629 research outputs found

    How tight are the limits to land and water use? - Combined impacts of food demand and climate change

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    In the coming decades, world agricultural systems will face serious transitions. Population growth, income and lifestyle changes will lead to considerable increases in food demand. Moreover, a rising demand for renewable energy and biodiversity protection may restrict the area available for food production. On the other hand, global climate change will affect production conditions, for better or worse depending on regional conditions. In order to simulate these combined effects consistently and in a spatially explicit way, we have linked the Lund-Potsdam-Jena Dynamic Global Vegetation Model (LPJ) with a "Management model of Agricultural Production and its Impact on the Environment" (MAgPIE). LPJ represents the global biosphere with a spatial resolution of 0.5 degree. MAgPIE covers the most important agricultural crop and livestock production types. A prototype has been developed for one sample region. In the next stage this will be expanded to several economically relevant regions on a global scale, including international trade. The two models are coupled through a layer of productivity zones. In the paper we present the modelling approach, develop first joint scenarios and discuss selected results from the coupled modelling system

    Luchtcirculatie, kasklimaat en productie: Deel rapportage maart-oktober 2004

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    In kassen treedt veel luchtbeweging op. De invloed van geforceerde luchtbeweging in de kas ten gevolge van verwarming en/of ventilatoren in combinatie met luchtverdeelsystemen op de ruimtelijke klimaatverdeling en de daaraan gekoppelde fysische en fysiologische processen in het gewas zijn vrijwel onbekend. Uit het onderzoek met een gesloten kas (Schoonderbeek et al. 2003) kwam naar voren dat de geforceerde luchtbeweging een belangrijke verandering in het kasklimaat rond de plant tot gevolg had. De veronderstelling is dat deze verandering heeft bijgedragen aan de, in dat onderzoek gevonden, meerproductie en de behaalde energie-efficiëntie. Naar aanleiding van de resultaten van het gesloten kas experiment is door de LTO commissie tomaat gevraagd om nader onderzoek naar de oorzaken van de productieverhoging ten opzichte van de verhoging die op basis van simulatiemodellen werd verwacht. In de huidige gewasgroeimodellen is een vaste waarde aangenomen voor de grenslaagweerstand. Bij teeltsystemen, waarin luchtbeweging door geforceerde ventilatie of door beweging van planten optreedt, zal deze weerstand veranderen. Door verlaging van de weerstand kan als gevolg van een hogere CO2 uitwisseling de maximale fotosynthese toenemen. Een verlaging van de weerstand kan de transpiratie doen toenemen. Verder heeft geforceerde luchtbeweging invloed op de ruimtelijke klimaatverdeling voor temperatuur en vochtigheid. De verschillen in absolute luchtvochtigheid worden onder normale condities gering verondersteld. Een nadere analyse van het microklimaat, voor CO2 en vochtuitwisseling en de ruimtelijke verdeling bij geforceerde luchtbeweging en de daaraan gekoppelde gewasreacties geeft inzicht in de onderliggende mechanismen voor productieverbetering. Het onderzoek richt zich op de korte termijn effecten van luchtcirculatie. Benutting van deze kennis bij de keuze en besturing van de klimaatinstallaties in normale en (semi) gesloten kassen biedt uitstekende mogelijkheden om op energie-efficiënte wijze meerproductie te verkrijgen

    N2O emissions from the global agricultural nitrogen cycle – current state and future scenarios

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    Reactive nitrogen (Nr) is not only an important nutrient for plant growth, thereby safeguarding human alimentation, but it also heavily disturbs natural systems. To mitigate air, land, aquatic, and atmospheric pollution caused by the excessive availability of Nr, it is crucial to understand the long-term development of the global agricultural Nr cycle. For our analysis, we combine a material flow model with a land-use optimization model. In a first step we estimate the state of the Nr cycle in 1995. In a second step we create four scenarios for the 21st century in line with the SRES storylines. Our results indicate that in 1995 only half of the Nr applied to croplands was incorporated into plant biomass. Moreover, less than 10 per cent of all Nr in cropland plant biomass and grazed pasture was consumed by humans. In our scenarios a strong surge of the Nr cycle occurs in the first half of the 21st century, even in the environmentally oriented scenarios. Nitrous oxide (N2O) emissions rise from 3 Tg N2O-N in 1995 to 7–9 in 2045 and 5–12 Tg in 2095. Reinforced Nr pollution mitigation efforts are therefore required

    High-throughput synchrotron X-ray diffraction for combinatorial phase mapping

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    Discovery of new materials drives the deployment of new technologies. Complex technological requirements demand precisely tailored material functionalities, and materials scientists are driven to search for these new materials in compositionally complex and often non-equilibrium spaces containing three, four or more elements. The phase behavior of these high-order composition spaces is mostly unknown and unexplored. High-throughput methods can offer strategies for efficiently searching complex and multi-dimensional material genomes for these much needed new materials and can also suggest a processing pathway for synthesizing them. However, high-throughput structural characterization is still relatively under-developed for rapid material discovery. Here, a synchrotron X-ray diffraction and fluorescence experiment for rapid measurement of both X-ray powder patterns and compositions for an array of samples in a material library is presented. The experiment is capable of measuring more than 5000 samples per day, as demonstrated by the acquisition of high-quality powder patterns in a bismuth-vanadium-iron oxide composition library. A detailed discussion of the scattering geometry and its ability to be tailored for different material systems is provided, with specific attention given to the characterization of fiber textured thin films. The described prototype facility is capable of meeting the structural characterization needs for the first generation of high-throughput material genomic searches

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    The impact of high-end climate change on agricultural welfare

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    Climate change threatens agricultural productivity worldwide, resulting in higher food prices. Associated economic gains and losses differ not only by region but also between producers and consumers and are affected by market dynamics. On the basis of an impact modeling chain, starting with 19 different climate projections that drive plant biophysical process simulations and ending with agro-economic decisions, this analysis focuses on distributional effects of high-end climate change impacts across geographic regions and across economic agents. By estimating the changes in surpluses of consumers and producers, we find that climate change can have detrimental impacts on global agricultural welfare, especially after 2050, because losses in consumer surplus generally outweigh gains in producer surplus. Damage in agriculture may reach the annual loss of 0.3% of future total gross domestic product at the end of the century globally, assuming further opening of trade in agricultural products, which typically leads to interregional production shifts to higher latitudes. Those estimated global losses could increase substantially if international trade is more restricted. If beneficial effects of atmospheric carbon dioxide fertilization can be realized in agricultural production, much of the damage could be avoided. Although trade policy reforms toward further liberalization help alleviate climate change impacts, additional compensation mechanisms for associated environmental and development concerns have to be considered

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    Combined Chlorophyll Fluorescence and Transcriptomic Analysis Identifies the P3/P4 Transition as a Key stage in Rice Leaf Photosynthetic Development

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    Leaves are derived from heterotrophic meristem tissue that, at some point, must make the transition to autotrophy via the initiation of photosynthesis. However, the timing and spatial coordination of the molecular and cellular processes underpinning this switch are poorly characterized. Here, we report on the identification of a specific stage in rice (Oryza sativa) leaf development (P3/P4 transition) when photosynthetic competence is first established. Using a combined physiological and molecular approach, we show that elements of stomatal and vascular differentiation are coordinated with the onset of measurable light absorption for photosynthesis. Moreover, by exploring the response of the system to environmental perturbation, we show that the earliest stages of rice leaf development have significant plasticity with respect to elements of cellular differentiation of relevance for mature leaf photosynthetic performance. Finally, by performing an RNA sequencing analysis targeted at the early stages of rice leaf development, we uncover a palette of genes whose expression likely underpins the acquisition of photosynthetic capability. Our results identify the P3/P4 transition as a highly dynamic stage in rice leaf development when several processes for the initiation of photosynthetic competence are coordinated. As well as identifying gene targets for future manipulation of rice leaf structure/function, our data highlight a developmental window during which such manipulations are likely to be most effective
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