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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Characterization of phenology, physiology, morphology and biomass traits across a broad Euro-Mediterranean ecotypic panel of the lignocellulosic feedstock Arundo donax
Fabbrini, Francesco ; Ludovisi, Riccardo ; Alasia, Omar ; Flexas, Jaume ; Douthe, Cyril ; Ribas Carbó, Miquel ; Robson, Paul ; Taylor, Gail ; Scarascia-Mugnozza, Giuseppe ; Keurentjes, Joost J.B. ; Harfouche, Antoine - \ 2018
Global change biology Bioenergy (2018). - ISSN 1757-1693
Arundo donax - biomass - ecotype variability - growth traits - lignocellulosic biomass - multivariate analysis - perennial grasses - phenology - physiology

Giant reed (Arundo donax L.) is a perennial rhizomatous grass, which has attracted great attention as a potential lignocellulosic feedstock for bioethanol production due to high biomass yield in marginal land areas, high polysaccharide content and low inhibitor levels in microbial fermentations. However, little is known about the trait variation that is available across a broad ecotypic panel of A. donax nor the traits that contribute most significantly to yield and growth in drought prone environments. A collection of 82 ecotypes of A. donax sampled across the Mediterranean basin was planted in a common garden experimental field in Savigliano, Italy. We analysed the collection using 367 clumps representing replicate plantings of 82 ecotypes for variation in 21 traits important for biomass accumulation and to identify the particular set of ecotypes with the most promising potential for biomass production. We measured morpho-physiological, phenological and biomass traits and analysed causal relationships between traits and productivity characteristics assessed at leaf and canopy levels. The results identified differences among the 82 ecotypes for all studied traits: those showing the highest level of variability included stomatal resistance, stem density (StN), stem dry mass (StDM) and total biomass production (TotDM). Multiple regression analysis revealed that leaf area index, StDM, StN, number of nodes per stem, stem height and diameter were the most significant predictors of TotDM and the most important early selection criteria for bioenergy production from A. donax. These traits were used in a hierarchical cluster analysis to identify groups of similar ecotypes, and a selection was made of promising ecotypes for multiyear and multisite testing for biomass production. Heritability estimates were significant for all traits. The potential of this ecotype collection as a resource for studies of germplasm diversity and for the analysis of traits underpinning high productivity of A. donax is highlighted.

Warming enhances sedimentation and decomposition of organic carbon in shallow macrophyte-dominated systems with zero net effect on carbon burial
Velthuis, Mandy ; Kosten, Sarian ; Aben, Ralf ; Kazanjian, Garabet ; Hilt, Sabine ; Peeters, Edwin T.H.M. ; Donk, Ellen van; Bakker, Elisabeth S. - \ 2018
Global Change Biology 24 (2018)11. - ISSN 1354-1013 - p. 5231 - 5242.
carbon cycle - decomposition - global warming - mineralization - phenology - primary production - sedimentation - submerged aquatic plant

Temperatures have been rising throughout recent decades and are predicted to rise further in the coming century. Global warming affects carbon cycling in freshwater ecosystems, which both emit and bury substantial amounts of carbon on a global scale. Currently, most studies focus on the effect of warming on overall carbon emissions from freshwater ecosystems, while net effects on carbon budgets may strongly depend on burial in sediments. Here, we tested whether year-round warming increases the production, sedimentation, or decomposition of particulate organic carbon and eventually alters the carbon burial in a typical shallow freshwater system. We performed an indoor experiment in eight mesocosms dominated by the common submerged aquatic plant Myriophyllum spicatum testing two temperature treatments: a temperate seasonal temperature control and a warmed (+4°C) treatment (n = 4). During a full experimental year, the carbon stock in plant biomass, dissolved organic carbon in the water column, sedimented organic matter, and decomposition of plant detritus were measured. Our results showed that year-round warming nearly doubled the final carbon stock in plant biomass from 6.9 ± 1.1 g C in the control treatment to 12.8 ± 0.6 g C (mean ± SE), mainly due to a prolonged growing season in autumn. DOC concentrations did not differ between the treatments, but organic carbon sedimentation increased by 60% from 96 ± 9.6 to 152 ± 16 g C m−2 yaer−1 (mean ± SE) from control to warm treatments. Enhanced decomposition of plant detritus in the warm treatment, however, compensated for the increased sedimentation. As a result, net carbon burial was 40 ± 5.7 g C m−2 year−1 in both temperature treatments when fluxes were combined into a carbon budget model. These results indicate that warming can increase the turnover of organic carbon in shallow macrophyte-dominated systems, while not necessarily affecting net carbon burial on a system scale.

Data from: Explaining European fungal fruiting phenology with climate variability
Andrew, Carrie ; Heegaard, Einar ; Høiland, Klaus ; Senn-Irlet, Beatrice ; Kuijper, T.W.M. ; Krisai-Greilhuber, Irmgard ; Kirk, Paul M. ; Heilmann-Clausen, Jacob ; Gange, Alan C. ; Egli, Simon ; Bässler, Claus ; Büntgen, Ulf ; Boddy, Lynne ; Kauserud, Håvard - \ 2018
climate - fungi - fruit bodies - distribution - NDVI - nutritional mode - path analysis - phenology
Here we assess the impact of geographically dependent (latitude, longitude and altitude) changes in bioclimatic (temperature, precipitation and primary productivity) variability on fungal fruiting phenology across Europe. Two main nutritional guilds of fungi, saprotrophic and ectomycorrhizal, were further separated into spring and autumn fruiters. We used a path‐analysis to investigate how biogeographic patterns in fungal fruiting phenology coincided with seasonal changes in climate and primary production. Across central to northern Europe, mean fruiting varied by approximately 25 days, primarily with latitude. Altitude affected fruiting by up to 30 days, with spring delays and autumnal accelerations. Fruiting was as much explained by the effects of bioclimatic variability as by their large‐scale spatial patterns. Temperature drove fruiting of autumnal ectomycorrhizal and saprotrophic, as well as spring saprotrophic groups, while primary production and precipitation were major drivers for spring‐fruiting ectomycorrhizal fungi. Species‐specific phenology predictors were not stable, instead deviating from the overall mean. There is significant likelihood that further climatic change, especially in temperature, will impact fungal phenology patterns at large spatial scales. The ecological implications are diverse, potentially affecting food webs (asynchrony), nutrient cycling and the timing of nutrient availability in ecosystems.
Explaining European fungal fruiting phenology with climate variability
Andrew, Carrie ; Heegaard, Einar ; Høiland, Klaus ; Senn-Irlet, Beatrice ; Kuyper, Thomas W. ; Krisai-Greilhuber, Irmgard ; Kirk, Paul M. ; Heilmann-Clausen, Jacob ; Gange, Alan C. ; Egli, Simon ; Bässler, Claus ; Büntgen, Ulf ; Boddy, Lynne ; Kauserud, Håvard - \ 2018
Ecology 99 (2018)6. - ISSN 0012-9658 - p. 1306 - 1315.
climate - distribution - Europe - fruit bodies - fungi - NDVI - nutritional mode - path analysis - phenology
Here we assess the impact of geographically dependent (latitude, longitude, and altitude) changes in bioclimatic (temperature, precipitation, and primary productivity) variability on fungal fruiting phenology across Europe. Two main nutritional guilds of fungi, saprotrophic and ectomycorrhizal, were further separated into spring and autumn fruiters. We used a path analysis to investigate how biogeographic patterns in fungal fruiting phenology coincided with seasonal changes in climate and primary production. Across central to northern Europe, mean fruiting varied by approximately 25 d, primarily with latitude. Altitude affected fruiting by up to 30 d, with spring delays and autumnal accelerations. Fruiting was as much explained by the effects of bioclimatic variability as by their large-scale spatial patterns. Temperature drove fruiting of autumnal ectomycorrhizal and saprotrophic groups as well as spring saprotrophic groups, while primary production and precipitation were major drivers for spring-fruiting ectomycorrhizal fungi. Species-specific phenology predictors were not stable, instead deviating from the overall mean. There is significant likelihood that further climatic change, especially in temperature, will impact fungal phenology patterns at large spatial scales. The ecological implications are diverse, potentially affecting food webs (asynchrony), nutrient cycling and the timing of nutrient availability in ecosystems.
Data from: Plant quantity affects development and survival of a gregarious insect herbivore and its endoparasitoid wasp
Fei, Minghui ; Gols, R. ; Zhu, F. ; Harvey, Jeffrey A. - \ 2016
development - group-living - herbivore - mortality - parasitiod - phenology - starvation - survival
Data for the paper of plant quantity represents a greater constraint than quality for a gregarious insect herbivore and its endoparasitoid wasp
Detecting QTLs and putative candidate genes involved in budbreak and flowering time in an apple multiparental population
Allard, Alix ; Bink, Marco C.A.M. ; Martinez, Sebastien ; Kelner, Jean Jacques ; Legave, Jean Michel ; Guardo, Mario Di; Pierro, Erica A. Di; Laurens, François ; De Weg, Eric W. Van; Costes, Evelyne - \ 2016
Journal of Experimental Botany 67 (2016)9. - ISSN 0022-0957 - p. 2875 - 2888.
Climate change - DAM genes - dormancy - flowering genes - Malus×domestica (Borkh) - pedigree-based analysis - phenology - QTL

In temperate trees, growth resumption in spring time results from chilling and heat requirements, and is an adaptive trait under global warming. Here, the genetic determinism of budbreak and flowering time was deciphered using five related full-sib apple families. Both traits were observed over 3 years and two sites and expressed in calendar and degree-days. Best linear unbiased predictors of genotypic effect or interaction with climatic year were extracted from mixed linear models and used for quantitative trait locus (QTL) mapping, performed with an integrated genetic map containing 6849 single nucleotide polymorphisms (SNPs), grouped into haplotypes, and with a Bayesian pedigree-based analysis. Four major regions, on linkage group (LG) 7, LG10, LG12, and LG9, the latter being the most stable across families, sites, and years, explained 5.6-21.3% of trait variance. Co-localizations for traits in calendar days or growing degree hours (GDH) suggested common genetic determinism for chilling and heating requirements. Homologs of two major flowering genes, AGL24 and FT, were predicted close to LG9 and LG12 QTLs, respectively, whereas Dormancy Associated MADs-box (DAM) genes were near additional QTLs on LG8 and LG15. This suggests that chilling perception mechanisms could be common among perennial and annual plants. Progenitors with favorable alleles depending on trait and LG were identified and could benefit new breeding strategies for apple adaptation to temperature increase.

The importance of phenology in studies of plant-herbivore-parasitoid interactions
Fei, Minghui - \ 2016
University. Promotor(en): Louise Vet; J.A. Harvey; Rieta Gols. - Wageningen : Wageningen University - ISBN 9789462576551 - 170 p.
016-3952 - phenology - plant-herbivore interactions - parasitoids - interactions - annuals - insects - pieris brassicae - cotesia glomerata - brassicaceae - host plants - fenologie - plant-herbivoor relaties - parasitoïden - interacties - eenjarigen - insecten - waardplanten
Geen winter? Niet erg hoor
Vliet, Arnold van - \ 2016
phenology - winter - climatic change - plant ecology - resilience of nature - nature
Plant functional type classification for earth system models: results from the European Space Agency's Land Cover Climate Change Initiative
Poulter, B. ; MacBean, N. ; Hartley, A. ; Khlystova, I. ; Arino, O. ; Betts, R. ; Bontemps, S. ; Boettcher, M. ; Brockmann, C. ; Defourny, P. ; Hagemann, S. ; Herold, M. ; Kirches, C. ; Lamarche, C. ; Lederer, D. ; Ottlé, C. ; Peters, M. ; Peylin, P. - \ 2015
Geoscientific Model Development 8 (2015). - ISSN 1991-959X - p. 2315 - 2328.
global vegetation model - world map - ecosystems - forests - cycle - uncertainties - resolution - feedbacks - phenology - database
Global land cover is a key variable in the earth system with feedbacks on climate, biodiversity and natural resources. However, global land cover data sets presently fall short of user needs in providing detailed spatial and thematic information that is consistently mapped over time and easily transferable to the requirements of earth system models. In 2009, the European Space Agency launched the Climate Change Initiative (CCI), with land cover (LC_CCI) as 1 of 13 essential climate variables targeted for research development. The LC_CCI was implemented in three phases: first responding to a survey of user needs; developing a global, moderate-resolution land cover data set for three time periods, or epochs (2000, 2005, and 2010); and the last phase resulting in a user tool for converting land cover to plant functional type equivalents. Here we present the results of the LC_CCI project with a focus on the mapping approach used to convert the United Nations Land Cover Classification System to plant functional types (PFTs). The translation was performed as part of consultative process among map producers and users, and resulted in an open-source conversion tool. A comparison with existing PFT maps used by three earth system modeling teams shows significant differences between the LC_CCI PFT data set and those currently used in earth system models with likely consequences for modeling terrestrial biogeochemistry and land–atmosphere interactions. The main difference between the new LC_CCI product and PFT data sets used currently by three different dynamic global vegetation modeling teams is a reduction in high-latitude grassland cover, a reduction in tropical tree cover and an expansion in temperate forest cover in Europe. The LC_CCI tool is flexible for users to modify land cover to PFT conversions and will evolve as phase 2 of the European Space Agency CCI program continues.
The Earth Observation Data for Habitat Monitoring (EODHaM) System
Lucas, R.M. ; Blonda, P. ; Bunting, P. ; Jones, G. ; Inglada, J. ; Arias-Maldonado, M. ; Kosmidou, V. ; Petrou, Z. ; Manakos, I. ; Adamo, M. ; Charnock, R. ; Tarantino, C. ; Mücher, C.A. ; Kramer, H. ; Jongman, R.H.G. ; Honrado, J. ; Mairota, P. - \ 2015
International Journal of applied Earth Observation and Geoinformation 37 (2015). - ISSN 0303-2434 - p. 17 - 28.
remotely-sensed data - categories ghc - file format - vegetation - satellite - classifications - biodiversity - reflectance - phenology - software
To support decisions relating to the use and conservation of protected areas and surrounds, the EU-funded BIOdiversity multi-SOurce monitoring System: from Space TO Species (BIO_SOS) project has developed the Earth Observation Data for HAbitat Monitoring (EODHaM) system for consistent mapping and monitoring of biodiversity. The EODHaM approach has adopted the Food and Agriculture Organization Land Cover Classification System (LCCS) taxonomy and translates mapped classes to General Habitat Categories (GHCs) from which Annex I habitats (EU Habitats Directive) can be defined. The EODHaM system uses a combination of pixel and object-based procedures. The 1st and 2nd stages use earth observation (EO) data alone with expert knowledge to generate classes according to the LCCS taxonomy (Levels 1 to 3 and beyond). The 3rd stage translates the final LCCS classes into GHCs from which Annex I habitat type maps are derived. An additional module quantifies changes in the LCCS classes and their components, indices derived from earth observation, object sizes and dimensions and the translated habitat maps (i.e., GHCs or Annex I). Examples are provided of the application of EODHaM system elements to protected sites and their surrounds in Italy, Wales (UK), the Netherlands, Greece, Portugal and India.
Monitoring vegetation change and dynamics on U.S. Army training lands using satellite image time series analysis
Hutchinson, J.M.S. ; Jacquin, A. ; Hutchinson, S.L. ; Verbesselt, J. - \ 2015
Journal of Environmental Management 150 (2015). - ISSN 0301-4797 - p. 355 - 366.
locally weighted regression - structural-change models - plant community - trend analysis - modis ndvi - phenology - wildlife - gimms
Given the significant land holdings of the U.S. Department of Defense, and the importance of those lands to support a variety of inherently damaging activities, application of sound natural resource conservation principles and proactive monitoring practices are necessary to manage military training lands in a sustainable manner. This study explores a method for, and the utility of, analyzing vegetation condition and trends as sustainability indicators for use by military commanders and land managers, at both the national and local levels, in identifying when and where vegetation-related environmental impacts might exist. The BFAST time series decomposition method was applied to a ten-year MODIS NDVI time series dataset for the Fort Riley military installation and Konza Prairie Biological Station (KPBS) in northeastern Kansas. Imagery selected for time-series analysis were 16-day MODIS NDVI (MOD13Q1 Collection 5) composites capable of characterizing vegetation change induced by human activities and climate variability. Three indicators related to gradual interannual or abrupt intraannual vegetation change for each pixel were calculated from the trend component resulting from the BFAST decomposition. Assessment of gradual interannual NDVI trends showed the majority of Fort Riley experienced browning between 2001 and 2010. This result is supported by validation using high spatial resolution imagery. The observed versus expected frequency of linear trends detected at Fort Riley and KPBS were significantly different and suggest a causal link between military training activities and/or land management practices. While both sites were similar with regards to overall disturbance frequency and the relative spatial extents of monotonic or interrupted trends, vegetation trajectories after disturbance were significantly different. This suggests that the type and magnitude of disturbances characteristic of each location result in distinct post-disturbance vegetation responses. Using a remotely-sensed vegetation index time series with BFAST and the indicators outlined here provides a consistent and relatively rapid assessment of military training lands with applicability outside of grassland biomes. Characterizing overall trends and disturbance responses of vegetation can promote sustainable use of military lands and assist land managers in targeting specific areas for various rehabilitation activities.
Multi-resolution time series imagery for forest disturbance and regrowth monitoring in Queensland, Australia
Schmidt, M. ; Lucas, R. ; Bunting, P. ; Verbesselt, J. ; Armston, J. - \ 2015
Remote Sensing of Environment 158 (2015). - ISSN 0034-4257 - p. 156 - 168.
reflectance fusion model - surface reflectance - aerial-photography - landsat data - vegetation - plus - phenology - framework - lidar
High spatio-temporal resolution optical remote sensing data provide unprecedented opportunities to monitor and detect forest disturbance and loss. To demonstrate this potential, a 12-year time series (2000 to 2011) with an 8-day interval of a 30 m spatial resolution data was generated by the use of the Spatial and Temporal Adaptive Reflectance Fusion Model (STARFM) with Landsat sensor observations and Moderate Resolution Imaging Spectroradiometer (MODIS) data as input. The time series showed a close relationship over homogeneous forested and grassland sites, with r2 values of 0.99 between Landsat and the closest STARFM simulated data; and values of 0.84 and 0.94 between MODIS and STARFM. The time and magnitude of clearing and re-clearing events were estimated through a phenological breakpoint analysis, with 96.2% of the estimated breakpoints of the clearing event and 83.6% of the re-clearing event being within 40 days of the true clearing. The study highlights the benefits of using these moderate resolution data for quantifying and understanding land cover change in open forest environments.
Time-dependent effects of climate and drought on tree growth in a Neotropical dry forest: Short-term tolerance vs. long-term sensitivity
Mendivelso, H.A. ; Camarero, J.J. ; Gutierrez, E. ; Zuidema, P. - \ 2014
Agricultural and Forest Meteorology 188 (2014). - ISSN 0168-1923 - p. 13 - 23.
tropical forests - ring chronologies - rain-forest - santa-cruz - water-use - phenology - patterns - bolivia - precipitation - coordination
We analyzed the effects of climate and drought on radial growth using dendrochronology in seven deciduous tree species coexisting in a Bolivian tropical dry forest subjected to seasonal drought. Precipitation, temperature and a multiscalar drought index were related to tree-ring width data at different time-scales (from one month to 42 years). Precipitation affected positively tree growth in all species, mainly during the wet season, while temperature affected it negatively in five species. Tree growth responses to precipitation and temperature were species-specific and peaked at short-time scales, specifically from one to nine months. At inter-annual scales tree growth always responded positively to less dry conditions at short-time scales, particularly from two to seven months, and also at long-time scales from six to 30 years. Tree growth was mainly sensitive to multi-annual droughts and such sensitivity differed among species. Our findings suggest that tree species of the studied tropical dry forest are predominantly sensitive in terms of growth reduction to long-lasting droughts. This time-dependency of growth responses to drought should be explicitly considered as an additional constraint of the community dynamics in evaluations of the future responses of tropical dry forests to climate warming. (C) 2014 Elsevier B.V. All rights reserved.
A cost-effective approach for improving the quality of soil sealing change detection from Landsat imagery
Smiraglia, D. ; Rinaldo, S. ; Ceccarelli, T. ; Bajocco, S. ; Salvati, L. ; Ricotta, C. ; Perini, L. - \ 2014
European Journal of Remote Sensing 47 (2014). - ISSN 2279-7254 - p. 805 - 819.
urban - modis - tm - transformation - segmentation - phenology - sprawl - region - ndvi - area
The aim of this study is to develop a cost-effective approach for soil sealing change detection integrating radiometric analysis, multi-resolution segmentation and object-based classifiers in two study areas in Italy: Campania region and Veneto region. The integrated approach uses multi-temporal satellite images and CORINE Land Cover (CLC) maps. A good overall accuracy was obtained for the soil sealing maps produced. The results show an improvement in terms of size of the minimum mapping unit and of the changed object (1,44 ha in both cases) in respect to the CLC. The approach proves to be cost-effective given the data which are provided at low or no cost and as well as the level of automation achievable.
'Media-aandacht is cruciaal': Arnold van Vliet : wetenschapper voor het publiek
Kleis, R. ; Vliet, A.J.H. van - \ 2014
WageningenWorld (2014)4. - ISSN 2210-7908 - p. 34 - 39.
fenologie - flora - fauna - natuurverschijnselen - monitoring - wetenschappelijk onderzoek - phenology - natural phenomena - scientific research
Van Vliet ontdekte de kracht van citizen science al in zijn studententijd in Wageningen. ‘Voor een afstudeervak bij het IBN, nu Alterra, kwam ik in contact met de archieven van het Nederlands Fenologisch Waarnemingsnetwerk. Stapels ordners met waarnemingen van mensen sinds 1868. Bij analyse van die gegevens zie je dat er een heel duidelijk effect is van de temperatuur op wat er om je heen gebeurt. Fenologie blijkt een heel goede indicator voor veranderingen in de natuur als gevolg van veranderingen in weer en klimaat. Op basis van waarnemingen van vrijwilligers krijg je een goed beeld van hoe een jaar eruit ziet en hoe het zich verhoudt tot andere jaren.
Bioloog met een missie : Wageningse kopstukken: Arnold van Vliet
Kleis, R. ; Vliet, A.J.H. van - \ 2014
Resource: weekblad voor Wageningen UR 9 (2014)821. - ISSN 1874-3625 - p. 19 - 21.
fenologie - natuurbescherming - klimaatverandering - phenology - nature conservation - climatic change
Het jaar is nog niet voorbij, we moeten nog een maandje. Maar nu al staat vast dat 2014 een uitzonderlijk jaar was voor de natuur. Van Vliet bestudeert veranderingen in de timing van jaarlijks terugkerende verschijnselen in de natuur. Fenologie in vaktaal. En dan vooral het effect van klimaatverandering op die timing.
Extreem vroege start herfst
Vliet, A.J.H. van; Bron, W.A. ; Roerink, G.J. - \ 2014
Stichting voor Duurzame Ontwikkeling
bomen - openbaar groen - herfst - temperatuur - fenologie - trees - public green areas - autumn - temperature - phenology
Bij heel veel boomsoorten beginnen de bladeren al een herfstkleur te krijgen en bladeren vallen al van de bomen. De bladverkleuring en bladval komen daarmee onverwacht zo’n drie tot vier weken eerder dan normaal op gang. De laatste jaren begon de herfst juist later dan normaal door hoge temperaturen. Uit de Groenmonitor blijkt dat de bossen momenteel zo’n 8% minder groen zijn dan vorig jaar. Graslanden zijn daarentegen 3% groener. De vroege herfst komt waarschijnlijk door de lage temperaturen in augustus in combinatie met de zeer vroege start van het voorjaar.
Voorlente begonnen en natuurverwachting voor 2014
Vliet, A.J.H. van - \ 2014
Wageningen : Wageningen UR
fenologie - bloeidatum - flora - fauna - biodiversiteit - phenology - flowering date - biodiversity
Met de eerste bloeiwaarnemingen van hazelaar, speenkruid, fluitenkruid en sneeuwklokje die bij De Natuurkalender binnen zijn gekomen, lijkt de voorlente van 2014 al van start gegaan te zijn. De gemiddelde temperatuur van de afgelopen weken hoort dan ook eerder bij maart dan bij december en januari. Hoe zal het de natuur in de rest van het jaar vergaan? Ik verwacht een stijgende lijn voor onze biodiversiteit met veel libellen, vlinders en langpootmuggen maar een daling van tien procent van schelpdieren in onze kustwateren. Ook zullen er vrijwel geen beukennootjes aan de bomen komen.
Improving resource-use efficiency in rice-based systems of Pakistan
Awan, M.I. - \ 2013
University. Promotor(en): Holger Meinke, co-promotor(en): Lammert Bastiaans; Pepijn van Oort. - S.l. : s.n. - ISBN 9789461737526 - 151
oryza sativa - rijst - bedrijfssystemen - hulpbronnengebruik - gebruiksefficiëntie - watergebruiksrendement - fenologie - voedselzekerheid - pakistan - rice - farming systems - resource utilization - use efficiency - water use efficiency - phenology - food security

Keywords: Aerobic rice, water productivity, pre-flowering phenology, eco-efficiency, perceptions, transformational technology, food security, resource constraints, Punjab, Pakistan.

Just like in many other parts of the world, diminishing resources of water, labour and energy threaten the sustainability of conventional flooded rice systems in Pakistan. Changing the current production system to non-flooded aerobic rice could considerably increase resource-use efficiencies. However, for subtropical conditions, such as those in South Asia, the non-conventional system is still very much in the development phase. The main objective of this study was to evaluate the aerobic rice system of the Punjab in Pakistan from a biophysical and socio-technological perspective. I employed a combined approach of experimentation and farmer surveys to contribute important information on aerobic rice crop performance, pre-flowering photothermal responses, and farmers’ perspective.

Two seasons of field experiments (2009 and 2010) at the research station of the University of Agriculture, Faisalabad–Pakistan tested local (KSK133, IR6, RSP1) and exotic (Apo, IR74371-54-1-1) genotypes against different combinations of irrigation levels (high, moderate, low) and nitrogen rates (0, 170, 220 kg N ha−1). Under aerobic conditions, the water productivity (WPg; g grain kg–1 total water input) improved significantly, showing a potential water saving of about 20%. However, this improved water productivity was at the cost of declining land productivity, as the actual production per unit area decreased. Grain yield and total aboveground N uptake were mainly limited by irrigation and not by N. The results suggest significant losses of applied N, and indicate that improvements in N use efficiency might be expected if N application is better synchronised with the N-demand of the crop.

Accurate knowledge on rice phenological development is an important feature when the aim is to better match supply and demand for further improvement in resource use efficiencies. A controlled-environment growth chamber study, aimed at estimating pre-flowering photothermal responses, gave a robust set of photoperiod-parameters and demonstrated that all four tested genotypes (KSK133, RSP1, Apo, IR74371-54-1-1) were strongly photoperiod-sensitive. The temperature range in the field experiments was too narrow to achieve convergence to a unique set of optimal temperature response parameters. Yet, sensitivity analysis clearly showed that commonly used standard cardinal temperatures (base, optimum, maximum: 8, 30, 42°C, respectively) overestimated the time to flowering. Data obtained under a wider range of temperatures should result in more accurate estimation of temperature response parameters.

To supplement the basic biophysical research, I conducted farmer surveys (n=215) in three major cropping systems viz. rice-wheat, mixed-cropping and cotton-wheat to understand farmers’ perspective about the future prospects of aerobic rice system. Most of the farmers were unaware of aerobic rice technology but expressed their keen interest in experimenting. Farmers perceived aerobic rice as a system to improve resource use efficiency particularly for labour and water but they consider it a knowledge intensive system requiring careful and timely management practices especially for weeds. The unavailability of suitable fine grain aerobic basmati varieties was identified as a major constraint for large scale adoption. Understanding farmers’ perspective helped to develop guidelinesfor the emerging aerobic rice system. The aerobic rice system is a rational approach for improving WPg and eco-efficiencies of water, labour and energy. Associated risks of crop failure can be reduced by filling the identified knowledge and technological gaps through additional research and adequate training of farmers.

Changing weather conditions and floating plants in temperate drainage ditches
Peeters, E.T.H.M. ; Zuidam, B.G. van; Zuidam, J.P. van; Nes, E.H. van; Kosten, S. ; Heuts, P.G.M. ; Roijackers, R.M.M. ; Netten, J.J.C. ; Scheffer, M. - \ 2013
Journal of Applied Ecology 50 (2013)3. - ISSN 0021-8901 - p. 585 - 593.
climate-change - submerged macrophytes - aquatic macrophytes - species richness - shallow lakes - lemna-minor - eutrophication - growth - phytoplankton - phenology
Dominance of free-floating plants such as duckweed is undesirable as it indicates eutrophication. The objectives of this study are to investigate whether the onset of duckweed dominance is related to weather conditions by analysing field observations, to evaluate the effect of different climate scenarios on the timing of duckweed dominance using a model and to evaluate to what extent nutrient levels should be lowered to counteract effects of global warming. To analyse the onset of duckweed dominance in relation to weather conditions, duckweed cover in Dutch ditches was correlated with weather conditions for the period 1980-2005. Furthermore, a model was developed that describes biomass development over time as a function of temperature, light and nutrient availability, crowding and mortality. This model was used to evaluate the effects of climate change scenarios and the effects of lowering nutrients. The onset of duckweed dominance in the field advanced by approximately 14 days with an increase of 1 °C in the average maximum daily winter temperature. The modelled biomass development correlated well with the field observations. Scenarios showed that expected climate change will affect onset and duration of duckweed dominance in temperate ditches. Reducing nutrient levels may counteract the effect of warming. Synthesis and applications. Global warming may lead to an increase in the dominance of free-floating plants in drainage ditches in the Netherlands. The expected reductions in nutrient-loading to surface waters as a result of different measures taken so far are likely not sufficient to counteract these effects of warming. Therefore, additional measures should be taken to avoid a further deterioration of the ecological water quality in ditches. © 2013 The Authors. Journal of Applied Ecology © 2013 British Ecological Society.
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