used as the indicators to evaluate the drought resistance of mycorrhizal seedlings.

  11. Evaluation of physiological screening techniques for drought ...

    African Journals Online (AJOL)

    Administrator

    2011-09-26

    Sep 26, 2011 ... ISSN 1684–5315 © 2011 Academic Journals. Full Length ... Canopy temperature depression (CTD) and chlorophyll content (CHL) was used to estimate crop yield .... interested in relative performance since drought stress.

  12. Changes in drought risk with climate change

    International Nuclear Information System (INIS)

    Mullan, B.; Porteous, A.; Wratt, D.; Hollis, M.

    2005-05-01

    As human activity adds more greenhouse gases to the atmosphere, most climate change scenarios predict rising temperatures and decreased rainfall in the east of New Zealand. This means eastern parts of the country are expected to experience more droughts as the 21st century goes on. Our report seeks for the first time to define the possible range of changes in future drought risk. This report was commissioned because of the importance of drought for agriculture and water resources. The report aims to give central and local government and the agriculture sector an indication of how big future drought changes could be in the various regions. This information can be relevant in managing long-term water resources and land use, including planning for irrigation schemes.

  13. Physiological and molecular insights into drought tolerance ...

    African Journals Online (AJOL)

    Physiological and molecular insights into drought tolerance. Sagadevan G Mundree, Bienyameen Baker, Shaheen Mowla, Shaun Peters, Saberi Marais, Clare Vander Willigen, Kershini Govender, Alice Maredza, Samson Muyanga, Jill M Farrant, Jennifer A Thomson ...

  14. heritability analysis of putative drought adaptation traits

    African Journals Online (AJOL)

    ACSS

    2014-02-11

    Feb 11, 2014 ... College of Agricultural and Environmental Sciences, School of Agricultural ... effects is most appropriate for drought tolerance improvement in sweetpotato. ..... GCA, SCA mean squares and heritability values for the various ...

  15. Brief communication: Drought likelihood for East Africa

    Science.gov (United States)

    Yang, Hui; Huntingford, Chris

    2018-02-01

    The East Africa drought in autumn of year 2016 caused malnutrition, illness and death. Close to 16 million people across Somalia, Ethiopia and Kenya needed food, water and medical assistance. Many factors influence drought stress and response. However, inevitably the following question is asked: are elevated greenhouse gas concentrations altering extreme rainfall deficit frequency? We investigate this with general circulation models (GCMs). After GCM bias correction to match the climatological mean of the CHIRPS data-based rainfall product, climate models project small decreases in probability of drought with the same (or worse) severity as 2016 ASO (August to October) East African event. This is by the end of the 21st century compared to the probabilities for present day. However, when further adjusting the climatological variability of GCMs to also match CHIRPS data, by additionally bias-correcting for variance, then the probability of drought occurrence will increase slightly over the same period.

  16. Global Drought Hazard Frequency and Distribution

    Data.gov (United States)

    National Aeronautics and Space Administration — Global Drought Hazard Frequency and Distribution is a 2.5 minute grid based upon the International Research Institute for Climate Prediction's (IRI) Weighted Anomaly...

  17. Brief communication: Drought likelihood for East Africa

    Directory of Open Access Journals (Sweden)

    H. Yang

    2018-02-01

    Full Text Available The East Africa drought in autumn of year 2016 caused malnutrition, illness and death. Close to 16 million people across Somalia, Ethiopia and Kenya needed food, water and medical assistance. Many factors influence drought stress and response. However, inevitably the following question is asked: are elevated greenhouse gas concentrations altering extreme rainfall deficit frequency? We investigate this with general circulation models (GCMs. After GCM bias correction to match the climatological mean of the CHIRPS data-based rainfall product, climate models project small decreases in probability of drought with the same (or worse severity as 2016 ASO (August to October East African event. This is by the end of the 21st century compared to the probabilities for present day. However, when further adjusting the climatological variability of GCMs to also match CHIRPS data, by additionally bias-correcting for variance, then the probability of drought occurrence will increase slightly over the same period.

  18. Oak Forest Responses to Episodic-Seasonal-Drought, Chronic Multi-year Precipitation Change and Acute Drought Manipulations in a Region With Deep Soils and High Precipitation

    Science.gov (United States)

    Hanson, Paul J.; Wullschleger, Stan D.; Todd, Donald E.; Auge, Robert M.; Froberg, Mats; Johnson, Dale W.

    2010-05-01

    Implications of episodic-seasonal drought (extremely dry late summers), chronic multi-year precipitation manipulations (±33 percent over 12 years) and acute drought (-100 percent over 3 years) were evaluated for the response of vegetation and biogeochemical cycles for an upland-oak forest. The Quercus-Acer forest is located in eastern Tennessee on deep acidic soils with mean annual temperatures of 14.2 °C and abundant precipitation (1352 mm y-1). The multi-year observations and chronic manipulations were conducted from 1993 through 2005 using understory throughfall collection troughs and redistribution gutters and pipes. Acute manipulations of dominant canopy trees (Quercus prinus; Liriodendron tulipifera) were conducted from 2003 through 2005 using full understory tents. Regional and severe late-summer droughts were produced reduced stand water use and photosynthetic carbon gain as expected. Likewise, seedlings and saplings exhibited reduced survival and cumulative growth reductions. Conversely, multi-year chronic increases or decreases in precipitation and associated soil water deficits did not reduce large tree basal area growth for the tree species present. The resilience of canopy trees to chronic-change was the result of a disconnect between carbon allocation to tree growth (an early-season phenomenon) and late-season drought occurrence. Acute precipitation exclusion from the largest canopy trees also produced limited physiological responses and minimal cumulative growth reductions. Lateral root water sources were removed through trenching and could not explain the lack of response to extreme soil drying. Therefore, deep rooting the primary mechanism for large-tree resilience to severe drought. Extensive trench-based assessments of rooting depth suggested that ‘deep' water supplies were being obtained from limited numbers of deep fine roots. Observations of carbon stocks in organic horizons demonstrated accumulation with precipitation reductions and

  19. Record dry summer in 2015 challenges precipitation projections in Central Europe

    Science.gov (United States)

    Orth, René; Zscheischler, Jakob; Seneviratne, Sonia I.

    2016-06-01

    Central Europe was characterized by a humid-temperate climate in the 20th century. Climate change projections suggest that climate in this area will shift towards warmer temperatures by the end of the 21st century, while projected precipitation changes are highly uncertain. Here we show that the 2015 summer rainfall was the lowest on record since 1901 in Central Europe, and that climate models that perform best in the three driest years of the historical time period 1901-2015 project stronger drying trends in the 21st century than models that perform best in the remaining years. Analyses of precipitation and derived soil moisture reveal that the 2015 event was drier than both the recent 2003 or 2010 extreme summers in Central Europe. Additionally there are large anomalies in satellite-derived vegetation greenness. In terms of precipitation and temperature anomalies, the 2015 summer in Central Europe is found to lie between historical climate in the region and that characteristic of the Mediterranean area. Even though the models best capturing past droughts are not necessarily generally more reliable in the future, the 2015 drought event illustrates that potential future drying trends have severe implications and could be stronger than commonly assumed from the entire IPCC AR5 model ensemble.

  20. Drought effects on ecosystem functioning and interactions with CO2 and warming - results from CLIMAITE

    Science.gov (United States)

    Beier, Claus; Ibrom, Andreas; Linden, Leon G.; Selsted, Merete B.; Albert, Kristian R.; Kongstad, Jane; Andresen, Louise C.

    2010-05-01

    Current predictions indicate that, unless greenhouse gas emissions are significantly curtailed, atmospheric CO2 concentrations will double during the present century inducing an additional 1.4 to 5.8oC increase in mean global temperature, alterations in global and regional precipitation patterns, and increase the frequency and magnitude of severe weather events (e.g. droughts and floods). Such changes will have strong effects on the terrestrial ecosystems as CO2, temperature and water are main drivers in ecosystem processes. There is growing concern that climate driven changes in precipitation patterns and water availability will have significant effects on ecosystem processes and functioning, and in some regions may be the most influential climate change factor. Yet, it has received much less attention in recent climate change research relative to elevated CO2 and temperature. Furthermore, most precipitation experiments have focussed on water alone despite the fact that at least CO2 and temperature will change simultaneously and both of these factors will have direct or indirect effects on water status and use in the ecosystem. In the CLIMAITE project a Danish heathland has been exposed since 2005 to elevated CO2, temperature and extended drought in a full factorial experiment (Mikkelsen et al., 2008). The CO2 concentration in the canopy level is elevated by 50% by the Free Air Carbon Enrichment (FACE) technique, temperature is elevated by 1-2 °C by the passive night time warming technique and summer drought is extended for 4-6 weeks by rain out shelters. The full factor combination mimics recent climate projections for Denmark 2075. Following the experiments, responses of major ecosystem processes and functioning is recorded. Drought generally leads to hypothesised reductions in most ecosystem processes during and shortly after the drought but on the short term, many of these processes also show a strong potential to recover during rewetting. Drought reduces

  1. Identification of the influencing factors on groundwater drought in Bangladesh

    Science.gov (United States)

    Touhidul Mustafa, Syed Md.; Huysmans, Marijke

    2015-04-01

    Groundwater drought is a specific type of drought that concerns groundwater bodies. It may have a significant adverse effect on the socio-economic, agricultural, and environmental conditions. Investigating the effect of response different climatic and manmade factors on groundwater drought provides essential information for sustainable planning and management of water resources. The aim of this study is to identify the influencing factors on groundwater drought in a drought prone region in Bangladesh to understand the forcing mechanisms. The Standardised Precipitation Index (SPI) and Reconnaissance Drought Index (RDI) have been used to quantify the aggregated deficit between precipitation and the evaporative demand of the atmosphere. The influence of land use patterns on the groundwater drought has been identified by calculating spatially distributed groundwater recharge as a function of land use. The result shows that drought intensity is more severe during the dry season (November to April) compared to the rainy season (May to October). The evapotranspiration and rainfall deficit has a significant effect on meteorological drought which has a direct relation with groundwater drought. Urbanization results in a decrease of groundwater recharge which increases groundwater drought severity. Overexploitation of groundwater for irrigation and recurrent meteorological droughts are the main causes of groundwater drought in the study area. Efficient irrigation management is essential to reduce the growing pressure on groundwater resources and ensure sustainable water management. More detailed studies on climate change and land use change effects on groundwater drought are recommended. Keywords: Groundwater drought, SPI & RDI, Spatially distributed groundwater recharge, Irrigation, Bangladesh

  2. The Temporospatial Variations and Propagation of Drought in China

    Science.gov (United States)

    Ma, F.; Ye, A.; Luo, L.; Duan, Q.

    2017-12-01

    Drought monitoring and forecasting system is a crucial component of drought preparedness. However, under the changing environment, the hydro-climate presents non-stationarity due to climate change and anthropogenic activities, which brings great challenges for drought forecasts. This study investigates the temporospatial characteristics and propagation of different types of droughts from 1961 to 2016 in China. Standardized Precipitation Index (SPI), Standardized Soil Moisture Index (SSMI) and Standardized Streamflow Index (SSI) are used to characterize meteorological, agricultural and hydrological droughts, respectively. The soil moisture and streamflow datasets are obtained from simulations by the distributed time-variant gain model (DTVGM) hydrological model, which has been calibrated and validated in China. The spatial patterns of drought frequency and severity, and temporal characteristics of drought coverage, drought duration and drought intensity are investigated. The cross wavelet analysis is used to examine the correlations between meteorological, agricultural and hydrological droughts. The study also explores how different types of droughts are linked and how one drought morphs into another through time. The findings on temporospatial variations and propagation of drought will provide better understanding on drought development to be helpful for improvement of drought monitoring and forecasting.

  3. Anomalous summer climate in China influenced by the tropical Indo-Pacific Oceans

    Energy Technology Data Exchange (ETDEWEB)

    Weng, Hengyi; Wu, Guoxiong; Liu, Yimin [Chinese Academy of Sciences, LASG, Institute of Atmospheric Physics, Beijing (China); Behera, Swadhin K. [Application Laboratory, JAMSTEC, Yokohama (Japan); Yamagata, Toshio [Application Laboratory, JAMSTEC, Yokohama (Japan); Graduate School of Science, University of Tokyo, Tokyo (Japan)

    2011-02-15

    Possible influences of three coupled ocean-atmosphere phenomena in the Indo-Pacific Oceans, El Nino, El Nino Modoki and the Indian Ocean Dipole (IOD), on summer climate in China are studied based on data analysis for the summers of 1951-2007. Partial correlation/regression analysis is used to find the influence paths through the related anomalous mid- and low-level tropospheric circulations over the oceanic region and East Eurasia, including the western North Pacific summer monsoon (WNPSM). Among the three phenomena, El Nino Modoki has the strongest relationship with the WNPSM. When two or three phenomena coexist with either positive or negative phase, the influences exerted by one phenomenon on summer climate in different regions of China may be enhanced or weakened by other phenomena. In 1994 when both El Nino Modoki and IOD are prominent without El Nino, a strong WNPSM is associated with severe flooding in southern China and severe drought in the Yangtze River Valley (YRV). The 500 hPa high systems over China are responsible for heat waves in most parts of China. In 1983 when a strong negative phase of El Nino Modoki is accompanied by moderate El Nino and IOD, a weak WNPSM is associated with severe flooding in the YRV and severe drought in southern China. The 500 hPa low systems over China are responsible for the cold summer in the YRV and northeastern China. For rainfall, the influence path seems largely through the low-level tropospheric circulations including the WNPSM. For temperature, the influence path seems largely through the mid-level tropospheric circulations over East Eurasia/western North Pacific Ocean. (orig.)

  4. Abscisic acid metabolite profiling as indicators of plastic responses to drought in grasses from arid Patagonian Monte (Argentina).

    Science.gov (United States)

    Cenzano, Ana M; Masciarelli, O; Luna, M Virginia

    2014-10-01

    The identification of hormonal and biochemical traits that play functional roles in the adaptation to drought is necessary for the conservation and planning of rangeland management. The aim of this study was to evaluate the effects of drought on i) the water content (WC) of different plant organs, ii) the endogenous level of abscisic acid (ABA) and metabolites (phaseic acid-PA, dihydrophaseic acid-DPA and abscisic acid conjugated with glucose ester-ABA-GE), iii) the total carotenoid concentration and iv) to compare the traits of two desert perennial grasses (Pappostipa speciosa and Poa ligularis) with contrasting morphological and functional drought resistance traits and life-history strategies. Both species were subjected to two levels of gravimetric soil moisture (the highest near field capacity during autumn-winter and the lowest corresponding to summer drought). Drought significantly increased the ABA and DPA levels in the green leaves of P. speciosa and P. ligularis. Drought decreased ABA in the roots of P. speciosa while it increased ABA in the roots of P. ligularis. P. ligularis had the highest ABA level and WC in green leaves. While P. speciosa had the highest DPA levels in leaves. In conclusion, we found the highest ABA level in the mesophytic species P. ligularis and the lowest ABA level in the xerophytic species P. speciosa, revealing that the ABA metabolite profile in each grass species is a plastic response to drought resistance. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  5. Belowground Carbon Allocation and Plant-Microbial Interactions Drive Resistance and Resilience of Mountain Grassland Communities to Drought

    Science.gov (United States)

    Karlowsky, S.; Augusti, A.; Ingrisch, J.; Hasibeder, R.; Lavorel, S.; Bahn, M.; Gleixner, G.

    2016-12-01

    Belowground carbon allocation (BCA) and plant-microbial interactions are crucial for the functioning of terrestrial ecosystems. Recent research suggests that extreme events can have severe effects on these processes but it is unknown how land use intensity potentially modifies their responses. We studied the resistance and resilience of mountain grassland communities to prolonged drought and investigated the role of plant C allocation and soil microbial communities in mediating drought resistance and immediate recovery. In a common garden experiment we exposed monoliths from an abandoned grassland and a hay meadow to an early summer drought. Two independent 13C pulse labeling experiments were conducted, the first during peak drought and the second during the recovery phase. The 13C incorporation was analyzed in above- and belowground plant parts and in phospho- and neutral lipid fatty acids of soil microorganisms. In addition, a 15N label was added at the rewetting to determine plant N uptake. We found that C uptake, BCA and C transfer to soil microorganisms were less strongly reduced by drought in the abandoned grassland than in the meadow. Moreover, drought induced an increase of arbuscular mycorrhiza fungi (AMF) marker in the abandoned grassland. Nevertheless, C uptake and related parameters were quickly recovered and N uptake increased in the meadow during recovery. Unexpectedly, AMF and their C uptake were generally reduced during recovery, while bacteria increased and quickly recovered C uptake, particularly in the meadow. Our results showed a negative relation between high resistance and fast recovery. The more resistant abandoned grassland plant communities seemed to invest more C below ground and into interactions with AMF during drought, likely to access water through their hyphal network. Conversely, meadow communities invested more C from recent photosynthesis into bacterial communities during recovery, obviously to gain more nutrients for regrowth

  6. Assessment of groundwater response to droughts in a complex runoff-dominated watershed by using an integrated hydrologic model

    Science.gov (United States)

    Woolfenden, L. R.; Hevesi, J. A.; Nishikawa, T.

    2014-12-01

    Groundwater is an important component of the water supply, especially during droughts, within the Santa Rosa Plain watershed (SRPW), California, USA. The SRPW is 680 km2 and includes a network of natural and engineered stream channels. Streamflow is strongly seasonal, with high winter flows, predominantly intermittent summer flows, and comparatively rapid response time to larger storms. Groundwater flow is influenced primarily by complex geology, spatial and temporal variation in recharge, and pumping for urban, agricultural, and rural demands. Results from an integrated hydrologic model (GSFLOW) for the SRPW were analyzed to assess the effect of droughts on groundwater resources during water years 1976-2010. Model results indicate that, in general, below-average precipitation during historical drought periods reduced groundwater recharge (focused within stream channels and diffuse outside of channels on alluvial plains), groundwater evapotranspiration (ET), and groundwater discharge to streams (baseflow). In addition, recharge during wet periods was not sufficient to replenish groundwater-storage losses caused by drought and groundwater pumping, resulting in an overall 150 gigaliter loss in groundwater storage for water years 1976-2010. During drought periods, lower groundwater levels from reduced recharge broadly increased the number and length of losing-stream reaches, and seepage losses in streams became a higher percentage of recharge relative to the diffuse recharge outside of stream channels (for example, seepage losses in streams were 36% of recharge in 2006 and 57% at the end of the 2007-09 drought). Reductions in groundwater storage during drought periods resulted in decreased groundwater ET (loss of riparian habitat) and baseflow, especially during the warmer and dryer months (May through September) when groundwater is the dominant component of streamflow.

  7. Predicting above normal wildfire activity in southern Europe as a function of meteorological drought

    International Nuclear Information System (INIS)

    Gudmundsson, L; Seneviratne, S I; Rego, F C; Rocha, M

    2014-01-01

    Wildfires are a recurrent feature of ecosystems in southern Europe, regularly causing large ecological and socio-economic damages. For efficient management of this hazard, long lead time forecasts could be valuable tools. Using logistic regression, we show that the probability of above normal summer wildfire activity in the 1985–2010 time period can be forecasted as a function of meteorological drought with significant predictability (p <0.05) several months in advance. The results show that long lead time forecasts of this natural hazard are feasible in southern Europe, which could potentially aid decision-makers in the design of strategies for forest management. (letter)

  8. A Look into the National Drought Mitigation Center: Providing 15 Years of Drought Services (Invited)

    Science.gov (United States)

    Svoboda, M. D.; Hayes, M. J.; Knutson, C. L.; Wardlow, B. D.

    2009-12-01

    The National Drought Mitigation Center (NDMC) was formed in 1995 at the University of Nebraska-Lincoln. Over the past 15 years, the NDMC has made it a priority to work with various local, state, tribal and federal entities to provide a suite of drought/climate services, with a goal of bringing research to fruition through applications and operations. Through our research and outreach projects, the NDMC has worked to reduce risk to drought by developing several mitigation strategies, monitoring and decision making tools and other services aimed at enhancing our nation’s capacity to cope with drought. Two of the earliest NDMC activities were the creation of a website and assessing drought conditions around the United States. An electronic drought clearinghouse was built in 1995 at drought.unl.edu. The site was designed, and still concentrates, on the concepts of drought monitoring, planning, and mitigation and also serves as a repository of information from around the world. The NDMC’s electronic quarterly newsletter, DroughtScape, disseminates information about all things drought to people across the country. In addition, the NDMC has developed and is home to websites for the U.S. Drought Monitor (USDM), Drought Impact Reporter (DIR), and the Vegetation Drought Response Index (VegDRI). In an effort to inform decision makers, the NDMC continually pursues ways to raise the awareness and visibility of drought as one of the most costly hazards we face. This began in the mid-1990s with the creation of a state-based drought impact assessment map that would help lead to the formation of the USDM in 1999 and the DIR in 2005. The NDMC plays a key role in producing the weekly USDM and the monthly North American Drought Monitor (NADM). The USDM was created out of collaborations between the NDMC, United States Department of Agriculture (USDA) and National Oceanic and Atmospheric Administration (NOAA) and has quickly become one of the most widely used products in assessing

  9. Enhanced growth of Juniperus thurifera under a warmer climate is explained by a positive carbon gain under cold and drought.

    Science.gov (United States)

    Gimeno, Teresa E; Camarero, J Julio; Granda, Elena; Pías, Beatriz; Valladares, Fernando

    2012-03-01

    Juniperus thurifera L. is an endemic conifer of the western Mediterranean Basin where it is subjected to a severe climatic stress characterized by low winter temperatures and summer drought. Given the trend of increased warming-induced drought stress in this area and the climatic sensitivity of this species, we expect a negative impact of climate change on growth and ecophysiological performance of J. thurifera in the harsh environments where it dominates. To evaluate this, we measured long- and short-term radial growth using dendrochronology, photosynthesis and water-use efficiency in males, females and juveniles in three sites in Central Spain. Climate was monitored and completed with historical records. Mean annual temperature has increased +0.2 °C per decade in the study area, and the main warming trends corresponded to spring (+0.2 °C per decade) and summer (+0.3 °C per decade). Radial growth and maximum photosynthesis peaked in spring and autumn. Positive photosynthetic rates were maintained all year long, albeit at reduced rates in winter and summer. Radial growth was enhanced by wet conditions in the previous autumn and by warm springs and high precipitation in summer of the year of tree-ring formation. Cloud cover during the summer increased growth, while cloudy winters led to impaired carbon gain and reduced growth in the long term. We argue that maintenance of carbon gain under harsh conditions (low winter temperatures and dry summer months) and plastic xylogenesis underlie J. thurifera's ability to profit from changing climatic conditions such as earlier spring onset and erratic summer rainfall. Our results highlight that not only the magnitude but also the sign of the impact of climate change on growth and persistence of Mediterranean trees is species specific.

  10. Earthworms accumulate alanine in response to drought.

    Science.gov (United States)

    Holmstrup, Martin; Slotsbo, Stine; Henriksen, Per G; Bayley, Mark

    2016-09-01

    Earthworms have ecologically significant functions in tropical and temperate ecosystems and it is therefore important to understand how these animals survive during drought. In order to explore the physiological responses to dry conditions, we simulated a natural drought incident in a laboratory trial exposing worms in slowly drying soil for about one month, and then analyzed the whole-body contents of free amino acids (FAAs). We investigated three species forming estivation chambers when soils dry out (Aporrectodea tuberculata, Aporrectodea icterica and Aporrectodea longa) and one species that does not estivate during drought (Lumbricus rubellus). Worms subjected to drought conditions (alanine that was significantly upregulated in all tested species. Alanine was the most important FAA reaching 250-650μmolg(-1) dry weight in dehydrated Aporrectodea species and 300μmolg(-1) dry weight in L. rubellus. Proline was only weakly upregulated in some species as were a few other FAAs. Species forming estivation chambers (Aporrectodea spp.) did not show a better ability to conserve body water than the non-estivating species (L. rubellus) at the same drought level. These results suggest that the accumulation of alanine is an important adaptive trait in drought tolerance of earthworms in general. Copyright © 2016 Elsevier Inc. All rights reserved.

  11. Summer Camp July 2017 - Registration

    CERN Multimedia

    EVE et École

    2017-01-01

    The CERN Staff Association’s Summer Camp will be open for children from 4 to 6 years old during four weeks, from 3 to 28 July. Registration is offered on a weekly basis for 450 CHF, lunch included. This year, the various activities will revolve around the theme of the Four Elements. Registration opened on 20 March 2017 for children currently attending the EVE and School of the Association. It will be open from 3 April for children of CERN Members of Personnel, and starting from 24 April for all other children. The general conditions are available on the website of the EVE and School of CERN Staff Association: http://nurseryschool.web.cern.ch. For further questions, please contact us by email at Summer.Camp@cern.ch.

  12. National Nuclear Physics Summer School

    CERN Document Server

    2016-01-01

    The 2016 National Nuclear Physics Summer School (NNPSS) will be held from Monday July 18 through Friday July 29, 2016, at the Massachusetts Institute of Technology (MIT). The summer school is open to graduate students and postdocs within a few years of their PhD (on either side) with a strong interest in experimental and theoretical nuclear physics. The program will include the following speakers: Accelerators and Detectors - Elke-Caroline Aschenauer, Brookhaven National Laboratory Data Analysis - Michael Williams, MIT Double Beta Decay - Lindley Winslow, MIT Electron-Ion Collider - Abhay Deshpande, Stony Brook University Fundamental Symmetries - Vincenzo Cirigliano, Los Alamos National Laboratory Hadronic Spectroscopy - Matthew Shepherd, Indiana University Hadronic Structure - Jianwei Qiu, Brookhaven National Laboratory Hot Dense Nuclear Matter 1 - Jamie Nagle, Colorado University Hot Dense Nuclear Matter 2 - Wilke van der Schee, MIT Lattice QCD - Sinead Ryan, Trinity College Dublin Neutrino Theory - Cecil...

  13. Summer Mini Atomiade June 2016

    CERN Multimedia

    Staff Association

    2016-01-01

    The Mini Atomiade are coming to CERN! Members of Clubs supported by the CERN Staff Association and in conjunction with ASCERI (Association of the Sports Communities of the European Research Institutes) will be organising the summer games at the beginning of June. ASCERI aims to contribute to a united Europe through regular sports meetings, bringing together members of public Research Institutes at European level. The Association's members come from over 40 Research Institutes spanning 16 countries. Numerous sports and leisure activities are represented at regular events and each tournament is organised by a different research institute. Clubs in conjunction with the CERN Staff Association have sent teams to previous winter and summer games and now, the CERN Club’s Coordination Committee (CCC) has now taken on the challenge of organising a Mini Atomiade from Friday June 3rd to Monday June 6th 2016 in Divonne-les-Bains. The games are made up of four different tournaments/competitions: Small Fi...

  14. The influence of drought on flow‐ecology relationships in Ozark Highland streams

    Science.gov (United States)

    Lynch, Dustin T.; Leasure, D. R.; Magoulick, Daniel D.

    2018-01-01

    Drought and summer drying can have strong effects on abiotic and biotic components of stream ecosystems. Environmental flow‐ecology relationships may be affected by drought and drying, adding further uncertainty to the already complex interaction of flow with other environmental variables, including geomorphology and water quality.Environment–ecology relationships in stream communities in Ozark Highland streams, USA, were examined over two years with contrasting environmental conditions, a drought year (2012) and a flood year (2013). We analysed fish, crayfish and benthic macroinvertebrate assemblages using two different approaches: (1) a multiple regression analysis incorporating predictor variables related to habitat, water quality, geomorphology and hydrology and (2) a canonical ordination procedure using only hydrologic variables in which forward selection was used to select predictors that were most related to our response variables.Reach‐scale habitat quality and geomorphology were found to be the most important influences on community structure, but hydrology was also important, particularly during the flood year. We also found substantial between‐year variation in environment–ecology relationships. Some ecological responses differed significantly between drought and flood years, while others remained consistent. We found that magnitude was the most important flow component overall, but that there was a shift in relative importance from low flow metrics during the drought year to average flow metrics during the flood year, and the specific metrics of importance varied markedly between assemblages and years.Findings suggest that understanding temporal variation in flow‐ecology relationships may be crucial for resource planning. While some relationships show temporal variation, others are consistent between years. Additionally, different kinds of hydrologic variables can differ greatly in terms of which assemblages they affect and how they affect

  15. Drought, Fire and Insects in Western US Forests: Observations to Improve Regional Land System Modeling

    Science.gov (United States)

    Law, B. E.; Yang, Z.; Berner, L. T.; Hicke, J. A.; Buotte, P.; Hudiburg, T. W.

    2015-12-01

    Drought, fire and insects are major disturbances in the western US, and conditions are expected to get warmer and drier in the future. We combine multi-scale observations and modeling with CLM4.5 to examine the effects of these disturbances on forests in the western US. We modified the Community Land Model, CLM4.5, to improve simulated drought-related mortality in forests, and prediction of insect outbreaks under future climate conditions. We examined differences in plant traits that represent species variation in sensitivity to drought, and redefined plant groupings in PFTs. Plant traits, including sapwood area: leaf area ratio and stemwood density were strongly correlated with water availability during the ecohydrologic year. Our database of co-located observations of traits for 30 tree species was used to produce parameterization of the model by species groupings according to similar traits. Burn area predicted by the new fire model in CLM4.5 compares well with recent years of GFED data, but has a positive bias compared with Landsat-based MTBS. Biomass mortality over recent decades increased, and was captured well by the model in general, but missed mortality trends of some species. Comparisons with AmeriFlux data showed that the model with dynamic tree mortality only (no species trait improvements) overestimated GPP in dry years compared with flux data at semi-arid sites, and underestimated GPP at more mesic sites that experience dry summers. Simulations with both dynamic tree mortality and species trait parameters improved estimates of GPP by 17-22%; differences between predicted and observed NEE were larger. Future projections show higher productivity from increased atmospheric CO2 and warming that somewhat offsets drought and fire effects over the next few decades. Challenges include representation of hydraulic failure in models, and availability of species trait and carbon/water process data in disturbance- and drought-impacted regions.

  16. Perception of the drought hazard on the Great Plains and its sociological impacts

    Science.gov (United States)

    Woudenberg, Donna Louise

    Drought, a defining characteristic of the Great Plains, continues to be one of the most expensive natural disasters in the United States, with the lion's share of financial losses shouldered by crop and livestock producers. These producer's perceptions of and responses to drought were studied in the mid-1960s, the mid-1980s, and were examined again in this study, providing valuable longitudinal data. A number of direct and indirect impacts are experienced by non-farm businesses, communities, and individuals, as well. Some of those impacts have not been well researched and were integral to this project. Interviews with crop producers, livestock producers, and community members were conducted in Frontier County, Nebraska in late summer 2006. It was found that producers are very perceptive of the drought hazard, a result found in the two previous studies; recollections and estimates were well supported with 100 years of SPI and PDSI values. Adoption of drought mitigation practices has increased over the past 40 years. Producers were concerned about the myriad of factors they must consider when planning their farm/ranch operations, particularly as they are trying to adjust to water restrictions imposed as an outcome of the Kansas-Nebraska lawsuit on the Republican River (a task exacerbated by the long-term drought in recent years), but overall they are basically optimistic. Community members were very concerned about the future of farming and the quality of rural life. They expressed fears that changes in farming practices may lower the value of land, affect the tax base, and ultimately impact the school system and other county services.

  17. Film repeats in radiology department

    International Nuclear Information System (INIS)

    Suwan, A. Z.; Al-Shakharah, A. I

    1997-01-01

    During a one year period, 4910 radiographs of 55780 films were repeated. The objective of our study was to analyse and to classify the causes in order to minimize the repeats, cut the expenses and to provide optimal radiographs for accurate diagnosis. Analysis of the different factors revealed that, 43.6% of film repeats in our service were due to faults in exposure factors, centering comprises 15.9% of the repeats, while too much collimation was responsible for 7.6% of these repeats. All of which can be decreased by awareness and programmed training of technicians. Film blurring caused by patient motion was also responsible for 4.9% for radiographs reexamination, which can be minimized by detailed explanation to the patient and providing the necessary privacy. Fogging of X-Ray films by improper storage or inadequate handling or processing faults were responsible for 14.5% in repeats in our study. Methods and criteria for proper storage and handling of films were discussed. Recommendation for using modern day-light and laser processor has been high lighted. Artefacts are noticeably high in our cases, due to spinal dresses and frequent usage of precious metals for c osmotic purposes in this part of the world. The repeated films comprise 8.8% of all films We conclude that, the main factor responsible for repeats of up to 81.6% of cases was the technologists, thus emphasizing the importance of adequate training of the technologists. (authors). 15 refs., 9 figs., 1 table

  18. Nifty Nines and Repeating Decimals

    Science.gov (United States)

    Brown, Scott A.

    2016-01-01

    The traditional technique for converting repeating decimals to common fractions can be found in nearly every algebra textbook that has been published, as well as in many precalculus texts. However, students generally encounter repeating decimal numerals earlier than high school when they study rational numbers in prealgebra classes. Therefore, how…

  19. Repeated Prescribed Burning in Aspen

    Science.gov (United States)

    Donald A. Perala

    1974-01-01

    Infrequent burning weather, low flammability of the aspen-hardwood association, and prolific sprouting and seeding of shrubs and hardwoods made repeated dormant season burning a poor tool to convert good site aspen to conifers. Repeat fall burns for wildlife habitat maintenance is workable if species composition changes are not important.

  20. SNOWMASS (DPF Community Summer Study)

    Energy Technology Data Exchange (ETDEWEB)

    Cronin-Hennessy, et al, Daniel

    2013-08-06

    The 2013 Community Summer Study, known as Snowmass," brought together nearly 700 physicists to identify the critical research directions for the United States particle physics program. Commissioned by the American Physical Society, this meeting was the culmination of intense work over the past year by more than 1000 physicists that defined the most important questions for this field and identified the most promising opportunities to address them. This Snowmass study report is a key resource for setting priorities in particle physics.

  1. Artists Paint ... Summer: Grade 2

    Science.gov (United States)

    Herberholz, Barbara

    2012-01-01

    A humid summer haze covers the River Seine and the grassy bank where young men and boys go swimming on Sunday. Everything seems so quiet, still, and very hot. They wear hats to protect them from the hot sun. The artist Georges Seurat used warm tones to give viewers the feeling of the hot sun. Seurat was trying to catch the dazzle of hot sunlight…

  2. Tropical influence on boreal summer mid-latitude stationary waves

    Energy Technology Data Exchange (ETDEWEB)

    Douville, Herve [Meteo-France/CNRM-GAME, Toulouse (France); CNRM/GMGEC/VDR, Toulouse (France); Bielli, S.; Deque, M.; Tyteca, S.; Voldoire, A. [Meteo-France/CNRM-GAME, Toulouse (France); Cassou, C. [CNRS-Cerfacs, Toulouse (France); Hall, N.M.J. [CNES/LEGOS, Toulouse (France)

    2011-11-15

    and suggest a weak influence of prescribed observed SST in the northern extratropics. Results therefore indicate that improving the tropical divergent circulation and its response to tropical SST anomalies remains a key issue for increasing the skill of extratropical seasonal predictions, not only in the winter hemisphere but also in the boreal summer hemisphere where the prediction of heatwave and drought likelihood is expected to become an important challenge with increasing concentrations of greenhouse gases. (orig.)

  3. Drought timing and local climate determine the sensitivity of eastern temperate forests to drought.

    Science.gov (United States)

    D'Orangeville, Loïc; Maxwell, Justin; Kneeshaw, Daniel; Pederson, Neil; Duchesne, Louis; Logan, Travis; Houle, Daniel; Arseneault, Dominique; Beier, Colin M; Bishop, Daniel A; Druckenbrod, Daniel; Fraver, Shawn; Girard, François; Halman, Joshua; Hansen, Chris; Hart, Justin L; Hartmann, Henrik; Kaye, Margot; Leblanc, David; Manzoni, Stefano; Ouimet, Rock; Rayback, Shelly; Rollinson, Christine R; Phillips, Richard P

    2018-02-20

    Projected changes in temperature and drought regime are likely to reduce carbon (C) storage in forests, thereby amplifying rates of climate change. While such reductions are often presumed to be greatest in semi-arid forests that experience widespread tree mortality, the consequences of drought may also be important in temperate mesic forests of Eastern North America (ENA) if tree growth is significantly curtailed by drought. Investigations of the environmental conditions that determine drought sensitivity are critically needed to accurately predict ecosystem feedbacks to climate change. We matched site factors with the growth responses to drought of 10,753 trees across mesic forests of ENA, representing 24 species and 346 stands, to determine the broad-scale drivers of drought sensitivity for the dominant trees in ENA. Here we show that two factors-the timing of drought, and the atmospheric demand for water (i.e., local potential evapotranspiration; PET)-are stronger drivers of drought sensitivity than soil and stand characteristics. Drought-induced reductions in tree growth were greatest when the droughts occurred during early-season peaks in radial growth, especially for trees growing in the warmest, driest regions (i.e., highest PET). Further, mean species trait values (rooting depth and ψ 50 ) were poor predictors of drought sensitivity, as intraspecific variation in sensitivity was equal to or greater than interspecific variation in 17 of 24 species. From a general circulation model ensemble, we find that future increases in early-season PET may exacerbate these effects, and potentially offset gains in C uptake and storage in ENA owing to other global change factors. © 2018 John Wiley & Sons Ltd.

  4. Towards Improved Understanding of Drought and Drought Impacts from Long Term Earth Observation Records

    Science.gov (United States)

    Champagne, C.; Wang, S.; Liu, J.; Hadwen, T. A.

    2017-12-01

    Drought is a complex natural disaster, which often emerges slowly, but can occur at various time scales and have impacts that are not well understood. Long term observations of drought intensity and frequency are often quantified from precipitation and temperature based indices or modelled estimates of soil water storage. The maturity of satellite based observations has created the potential to enhance the understanding of drought and drought impacts, particularly in regions where traditional data sets are limited by remoteness or inaccessibility, and where drought processes are not well-quantified by models. Long term global satellite data records now provide observations of key hydrological variables, including evaporation modelled from thermal sensors, soil moisture from microwave sensors, ground water from gravity sensors and vegetation condition that can be modelled from optical sensors. This study examined trends in drought frequency, intensity and duration over diverse ecoregions in Canada, including agricultural, grassland, forested and wetland areas. Trends in drought were obtained from the Canadian Drought Monitor as well as meteorological based indices from weather stations, and evaluated against satellite derived information on evaporative stress (Anderson et al. 2011), soil moisture (Champagne et al. 2015), terrestrial water storage (Wang and Li 2016) and vegetation condition (Davidson et al. 2009). Data sets were evaluated to determine differences in how different sensors characterize the hydrology and impacts of drought events from 2003 to 2016. Preliminary results show how different hydrological observations can provide unique information that can tie causes of drought (water shortages resulting from precipitation, lack of moisture storage or evaporative stress) to impacts (vegetation condition) that hold the potential to improve the understanding and classification of drought events.

  5. My Summer with Science Policy

    Science.gov (United States)

    Murray, Marissa

    This past summer I interned at the American Institute of Physics and helped research and write articles for the FYI Science Policy Bulletin. FYI is an objective digest of science policy developments in Washington, D.C. that impact the greater physical sciences community. Over the course of the summer, I independently attended, analyzed, and reported on a variety of science, technology, and funding related events including congressional hearings, government agency advisory committee meetings, and scientific society events. I wrote and co-wrote three articles on basic energy research legislation, the National Institute of Standards and Technology improvement act, and the National Science Foundation's big ideas for future investment. I had the opportunity to examine some challenging questions such as what is the role of government in funding applied research? How should science priorities be set? What is the right balance of funding across different agencies and programs? I learned about how science policy is a two-way street: science is used to inform policy decisions and policy is made to fund and regulate the conduct of science. I will conclude with how my summer working with FYI showed me the importance of science advocacy, being informed, and voting. Society of Physics Students.

  6. Tevatron serial data repeater system

    International Nuclear Information System (INIS)

    Ducar, R.J.

    1981-01-01

    A ten megabit per second serial data repeater system has been developed for the 6.28km Tevatron accelerator. The repeaters are positioned at each of the thirty service buildings and accommodate control and abort system communications as well as distribution of the Tevatron time and energy clocks. The repeaters are transparent to the particular protocol of the transmissions. Serial data are encoded locally as unipolar two volt signals employing the self-clocking Manchester Bi-Phase code. The repeaters modulate the local signals to low-power bursts of 50 MHz rf carrier for the 260m transmission between service buildings. The repeaters also demodulate the transmission and restructure the data for local utilization. The employment of frequency discrimination techniques yields high immunity to the characteristic noise spectrum

  7. All-photonic quantum repeaters

    Science.gov (United States)

    Azuma, Koji; Tamaki, Kiyoshi; Lo, Hoi-Kwong

    2015-01-01

    Quantum communication holds promise for unconditionally secure transmission of secret messages and faithful transfer of unknown quantum states. Photons appear to be the medium of choice for quantum communication. Owing to photon losses, robust quantum communication over long lossy channels requires quantum repeaters. It is widely believed that a necessary and highly demanding requirement for quantum repeaters is the existence of matter quantum memories. Here we show that such a requirement is, in fact, unnecessary by introducing the concept of all-photonic quantum repeaters based on flying qubits. In particular, we present a protocol based on photonic cluster-state machine guns and a loss-tolerant measurement equipped with local high-speed active feedforwards. We show that, with such all-photonic quantum repeaters, the communication efficiency scales polynomially with the channel distance. Our result paves a new route towards quantum repeaters with efficient single-photon sources rather than matter quantum memories. PMID:25873153

  8. Repeatability of visual acuity measurement.

    Science.gov (United States)

    Raasch, T W; Bailey, I L; Bullimore, M A

    1998-05-01

    This study investigates features of visual acuity chart design and acuity testing scoring methods which affect the validity and repeatability of visual acuity measurements. Visual acuity was measured using the Sloan and British Standard letter series, and Landolt rings. Identifiability of the different letters as a function of size was estimated, and expressed in the form of frequency-of-seeing curves. These functions were then used to simulate acuity measurements with a variety of chart designs and scoring criteria. Systematic relationships exist between chart design parameters and acuity score, and acuity score repeatability. In particular, an important feature of a chart, that largely determines the repeatability of visual acuity measurement, is the amount of size change attributed to each letter. The methods used to score visual acuity performance also affect repeatability. It is possible to evaluate acuity score validity and repeatability using the statistical principles discussed here.

  9. Multi-index time series monitoring of drought and fire effects on desert grasslands

    Science.gov (United States)

    Villarreal, Miguel; Norman, Laura M.; Buckley, Steven; Wallace, Cynthia S.A.; Coe, Michelle A.

    2016-01-01

    The Western United States is expected to undergo both extended periods of drought and longer wildfire seasons under forecasted global climate change and it is important to understand how these disturbances will interact and affect recovery and composition of plant communities in the future. In this research paper we describe the temporal response of grassland communities to drought and fire in southern Arizona, where land managers are using repeated, prescribed fire as a habitat restoration tool. Using a 25-year atlas of fire locations, we paired sites with multiple fires to unburned control areas and compare satellite and field-based estimates of vegetation cover over time. Two hundred and fifty Landsat TM images, dating from 1985–2011, were used to derive estimates of Total Vegetation Fractional Cover (TVFC) of live and senescent grass using the Soil-Adjusted Total Vegetation Index (SATVI) and post-fire vegetation greenness using the Normalized Difference Vegetation Index (NDVI). We also implemented a Greenness to Cover Index that is the difference of time-standardized SATVI-TVFC and NDVI values at a given time and location to identify post-fire shifts in native, non-native, and annual plant cover. The results highlight anomalous greening and browning during drought periods related to amounts of annual and non-native plant cover present. Results suggest that aggressive application of prescribed fire may encourage spread of non-native perennial grasses and annual plants, particularly during droughts.

  10. Assessing Ecosystem Drought Response in CLM 4.5 Using Site-Level Flux and Carbon-Isotope Measurements: Results From a Pacific Northwest Coniferous Forest

    Science.gov (United States)

    Duarte, H.; Raczka, B. M.; Koven, C. D.; Ricciuto, D. M.; Lin, J. C.; Bowling, D. R.; Ehleringer, J. R.

    2015-12-01

    The frequency, extent, and severity of droughts are expected to increase in the western United States as climate changes occur. The combination of warmer temperature, larger vapor pressure deficit, reduced snowfall and snow pack, earlier snow melt, and extended growing seasons is expected to lead to an intensification of summer droughts, with a direct impact on ecosystem productivity and therefore on the carbon budget of the region. In this scenario, an accurate representation of ecosystem drought response in land models becomes fundamental, but the task is challenging, especially in regards to stomatal response to drought. In this study we used the most recent release of the Community Land Model (CLM 4.5), which now includes photosynthetic carbon isotope discrimination and revised photosynthesis and hydrology schemes, among an extensive list of updates. We evaluated the model's performance at a coniferous forest site in the Pacific northwest (Wind River AmeriFlux Site), characterized by a climate that has a strong winter precipitation component followed by a summer drought. We ran the model in offline mode (i.e., decoupled from an atmospheric model), forced by observed meteorological data, and used site observations (e.g., surface fluxes, biomass values, and carbon isotope data) to assess the model. Previous field observations indicated a significant negative correlation between soil water content and the carbon isotope ratio of ecosystem respiration (δ13CR), suggesting that δ13CR was closely related to the photosynthetic discrimination against 13CO2 as controlled by stomatal conductance. We used these observations and latent-heat flux measurements to assess the modeled stomatal conductance values and their responses to extended summer drought. We first present the model results, followed by a discussion of potential CLM model improvements in stomatal conductance responses and in the representation of soil water stress (parameter βt) that would more precisely

  11. Drought vulnerability assesssment and mapping in Morocco

    Science.gov (United States)

    Imani, Yasmina; Lahlou, Ouiam; Bennasser Alaoui, Si; Naumann, Gustavo; Barbosa, Paulo; Vogt, Juergen

    2014-05-01

    Drought vulnerability assessment and mapping in Morocco Authors: Yasmina Imani 1, Ouiam Lahlou 1, Si Bennasser Alaoui 1 Paulo Barbosa 2, Jurgen Vogt 2, Gustavo Naumann 2 1: Institut Agronomique et Vétérinaire Hassan II (IAV Hassan II), Rabat Morocco. 2: European Commission, Joint Research Centre (JRC), Institute for Environment and Sustainability (IES), Ispra, Italy. In Morocco, nearly 50% of the population lives in rural areas. They are mostly small subsistent farmers whose production depends almost entirely on rainfall. They are therefore very sensitive to drought episodes that may dramatically affect their incomes. Although, as a consequence of the increasing frequency, length and severity of drought episodes in the late 90's, the Moroccan government decided, to move on from a crisis to a risk management approach, drought management remains in practice mainly reactive and often ineffective. The lack of effectiveness of public policy is in part a consequence of the poor understanding of drought vulnerability at the rural community level, which prevents the development of efficient mitigation actions and adaptation strategies, tailored to the needs and specificities of each rural community. Thus, the aim of this study is to assess and map drought vulnerability at the rural commune level in the Oum Er-Rbia basin which is a very heterogeneous basin, showing a big variability of climates, landscapes, cropping systems and social habits. Agricultural data collected from the provincial and local administrations of Agriculture and socio-economic data from the National Department of Statistics were used to compute a composite vulnerability index (DVI) integrating four different components: (i) the renewable natural capacity, (ii) the economic capacity, (iii) human and civic resources, and (iv) infrastructure and technology. The drought vulnerability maps that were derived from the computation of the DVI shows that except very specific areas, most of the Oum er Rbia

  12. Defining Drought Characteristics for Natural Resource Management

    Science.gov (United States)

    Ojima, D. S.; Senay, G. B.; McNeeley, S.; Morisette, J. T.

    2016-12-01

    In the north central region of the US, on-going drought studies are investigating factors determining how drought impacts various ecosystem services and challenge natural resource management decisions. The effort reported here stems from research sponsored by the USGS North Central Climate Science Center, to deal with ecosystem response to drought with the goal to see if there are indicators of drought emerging from the ecosystem interactions with various weather patterns, soil moisture dynamics, and the structural aspects of the ecosystem in question. The North Central domain covers a region from the headwaters of the Missouri River Basin to the northern Great Plains. Using spatial and temporal analysis of remote sensing products and mechanistic daily time-step ecosystem model simulations across the northern Great Plains and northern Rockies, analysis of recent drought conditions over the region will be provided. Drought characteristics will be analyzed related to resource management targets, such as water supply, landscape productivity, or habitat needs for key species. Analysis of ecosystem and landscape patterns of drought relative to net primary productivity, surface temperatures, soil moisture content, evaporation, transpiration, and water use efficiency from 2000 through 2014 will be analyzed for different drought and non-drought events. Comparisons between satellite-derived ET and NPP of different Great Plains ecosystems related to simulated ET and NPP will be presented. These comparisons provide indications of the role that soil moisture dynamics, groundwater recharge and rooting depth of different ecosystems have on determining the sensitivity to water stress due to seasonal warming and reduced precipitation across the region. In addition, indications that average annual rainfall levels over certain ecosystems may result in reduced production due to higher rates of water demand under the observed warmer temperatures and the prolonged warming in the spring

  13. Close the Achievement Gap with Summer Learning

    Science.gov (United States)

    Huggins, Gary

    2012-01-01

    Summer vacation from school can bring afternoons at the swimming pool, family vacations, and maybe a spirit-filled summer camp that ignites a passion for art or rock climbing. But for many children, summer also means setbacks in learning that take a tremendous toll on teaching and student performance over time. PTA leaders can make a vital…

  14. Finding Funds to Move Summer Learning Forward

    Science.gov (United States)

    Seidel, Bob

    2015-01-01

    Summer learning loss creates a permanent drag on the US education system. With the generous support of the Charles Stewart Mott Foundation, the National Summer Learning Association (NSLA) developed "Moving Summer Learning Forward: A Strategic Roadmap for Funding in Tough Times" to provide out-of-school time programs, school districts,…

  15. GRACE-Assimilated Drought Indicators for the U.S. Drought Monitor

    Science.gov (United States)

    Rui, Hualan; Vollmer, Bruce; Teng, Bill; Loeser, Carlee; Beaudoing, Hiroko; Rodell, Matt

    2018-01-01

    The Gravity Recovery and Climate Experiment (GRACE) mission detects changes in Earth's gravity field by precisely monitoring the changes in distance between two satellites orbiting the Earth in tandem. Scientists at NASA's Goddard Space Flight Center generate GRACE-assimilated groundwater and soil moisture drought indicators each week, for drought monitor-related studies and applications. The GRACE-assimilated Drought Indicator Version 2.0 data product (GRACE-DA-DM V2.0) is archived at, and distributed by, the NASA GES DISC (Goddard Earth Sciences Data and Information Services Center). More information about the data and data access is available on the data product landing page at https://disc.gsfc.nasa.gov/datasets /GRACEDADM_CLSM0125US_7D_2.0/summary. The GRACE-DA-DM V2.0 data product contains three drought indicators: Groundwater Percentile, Root Zone Soil Moisture Percentile, and Surface Soil Moisture Percentile. The drought indicators are of wet or dry conditions, expressed as a percentile, indicating the probability of occurrence within the period of record from 1948 to 2012. These GRACE-assimilated drought indicators, with improved spatial and temporal resolutions, should provide a more comprehensive and objective identification of drought conditions. This presentation describes the basic characteristics of the data and data services at NASA GES DISC and collaborative organizations, and uses a few examples to demonstrate the simple ways to explore the GRACE-assimilated drought indicator data.

  16. Coping with drought risk: empirical analysis of farmers' drought adaption in the south-west Netherlands

    NARCIS (Netherlands)

    van Duinen, Rianne; Filatova, Tatiana; Geurts, Petrus A.T.M.; van der Veen, A.

    2014-01-01

    Climate change projections show that periods of droughts are likely to increase, causing decreasing water availability, salinization, and consequently farm income loss in the south-west Netherlands. Adaptation is the key to decrease a farmer's drought vulnerability and to secure the agricultural

  17. Drought tolerance in potato (S. tuberosum L.): Can we learn from drought tolerance research in cereals?

    Science.gov (United States)

    Monneveux, Philippe; Ramírez, David A; Pino, María-Teresa

    2013-05-01

    Drought tolerance is a complex trait of increasing importance in potato. Our knowledge is summarized concerning drought tolerance and water use efficiency in this crop. We describe the effects of water restriction on physiological characteristics, examine the main traits involved, report the attempts to improve drought tolerance through in vitro screening and marker assisted selection, list the main genes involved and analyze the potential interest of native and wild potatoes to improve drought tolerance. Drought tolerance has received more attention in cereals than in potato. The review compares these crops for indirect selection methods available for assessment of drought tolerance related traits, use of genetic resources, progress in genomics, application of water saving techniques and availability of models to anticipate the effects of climate change on yield. It is concluded that drought tolerance improvement in potato could greatly benefit from the transfer of research achievements in cereals. Several promising research directions are presented, such as the use of fluorescence, reflectance, color and thermal imaging and stable isotope techniques to assess drought tolerance related traits, the application of the partial root-zone drying technique to improve efficiency of water supply and the exploitation of stressful memory to enhance hardiness. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  18. Drought, Climate Change and the Canadian Prairies

    Science.gov (United States)

    Stewart, R. E.

    2010-03-01

    The occurrence of drought is a ubiquitous feature of the global water cycle. Such an extreme does not necessarily lead to an overall change in the magnitude of the global water cycle but it of course affects the regional cycling of water. Droughts are recurring aspects of weather and climate extremes as are floods and tornadoes, but they differ substantially since they have long durations and lack easily identified onsets and terminations. Drought is a relatively common feature of the North American and Canadian climate system and all regions of the continent are affected from time-to-time. However, it tends to be most common and severe over the central regions of the continent. The Canadian Prairies are therefore prone to drought. Droughts in the Canadian Prairies are distinctive in North America. The large scale atmospheric circulations are influenced by blocking from intense orography to the west and long distances from all warm ocean-derived atmospheric water sources; growing season precipitation is generated by a highly complex combination of frontal and convective systems; seasonality is severe and characterized by a relatively long snow-covered and short growing seasons; local surface runoff is primarily produced by snowmelt water; there is substantial water storage potential in the poorly drained, post-glacial topography; and aquifers are overlain by impermeable glacial till, but there are also important permeable aquifers. One example of Prairie drought is the recent one that began in 1999 with cessation of its atmospheric component in 2004/2005 and many of its hydrological components in 2005. This event produced the worst drought for at least a hundred years in parts of the Canadian Prairies. Even in the dust bowl of the 1930s, no single year over the central Prairies were drier than in 2001. The drought affected agriculture, recreation, tourism, health, hydro-electricity, and forestry in the Prairies. Gross Domestic Product fell some 5.8 billion and

  19. Drought impacts on cereal yields in Iberia

    Science.gov (United States)

    Gouveia, Célia; Liberato, Margarida L. R.; Russo, Ana; Montero, Irene

    2014-05-01

    In the present context of climate change, land degradation and desertification it becomes crucial to assess the impact of droughts to determine the environmental consequences of a potential change of climate. Large drought episodes in Iberian Peninsula have widespread ecological and environmental impacts, namely in vegetation dynamics, resulting in significant crop yield losses. During the hydrological years of 2004/2005 and 2011/2012 Iberia was affected by two extreme drought episodes (Garcia-Herrera et al., 2007; Trigo et al., 2013). This work aims to analyze the spatial and temporal behavior of climatic droughts at different time scales using spatially distributed time series of drought indicators, such as the Standardized Precipitation Evapotranspiration Index (SPEI) (Vicente-Serrano et al., 2010). This climatic drought index is based on the simultaneous use of precipitation and temperature. We have used CRU TS3 dataset to compute SPEI and the Standardized Precipitation Index (SPI). Results will be analyzed in terms of the mechanisms that are responsible by these drought events and will also be used to assess the impact of droughts in crops. Accordingly an analysis is performed to evaluate the large-scale conditions required for a particular extreme anomaly of long-range transport of water vapor from the subtropics. We have used the European Centre for Medium-Range Weather Forecasts (ECMWF) ERA Interim reanalyses, namely, the geopotential height fields, temperature, wind, divergence data and the specific humidity at all pressure levels and mean sea level pressure (MSLP) and total column water vapor (TCWV) for the Euro-Atlantic sector (100°W to 50°E, 0°N-70°N) at full temporal (six hourly) and spatial (T255; interpolated to 0.75° regular horizontal grid) resolutions available to analyse the large-scale conditions associated with the drought onset. Our analysis revealed severe impacts on cereals crop productions and yield (namely wheat) for Portugal and

  20. Woody plant richness and NDVI response to drought events in Catalonian (northeastern Spain) forests.

    Science.gov (United States)

    Lloret, F; Lobo, A; Estevan, H; Maisongrande, P; Vayreda, J; Terradas, J

    2007-09-01

    The role of species diversity on ecosystem resistance in the face of strong environmental fluctuations has been addressed from both theoretical and experimental viewpoints to reveal a variety of positive and negative relationships. Here we explore empirically the relationship between the richness of forest woody species and canopy resistance to extreme drought episodes. We compare richness data from an extensive forest inventory to a temporal series of satellite imagery that estimated drought impact on forest canopy as NDVI (normalized difference vegetation index) anomalies of the dry summer in 2003 in relation to records of previous years. We considered five different types of forests that are representative of the main climatic and altitudinal gradients of the region, ranging from lowland Mediterranean to mountain boreal-temperate climates. The observed relationship differed among forest types and interacted with the climate, summarised by the Thorntwaite index. In Mediterranean Pinus halepensis forests, NDVI decreased during the drought. This decrease was stronger in forests with lower richness. In Mediterranean evergreen forests of Quercus ilex, drought did not result in an overall NDVI loss, but lower NDVI values were observed in drier localities with lower richness, and in more moist localities with higher number of species. In mountain Pinus sylvestris forests NDVI decreased, mostly due to the drought impact on drier localities, while no relation to species richness was observed. In moist Fagus sylvatica forests, NDVI only decreased in plots with high richness. No effect of drought was observed in the high mountain Pinus uncinata forests. Our results show that a shift on the diversity-stability relationship appears across the regional, climatic gradient. A positive relationship appears in drier localities, supporting a null model where the probability of finding a species able to cope with drier conditions increases with the number of species. However, in

  1. The Sahel Region of West Africa: Examples of Climate Analyses Motivated By Drought Management Needs

    Science.gov (United States)

    Ndiaye, O.; Ward, M. N.; Siebert, A. B.

    2011-12-01

    The Sahel is one of the most drought-prone regions in the world. This paper focuses on climate sources of drought, and some new analyses mostly driven by users needing climate information to help in drought management strategies. The Sahel region of West Africa is a transition zone between equatorial climate and vegetation to the south, and desert to the north. The climatology of the region is dominated by dry conditions for most of the year, with a single peak in rainfall during boreal summer. The seasonal rainfall total contains both interannual variability and substantial decadal to multidecadal variability (MDV). This brings climate analysis and drought management challenges across this range of timescales. The decline in rainfall from the wet decades of the 1950s and 60s to the dry decades of the 1970s and 80s has been well documented. In recent years, a moderate recovery has emerged, with seasonal totals in the period 1994-2010 significantly higher than the average rainfall 1970-1993. These MDV rainfall fluctuations have expression in large-scale sea-surface temperature fluctuations in all ocean basins, placing the changes in drought frequency within broader ocean-atmosphere climate fluctuation. We have evaluated the changing character of low seasonal rainfall total event frequencies in the Sahel region 1950-2010, highlighting the role of changes in the mean, variance and distribution shape of seasonal rainfall totals as the climate has shifted through the three observed phases. We also consider the extent to which updating climate normals in real-time can damp the bias in expected event frequency, an important issue for the feasibility of index insurance as a drought management tool in the presence of a changing climate. On the interannual timescale, a key factor long discussed for agriculture is the character of rainfall onset. An extended dry spell often occurs early in the rainy season before the crop is fully established, and this often leads to crop

  2. Drought impact on vegetation in pre and post fire events in Iberian Peninsula

    Science.gov (United States)

    Gouveia, C. M.; Bastos, A.; Trigo, R. M.; DaCamara, C.

    2012-04-01

    In 2004/2005, the Iberian Peninsula was stricken by an exceptional drought that affected more than one third of Portugal and part of southern Spain during more than 9 months. This severe drought had a strong negative impact on vegetation dynamics, as it coincided with the period of high photosynthetic activity (Gouveia et al., 2009). Since water availability is a crucial factor in post-fire vegetation recovery, it is desirable to assess the impact that such water-stress conditions had on fire sensitivity and post-fire vegetation recovery. Fire events in the European Mediterranean areas have become a serious problem and a major ecosystem disturbance, increasing erosion and soil degradation. In Portugal, the years 2003 and 2005 were particularly devastating. In 2003 it was registered the maximal burnt area since 1980, with more than 425000 ha burned, representing about 5% of Portuguese mainland. The 2005 fire season registered the highest number of fire occurrences in Portugal and the second year with the greatest number of fires in Spain. The high number of fire events observed during the summer 2005 in the Iberian Peninsula is linked, in part, to the extreme drought conditions that prevailed during the preceding winter and spring seasons of 2004/2005. Vegetation recovery after the 2003 and 2005 fire seasons was estimated using the mono-parametric model developed by Gouveia et al. (2010), which relies on monthly values of Normalized Difference Vegetation Index (NDVI), from 1999 to 2009, at 1kmresolution, as obtained from the VEGETATION-SPOT5 instrument.. This model was further used to evaluate the effect of drought in pre and post vegetation activity. Besides the standard NDVI, the Normalized Difference Water Index (NDWI) and the Normalized Difference Drought Index (NDDI) were computed in order to evaluate drought intensity. In the case of the burnt scars of 2003, when data corresponding to the months of drought are removed, recovery times are considerably shorter

  3. Drought and frost tolerance in rhododendron collection of the Mlyňany Arboretum (Slovakia: a screening for future climate

    Directory of Open Access Journals (Sweden)

    Ferus Peter

    2017-12-01

    Full Text Available Rhododendrons are jewels of the Mlyňany Arboretum, Institute of Forest Ecology of the Slovak Academy of Sciences (IFE SAS. Blossoming in May, they attract thousands of visitors. But recently these woody plants have much suffered from climatic extremes such as summer droughts and winter frosts, associated with the advancing climate change. To assess the rhododendron collection’s stability, its drought and frost injury level were tested in field, in summer 2015 and winter 2017, respectively. The tested parameters were: leaf wilting and electrolyte leakage combined with shrub leaf area, insolation level and overall health state. We found that the drought effect was strong or very strong in only ca. 30% rhododendron species and ca. 10% rhododendron cultivars, and that around 60% shrubs showed no or only moderate symptoms of water deficit. The drought injury level was only associated with the genotype. The most tolerant / sensitive genotypes, commonly occurring in the park, were: R. catawbiense, R. ponticum, R. smirnowii, cv. ‘Boursault’, cv. ‘Cunningham’s White’ and cv. ‘Purpureum Elegans’ / R. fortunei and cv. ‘Tamarindos’. On the other hand, the most frequent response to frost in the observed rhododendron genotypes was moderate injury (28 and 37% for species and cultivars, respectively, nevertheless more than 18% species and almost 6% cultivars exhibited strong frost damage. Despite absence of significant differences in the factor-response between the species, we may suggest this decreasing sequence of the genotypes ordered according to their frost resistance: genotypes: cv. ‘Cunningham’s White’ > R. decorum > R. fortunei and cv. ‘Duke of York’ > R. smirnowii > cvs. ‘Purpureum Elegans’ and ‘Tamarindos’ > R. macrophyllum and cv. ‘Nova Zembla’ > R. catawbiense > R. ponticum. These results have been compared with similar works in rhododendron species/cultivars as well as suggested species drought

  4. Novel Digital Features Discriminate Between Drought Resistant and Drought Sensitive Rice Under Controlled and Field Conditions

    Directory of Open Access Journals (Sweden)

    Lingfeng Duan

    2018-04-01

    Full Text Available Dynamic quantification of drought response is a key issue both for variety selection and for functional genetic study of rice drought resistance. Traditional assessment of drought resistance traits, such as stay-green and leaf-rolling, has utilized manual measurements, that are often subjective, error-prone, poorly quantified and time consuming. To relieve this phenotyping bottleneck, we demonstrate a feasible, robust and non-destructive method that dynamically quantifies response to drought, under both controlled and field conditions. Firstly, RGB images of individual rice plants at different growth points were analyzed to derive 4 features that were influenced by imposition of drought. These include a feature related to the ability to stay green, which we termed greenness plant area ratio (GPAR and 3 shape descriptors [total plant area/bounding rectangle area ratio (TBR, perimeter area ratio (PAR and total plant area/convex hull area ratio (TCR]. Experiments showed that these 4 features were capable of discriminating reliably between drought resistant and drought sensitive accessions, and dynamically quantifying the drought response under controlled conditions across time (at either daily or half hourly time intervals. We compared the 3 shape descriptors and concluded that PAR was more robust and sensitive to leaf-rolling than the other shape descriptors. In addition, PAR and GPAR proved to be effective in quantification of drought response in the field. Moreover, the values obtained in field experiments using the collection of rice varieties were correlated with those derived from pot-based experiments. The general applicability of the algorithms is demonstrated by their ability to probe archival Miscanthus data previously collected on an independent platform. In conclusion, this image-based technology is robust providing a platform-independent tool for quantifying drought response that should be of general utility for breeding and functional

  5. Flooding During Drought: Learning from Stakeholder Engagement & Partner Coordination in the California-Nevada Drought Early Warning System (DEWS)

    Science.gov (United States)

    Sheffield, A. M.

    2017-12-01

    After more than 5 years of drought, extreme precipitation brought drought relief in California and Nevada and presents an opportunity to reflect upon lessons learned while planning for the future. NOAA's National Integrated Drought Information System (NIDIS) California-Nevada Drought Early Warning System (DEWS) in June 2017 convened a regional coordination workshop to provide a forum to discuss and build upon past drought efforts in the region and increase coordination, collaboration and information sharing across the region as a whole. Participants included federal, tribal, state, academic, and local partners who provided a post-mortem on the recent drought and impacts as well as recent innovations in drought monitoring, forecasts, and decision support tools in response to the historic drought. This presentation will highlight lessons learned from stakeholder outreach and engagement around flooding during drought, and pathways for moving forward coordination and collaboration in the region. Additional focus will be on the potential opportunities from examining California decision making calendars from this drought. Identified gaps and challenges will also be shared, such as the need to connect observations with social impacts, capacity building around available tools and resources, and future drought monitoring needs. Drought will continue to impact California and Nevada, and the CA-NV DEWS works to make climate and drought science readily available, easily understandable and usable for decision makers; and to improve the capacity of stakeholders to better monitor, forecast, plan for and cope with the impacts of drought.

  6. Recovery of Physiological Traits in Saplings of Invasive Bischofia Tree Compared with Three Species Native to the Bonin Islands under Successive Drought and Irrigation Cycles.

    Science.gov (United States)

    Yazaki, Kenichi; Kuroda, Katsushi; Nakano, Takashi; Kitao, Mitsutoshi; Tobita, Hiroyuki; Ogasa, Mayumi Y; Ishida, Atsushi

    2015-01-01

    Partial leaf shedding induced by hydraulic failure under prolonged drought can prevent excess water consumption, resulting in delayed recovery of carbon productivity following rainfall. To understand the manner of water use of invasive species in oceanic island forests under a fluctuating water regime, leaf shedding, multiple physiological traits, and the progress of embolism in the stem xylem under repeated drought-irrigation cycles were examined in the potted saplings of an invasive species, Bischofia javanica Blume, and three endemic native species, Schima mertensiana (Sieb. Et Zucc,) Koitz., Hibiscus glaber Matsum, and Distylium lepidotum Nakai, from the Bonin Islands, Japan. The progress of xylem embolism was observed by cryo-scanning electron microscopy. The samples exhibited different processes of water saving and drought tolerance based on the different combinations of partial leaf shedding involved in embolized conduits following repeated de-rehydration. Predawn leaf water potential largely decreased with each successive drought-irrigation cycle for all tree species, except for B. javanica. B. javanica shed leaves conspicuously under drought and showed responsive stomatal conductance to VPD, which contributed to recover leaf gas exchange in the remaining leaves, following a restored water supply. In contrast, native tree species did not completely recover photosynthetic rates during the repeated drought-irrigation cycles. H. glaber and D. lepidotum preserved water in vessels and adjusted leaf osmotic rates but did not actively shed leaves. S. mertensiana exhibited partial leaf shedding during the first cycle with an osmotic adjustment, but they showed less responsive stomatal conductance to VPD. Our data indicate that invasive B. javanica saplings can effectively use water supplied suddenly under drought conditions. We predict that fluctuating precipitation in the future may change tree distributions even in mesic or moist sites in the Bonin Islands.

  7. Recovery of Physiological Traits in Saplings of Invasive Bischofia Tree Compared with Three Species Native to the Bonin Islands under Successive Drought and Irrigation Cycles.

    Directory of Open Access Journals (Sweden)

    Kenichi Yazaki

    Full Text Available Partial leaf shedding induced by hydraulic failure under prolonged drought can prevent excess water consumption, resulting in delayed recovery of carbon productivity following rainfall. To understand the manner of water use of invasive species in oceanic island forests under a fluctuating water regime, leaf shedding, multiple physiological traits, and the progress of embolism in the stem xylem under repeated drought-irrigation cycles were examined in the potted saplings of an invasive species, Bischofia javanica Blume, and three endemic native species, Schima mertensiana (Sieb. Et Zucc, Koitz., Hibiscus glaber Matsum, and Distylium lepidotum Nakai, from the Bonin Islands, Japan. The progress of xylem embolism was observed by cryo-scanning electron microscopy. The samples exhibited different processes of water saving and drought tolerance based on the different combinations of partial leaf shedding involved in embolized conduits following repeated de-rehydration. Predawn leaf water potential largely decreased with each successive drought-irrigation cycle for all tree species, except for B. javanica. B. javanica shed leaves conspicuously under drought and showed responsive stomatal conductance to VPD, which contributed to recover leaf gas exchange in the remaining leaves, following a restored water supply. In contrast, native tree species did not completely recover photosynthetic rates during the repeated drought-irrigation cycles. H. glaber and D. lepidotum preserved water in vessels and adjusted leaf osmotic rates but did not actively shed leaves. S. mertensiana exhibited partial leaf shedding during the first cycle with an osmotic adjustment, but they showed less responsive stomatal conductance to VPD. Our data indicate that invasive B. javanica saplings can effectively use water supplied suddenly under drought conditions. We predict that fluctuating precipitation in the future may change tree distributions even in mesic or moist sites in the

  8. Research summer camp in photonics

    Science.gov (United States)

    Buyanovskaya, Elizaveta; Melnik, Maksim; Egorov, Vladimir; Gleim, Artur; Lukishova, Svetlana; Kozlov, Sergei; Zhang, Xi-Cheng

    2017-08-01

    ITMO University and the University of Rochester became close partners several years ago. One of the first outcomes of this mutually beneficial partnership was the creation of International Institute of Photonics and Optical Information Technologies led by Prof. Sergei Kozlov and Prof. Xi-Cheng Zhang. Universities have created a double Masters-degree program in optics in 2014, and several ITMO students have been awarded degrees from Rochester. At the same time ITMO University organizes Summer Research camp in Photonics for University of Rochester students. Students spent two weeks in the Northern Capital of Russia learning about the emerging practical applications of femtosecond optics, terahertz biomedicine and quantum information technologies.

  9. SAAPMB summer school and congress

    International Nuclear Information System (INIS)

    1990-01-01

    Medical and health physics are greatly stimulated by the exchange of personal experiences and research results among scientists working in their particular fields of interests. Individual contact is of exceptional importance in those rapidly developing areas of high technology which we find in hospitals and industry and therefor the social exchange of ideas at the Summer School and Congress is very important. Research in the fields of medical and health physics is covered by the papers and posters presented. 53 articles have been indexed (27 papers and 26 poster presentations), and 14 articles have been considered to be out of scope for INIS

  10. The Vulcano 1994 summer campaign

    Energy Technology Data Exchange (ETDEWEB)

    Caruso, P.; Valenza, M. [CNR, Palermo (Italy). Istituto Geochimica dei Fluidi; Graziani, G.; Martilli, A.; Mosca, S. [JRC Environment Institute, Ispra, Varese (Italy); Pareschi, M.T. [CNR, Pisa, (Italy). Centro di Studio per la Geologia Strutturale e Dinamica dell`Appennino

    1996-03-01

    A set of measurements from various sources was collected for the island of Vulcano (Aeolian archipelago, South Tyrrhenian sea) during summer 1994 with the scope of characterising the circulation pattern and the volcanic emission of the island. Ground meteorological stations were activated, wind profiles from pilot balloons were obtained, ground temperature measurements were produced. Furthermore, temperature and humidity data from satellite (Landsat TM) were also derived. A critical analysis of the data on the gathered information was performed to quantify the volcanic risk related to the toxic-volcanic-gas release in foreseeable paroxysmal events.

  11. Summer Oral Expression English course

    CERN Multimedia

    2012-01-01

    An English Oral Expression course will take place this summer from 20 August to 29 September.   Schedule: to be determined (2 sessions of 2 hours per week). Please note that this course is for learners who have a good knowledge of English (CERN level 7 upwards). If you are interested in following this course, please enroll through this link. Please be sure to indicate your planned absences in the comments field so we can schedule the course. If you need more information please send a message to English.training@cern.ch

  12. Summer Oral Expression English course

    CERN Document Server

    2012-01-01

    An English Oral Expression course will take place this summer at some time between 25 June and 28 September. The exact dates will be decided according to the preferences of the students.   Schedule: to be determined (2 sessions of 2 hours per week). Please note that this course is for learners who have a good knowledge of English (CERN level 7 upwards). If you are interested in following this course, please enroll through this link. Please be sure to indicate your planned absences in the comments field so we can schedule the course. If you need more information please send a message to English.training@cern.ch

  13. Summer Oral Expression English course

    CERN Document Server

    2013-01-01

    An English Oral Expression course will take place this summer at some time between August 19 and October 4.   Schedule: to be determined (2 sessions of 2 hours per week). Please note that this course is for learners who have a good knowledge of English (CERN level 7 upwards). If you are interested in following this course, please enroll through this link. Please be sure to indicate your planned absences in the comments field so we can schedule the course. If you need more information please send a message to English.training@cern.ch.

  14. Analysis of repeated measures data

    CERN Document Server

    Islam, M Ataharul

    2017-01-01

    This book presents a broad range of statistical techniques to address emerging needs in the field of repeated measures. It also provides a comprehensive overview of extensions of generalized linear models for the bivariate exponential family of distributions, which represent a new development in analysing repeated measures data. The demand for statistical models for correlated outcomes has grown rapidly recently, mainly due to presence of two types of underlying associations: associations between outcomes, and associations between explanatory variables and outcomes. The book systematically addresses key problems arising in the modelling of repeated measures data, bearing in mind those factors that play a major role in estimating the underlying relationships between covariates and outcome variables for correlated outcome data. In addition, it presents new approaches to addressing current challenges in the field of repeated measures and models based on conditional and joint probabilities. Markov models of first...

  15. Repeated DNA sequences in fungi

    Energy Technology Data Exchange (ETDEWEB)

    Dutta, S K

    1974-11-01

    Several fungal species, representatives of all broad groups like basidiomycetes, ascomycetes and phycomycetes, were examined for the nature of repeated DNA sequences by DNA:DNA reassociation studies using hydroxyapatite chromatography. All of the fungal species tested contained 10 to 20 percent repeated DNA sequences. There are approximately 100 to 110 copies of repeated DNA sequences of approximately 4 x 10/sup 7/ daltons piece size of each. Repeated DNA sequence homoduplexes showed on average 5/sup 0/C difference of T/sub e/50 (temperature at which 50 percent duplexes dissociate) values from the corresponding homoduplexes of unfractionated whole DNA. It is suggested that a part of repetitive sequences in fungi constitutes mitochondrial DNA and a part of it constitutes nuclear DNA. (auth)

  16. Climate Change: Drought and Desertification in Kenya

    International Nuclear Information System (INIS)

    Awuor, V.O

    1997-01-01

    Drought is the failure of expected rain which leads to various effects in physical environment and human activities. Droughts are classified into three types namely; meteorological drought, agricultural and hydrological. Meteorological occurs when precipitation is below expectation, hydrological drought is experienced when water resources used for various activities reach levels when they become insufficient for those purposes. On the other hand agricultural drought occurs when when water supply for agriculture gets scarce and can defined as a moisture deficit that they cause un tolerable water stress during the growing season.In Kenya desertification is characterized by high temperatures that ranges between 14-31 degrees centigrade, with shallow soils of poor water holding capacity, the vegetation consists of variety of grasses, bushes and woodlands. Evergreen forest occurs along the major rivers such as Tana. Agricultural activities are usually concentrated in areas which are relatively wet like the highlands and flood plains with flood plains of permanent and seasonal seasonal rivers, surface storage areas and areas of seasonally -recharged shallow groundwater

  17. Induction of drought tolerant mutants of rice

    International Nuclear Information System (INIS)

    El-Hissewy, A.A.; Abd Allah, A.

    2001-01-01

    The ultimate goal of crop breeding is to develop varieties with a high yield potential and desirable agronomic characteristics. In Egypt, the most important qualities sought by breeders have been high yield potential, resistance to major diseases and insects, and improved grain and eating quality. However, breeding efforts should concentrate on varieties with the potential to minimize yield losses under unfavorable conditions such as drought, and to maximize yields when conditions are favorable. Rice (Oryza sativa L.) in Egypt is completely irrigated and a significant portion of the rice cultivated area is subject to water deficit resulting from an inadequate or insufficient irrigation supply. Drought tolerance is a complex trait in that it results from the interaction of histological and physiological characters of plant with environmental factors, both above-ground and under-ground. Accordingly, root characters are closely related to drought tolerance. Little attention has been paid in Egyptian breeding programs to root characters and their relation to shoot characters. Furthermore, induced mutations are considered as one of the most important methods to induce useful mutants, especially with improved root characters, to overcome the drought problem. The present investigation aimed to study the effect of different doses of gamma rays on several characters of three Egyptian rice varieties, i.e. 'Giza 171', 'Giza 175' and 'Giza 176' and to induce one or more mutants possessing drought tolerance

  18. Anthropogenic warming exacerbates European soil moisture droughts

    Science.gov (United States)

    Samaniego, L.; Thober, S.; Kumar, R.; Wanders, N.; Rakovec, O.; Pan, M.; Zink, M.; Sheffield, J.; Wood, E. F.; Marx, A.

    2018-05-01

    Anthropogenic warming is anticipated to increase soil moisture drought in the future. However, projections are accompanied by large uncertainty due to varying estimates of future warming. Here, using an ensemble of hydrological and land-surface models, forced with bias-corrected downscaled general circulation model output, we estimate the impacts of 1-3 K global mean temperature increases on soil moisture droughts in Europe. Compared to the 1.5 K Paris target, an increase of 3 K—which represents current projected temperature change—is found to increase drought area by 40% (±24%), affecting up to 42% (±22%) more of the population. Furthermore, an event similar to the 2003 drought is shown to become twice as frequent; thus, due to their increased occurrence, events of this magnitude will no longer be classified as extreme. In the absence of effective mitigation, Europe will therefore face unprecedented increases in soil moisture drought, presenting new challenges for adaptation across the continent.

  19. CreativeDrought: An interdisciplinary approach to building resilience to drought

    Science.gov (United States)

    Rangecroft, Sally; Van Loon, Anne; Rohse, Melanie; Day, Rosie; Birkinshaw, Stephen; Makaya, Eugine

    2017-04-01

    Drought events cause severe water and food insecurities in many developing countries where resilience to natural hazards and change is low due to a number of reasons (including poverty, social and political inequality, and limited access to information). Furthermore, with climate change and increasing pressures from population and societal change, populations are expected to experience future droughts outside of their historic range. Integrated water resources management is an established tool combining natural science, engineering and management to help address drought and associated impacts. However, it often lacks a strong social and cultural aspect, leading to poor implementation on the ground. For a more holistic approach to building resilience to future drought, a stronger interdisciplinary approach is required which can incorporate the local cultural context and perspectives into drought and water management, and communicate information effectively to communities. In this pilot project 'CreativeDrought', we use a novel interdisciplinary approach aimed at building resilience to future drought in rural Africa by combining hydrological modelling with rich local information and engaging communicative approaches from social sciences. The work is conducted through a series of steps in which we i) engage with local rural communities to collect narratives on drought experiences; ii) generate hydrological modelling scenarios based on IPCC projections, existing data and the collected narratives; iii) feed these back to the local community to gather their responses to these scenarios; iv) iteratively adapt them to obtain hypothetical future drought scenarios; v) engage the community with the scenarios to formulate new future drought narratives; and vi) use this new data to enhance local water resource management. Here we present some of the indigenous knowledge gathered through narratives and the hydrological modelling scenarios for a rural community in Southern Africa

  20. Drought Characterisation Using Ground and Remote Sensing Data

    Science.gov (United States)

    Hore, Sudipta Kumar; Werner, Micha; Maskey, Shreedhar

    2016-04-01

    The North-West of Bangladesh is frequently affected by drought, which may have profound impacts to different water related sectors. The characterisation and identification of drought is, however, challenging. Despite several standard drought indices being available it is important that indicators proposed in support of an effective drought management are related to the impacts drought may have. In this study we present the characterisation of drought in the districts of Rajshahi and Rangpur in North-Western Bangladesh. Drought indicators were developed using available temperature, precipitation, river discharge and groundwater level data, as well as from remotely sensed NDVI data. We compare these indicators to records of drought impacts to agriculture, fisheries and migration collected from relevant organisations, as well as through interviews with key stakeholders, key informants, and community leaders. The analysis shows that droughts occur frequently, with nine occurrences in the last 42 years, as found using common meteorological drought indicators. NDVI data corroborated these events, despite being only available from 2001. The agricultural sector was adversely impacted in all events, with impacts correlated to drought severity. Impacts to the fisheries sector were, however, reported only three times, though impacts to fisheries are less well recorded. Interestingly, the good relationship between meteorological drought indicators and agricultural impacts weakens in the last decade. This appears to be due to the intensification of irrigation using groundwater, with the declining groundwater levels found in Rajshahi district suggesting overexploitation of the resource, and the increasing importance of groundwater drought indicators. The study reveals the drought indicators that are important to the agriculture and fisheries sectors, and also tentative threshold values at which drought start to impact these sectors. Such sector relevant drought indicators, as

  1. Understanding and seasonal forecasting of hydrological drought in the Anthropocene

    Directory of Open Access Journals (Sweden)

    X. Yuan

    2017-11-01

    Full Text Available Hydrological drought is not only caused by natural hydroclimate variability but can also be directly altered by human interventions including reservoir operation, irrigation, groundwater exploitation, etc. Understanding and forecasting of hydrological drought in the Anthropocene are grand challenges due to complicated interactions among climate, hydrology and humans. In this paper, five decades (1961–2010 of naturalized and observed streamflow datasets are used to investigate hydrological drought characteristics in a heavily managed river basin, the Yellow River basin in north China. Human interventions decrease the correlation between hydrological and meteorological droughts, and make the hydrological drought respond to longer timescales of meteorological drought. Due to large water consumptions in the middle and lower reaches, there are 118–262 % increases in the hydrological drought frequency, up to 8-fold increases in the drought severity, 21–99 % increases in the drought duration and the drought onset is earlier. The non-stationarity due to anthropogenic climate change and human water use basically decreases the correlation between meteorological and hydrological droughts and reduces the effect of human interventions on hydrological drought frequency while increasing the effect on drought duration and severity. A set of 29-year (1982–2010 hindcasts from an established seasonal hydrological forecasting system are used to assess the forecast skill of hydrological drought. In the naturalized condition, the climate-model-based approach outperforms the climatology method in predicting the 2001 severe hydrological drought event. Based on the 29-year hindcasts, the former method has a Brier skill score of 11–26 % against the latter for the probabilistic hydrological drought forecasting. In the Anthropocene, the skill for both approaches increases due to the dominant influence of human interventions that have been implicitly

  2. Network Candidate Genes in Breeding for Drought Tolerant Crops

    Directory of Open Access Journals (Sweden)

    Christoph Tim Krannich

    2015-07-01

    Full Text Available Climate change leading to increased periods of low water availability as well as increasing demands for food in the coming years makes breeding for drought tolerant crops a high priority. Plants have developed diverse strategies and mechanisms to survive drought stress. However, most of these represent drought escape or avoidance strategies like early flowering or low stomatal conductance that are not applicable in breeding for crops with high yields under drought conditions. Even though a great deal of research is ongoing, especially in cereals, in this regard, not all mechanisms involved in drought tolerance are yet understood. The identification of candidate genes for drought tolerance that have a high potential to be used for breeding drought tolerant crops represents a challenge. Breeding for drought tolerant crops has to focus on acceptable yields under water-limited conditions and not on survival. However, as more and more knowledge about the complex networks and the cross talk during drought is available, more options are revealed. In addition, it has to be considered that conditioning a crop for drought tolerance might require the production of metabolites and might cost the plants energy and resources that cannot be used in terms of yield. Recent research indicates that yield penalty exists and efficient breeding for drought tolerant crops with acceptable yields under well-watered and drought conditions might require uncoupling yield penalty from drought tolerance.

  3. The potential of SMAP soil moisture data for analyzing droughts

    Science.gov (United States)

    Rajasekaran, E.; Das, N. N.; Entekhabi, D.; Yueh, S. H.

    2017-12-01

    Identification of the onset and the end of droughts are important for socioeconomic planning. Different datasets and tools are either available or being generated for drought analysis to recognize the status of drought. The aim of this study is to understand the potential of the SMAP soil moisture (SM) data for identification of onset, persistence and withdrawal of droughts over the Contiguous United States. We are using the SMAP-passive level 3 soil moisture observations and the United States Drought Monitor (http://droughtmonitor.unl.edu) data for understanding the relation between change in SM and drought severity. The daily observed SM data are temporally averaged to match the weekly drought monitor data and subsequently the weekly, monthly, 3 monthly and 6 monthly change in SM and drought severity were estimated. The analyses suggested that the change in SM and drought severity are correlated especially over the mid-west and west coast of USA at monthly and longer time scales. The spatial pattern of the SM change maps clearly indicated the regions that are moving between different levels of drought severity. Further, the time series of effective saturation [Se =(θ-θr)/(θs-θr)] indicated the temporal dynamics of drought conditions over California which is recovering from a long-term drought. Additional analyses are being carried out to develop statistics between drought severity and soil moisture level.

  4. Fostering repeat donations in Ghana.

    Science.gov (United States)

    Owusu-Ofori, S; Asenso-Mensah, K; Boateng, P; Sarkodie, F; Allain, J-P

    2010-01-01

    Most African countries are challenged in recruiting and retaining voluntary blood donors by cost and other complexities and in establishing and implementing national blood policies. The availability of replacement donors who are a cheaper source of blood has not enhanced repeat voluntary donor initiatives. An overview of activities for recruiting and retaining voluntary blood donors was carried out. Donor records from mobile sessions were reviewed from 2002 to 2008. A total of 71,701 blood donations; 45,515 (63.5%) being voluntary donations with 11,680 (25%) repeat donations were collected during the study period. Donations from schools and colleges contributed a steady 60% of total voluntary whilst radio station blood drives increased contribution from 10 to 27%. Though Muslim population is less than 20%, blood collection was above the 30-donation cost-effectiveness threshold with a repeat donation trend reaching 60%. In contrast Christian worshippers provided donations. Repeat donation trends amongst school donors and radio blood drives were 20% and 70% respectively. Repeat donations rates have been variable amongst different blood donor groups in Kumasi, Ghana. The impact of community leaders in propagating altruism cannot be overemphasized. Programs aiming at motivating replacement donors to be repeat donors should be developed and assessed. Copyright 2009 The International Association for Biologicals. All rights reserved.

  5. A pollen-based reconstruction of summer temperature in central North America and implications for circulation patterns during medieval times

    Science.gov (United States)

    Wahl, Eugene R.; Diaz, Henry F.; Ohlwein, Christian

    2012-03-01

    We present a reconstruction of mean summer temperature for the northern Midwest of the USA based on lacustrine pollen records from three different lakes in Wisconsin. The results suggest a relatively warm period during the earlier part of the record (~ 1200-1500 CE) followed by a cooler Little Ice Age (~ 1500-1900) and a subsequent warming to modern conditions. The reconstructed modern summer mean temperature is in good agreement with observations, and the decades of the 1930s to 1950s appear to be the warmest such period in the proxy record (through 1974). Analyses of circulation features associated with the warmest summers in the recent climate record suggest a prevalence of continental ridging accompanied by generally dry conditions during these warm summers in the Midwest. Drought reconstruction using the Palmer Drought Severity Index (PDSI) and tree-ring records as predictors also yield relatively dry conditions in medieval times for the central US. As reported in a number of recent studies, possible forcing mechanisms include La Niña-like conditions in the equatorial Pacific and warmer than average waters in the tropical Indo-western Pacific Ocean possibly coupled to a positive mode of the AMO/NAO North Atlantic circulation pattern.

  6. Responses of nitrogen metabolism and seed nutrition to drought stress in soybean genotypes differing in slow-wilting phenotype

    Directory of Open Access Journals (Sweden)

    Nacer eBellaloui

    2013-12-01

    Full Text Available Recent advances in soybean breeding have resulted in genotypes that express the slow-wilting phenotype (trait under drought stress conditions. The physiological mechanisms of this trait remain unknown due to the complexity of trait × environment interactions. The objective of this research was to investigate nitrogen metabolism and leaf and seed nutrients composition of the slow-wilting soybean genotypes under drought stress conditions. A repeated greenhouse experiment was conducted using check genotypes: NC-Roy (fast wilting, Boggs (intermediate in wilting; and NTCPR94-5157 and N04-9646 (slow-wilting, SLW genotypes. Plants were either well-watered or drought stressed. Results showed that under well-watered conditions, nitrogen fixation (NF, nitrogen assimilation (NA, and leaf and seed composition differed between genotypes. Under drought stress, NF and NA were higher in NTCPR94-5157 and N04-9646 than in NC-Roy and Boggs. Under severe water stress, however, NA was low in all genotypes. Leaf water potential was significantly lower in checks (-2.00 MPa than in the SLW genotypes (-1.68 MPa. Leaf and seed concentrations of K, P, Ca, Cu, Na, B were higher in SLW genotypes than in the checks under drought stress conditions. Seed protein, oleic acid, and sugars were higher in SLW genotypes, and oil, linoleic and linolenic acids were lower in SLW genotypes. This research demonstrated that K, P, Ca, Cu, Na, and B may be involved in SLW trait by maintaining homeostasis and osmotic regulation. Maintaining higher leaf water potential in NTCPR94-5157 and N04-9646 under drought stress could be a possible water conservation mechanism to maintain leaf turgor pressure. The increase in osmoregulators such as minerals, raffinose and stachyose, and oleic acid could be beneficial for soybean breeders in selecting for drought stress tolerance.

  7. De Novo Sequencing and Comparative Analysis of Schima superba Seedlings to Explore the Response to Drought Stress.

    Directory of Open Access Journals (Sweden)

    Bao-Cai Han

    Full Text Available Schima superba is an important dominant species in subtropical evergreen broadleaved forests of China, and plays a vital role in community structure and dynamics. However, the survival rate of its seedlings in the field is low, and water shortage could be a factor that limits its regeneration. In order to better understand the response of its seedlings to drought stress on a functional genomics scale, RNA-seq technology was utilized in this study to perform a large-scale transcriptome sequencing of the S. superba seedlings under drought stress. More than 320 million clean reads were generated and 72218 unique transcripts were obtained through de novo assembly. These unigenes were further annotated by blasting with different public databases and a total of 53300 unique transcripts were annotated. A total of 31586 simple sequence repeat (SSR loci were presented. Through gene expression profiling analysis between drought treatment and control, 11038 genes were found to be significantly enriched in drought-stressed seedlings. Based on these differentially expressed genes (DEGs, Gene Ontology (GO terms enrichment and Kyoto Encyclopedia of Genes and Genomes pathway (KEGG enrichment analysis indicated that drought stress caused a number of changes in the types of sugars, enzymes, secondary mechanisms, and light responses, and induced some potential physical protection mechanisms. In addition, the expression patterns of 18 transcripts induced by drought, as determined by quantitative real-time PCR, were consistent with their transcript abundance changes, as identified by RNA-seq. This transcriptome study provides a rapid method for understanding the response of S. superba seedlings to drought stress and provides a number of gene sequences available for further functional genomics studies.

  8. Oasis desert farming selects environment-specific date palm root endophytic communities and cultivable bacteria that promote resistance to drought

    KAUST Repository

    Cherif, Hanene; Marasco, Ramona; Rolli, Eleonora; Ferjani, Raoudha; Fusi, Marco; Soussi, Asma; Mapelli, Francesca; Blilou, Ikram; Borin, Sara; Boudabous, Abdellatif; Cherif, Ameur; Daffonchio, Daniele; Ouzari, Hadda

    2015-01-01

    Oases are desert-farming agro-ecosystems, where date palm (Phoenix dactyliferaL.) plays a keystone role in offsetting the effects of drought and maintaining a suitable microclimate for agriculture. At present, abundance, diversity and plant growth promotion (PGP) of date palm root-associated bacteria remain unknown. Considering the environmental pressure determined by the water scarcity in the desert environments, we hypothesized that bacteria associated with date palm roots improve plant resistance to drought. Here, the ecology of date palm root endophytes from oases in the Tunisian Sahara was studied with emphasis on their capacity to promote growth under drought. Endophytic communities segregated along a north-south gradient in correlation with geo-climatic parameters. Screening of 120 endophytes indicated that date palm roots select for bacteria with multiple PGP traits. Bacteria rapidly cross-colonized the root tissues of different species of plants, including the original Tunisian date palm cultivar, Saudi Arabian cultivars and Arabidopsis. Selected endophytes significantly increased the biomass of date palms exposed to repeated drought stress periods during a 9-month greenhouse experiment. Overall, results indicate that date palm roots shape endophytic communities that are capable to promote plant growth under drought conditions, thereby contributing an essential ecological service to the entire oasis ecosystem. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

  9. Oasis desert farming selects environment-specific date palm root endophytic communities and cultivable bacteria that promote resistance to drought

    KAUST Repository

    Cherif, Hanene

    2015-07-21

    Oases are desert-farming agro-ecosystems, where date palm (Phoenix dactyliferaL.) plays a keystone role in offsetting the effects of drought and maintaining a suitable microclimate for agriculture. At present, abundance, diversity and plant growth promotion (PGP) of date palm root-associated bacteria remain unknown. Considering the environmental pressure determined by the water scarcity in the desert environments, we hypothesized that bacteria associated with date palm roots improve plant resistance to drought. Here, the ecology of date palm root endophytes from oases in the Tunisian Sahara was studied with emphasis on their capacity to promote growth under drought. Endophytic communities segregated along a north-south gradient in correlation with geo-climatic parameters. Screening of 120 endophytes indicated that date palm roots select for bacteria with multiple PGP traits. Bacteria rapidly cross-colonized the root tissues of different species of plants, including the original Tunisian date palm cultivar, Saudi Arabian cultivars and Arabidopsis. Selected endophytes significantly increased the biomass of date palms exposed to repeated drought stress periods during a 9-month greenhouse experiment. Overall, results indicate that date palm roots shape endophytic communities that are capable to promote plant growth under drought conditions, thereby contributing an essential ecological service to the entire oasis ecosystem. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

  10. Genetic Variation and Association Analysis of the SSR Markers Linked to the Major Drought-Yield QTLs of Rice.

    Science.gov (United States)

    Tabkhkar, Narjes; Rabiei, Babak; Samizadeh Lahiji, Habibollah; Hosseini Chaleshtori, Maryam

    2018-02-24

    Drought is one of the major abiotic stresses, which hampers the production of rice worldwide. Informative molecular markers are valuable tools for improving the drought tolerance in various varieties of rice. The present study was conducted to evaluate the informative simple sequence repeat (SSR) markers in a diverse set of rice genotypes. The genetic diversity analyses of the 83 studied rice genotypes were performed using 34 SSR markers closely linked to the major quantitative trait loci (QTLs) of grain yield under drought stress (qDTYs). In general, our results indicated high levels of polymorphism. In addition, we screened these rice genotypes at the reproductive stage under both drought stress and nonstressful conditions. The results of the regression analysis demonstrated a significant relationship between 11 SSR marker alleles and the plant paddy weight under stressful conditions. Under the nonstressful conditions, 16 SSR marker alleles showed a significant correlation with the plant paddy weight. Finally, four markers (RM279, RM231, RM166, and RM231) demonstrated a significant association with the plant paddy weight under both stressful and nonstressful conditions. These informative-associated alleles may be useful for improving the crop yield under both drought stress and nonstressful conditions in breeding programs.

  11. Morphological and phenological shoot plasticity in a Mediterranean evergreen oak facing long-term increased drought.

    Science.gov (United States)

    Limousin, Jean-Marc; Rambal, Serge; Ourcival, Jean-Marc; Rodríguez-Calcerrada, Jesus; Pérez-Ramos, Ignacio M; Rodríguez-Cortina, Raquel; Misson, Laurent; Joffre, Richard

    2012-06-01

    Mediterranean trees must adjust their canopy leaf area to the unpredictable timing and severity of summer drought. The impact of increased drought on the canopy dynamics of the evergreen Quercus ilex was studied by measuring shoot growth, leaf production, litterfall, leafing phenology and leaf demography in a mature forest stand submitted to partial throughfall exclusion for 7 years. The leaf area index rapidly declined in the throughfall-exclusion plot and was 19% lower than in the control plot after 7 years of treatment. Consequently, leaf litterfall was significantly lower in the dry treatment. Such a decline in leaf area occurred through a change in branch allometry with a decreased number of ramifications produced and a reduction of the leaf area supported per unit sapwood area of the shoot (LA/SA). The leafing phenology was slightly delayed and the median leaf life span was slightly longer in the dry treatment. The canopy dynamics in both treatments were driven by water availability with a 1-year lag: leaf shedding and production were reduced following dry years; in contrast, leaf turnover was increased following wet years. The drought-induced decrease in leaf area, resulting from both plasticity in shoot development and slower leaf turnover, appeared to be a hydraulic adjustment to limit canopy transpiration and maintain leaf-specific hydraulic conductivity under drier conditions.

  12. Drought-induced photosynthetic inhibition and autumn recovery in two Mediterranean oak species (Quercus ilex and Quercus suber).

    Science.gov (United States)

    Vaz, M; Pereira, J S; Gazarini, L C; David, T S; David, J S; Rodrigues, A; Maroco, J; Chaves, M M

    2010-08-01

    Responses of leaf water relations and photosynthesis to summer drought and autumn rewetting were studied in two evergreen Mediterranean oak species, Quercus ilex spp. rotundifolia and Quercus suber. The predawn leaf water potential (Ψ(lPD)), stomatal conductance (gs) and photosynthetic rate (A) at ambient conditions were measured seasonally over a 3-year period. We also measured the photosynthetic response to light and to intercellular CO₂ (A/PPFD and A/C(i) response curves) under water stress (summer) and after recovery due to autumn rainfall. Photosynthetic parameters, Vc(max), J(max) and triose phosphate utilization (TPU) rate, were estimated using the Farquhar model. RuBisCo activity, leaf chlorophyll, leaf nitrogen concentration and leaf carbohydrate concentration were also measured. All measurements were performed in the spring leaves of the current year. In both species, the predawn leaf water potential, stomatal conductance and photosynthetic rate peaked in spring, progressively declined throughout the summer and recovered upon autumn rainfall. During the drought period, Q. ilex maintained a higher predawn leaf water potential and stomatal conductance than Q. suber. During this period, we found that photosynthesis was not only limited by stomatal closure, but was also downregulated as a consequence of a decrease in the maximum carboxylation rate (Vc(max)) and the light-saturated rate of photosynthetic electron transport (J(max)) in both species. The Vc(max) and J(max) increased after the first autumnal rains and this increase was related to RuBisCo activity, leaf nitrogen concentration and chlorophyll concentration. In addition, an increase in the TPU rate and in soluble leaf sugar concentration was observed in this period. The results obtained indicate a high resilience of the photosynthetic apparatus to summer drought as well as good recovery in the following autumn rains of these evergreen oak species.

  13. Operationalising resilience to drought: Multi-layered safety for flooding applied to droughts

    Science.gov (United States)

    Rijke, Jeroen; Smith, Jennifer Vessels; Gersonius, Berry; van Herk, Sebastiaan; Pathirana, Assela; Ashley, Richard; Wong, Tony; Zevenbergen, Chris

    2014-11-01

    This paper sets out a way of thinking about how to prepare for and respond to droughts in a holistic way using a framework developed for managing floods. It shows how the multi-layered safety (MLS) approach for flood resilience can be utilised in the context of drought in a way that three layers of intervention can be distinguished for operationalising drought resilience: (1) protection against water shortage through augmentation and diversification of water supplies; (2) prevention of damage in case of water shortage through increased efficiency of water use and timely asset maintenance; (3) preparedness for future water shortages through mechanisms to reduce the use of water and adopt innovative water technologies. Application of MLS to the cities of Adelaide, Melbourne and Sydney shows that recent water reforms in these cities were primarily focused on protection measures that aim to reduce the hazard source or exposure to insufficient water supplies. Prevention and preparedness measures could be considered in defining interventions that aim to further increase the drought resilience of these cities. Although further research is needed, the application suggests that MLS can be applied to the context of drought risk management. The MLS framework can be used to classify the suite of plans deployed by a city to manage future drought risks and can be considered a planning tool to identify opportunities for increasing the level of redundancy and hence resilience of the drought risk management system.

  14. Evaluating Yield and Drought Stress Indices under End Season Drought Stress in Promising Genotypes of Barley

    Directory of Open Access Journals (Sweden)

    H. Tajalli

    2012-08-01

    Full Text Available To study the effects of end season drought stress on yield, yield components and drought stress indices in barley, a split plot experiment arranged in randomized complete block design with three replications was conducted at the Agricultural Research Center of Birjand in 2008-2009 crop years. Drought stress, in 2 levels, consists of control (complete irrigation and stopping irrigation at the 50% of heading stage, and 20 promising genotypes of barley were the treatments of the experiment. Results revealed that stopping irrigation lead to declining of 14.64 and 8.12 percent of seed and forage yields against control condition, respectively. Using stress susceptibility index (SSI indicated that genotypes 2, 3, 7, 9, 10 and 15; using STI and GMP indices, genotypes 5, 8, 18 and 20 using MP, genotypes 8, 18 and 20, and TOL, genotypes 2, 3, 7, 9, and 10, were the most drought tolerant genotypes. Correlation between seed yield and stress evaluation indices showed that MP, GMP and STI are the best indices to be used in selection and introducing drought tolerant genotypes of barley. Considering all indices, and given that the best genotypes are those with high yield under normal condition and minimum yield reduction under drought stress, No. 18 and 20 could be introduced as the most tolerant barley genotypes to drought.

  15. Arbuscular mycorrhizal symbiosis induces strigolactone biosynthesis under drought and improves drought tolerance in lettuce and tomato.

    Science.gov (United States)

    Ruiz-Lozano, Juan Manuel; Aroca, Ricardo; Zamarreño, Ángel María; Molina, Sonia; Andreo-Jiménez, Beatriz; Porcel, Rosa; García-Mina, José María; Ruyter-Spira, Carolien; López-Ráez, Juan Antonio

    2016-02-01

    Arbuscular mycorrhizal (AM) symbiosis alleviates drought stress in plants. However, the intimate mechanisms involved, as well as its effect on the production of signalling molecules associated with the host plant-AM fungus interaction remains largely unknown. In the present work, the effects of drought on lettuce and tomato plant performance and hormone levels were investigated in non-AM and AM plants. Three different water regimes were applied, and their effects were analysed over time. AM plants showed an improved growth rate and efficiency of photosystem II than non-AM plants under drought from very early stages of plant colonization. The levels of the phytohormone abscisic acid, as well as the expression of the corresponding marker genes, were influenced by drought stress in non-AM and AM plants. The levels of strigolactones and the expression of corresponding marker genes were affected by both AM symbiosis and drought. The results suggest that AM symbiosis alleviates drought stress by altering the hormonal profiles and affecting plant physiology in the host plant. In addition, a correlation between AM root colonization, strigolactone levels and drought severity is shown, suggesting that under these unfavourable conditions, plants might increase strigolactone production in order to promote symbiosis establishment to cope with the stress. © 2015 John Wiley & Sons Ltd.

  16. Floods and droughts: friends or foes?

    Science.gov (United States)

    Prudhomme, Christel

    2017-04-01

    Water hazards are some of the biggest threats to lives and livelihoods globally, causing serious damages to society and infrastructure. But floods and droughts are an essential part of the hydrological regime that ensures fundamental ecosystem functions, providing natural ways to bring in nutrients, flush out pollutants and enabling soils, rivers and lakes natural biodiversity to thrive. Traditionally, floods and droughts are too often considered separately, with scientific advance in process understanding, modelling, statistical characterisation and impact assessment are often done independently, possibly delaying the development of innovative methods that could be applied to both. This talk will review some of the key characteristics of floods and droughts, highlighting differences and commonalties, losses and benefits, with the aim of identifying future key research challenges faced by both current and next generation of hydrologists.

  17. Increasing drought risk in large-dam basins of South Korea

    Science.gov (United States)

    Jung, I. W.; Shin, Y.; Park, J.; Kim, D.

    2017-12-01

    In 2015, South Korea suffered one of the worst droughts in recent years. Seoul and Gyeonggi and Gangwon provinces experienced severe drought conditions, receiving less than 43 percent of the annual precipitation average of the past 30 years. Additionally, the 2015 summer precipitation was less than half of the average. The lack of summer precipitation induced serious shortages in dam storages, which are important supplies for the dry season. K-water, a public company managing South Korea's public water supply system, is fighting to secure public water supply and minimize potential damage that may occur before the subsequent wet season. This study detected significant decreasing trends (95% confidence interval) in dry-seasonal runoff rates (=dam inflow / precipitation) in three dams basins (Soyang, Chungju, and Andong). Changes in potential evapotranspiration (PET) and precipitation indices were examined to investigate potential causes of decreasing runoff rates trends. However, there were no clear relations among changes in runoff rates, PET, and precipitation indices. Runoff rate reduction in the three dams may increase the risk of dam operational management and long-term water resource planning. Therefore, it will be necessary to perform a multilateral analysis to better understand decreasing runoff rates.AcknowledgementsThis research was supported by a grant(2017-MPSS31-001) from Supporting Technology Development Program for Disaster Management funded by Ministry of Public Safety and Security(MPSS) of the Korean government.

  18. Improved tolerance to post-anthesis drought stress by pre-drought priming at vegetative stages in drought-tolerant and -sensitive wheat cultivars.

    Science.gov (United States)

    Abid, Muhammad; Tian, Zhongwei; Ata-Ul-Karim, Syed Tahir; Liu, Yang; Cui, Yakun; Zahoor, Rizwan; Jiang, Dong; Dai, Tingbo

    2016-09-01

    Wheat crop endures a considerable penalty of yield reduction to escape the drought events during post-anthesis period. Drought priming under a pre-drought stress can enhance the crop potential to tolerate the subsequent drought stress by triggering a faster and stronger defense mechanism. Towards these understandings, a set of controlled moderate drought stress at 55-60% field capacity (FC) was developed to prime the plants of two wheat cultivars namely Luhan-7 (drought tolerant) and Yangmai-16 (drought sensitive) during tillering (Feekes 2 stage) and jointing (Feekes 6 stage), respectively. The comparative response of primed and non-primed plants, cultivars and priming stages was evaluated by applying a subsequent severe drought stress at 7 days after anthesis. The results showed that primed plants of both cultivars showed higher potential to tolerate the post-anthesis drought stress through improved leaf water potential, more chlorophyll, and ribulose-1, 5-bisphosphate carboxylase/oxygenase contents, enhanced photosynthesis, better photoprotection and efficient enzymatic antioxidant system leading to less yield reductions. The primed plants of Luhan-7 showed higher capability to adapt the drought stress events than Yangmai-16. The positive effects of drought priming to sustain higher grain yield were pronounced in plants primed at tillering than those primed at jointing. In consequence, upregulated functioning of photosynthetic apparatus and efficient enzymatic antioxidant activities in primed plants indicated their superior potential to alleviate a subsequently occurring drought stress, which contributed to lower yield reductions than non-primed plants. However, genotypic and priming stages differences in response to drought stress also contributed to affect the capability of primed plants to tolerate the post-anthesis drought stress conditions in wheat. Copyright © 2016. Published by Elsevier Masson SAS.

  19. Trends and variability of meteorological drought over the districts of ...

    Indian Academy of Sciences (India)

    4

    Keywords: Meteorological drought, standardized precipitation index, monsoon, sea ... Drought is one of the most serious problem for human societies and ecosystems. ... They found that SPI satisfactorily explains the development of conditions.

  20. rainmustfall – a theological reflection on drought, thirst

    African Journals Online (AJOL)

    drought, thirst, and the water of life in a time of drought. The negotiation of meaning that .... Southern African religious systems (Müller & Kruger 2013); water in the ...... Rain and water symbolism in Southern African religious systems: Continuity.

  1. Conditional and unconditional QTL mapping of drought-tolerance ...

    Indian Academy of Sciences (India)

    2013-08-12

    Aug 12, 2013 ... drought tolerance has been the yield obtained under drought conditions .... loci distributed in 27 linkage groups with six linkage gaps, and it covered ...... time in maize; they identified numerous minor-effect QTLs that were ...

  2. Comparison of the spatial and temporal variability of drought indices ...

    African Journals Online (AJOL)

    Churchill

    variability of regional water resources. Lake Chad for ... and water resources management question in drought prone regions of Africa .... implementation of contingency plans during the drought .... management (IWRM) by the Lake Chad Basin.

  3. Proteomic studies of drought stress response in Fabaceae

    Directory of Open Access Journals (Sweden)

    Tanja ZADRAŽNIK

    2015-11-01

    Full Text Available Drought stress is a serious threat to crop production that influences plant growth and development and subsequently causes reduced quantity and quality of the yield. Plant stress induces changes in cell metabolism, which includes differential expression of proteins. Proteomics offer a powerful approach to analyse proteins involved in drought stress response of plants. Analyses of changes in protein abundance of legumes under drought stress are very important, as legumes play an important role in human and animal diet and are often exposed to drought. The presented results of proteomic studies of selected legumes enable better understanding of molecular mechanisms of drought stress response. The study of drought stress response of plants with proteomic approach may contribute to the development of potential drought-response markers and to the development of drought-tolerant cultivars of different legume crop species.

  4. Environmental science: Trends in ecosystem recovery from drought

    Science.gov (United States)

    Seneviratne, Sonia I.; Ciais, Philippe

    2017-08-01

    An analysis suggests that the time taken for ecosystems to recover from drought increased during the twentieth century. If the frequency of drought events rises, some ecosystems might never have the chance to fully recover. See Letter p.202

  5. Assessing Agricultural Drought in the Anthropocene: A Modified Palmer Drought Severity Index

    Directory of Open Access Journals (Sweden)

    Mingzhi Yang

    2017-09-01

    Full Text Available In the current human-influenced era, drought is initiated by natural and human drivers, and human activities are as integral to drought as meteorological factors. In large irrigated agricultural regions with high levels of human intervention, where the natural farmland soil moisture has usually been changed significantly by high-frequency irrigation, the actual severity of agricultural drought is distorted in traditional drought indices. In this work, an agricultural drought index that considering irrigation processes based on the Palmer drought severity index (IrrPDSI was developed to interpret the real agricultural drought conditions in irrigated regions, with a case study in the Haihe River Basin in northeast China. The water balance model in the original PDSI was revised by an auto-irrigation threshold method combined with a local irrigation schedule. The auto-irrigation setting of the index was used by taking irrigation quotas during specific growth stages of specific crops (wheat–corn into consideration. A series of weekly comparative analyses are as follows: (1 The soil moisture analyses showed that soil moisture values calculated by the modified water balance model were close to the real values; (2 The statistical analyses indicated that most of the stations in the study area based on IrrPDSI had nearly normal distributed values; (3 The time series and spatial analyses showed that the results of the IrrPDSI-reported dry-wet evaluation were more consistent with documented real conditions. All the results revealed that IrrPDSI performed well when used to assess agricultural drought. This work has direct significance for agricultural drought management in large irrigated areas heavily disturbed by human activity.

  6. Seasonal UK Drought Forecasting using Statistical Methods

    Science.gov (United States)

    Richardson, Doug; Fowler, Hayley; Kilsby, Chris; Serinaldi, Francesco

    2016-04-01

    In the UK drought is a recurrent feature of climate with potentially large impacts on public water supply. Water companies' ability to mitigate the impacts of drought by managing diminishing availability depends on forward planning and it would be extremely valuable to improve forecasts of drought on monthly to seasonal time scales. By focusing on statistical forecasting methods, this research aims to provide techniques that are simpler, faster and computationally cheaper than physically based models. In general, statistical forecasting is done by relating the variable of interest (some hydro-meteorological variable such as rainfall or streamflow, or a drought index) to one or more predictors via some formal dependence. These predictors are generally antecedent values of the response variable or external factors such as teleconnections. A candidate model is Generalised Additive Models for Location, Scale and Shape parameters (GAMLSS). GAMLSS is a very flexible class allowing for more general distribution functions (e.g. highly skewed and/or kurtotic distributions) and the modelling of not just the location parameter but also the scale and shape parameters. Additionally GAMLSS permits the forecasting of an entire distribution, allowing the output to be assessed in probabilistic terms rather than simply the mean and confidence intervals. Exploratory analysis of the relationship between long-memory processes (e.g. large-scale atmospheric circulation patterns, sea surface temperatures and soil moisture content) and drought should result in the identification of suitable predictors to be included in the forecasting model, and further our understanding of the drivers of UK drought.

  7. Spatiotemporal drought forecasting using nonlinear models

    Science.gov (United States)

    Vasiliades, Lampros; Loukas, Athanasios

    2010-05-01

    Spatiotemporal data mining is the extraction of unknown and implicit knowledge, structures, spatiotemporal relationships, or patterns not explicitly stored in spatiotemporal databases. As one of data mining techniques, forecasting is widely used to predict the unknown future based upon the patterns hidden in the current and past data. In order to achieve spatiotemporal forecasting, some mature analysis tools, e.g., time series and spatial statistics are extended to the spatial dimension and the temporal dimension, respectively. Drought forecasting plays an important role in the planning and management of natural resources and water resource systems in a river basin. Early and timelines forecasting of a drought event can help to take proactive measures and set out drought mitigation strategies to alleviate the impacts of drought. Despite the widespread application of nonlinear mathematical models, comparative studies on spatiotemporal drought forecasting using different models are still a huge task for modellers. This study uses a promising approach, the Gamma Test (GT), to select the input variables and the training data length, so that the trial and error workload could be greatly reduced. The GT enables to quickly evaluate and estimate the best mean squared error that can be achieved by a smooth model on any unseen data for a given selection of inputs, prior to model construction. The GT is applied to forecast droughts using monthly Standardized Precipitation Index (SPI) timeseries at multiple timescales in several precipitation stations at Pinios river basin in Thessaly region, Greece. Several nonlinear models have been developed efficiently, with the aid of the GT, for 1-month up to 12-month ahead forecasting. Several temporal and spatial statistical indices were considered for the performance evaluation of the models. The predicted results show reasonably good agreement with the actual data for short lead times, whereas the forecasting accuracy decreases with

  8. Dynamical effects of vegetation on the 2003 summer heat waves

    Science.gov (United States)

    Stéfanon, M.

    2012-04-01

    Dynamical effects of vegetation on the 2003 summer heat waves Marc Stéfanon(1), Philippe Drobinski(1), Fabio D'Andrea(1), Nathalie de Noblet(2) (1) IPSL/LMD, France; (2) IPSL/LSCE, France The land surface model (LSM) in regional climate models (RCMs) plays a key role in energy and water exchanges between land and atmosphere. The vegetation can affect these exchanges through physical, biophysical and bio-geophysical mechanisms. It participates to evapo-transpiration process which determines the partitioning of net radiation between sensible and latent heat flux, through water evaporation from soil throughout the entire root system. For seasonal timescale leaf cover change induced leaf-area index (LAI) and albedo changes, impacting the Earth's radiative balance. In addition, atmospheric chemistry and carbon concentration has a direct effect on plant stomatal structure, the main exchange interface with the atmosphere. Therefore the surface energy balance is intimately linked to the carbon cycle and vegetation conditions and an accurate representation of the Earth's surface is required to improve the performance of RCMs. It is even more crucial for extreme events as heat waves and droughts which display highly nonlinear behaviour. If triggering of heat waves is determined by the large scale, local coupled processes over land can amplify or inhibit heat trough several feedback mechanism. One set of two simulation has been conducted with WRF, using different LSMs. They aim to study drought and vegetation effect on the dynamical and hydrological processes controlling the occurrence and life cycle of heat waves In the MORCE plateform, the dynamical global vegetation model (DGVM) ORCHIDEE is implemented in the atmospheric module WRF. ORCHIDEE is based on three different modules. The first module, called SECHIBA, describes the fast processes such as exchanges of energy and water between the atmosphere and the biosphere, and the soil water budget. The phenology and carbon

  9. A deeper look at the response of oxygenated and non oxygenated VOC to mid-term drought over the seasonal cycle: the case study of a drought-resistant species

    Science.gov (United States)

    Saunier, Amelie; Ormeño Lafuente, Elena; Wortham, Henri; Temime-Roussel, Brice; Fernandez, Catherine

    2015-04-01

    At the end of this century, climatic models plan an intensification of summer drought in the Mediterranean area due to a 30% rain reduction and a temperature rise of 3.4 °C. Plants respond to drought by modifying their primary (growth) and their secondary metabolism, the later being partly represented by volatile organic compound (VOC) emissions, such as terpenes. With drought, oxygenated and non oxygenated terpene emissions have been observed to increase, decrease or remain unchanged according to drought severity and vegetal model. By contrast, the response of non-terpenic oxygenated compounds to drought has been poorly studied. The aim of this study is to determine the potential impact of a two-year drought period on the full screen of VOC released by Q. pubescens, with a focus on both isoprene and methanol, issued from plant anabolism , and the numerous highly volatile oxygenated VOC, issued from plant catabolism (i.e. issued from oxidation of isoprene or methanol). A 70 years-old Downy oak forest (Quercus pubescens), highly resistant to drought stress, was selected as model ecosystem since it is well widespread in Southern France occupying 321 000 ha. Downy oak also represents the major source of isoprene emissions in the Mediterranean area and, unlike the other major Quercus sp. of the region (i.e. Quercus ilex, a monoterpene emitter) the impact of watering withholding over years has never been tackled. The study was performed at the experimental platform of O3HP (Oak Observatory at Observatoire de Haute Provence) in Southern France which is equipped with both a rain exclusion (by 30 %) and a rain addition structure (simulating the rainiest years of the region), allowing for comparison with naturally watered trees. Using dynamic enclosure chambers at the branch level and PTR-MS-Q-ToF, we screened the anabolic VOC (isoprene, methanol) and the catabolic VOC (e.g. methacrolein, methyl vinyl ketone, C6 aldehydes and carboxylic acids) of trees located under the

  10. Application of Dynamic naïve Bayesian classifier to comprehensive drought assessment

    Science.gov (United States)

    Park, D. H.; Lee, J. Y.; Lee, J. H.; KIm, T. W.

    2017-12-01

    Drought monitoring has already been extensively studied due to the widespread impacts and complex causes of drought. The most important component of drought monitoring is to estimate the characteristics and extent of drought by quantitatively measuring the characteristics of drought. Drought assessment considering different aspects of the complicated drought condition and uncertainty of drought index is great significance in accurate drought monitoring. This study used the dynamic Naïve Bayesian Classifier (DNBC) which is an extension of the Hidden Markov Model (HMM), to model and classify drought by using various drought indices for integrated drought assessment. To provide a stable model for combined use of multiple drought indices, this study employed the DNBC to perform multi-index drought assessment by aggregating the effect of different type of drought and considering the inherent uncertainty. Drought classification was performed by the DNBC using several drought indices: Standardized Precipitation Index (SPI), Streamflow Drought Index (SDI), and Normalized Vegetation Supply Water Index (NVSWI)) that reflect meteorological, hydrological, and agricultural drought characteristics. Overall results showed that in comparison unidirectional (SPI, SDI, and NVSWI) or multivariate (Composite Drought Index, CDI) drought assessment, the proposed DNBC was able to synthetically classify of drought considering uncertainty. Model provided method for comprehensive drought assessment with combined use of different drought indices.

  11. Dynamics of non-structural carbohydrates in three Mediterranean woody species following long-term experimental drought.

    Science.gov (United States)

    Rosas, Teresa; Galiano, Lucía; Ogaya, Romà; Peñuelas, Josep; Martínez-Vilalta, Jordi

    2013-01-01

    Stored non-structural carbohydrates (NSC) have been proposed as a key determinant of drought resistance in plants. However, the evidence for this role is controversial, as it comes mostly from observational, short-term studies. Here, we take advantage of a long-term experimental throughfall reduction to elucidate the response of NSC to increased drought 14 years after the beginning of the treatment in three Mediterranean resprouter trees (Quercus ilex L., Arbutus unedo L. and Phillyrea latifolia L.). In addition, we selected 20 Q. ilex individuals outside the experimental plots to directly assess the relationship between defoliation and NSC at the individual level. We measured the seasonal course of NSC concentrations in leaves, branches and lignotuber in late winter, late spring, summer, and autumn 2012. Total concentrations of NSC were highest in the lignotuber for all species. In the long-term drought experiment we found significant depletion in concentrations of total NSC in treatment plots only in the lignotuber of A. unedo. At the same time, A. unedo was the only species showing a significant reduction in BAI under the drought treatment during the 14 years of the experiment. By contrast, Q. ilex just reduced stem growth only during the first 4 years of treatment and P. latifolia remained unaffected over the whole study period. However, we found a clear association between the concentrations of NSC and defoliation in Q. ilex individuals sampled outside the experimental plots, with lower total concentrations of NSC and lower proportion of starch in defoliated individuals. Taken together, our results suggest that stabilizing processes, probably at the stand level, may have been operating in the long-term to mitigate any impact of drought on NSC levels, and highlight the necessity to incorporate long-term experimental studies of plant responses to drought.

  12. Dynamics of non-structural carbohydrates in three Mediterranean woody species following long-term experimental drought

    Directory of Open Access Journals (Sweden)

    Teresa eRosas

    2013-10-01

    Full Text Available Stored non-structural carbohydrates (NSC have been proposed as a key determinant of drought resistance in plants. However, the evidence for this role is controversial, as it comes mostly from observational, short-term studies. Here, we take advantage of a long-term experimental throughfall reduction to elucidate the response of NSC to increased drought 14 years after the beginning of the treatment in three Mediterranean woody species (Quercus ilex L., Arbutus unedo L. and Phillyrea latifolia L.. In addition, we selected 20 Q. ilex individuals outside the experimental plots to directly assess the relationship between defoliation and NSC at the individual level. We measured the seasonal course of NSC concentrations in leaves, branches and lignotuber in late winter, late spring, summer and autumn 2012. Total concentrations of NSC were highest in the lignotuber for all species. In the long-term drought experiment we found significant depletion in concentrations of total NSC in treatment plots only in the lignotuber of A. unedo. At the same time, A. unedo was the only species showing a significant reduction in BAI under the drought treatment during the 14 years of the experiment. By contrast, Q. ilex just reduced stem growth only during the first 4 years of treatment and P. latifolia remained unaffected over the whole study period. However, we found a clear association between the concentrations of NSC and defoliation in Q. ilex individuals sampled outside the experimental plots, with lower total concentrations of NSC and lower proportion of starch in defoliated individuals. Taken together, our results suggest that stabilizing processes, probably at the stand level, may have been operating in the long-term to mitigate any impact of drought on NSC levels, and highlight the necessity to incorporate long-term experimental studies of plant responses to drought.

  13. Roles of patch characteristics, drought frequency, and restoration in long-term trends of a widespread amphibian.

    Science.gov (United States)

    Hossack, Blake R; Adams, Michael J; Pearl, Christopher A; Wilson, Kristine W; Bull, Evelyn L; Lohr, Kristin; Patla, Debra; Pilliod, David S; Jones, Jason M; Wheeler, Kevin K; McKay, Samuel P; Corn, Paul Stephen

    2013-12-01

    Despite the high profile of amphibian declines and the increasing threat of drought and fragmentation to aquatic ecosystems, few studies have examined long-term rates of change for a single species across a large geographic area. We analyzed growth in annual egg-mass counts of the Columbia spotted frog (Rana luteiventris) across the northwestern United States, an area encompassing 3 genetic clades. On the basis of data collected by multiple partners from 98 water bodies between 1991 and 2011, we used state-space and linear-regression models to measure effects of patch characteristics, frequency of summer drought, and wetland restoration on population growth. Abundance increased in the 2 clades with greatest decline history, but declined where populations are considered most secure. Population growth was negatively associated with temporary hydroperiods and landscape modification (measured by the human footprint index), but was similar in modified and natural water bodies. The effect of drought was mediated by the size of the water body: populations in large water bodies maintained positive growth despite drought, whereas drought magnified declines in small water bodies. Rapid growth in restored wetlands in areas of historical population declines provided strong evidence of successful management. Our results highlight the importance of maintaining large areas of habitat and underscore the greater vulnerability of small areas of habitat to environmental stochasticity. Similar long-term growth rates in modified and natural water bodies and rapid, positive responses to restoration suggest pond construction and other forms of management can effectively increase population growth. These tools are likely to become increasingly important to mitigate effects of increased drought expected from global climate change. Papeles de las Características del Fragmento, Frecuencia de Sequía y Restauración en las Tendencias a Largo Plazo de un Anfibio Ampliamente Distribuido

  14. Roles of patch characteristics, drought frequency, and restoration in long-term trends of a widespread amphibian

    Science.gov (United States)

    Hossack, Blake R.; Adams, Michael J.; Pearl, Christopher A.; Pilliod, David S.; Corn, P. Stephen; , KRISTINE W. WILSON; , EVELYN L. BULL; , KRISTIN LOHR; , DEBRA PATLA; , JASON JONES

    2013-01-01

    Despite the high profile of amphibian declines and the increasing threat of drought and fragmentation to aquatic ecosystems, few studies have examined long-term rates of change for a single species across a large geographic area. We analyzed growth in annual egg-mass counts of the Columbia spotted frog (Rana luteiventris) across the northwestern United States, an area encompassing 3 genetic clades. On the basis of data collected by multiple partners from 98 water bodies between 1991 and 2011, we used state-space and linear-regression models to measure effects of patch characteristics, frequency of summer drought, and wetland restoration on population growth. Abundance increased in the 2 clades with greatest decline history, but declined where populations are considered most secure. Population growth was negatively associated with temporary hydroperiods and landscape modification (measured by the human footprint index), but was similar in modified and natural water bodies. The effect of drought was mediated by the size of the water body: populations in large water bodies maintained positive growth despite drought, whereas drought magnified declines in small water bodies. Rapid growth in restored wetlands in areas of historical population declines provided strong evidence of successful management. Our results highlight the importance of maintaining large areas of habitat and underscore the greater vulnerability of small areas of habitat to environmental stochasticity. Similar long-term growth rates in modified and natural water bodies and rapid, positive responses to restoration suggest pond construction and other forms of management can effectively increase population growth. These tools are likely to become increasingly important to mitigate effects of increased drought expected from global climate change.

  15. Avoiding Drought Risks and Social Conflict Under Climate Change

    Science.gov (United States)

    Towler, E.; Lazrus, H.; Paimazumder, D.

    2014-12-01

    Traditional drought research has mainly focused on physical drought risks and less on the cultural processes that also contribute to how drought risks are perceived and managed. However, as society becomes more vulnerable to drought and climate change threatens to increase water scarcity, it is clear that drought research would benefit from a more interdisciplinary approach. To assess avoided drought impacts from reduced climate change, drought risks need to be assessed in the context of both climate prediction as well as improved understanding of socio-cultural processes. To this end, this study explores a risk-based framework to combine physical drought likelihoods with perceived risks from stakeholder interviews. Results are presented from a case study on how stakeholders in south-central Oklahoma perceive drought risks given diverse cultural beliefs, water uses, and uncertainties in future drought prediction. Stakeholder interviews (n=38) were conducted in 2012 to understand drought risks to various uses of water, as well as to measure worldviews from the cultural theory of risk - a theory that explains why people perceive risks differently, potentially leading to conflict over management decisions. For physical drought risk, drought projections are derived from a large ensemble of future climates generated from two RCPs that represent higher and lower emissions trajectories (i.e., RCP8.5 and RCP4.5). These are used to develop a Combined Drought Risk Matrix (CDRM) that characterizes drought risks for different water uses as the products of both physical likelihood (from the climate ensemble) and risk perception (from the interviews). We use the CRDM to explore the avoided drought risks posed to various water uses, as well as to investigate the potential for reduction of conflict over water management.

  16. A new multi-sensor integrated index for drought monitoring

    Science.gov (United States)

    Jiao, W.; Wang, L.; Tian, C.

    2017-12-01

    Drought is perceived as one of the most expensive and least understood natural disasters. The remote-sensing-based integrated drought indices, which integrate multiple variables, could reflect the drought conditions more comprehensively than single drought indices. However, most of current remote-sensing-based integrated drought indices focus on agricultural drought (i.e., deficit in soil moisture), their application in monitoring meteorological drought (i.e., deficit in precipitation) was limited. More importantly, most of the remote-sensing-based integrated drought indices did not take into consideration of the spatially non-stationary nature of the related variables, so such indices may lose essential local details when integrating multiple variables. In this regard, we proposed a new mathematical framework for generating integrated drought index for meteorological drought monitoring. The geographically weighted regression (GWR) model and principal component analysis were used to composite Moderate-resolution Imaging Spectroradiometer (MODIS) based temperature condition index (TCI), the Vegetation Index based on the Universal Pattern Decomposition method (VIUPD) based vegetation condition index (VCI), tropical rainfall measuring mission (TRMM) based Precipitation Condition Index (PCI) and Advanced Microwave Scanning Radiometer-EOS (AMSR-E) based soil moisture condition index (SMCI). We called the new remote-sensing-based integrated drought index geographical-location-based integrated drought index (GLIDI). We examined the utility of the GLIDI for drought monitoring in various climate divisions across the continental United States (CONUS). GLIDI showed high correlations with in-situ drought indices and outperformed most other existing drought indices. The results also indicate that the performance of GLIDI is not affected by environmental factors such as land cover, precipitation, temperature and soil conditions. As such, the GLIDI has considerable potential for

  17. A study of 2014 record drought in India with CFSv2 model: role of water vapor transport

    KAUST Repository

    Ramakrishna, S. S. V. S.; Brahmananda Rao, V.; Srinivasa Rao, B. R.; Hari Prasad, D.; Nanaji Rao, N.; Panda, Roshmitha

    2016-01-01

    The Indian summer monsoon season of 2014 was erratic and ended up with a seasonal rainfall deficit of 12 % and a record drought in June. In this study we analyze the moisture transport characteristics for the monsoon season of 2014 using both NCEP FNL reanalysis (FNL) and CFSv2 (CFS) model data. In FNL, in June 2014 there was a large area of divergence of moisture flux. In other months also there was lesser flux. This probably is the cause of 2014 drought. The CFS model overestimated the drought and it reproduces poorly the observed rainfall over central India (65E–95E; 5N–35N). The correlation coefficient (CC) between the IMD observed rainfall and CFS model rainfall is only 0.1 while the CC between rainfall and moisture flux convergence in CFS model is only 0.20 and with FNL data −0.78. This clearly shows that the CFS model has serious difficulty in reproducing the moisture flux convergence and rainfall. We found that the rainfall variations are strongly related to the moisture convergence or divergence. The hypothesis of Krishnamurti et al. (J Atmos Sci 67:3423–3441, 2010) namely the intrusion of west African desert air and the associated low convective available potential energy inhibiting convection and rainfall shows some promise to explain dry spells in Indian summer monsoon. However, the rainfall or lack of it is mainly explained by convergence or divergence of moisture flux. © 2016 Springer-Verlag Berlin Heidelberg

  18. A study of 2014 record drought in India with CFSv2 model: role of water vapor transport

    KAUST Repository

    Ramakrishna, S. S. V. S.

    2016-09-16

    The Indian summer monsoon season of 2014 was erratic and ended up with a seasonal rainfall deficit of 12 % and a record drought in June. In this study we analyze the moisture transport characteristics for the monsoon season of 2014 using both NCEP FNL reanalysis (FNL) and CFSv2 (CFS) model data. In FNL, in June 2014 there was a large area of divergence of moisture flux. In other months also there was lesser flux. This probably is the cause of 2014 drought. The CFS model overestimated the drought and it reproduces poorly the observed rainfall over central India (65E–95E; 5N–35N). The correlation coefficient (CC) between the IMD observed rainfall and CFS model rainfall is only 0.1 while the CC between rainfall and moisture flux convergence in CFS model is only 0.20 and with FNL data −0.78. This clearly shows that the CFS model has serious difficulty in reproducing the moisture flux convergence and rainfall. We found that the rainfall variations are strongly related to the moisture convergence or divergence. The hypothesis of Krishnamurti et al. (J Atmos Sci 67:3423–3441, 2010) namely the intrusion of west African desert air and the associated low convective available potential energy inhibiting convection and rainfall shows some promise to explain dry spells in Indian summer monsoon. However, the rainfall or lack of it is mainly explained by convergence or divergence of moisture flux. © 2016 Springer-Verlag Berlin Heidelberg

  19. Influence of drought conditions on brown trout biomass and size structure in the Black Hills, South Dakota

    Science.gov (United States)

    James, Daniel A.; Wilhite, Jerry W.; Chipps, Steven R.

    2010-01-01

    We evaluated the influence of drought conditions on the biomass of brown trout Salmo trutta in Spearfish Creek, upper Rapid Creek, and lower Rapid Creek in the Black Hills of western South Dakota. Stream discharge, mean summer water temperature, the biomass of juvenile and adult brown trout, and brown trout size structure were compared between two time periods: early (2000–2002) and late drought (2005–2007). Mean summer water temperatures were similar between the early- and late-drought periods in Spearfish Creek (12.4°C versus 11.5°C), lower Rapid Creek (19.2°C versus 19.3°C), and upper Rapid Creek (9.8°C in both periods). In contrast, mean annual discharge differed significantly between the two time periods in Spearfish Creek (1.95 versus 1.50 m3/s), lower Rapid Creek (2.01 versus 0.94 m3/s), and upper Rapid Creek (1.41 versus 0.84 m3/s). The mean biomass of adult brown trout in all three stream sections was significantly higher in the early-drought than in the late-drought period (238 versus 69 kg/ha in Spearfish Creek, 272 versus 91 kg/ha in lower Rapid Creek, and 159 versus 32 kg/ha in upper Rapid Creek). The biomass of juvenile brown trout was similar (43 versus 23 kg/ha) in Spearfish Creek in the two periods, declined from 136 to 45 kg/ha in lower Rapid Creek, and increased from 14 to 73 kg/ha in upper Rapid Creek. Size structure did not differ between the early- and late-drought periods in lower Rapid and Spearfish creeks, but it did in upper Rapid Creek. In addition to drought conditions, factors such as angler harvest, fish movements, and the nuisance algal species Didymosphenia geminata are discussed as possible contributors to the observed changes in brown trout biomass and size structure in Black Hills streams.

  20. Candidate genes for drought tolerance and improved productivity in ...

    Indian Academy of Sciences (India)

    Madhu

    tropics. Improving drought tolerance and productivity is one of the most difficult tasks for cereal breeders. The diffi- culty arises from the diverse strategies adopted by plants themselves to combat drought stress depending on the timing,. Candidate genes for drought tolerance and improved productivity in rice (Oryza sativa L.).

  1. Hydrological drought and wildfire in the humid tropics

    NARCIS (Netherlands)

    Taufik, Muh

    2017-01-01

    Drought is a recurrent hazard, which has happened throughout human history, and it is anticipated to become more severe in multiple regions across the world. Drought occurs in all climate regimes from humid to dry and from hot to cold. Drought is often viewed through its impact on environment and

  2. Assessing Impacts of National Scale Droughts on Cereal Production

    Science.gov (United States)

    Udmale, P. D.; Ichikawa, Y.

    2017-12-01

    Till date, several drought indices have been developed and used to monitor local to regional scale droughts on various temporal scales. However, there are no generalized criteria to define a threshold to declare a national level drought using drought indices. EM-DAT (a global database on natural and technological disasters) lists disasters (including drought) from 1900 until the present confirming one of the following criteria: 10 or more people dead; 100 or more people affected; the declaration of a state of emergency; or a call for international assistance. This data is gathered from various organizations like United Nations Institutes, Governments, etc. and do not cover all disasters or have political limitations that could affect the numbers. These criteria are neither objective nor quantitative, and accordingly may cause uncertainties when the data is used for further investigation on disaster impacts. Here we present a methodology to define drought at a national scale and its impacts on national level crop production (mainly cereals). We define drought based on the percentage of cropland area affected by drought in a country during its seasonal rainfall. For this purpose meteorological definition of drought in combination with country's cropland area is proposed to prepare a drought inventory for major cereal producing countries (1902-2012). This drought inventory together with FAO's Crop data is used to identify the impacts of drought on a national level cereal production (and yield) using Superposed Epoch Analysis for the period 1961-2012.

  3. Evaluation of drought tolerance indices among some winter ...

    African Journals Online (AJOL)

    The main purpose of this study was to evaluate the effect of drought stress on seed yield of some winter rapeseed cultivars and to study relevant drought tolerance indices, along with identifying resistant cultivars to drought stress. Plant materials were sown in split plot arrangement based on a randomized complete blocks ...

  4. Isolation and characterization of some drought-related ESTs from ...

    African Journals Online (AJOL)

    Drought is one of the main constraints facing crops and affecting their production. In a trial to investigate and understand drought effect, differential display experiments were performed where; about 107 DD-fragments have been isolated from wild barley plants subjected to drought treatment. These fragments were ...

  5. Potentials of molecular based breeding to enhance drought ...

    African Journals Online (AJOL)

    The ability of plant to sustain itself in limited water conditions is crucial in the world of agriculture. To breed for drought tolerance in wheat, it is essential to clearly understand drought tolerant mechanisms. Conventional breeding is time consuming and labor intensive being inefficient with low heritability traits like drought ...

  6. Transformation of a savanna grassland by drought and grazing | O ...

    African Journals Online (AJOL)

    The relative effects of drought and heavy grazing on the floristic composition, population size and and structure, and basal cover of an African savanna grassland were differentiated by comparing changes over eight years over eight years, which included a severe drought year, across a gradient of grazing history. Drought ...

  7. Molecular markers for drought tolerance in bread wheat

    African Journals Online (AJOL)

    aghomotsegin

    2013-05-22

    May 22, 2013 ... Molecular markers for drought tolerance in bread wheat. Tharwat El Ameen. Department of Genetics, South Valley University, Qena, 83523, Egypt. Accepted 3 May, 2013. Random amplified polymorphic DNA (RAPD) primers associated with drought tolerance was used in this study to characterize drought ...

  8. An impact perspective on pan-European drought sensitivity

    NARCIS (Netherlands)

    Stahl, K.; Kohn, I.; Stefano, De L.; Tallaksen, L.M.; Rego, F.C.; Seneviratne, S.I.; Andreu, J.; Lanen, van H.A.J.

    2015-01-01

    In the past decades, Europe experienced several severe drought events with diverse environmental and socio-economic impacts. The EU FP-7 project DROUGHT R&SPI has investigated past drought impacts across different European countries and geoclimatic regions based on different approaches:

  9. An improved method for standardized mapping of drought conditions

    Science.gov (United States)

    Frank H. Koch; William D. Smith; John W. Coulston

    2013-01-01

    Virtually all U.S. forests experience droughts, although the intensity and frequency of the droughts vary widely between, as well as, within forest ecosystems (Hanson and Weltzin 2000). Generally, forests throughout the Western United States are subject to annual seasonal droughts, while forests in the Eastern United States can be characterized by one of two...

  10. The U.S./Canadian GEO Bilateral Drought Indices and Definitions Study: Implications for the Canadian Drought Monitor and a Global Drought Early Warning System

    Science.gov (United States)

    Hadwen, T.; Heim, R. R.; Howard, A.

    2011-12-01

    Drought is a difficult phenomenon to define; the way in which it is monitored, measured, assessed and even the very definition of drought vary from location to location based on the regional climate and the potential impacts. Drought is not an absolute condition but an evolving state brought on by relatively dry weather, growing more severe over time. There are many factors that define a drought and many more that define its impacts. Many definitions and indices are based solely on meteorological characteristics. Although this approach has merit, it is often necessary to go further to define those meteorological conditions in a way that is relevant to the land and water use in a region. A Drought Indices and Definitions Study was initiated in 2010 as part of a GEO Bilateral effort to examine drought across the U.S. and Canada. The Study's deliverables will include a survey of the drought indices used to monitor drought, and a bibliography of research addressing the nature of drought, across the diverse climates of the continent. With an increasing pressure to utilize drought monitoring as a primary indicator of need for disaster assistance, the reliability of drought indices must be validated and utilized in appropriate in various regions. In 2009, following over five years of participation in the North American Drought Monitor (NA-DM), the National Agroclimate Information Service of Agriculture and Agri-Food Canada initiated a project to develop a Canadian Drought Monitor (Can-DM), based on primary principles used in the NA-DM and the US Drought Monitor (US-DM). The process of developing an operational monitoring tool and using drought indices in a vast and environmentally diverse country has been challenging. in Canada, many of the commonly used indices are not appropriate in certain regions or data densities do not allow for proper use. This paper will discuss the experiences that the Can-DM team has had dealing with these challenges, how these experiences

  11. Long-term summer sunshine/moisture stress reconstruction from tree-ring widths from Bosnia and Herzegovina

    Directory of Open Access Journals (Sweden)

    S. Poljanšek

    2013-01-01

    Full Text Available We present the first summer sunshine reconstruction from tree-ring data for the western part of the Balkan Peninsula. Summer sunshine is tightly connected with moisture stress in trees, because the moisture stress and therefore the width of annual tree-rings is under the influence of the direct and interactive effects of sunshine duration (temperature, precipitation, cloud cover and evapotranspiration. The reconstruction is based on a calibrated z-scored mean chronology, calculated from tree-ring width measurements from 7 representative black pine (Pinus nigra Arnold sites in Bosnia and Herzegovina (BiH. A combined regression and scaling approach was used for the reconstruction of the summer sunshine. We found a significant negative correlation (r = −0.54, p < 0.0001 with mean June–July sunshine hours from Osijek meteorological station (Croatia. The developed model was used for reconstruction of summer sunshine for the time period 1660–2010. We identified extreme summer events and compared them to available documentary historical sources of drought, volcanic eruptions and other reconstructions from the broader region. All extreme summers with low sunshine hours (1712, 1810, 1815, 1843, 1899 and 1966 are connected with volcanic eruptions.

  12. A Comprehensive Study of Agricultural Drought Resistance and Background Drought Levels in Five Main Grain-Producing Regions of China

    OpenAIRE

    Lei Kang; Hongqi Zhang

    2016-01-01

    Drought control and resistance affect national food security. With this in mind, we studied five main grain-producing regions of China: Sanjiang Plain, Songnen Plain, Huang-Huai-Hai Plain, the middle Yangtze River and Jianghuai region and Sichuan Basin. Using GIS technology, we evaluated the comprehensive agricultural drought situation based on major crops, the basic drought resistance by integrating multiple indicators and the comprehensive drought resistance against background agricultural ...

  13. The transcriptional regulatory network in the drought response and its crosstalk in abiotic stress responses including drought, cold, and heat

    OpenAIRE

    Nakashima, Kazuo; Yamaguchi-Shinozaki, Kazuko; Shinozaki, Kazuo

    2014-01-01

    Drought negatively impacts plant growth and the productivity of crops around the world. Understanding the molecular mechanisms in the drought response is important for improvement of drought tolerance using molecular techniques. In plants, abscisic acid (ABA) is accumula