Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Inherent trait differences explain wheat cultivar responses to climate factor interactions: New insights for more robust crop modelling
    Eller, Franziska ; Hyldgaard, Benita ; Driever, Steven M. ; Ottosen, Carl Otto - \ 2020
    Global Change Biology 26 (2020)10. - ISSN 1354-1013 - p. 5965 - 5978.
    climate change - climatic factor interactions - crop modelling - elevated CO - Gladius - Paragon - temperature - water availability

    Climate change predictions foresee a combination of rising CO2, temperature and altered precipitation. Effects of single climatic variables are well defined, but the importance of combined variables and genotypic effects is less known, although pivotal for assessing climate change impacts, for example, with crop growth models. This study provides developmental and physiological data from combined climatic factors for two distinct wheat cultivars (Paragon and Gladius), as a basis to improve predictions for climate change scenarios. The two cultivars were grown in controlled climate chambers in a fully factorial setup of atmospheric CO2 concentration, growth temperature and watering regime. The cultivars differed considerably in their developmental rate, response pattern and the parameters responsible for most of their variation. The growth of Paragon was linked to climatic effects on photosynthesis and mainly affected by temperature. Paragon was overall more negatively affected by all treatment combinations compared to Gladius. Gladius was mostly affected by watering regime. The cultivars' acclimation strategies to climate factors varied significantly. Thus, considering a single factor is an oversimplification very likely impacting the accuracy of crop growth models. Intraspecific crop variation could help understanding genotype by environment variation. Cultivars with high phenotypic plasticity may have greater resilience against climatic variability.

    High species diversity and turnover in granite inselberg floras highlight the need for a conservation strategy protecting many outcrops
    Yates, Colin J. ; Robinson, Todd ; Wardell-Johnson, Grant W. ; Keppel, Gunnar ; Hopper, Stephen D. ; Schut, Antonius G.T. ; Byrne, Margaret - \ 2019
    Ecology and Evolution 9 (2019)13. - ISSN 2045-7758 - p. 7660 - 7675.
    beta diversity - conservation strategy - generalized dissimilarity modeling - granite inselbergs - OCBIL theory - rock outcrops - species turnover - water availability

    Determining patterns of plant diversity on granite inselbergs is an important task for conservation biogeography due to mounting threats. However, beyond the tropics there are relatively few quantitative studies of floristic diversity, or consideration of these patterns and their environmental, biogeographic, and historical correlates for conservation. We sought to contribute broader understanding of global patterns of species diversity on granite inselbergs and inform biodiversity conservation in the globally significant Southwest Australian Floristic Region (SWAFR). We surveyed floristics from 16 inselbergs (478 plots) across the climate gradient of the SWAFR stratified into three major habitats on each outcrop. We recorded 1,060 species from 92 families. At the plot level, local soil and topographic variables affecting aridity were correlated with species richness in herbaceous (HO) and woody vegetation (WO) of soil-filled depressions, but not in woody vegetation on deeper soils at the base of outcrops (WOB). At the outcrop level, bioclimatic variables affecting aridity were correlated with species richness in two habitats (WO and WOB) but, contrary to predictions from island biogeography, were not correlated with inselberg area and isolation in any of the three habitats. Species turnover in each of the three habitats was also influenced by aridity, being correlated with bioclimatic variables and with interplot geographic distance, and for HO and WO habitats with local site variables. At the outcrop level, species replacement was the dominant component of species turnover in each of the three habitats, consistent with expectations for long-term stable landscapes. Our results therefore highlight high species diversity and turnover associated with granite outcrop flora. Hence, effective conservation strategies will need to focus on protecting multiple inselbergs across the entire climate gradient of the region.

    Learn how to calculate the water balance. Part 1 | WURcast
    Dijksma, R. - \ 2017
    Wageningen : WURcast
    water balance - water availability
    Safeguarding water availability for food and ecosystems under global change : modelling and assessment of the role of environmental flows
    Pastor, Amandine V. - \ 2017
    Wageningen University. Promotor(en): P. Kabat, co-promotor(en): F. Ludwig; H. Biemans. - Wageningen : Wageningen University - ISBN 9789463431767 - 177
    water availability - water management - flow - water deficit - food security - food production - global warming - aquatic ecosystems - waterbeschikbaarheid - waterbeheer - stroming - watertekort - voedselzekerheid - voedselproductie - opwarming van de aarde - aquatische ecosystemen

    In a context of future population increase and intensification of water cycle by climate change, water demand for irrigation is projected to double. However, freshwater resources have been degraded the last decades especially in rivers via fragmentation, dam contraction and pollution. Flow alteration and degradation lead to 80% of freshwater ecosystem species loss. In this thesis, a robust and reliable Environmental Flow (EF) method was developed for global scale: the Variable Monthly Flow (VMF) method. This method allowed estimating EF deficit at global scale including its origin, timing, frequency and magnitude. By setting EFRs as priority user in a global vegetation and hydrological model (LPJmL), irrigation loss due to EFRs implementation were assessed at 30% leading to 5% global calorie loss. To maintain water allocation to humans and ecosystems under global change, food imports would require to increase by 15% especially from Latin America to South of Asia.

    Effect of water harvesting techniques on hydrological processes and sediment yield in Northern Ethiopia
    Woldegiorgis, Berhane Grum - \ 2017
    Wageningen University. Promotor(en): V. Geissen; C.J. Ritsema, co-promotor(en): R. Hessel; C.A. Kessler. - Wageningen : Wageningen University - ISBN 9789463431682 - 156
    hydrology - water harvesting - arid zones - semiarid zones - water availability - ethiopia - hydrologie - regenwateropvang - aride klimaatzones - semi-aride klimaatzones - waterbeschikbaarheid - ethiopië

    The study was conducted in the semi-arid northern Ethiopia aimed at selecting appropriate water harvesting techniques (WHTs) for implementation. A plot-scale experiment was set up, in the Gule catchment, on a farmland to monitor the effect of in-situ WHTs such as tied ridges and straw mulch mainly on event-based runoff, soil-moisture, and soil and nutrient losses. The off-site effect of WHTs such as check dams and percolation ponds on catchment-scale event-based runoff and sediment yield was also monitored in the Gule catchment (~12 km2) and Misbar sub-catchment (~2.4 km2), northern Ethiopia. First, a decision support approach was developed to aid the selection of WHTs in arid and semi-arid areas. The decision support approach was validated with a case study for WHTs in the upper Geba watershed in northern Ethiopia. Using the decision support methodology, eight potential WHTs were pre-selected for implementation in the watershed. Next, using suitability indicators for WHTs and a GIS-based multi-criteria analysis, suitable areas were identified for three of these WHTs, namely check dams, percolation ponds and bench terraces and suitability maps were generated. The multi-criteria analysis was validated by comparing the predicted suitable areas with the already existing locations of WHTs in the watershed. The result was that 90% of the existing check dams and 93% of the percolation ponds in the upper Geba watershed were correctly identified by the approach. The field study showed runoff reduction by WHTs from farmland between 40 to 88% and soil loss between 60 to 90%. Nutrient loss reduction from farmland by WHTs also ranged between 52 and 86%. Soil-moisture also improved due to the use of the in-situ WHTs. Model-based simulation at the Gule and Misbar outlets using LISEM showed that the current WHTs applied in the catchment are able to decrease event-based runoff by 41 and 45%, respectively. Similarly, sediment yield was reduced at both the Gule outlet and Misbar sub-outlet, by 67 and 55%, respectively. This study has verified that in semi-arid areas, such as the northern Ethiopian highlands, in-situ and catchment-scale WHTs can be used to improve the efficiency of rainwater harvesting and water availability for agricultural uses. Furthermore, these WHTs help to mitigate land degradation by decreasing soil and nutrient losses from farmland and sediment yield from catchments.

    South-South cooperation: Brazilian soy diplomacy looking East?
    Warner, J.F. - \ 2015
    Food Security 7 (2015)6. - ISSN 1876-4517 - p. 1175 - 1185.
    water availability - virtual water - oligopoly - soybean
    Ever since the food price crisis of 2007/8, concerns about global food supply interruptions have mounted. However, while exports from Brazil, the world’s leading soy exporter, are currently under threat, this is not due to geopolitical concerns, but due to resource mismanagement. As a consequence, the country with the most water availability per person is mired in an enduring water crisis, impacting on its major water transport routes. Brazil’s development model is based on an oligopolistic public-private, primary-sector conglomerate, fueled by the federal investment bank, BNDES. This article argues that Brazil has embarked on an unsustainable model of development and is exporting that model as part of its ‘South-South Cooperation’ (SSC) drive. Like the other BRICS, Brazil is using SSC to present itself as non-ideological and anti-imperialist but, in fact, uses the cooperation strategy for diplomatic and self-interested economic purposes. The Middle East is specifically targeted as a region with ‘complementary’ interests: rich in fossil fuels, poor in land and water and plenty of petrodollars to buy food security. The current water crisis shows limits to this complementarity, in the process undermining the assumption that ‘virtual-water exports’ promoted by competitive specialization are salutary to the global water balance.
    Verse groenten produceren in de woestijn
    Campen, J.B. - \ 2015
    Kas techniek 2015 (2015)oktober. - p. 16 - 18.
    tuinbouw - glastuinbouw - kastechniek - groenteteelt - midden-oosten - onderzoeksprojecten - voedselproductie - agrarische productiesystemen - teelt onder bescherming - waterbeschikbaarheid - klimaat - horticulture - greenhouse horticulture - greenhouse technology - vegetable growing - middle east - research projects - food production - agricultural production systems - protected cultivation - water availability - climate
    Voedselzekerheid en voedselveiligheid staan hoog op de agenda in het Midden-Oosten sinds de voedselcrisis in 2007-2008. Voedsel wordt voor een groot deel geïmporteerd uit omliggende landen, maar ook uit Nederland. Vooral in de zomermaanden zijn de prijzen van versproducten in deze landen hoog, omdat er dan weinig in de regio zelf wordt geproduceerd. Vanwege de hoge prijzen en de lage kwaliteit van producten uit omliggende landen zijn er verschillende programma’s gestart om het productiesysteem te verbeteren. Hierbij is ook veel aandacht voor waterbesparing, aangezien water een zeer schaars product is in een groot deel van deze regio.
    Water productivity of sunflower under different irrigation regimes on Gezira clay soil, Sudan
    Elsheikh, E.R.A. - \ 2015
    Wageningen University. Promotor(en): E. Schultz, co-promotor(en): H.S. Adam; A.M. Haile. - Leiden : CRC Press/Balkema - ISBN 9781138029149 - 162
    helianthus annuus - zonnebloemen - irrigatie - irrigatiesystemen - watergebruik - waterbeschikbaarheid - sudan - helianthus annuus - sunflowers - irrigation - irrigation systems - water use - water availability - sudan

    PhD candidate: Eman Rahamtalla Ahmed Elsheikh

    Department of Water Science and Engineering

    Chair Group Land and Water Development

    UNESCO-IHE institute for water education

    Westvest 7, Delft

    Sunflower has become an important crop for both farmers and consumers in Sudan. It is a crop that fits well in the local cropping system and is considered one of the most important oil crops of the country. Regular irrigation intervals could be reduced in order to increase total yield and maximize water productivity. In contrast prolonged irrigation intervals during sensitive growth stages may result in reduction in total yield. The application of water below the evapotranspiration requirements is termed deficit irrigation (DI). The experiments were conducted at Gezira Research Station Farm, WadMedani, Sudan, in a randomized complete block design with three replications. In this study irrigation intervals every week during the whole growing period, 10, 15 and 20 days intervals after flowering stage and 10, 15 and 20 days intervals after the seed filling stage were applied to study the effect of full and deficit irrigation on yield and yield components of sunflower during the two growing periods 2011/2012 and 2012/2013. Results showed that water stress decreased the number of filled seeds per head, weight of full seed and seed yield. The highest seed yield of (3130 and 3140 kg/ha) was obtained from the full irrigation treatment and the lowest seed yield of 2082 and 2130 kg/ha was obtained from irrigation every 20 days after the flowering stage in the first and second season respectively. Results indicated that there were no-significant differences on head diameter, plant height and stem diameter when the water deficit occurred after the flowering stage. Lower water productivity of 0.21-0.26 and 0.21-0.27 kg/m3 were obtained when sunflower was irrigated every 20 days after the flowering and seed filling stages in the first and second season respectively. Results revealed that water productivity was low under Gezira conditions.

    In addition, the  AquaCrop model was used to simulate seed yield and water productivity under different irrigation strategies. AquaCrop simulated seed yield accuratley with a root mean square error (RMSE) that ranged between 0.01 and 0.12 t/ha and 0.04 to 0.16 t/ha for the sunflower varieties Hysun 33 and Bohooth-1 respectively. The corresponding values of d-index of agreement ranged between 0.89 - 0.99 and 0.92-0.99 respectivley in 2012 and 2013. Results revealed that the AquaCrop model can be adequately applied to simulate seed yield response to water deficit and to explore the best irrigation stratgies that can maximize yield under current climatic conditions.

     

     

    Environmental changes drive the temporal stability of semi-arid natural grasslands through altering species asynchrony
    Xu, Z. ; Ren, H. ; Li, M.H. ; Ruijven, J. van; Han, X. ; Wan, S. ; Li, H. ; Yu, Q. ; Jiang, Y. ; Jiang, L. - \ 2015
    Journal of Ecology 103 (2015)5. - ISSN 0022-0477 - p. 1308 - 1316.
    nitrogen addition - statistical inevitability - competitive communities - ecosystem stability - water availability - plant diversity - inner-mongolia - biodiversity - productivity - precipitation
    1.Stability is an important property of ecological systems, many of which are experiencing increasing levels of anthropogenic environmental changes. However, how these environmental changes influence ecosystem stability remains poorly understood. 2.We conducted an 8-year field experiment in a semi-arid natural grassland to explore the effects of two common environmental changes, precipitation and nitrogen enrichment, on the temporal stability of plant above-ground biomass. A split-plot design, with precipitation as the main plot factor and nitrogen as the subplot factor, was used. Temporal stability was related to potential explanatory abiotic and biotic variables using regressions and structural equation modelling. 3.Increase in growing season precipitation enhanced plant species richness and promoted temporal stability of plant above-ground biomass. Nitrogen fertilization, however, reduced both plant species richness and temporal stability of plant above-ground biomass. Contrary to expectations, species richness was not an important driver of stability. Instead, community temporal stability was mainly driven by water and nitrogen availability that modulated the degree of species asynchrony and, to a lesser extent, by the stability of dominant plant species. 4.Synthesis. Our results highlight the importance of limiting resources for regulating community biomass stability and suggest that the projected increase in growing season precipitation may potentially offset negative effects of increased atmospheric nitrogen deposition on species diversity and community stability in semi-arid grasslands.
    The urban harvest approach as framework and planning tool for improved water and resource cycles
    Leusbrock, I. ; Nanninga, T.A. ; Lieberg, K. ; Agudelo, C. ; Keesman, K.J. ; Zeeman, G. ; Rijnaarts, H. - \ 2015
    Water Science and Technology 72 (2015)6. - ISSN 0273-1223 - p. 998 - 1006.
    waterbeschikbaarheid - waterbeheer - hulpbronnenbeheer - innovaties - urbanisatie - afvalwater - watergebruik - waterzekerheid - hulpbronnenbehoud - waterbescherming - stedelijke gebieden - water availability - water management - resource management - innovations - urbanization - waste water - water use - water security - resource conservation - water conservation - urban areas
    Water and resource availability in sufficient quantity and quality for anthropogenic needs represents one of the main challenges in the coming decades. To prepare for upcoming challenges such as increased urbanization and climate change related consequences, innovative and improved resource management concepts are indispensable. In recent years we have developed and applied the Urban Harvest Approach (UHA). The UHA proposes to model and quantify the urban water cycle on different temporal and spatial scales. This approach allowed us to quantify the impact of the implementation of water saving measures and new water treatment concepts in cities. In this paper we will introduce the UHA and present for urban water cycles. Furthermore, we will show first results for an extension to energy cycles and highlight future research items (e.g., nutrients, water-energy-nexus). Key words | Resource cycles, Water management, Water-Energy Nexus, Decision-Support
    River flow regime and snow cover of the Pamir Alay (Central Asia) in a changing climate
    Chevallier, P. ; Pouyaud, B. ; Mojaisky, M. ; Bolgov, M. ; Olsson, O. ; Bauer, M. ; Froebrich, J. - \ 2014
    Hydrological Sciences Journal 59 (2014)8. - ISSN 0262-6667 - p. 1491 - 1506.
    remote-sensing data - northern tien-shan - hydrological regime - water availability - glacier retreat - historical data - stereo imagery - aster imagery - mass balances - runoff
    The Vakhsh and Pyandj rivers, main tributaries of the Amu Darya River in the mountainous region of the Pamir Alay, play an important role in the water resources of the Aral Sea basin (Central Asia). In this region, the glaciers and snow cover significantly influence the water cycle and flow regime, which could be strongly modified by climate change. The present study, part of a project funded by the European Commission, analyses the hydrological situation in six benchmark basins covering areas of between 1800 and 8400km(2), essentially located in Tajikistan, with a variety of topographical situations, precipitation amounts and glacierized areas. Four types of parameter are discussed: temperature, glaciation, snow cover and river flows. The study is based mainly on a long-time series that ended in the 1990s (with the collapse of the Soviet Union) and on field observations and data collection. In addition, a short, more recent period (May 2000 to May 2002) was examined to better understand the role of snow cover, using scarce monitored data and satellite information. The results confirm the overall homogeneous trend of temperature increase in the mountain range and its impacts on the surface water regime. Concerning the snow cover, significant differences are noted in the location, elevation, orientation and morphology of snow cover in the respective basins. The changes in the river flow regime are regulated by the combination of the snow cover dynamics and the increasing trend of the air temperature.
    Growth adjustments of conifers to drought and to century-long irrigation
    Feichtinger, L.M. ; Eilmann, B. ; Buchmann, N. ; Rigling, A. - \ 2014
    Forest Ecology and Management 334 (2014). - ISSN 0378-1127 - p. 96 - 105.
    scots pine stands - water availability - climate-change - terrestrial ecosystems - wood formation - radial growth - tree-growth - ring width - sylvestris - mortality
    Our knowledge on tree responses to drought is mainly based on short-term manipulation experiments which do not capture any possible long-term adjustments in this response. Therefore, historical water channels in inner-Alpine dry valleys were used as century-long irrigation experiments to investigate adjustments in tree growth to contrasting water supply. This involved quantifying the tree-ring growth of irrigated and non-irrigated (control) Scots pine (Pinus sylvestris L.) in Valais (Switzerland), as well as European larch (Larix decidua Mill.) and black pine (Pinus nigra Arnold) in Vinschgau (Italy). Furthermore, the adjustments in radial growth of Scots pine and European larch to an abrupt stop in irrigation were analyzed. Irrigation promoted the radial growth of all tree species investigated compared to the control: (1) directly through increased soil water availability, and (2) indirectly through increased soil nutrients and humus contents in the irrigated plots. Irrigation led to a full elimination of growth responses to climate for European larch and black pine, but not for Scots pine, which might become more sensitive to drought with increasing tree size in Valais. For the control trees, the response of the latewood increment to water availability in July/August has decreased in recent decades for all species, but increased in May for Scots pine only. The sudden irrigation stop caused a drop in radial growth to a lower level for Scots pine or similar level for larch compared to the control for up to ten years. However, both tree species were then able to adjust to the new conditions and subsequently grew with similar (Scots pine) or even higher growth rates(larch) than the control. To estimate the impact of climate change on future forest development, the duration of manipulation experiments should be on longer time scales in order to capture adjustment processes and feedback mechanisms of forest ecosystems. (C) 2014 Published by Elsevier B.V.
    A new and scalable approach for rural sanitation in Egypt : the village of Deir Gabal El-Tair as a pilot
    Harmsen, J. ; Ghodell, K.O. ; Tony, M.S.S.S. El; Wagieh, H. El; Michael, E. ; Helmy, E. ; Veen, F. van der - \ 2014
    Wageningen : Alterra, Wageningen-UR (Alterra-rapport 2584) - 81
    volksgezondheidsbevordering - water - waterbeschikbaarheid - egypte - sanitation - water - water availability - egypt
    Coupling socio-economic factors and eco-hydrological processes using a cascade-modeling approach
    Odongo, V.O. ; Mulatu, D.W. ; Muthoni, F.K. ; Oel, P.R. van; Meins, F.M. ; Tol, C. van der; Skidmore, A.K. ; Groen, T.A. ; Becht, R. ; Onyando, J.O. ; Veen, A. van der - \ 2014
    Journal of Hydrology 518 (2014)Part A. - ISSN 0022-1694 - p. 49 - 59.
    land-use change - murray-darling basin - lake naivasha - population-dynamics - water availability - stream ecosystems - human impact - east-africa - kenya - rainfall
    Most hydrological studies do not account for the socio-economic influences on eco-hydrological processes. However, socio-economic developments often change the water balance substantially and are highly relevant in understanding changes in hydrological responses. In this study a multi-disciplinary approach was used to study the cascading impacts of socio-economic drivers of land use and land cover (LULC) changes on the eco-hydrological regime of the Lake Naivasha Basin. The basin has recently experienced substantial LULC changes exacerbated by socio-economic drivers. The simplified cascade models provided insights for an improved understanding of the socio-ecohydrological system. Results show that the upstream population has transformed LULC such that runoff during the period 1986–2010 was 32% higher than during the period 1961–1985. Cut-flower export volumes and downstream population growth explain 71% of the water abstracted from Lake Naivasha. The influence of upstream population on LULC and upstream hydrological processes explained 59% and 30% of the variance in lake storage volumes and sediment yield respectively. The downstream LULC changes had significant impact on large wild herbivore mammal species on the fringe zone of the lake. This study shows that, in cases where observed socio-economic developments are substantial, the use of a cascade-modeling approach, that couple socio-economic factors to eco-hydrological processes, can greatly improve our understanding of the eco-hydrological processes of a catchment.
    Explaining Bacterial Dispersion on Leaf Surfaces with an Individual-Based Model (PHYLLOSIM)
    Wal, A. van der; Tecon, R. ; Kreft, J.U. ; Mooij, W.M. ; Leveau, J.H.J. - \ 2013
    PLoS ONE 8 (2013)10. - ISSN 1932-6203
    plant-microbe interactions - pseudomonas-syringae - biofilm formation - water availability - growth - detachment - diffusion - motility - colonization - wettability
    We developed the individual-based model PHYLLOSIM to explain observed variation in the size of bacterial clusters on plant leaf surfaces (the phyllosphere). Specifically, we tested how different 'waterscapes' impacted the diffusion of nutrients from the leaf interior to the surface and the growth of individual bacteria on these nutrients. In the 'null' model or more complex 'patchy' models, the surface was covered with a continuous water film or with water drops of equal or different volumes, respectively. While these models predicted the growth of individual bacterial immigrants into clusters of variable sizes, they were unable to reproduce experimentally derived, previously published patterns of dispersion which were characterized by a much larger variation in cluster sizes and a disproportionate occurrence of clusters consisting of only one or two bacteria. The fit of model predictions to experimental data was about equally poor (
    Water en teeltsystemen : zorg voor goed water
    Werd, Rik de - \ 2013
    horticulture - cultural methods - water quality - water availability - emission - water treatment - risk factors - irrigation water
    Snowmelt contributions to discharge of the Ganges
    Siderius, C. ; Biemans, H. ; Wilthshire, A. ; Rao, S. ; Franssen, W.H.P. ; Kumar, P. ; Gosain, A.K. ; Vliet, A. van; Collins, D.N. - \ 2013
    Science of the Total Environment 468-469 (2013)Suppl.. - ISSN 0048-9697 - p. S93 - S101.
    climate-change - water availability - glaciers - hydrology - balance - basins - runoff - india
    Himalayan headwaters supply large quantities of runoff derived from snowmelt and monsoon rainfall to the Ganges River. Actual snowmelt contribution to discharge in the Ganges remains conjectural under both present and future climatic conditions. As snowmelt is likely to be perturbed through climatic warming, four hydrological models, VIC, JULES, LPJmL and SWAT, appropriate for coupling with regional climate models, were used to provide a baseline estimate of snowmelt contribution to flow at seasonal and annual timescales. The models constrain estimates of snowmelt contributions to between 1% and 5% of overall basin runoff. Snowmelt is, however, significant in spring months, a period in which other sources of runoff are scarce
    Hydrological drought across the world: impact of climate and physical catchment structure
    Lanen, H.A.J. van; Wanders, N. ; Tallaksen, L.M. ; Loon, A.F. van - \ 2013
    Hydrology and Earth System Sciences 17 (2013)5. - ISSN 1027-5606 - p. 1715 - 1732.
    water availability - european runoff - united-states - groundwater - flow - model - simulations - trends - classification - propagation
    Large-scale hydrological drought studies have demonstrated spatial and temporal patterns in observed trends, and considerable difference exists among global hydrological models in their ability to reproduce these patterns. In this study a controlled modeling experiment has been set up to systematically explore the role of climate and physical catchment structure (soils and groundwater systems) to better understand underlying drought-generating mechanisms. Daily climate data (1958-2001) of 1495 grid cells across the world were selected that represent Koppen-Geiger major climate types. These data were fed into a conceptual hydrological model. Nine realizations of physical catchment structure were defined for each grid cell, i.e., three soils with different soil moisture supply capacity and three groundwater systems (quickly, intermediately and slowly responding). Hydrological drought characteristics (number, duration and standardized deficit volume) were identified from time series of daily discharge. Summary statistics showed that the equatorial and temperate climate types (A-and C-climates) had about twice as many drought events as the arid and polar types (B-and E-climates), and the durations of more extreme droughts were about half the length. Selected soils under permanent grassland were found to have a minor effect on hydrological drought characteristics, whereas groundwater systems had major impact. Groundwater systems strongly controlled the hydrological drought characteristics of all climate types, but particularly those of the wetter A-, C-and D-climates because of higher recharge. The median number of droughts for quickly responding groundwater systems was about three times higher than for slowly responding systems. Groundwater systems substantially affected the duration, particularly of the more extreme drought events. Bivariate probability distributions of drought duration and standardized deficit for combinations of Koppen-Geiger climate, soil and groundwater system showed that the responsiveness of the groundwater system is as important as climate for hydrological drought development. This urges for an improvement of subsurface modules in global hydrological models to be more useful for water resources assessments. A foreseen higher spatial resolution in large-scale models would enable a better hydrogeological parameterization and thus inclusion of lateral flow.
    Opties voor een klimaatbestendige zoetwatervoorziening in Laag Nederland, tussentijds integratierapport
    Jeuken, A. ; Hoogvliet, M. ; Beek, E. van; Baaren, E. van; Duinen, R. ; Veen, A. van der; Linde, A. van der; Delsman, J. ; Pauw, P. ; Oude Essink, G. ; Zee, S. van der; Stofberg, S. ; Appelman, W. ; Cruesen, R. ; Paalman, M. ; Katschnig, D. ; Rozema, J. ; Mens, M. ; Kwakkel, J. ; Veraart, J.A. - \ 2012
    KvK - 86
    watervoorziening - zoet water - waterbeschikbaarheid - landbouwgronden - tuinbouwgronden - natuurgebieden - zelfvoorziening - zelfvoorzieningslandbouw - verzilting - regionale planning - water supply - fresh water - water availability - agricultural soils - horticultural soils - natural areas - self sufficiency - subsistence farming - salinization - regional planning
    Dit rapport geeft een tussentijds overzicht van ‘state of the art’ kennis uit lopend onderzoek van het consortium ‘Climate Proof Fresh Water Supply’ (CPFWS) dat in het kader van het onderzoeksprogramma Kennis voor Klimaat wordt uitgevoerd. De focus van dit onderzoek naar een klimaatbestendige zoetwatervoorziening ligt op lokale en regionale oplossingen in Laag Nederland voor land- en tuinbouw en natuur. De zoetwatervoorziening van dit gebied wordt naast droogte vooral bedreigd door verzilting van grond- en oppervlaktewater. In zes samenhangende werkpakketten wordt geanalyseerd hoe dit gebied meer zelfvoorzienend kan worden én hoe aanpassingen in het (hoofd)watersysteem kunnen bijdragen aan de watervoorziening van het gebied. Centraal in de aanpak zijn een 3-tal casestudies in de Hotspots Haaglanden, Rotterdam Regio en Zuidwestelijke delta.
    Defoliation and gender effects on fitness components in three congeneric and sympatric understorey palms
    Hernández-Barrios, J.C. ; Anten, N.P.R. ; Ackerly, D.D. - \ 2012
    Journal of Ecology 100 (2012)6. - ISSN 0022-0477 - p. 1544 - 1556.
    tropical rain-forest - neotropical dioecious palm - compensatory responses - chamaedorea-radicalis - resource availability - water availability - acer-negundo - leaf harvest - growth - herbivory
    1.Rain forest understorey perennial plants can be frequently exposed to leaf area losses induced by herbivory or physical damage from falling canopy debris. In dioecious species, tolerance to defoliation may differ between genders (e.g. females may suffer more than males), but this topic has so far received little attention. 2.Here, we quantified gender-dependent effects of increased levels (0–100%) of sustained defoliation (applied bi-annually for 2 years) on vital rates in three economically important dioecious understorey palm species in the genus Chamaedorea (C. elegans, C. ernesti-augustii and C. oblongata). We also quantified gender differences in functional and life-history traits and assessed the direct reproductive costs in terms of biomass allocation to reproduction. 3.In the three species, non-defoliated (control) females were smaller and had three to seven times higher reproductive allocation than males. 4.Defoliation did not affect survivorship in any of the three species, except in the 100% defoliation treatment. Stem growth (RGR) and especially reproduction (probability of reproduction and reproductive output) were negatively affected by defoliation. Females of C. ernesti-augustii suffered higher mortality than males at 100% defoliation, but this was not the case for the other two species. Also, only in C. ernesti-augustii females exhibited lower RGR than males. In all species, the probability of reproduction did not differ between genders. The reproductive output (production rate of inflorescences) differed among genders only in C. ernesti-augustii, where males were more productive than females. 5.Interestingly, in most cases, defoliation effects on vital rates did not differ significantly between males and females, indicating that tolerance to defoliation was similar between genders. Such results were independent of plant size (stem length). 6.Synthesis. Our results do not support the prevailing theory that the greater reproductive costs of females will lead to reduced tolerance to stresses such as defoliation. The implications of these results and their importance for designing sustainable leaf harvesting regimes are discussed.
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