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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    The SEEA EEA carbon account for the Netherlands
    Lof, Marjolein ; Schenau, Sjoerd ; Jong, Rixt de; Remme, Roy ; Graveland, Cor ; Hein, Lars - \ 2017
    The Hague : Statistics Netherlands - 64
    carbon dioxide - netherlands - carbon - economics - environment - biofuels - bioenergy - biogas - emission - kooldioxide - nederland - koolstof - economie - milieu - biobrandstoffen - bio-energie - biogas - emissie
    The carbon account provides a comprehensive overview of all relevant carbon stocks and flows. The carbon account for the Netherlands was developed within the scope of the ‘System of Environmental Economic Accounts – Experimen tal Ecosystem Accounting’ (SEEA EEA) project for the Netherlands (Natuurlijk Kapitaalrekeningen Nederland: NKR_NL), which is currently c arried out jointly by Statistics Netherlands and Wageningen University. Funding and support was provided by the Ministries of Economic Affairs and Infrastructure and the Environment. Within the NKR_NL project, a number of accounts are currently under devel opment. The carbon account is described in detail in this report.
    The uptake of carbon sources by Aspergillus niger
    Sloothaak, Jasper - \ 2017
    Wageningen University. Promotor(en): Vitor Martins dos Santos, co-promotor(en): P.J. Schaap; J.A. Tamayo-Ramos. - Wageningen : Wageningen University - ISBN 9789463432085 - 179
    aspergillus niger - carbon - proteomes - glucose - cell membranes - markov processes - organic acids - aspergillus niger - koolstof - proteomen - glucose - celmembranen - markov-processen - organische zuren

    Fungi have been used as food and in food fermentations long before written accounts were created and they have been used in folk medicine in ancient cultures. For centuries, species of the genus Aspergillus have been used for the preparation of traditional Asian foodstuffs or together with baker’s yeast in preparation of alcoholic beverages and have therefore been of great economical value. Later, Aspergillus niger has been used for large-scale production of organic acids, enzymes and other food-additives. Today, we aim to harness its saprophytic nature and extraordinary ability to degrade and utilize plant material that is naturally recalcitrant to degradation. To facilitate that ability, the range of sugar transporters employed by this fungus is large even among fungi. This makes it an excellent choice for the identification and characterization of a variety of proteins with different substrate specificities, with potential application in the design of newly engineered cell factories. This thesis was focused on the identification and characterization of previously unknown sugar uptake transporters. Aspergillus niger transporter proteins for the uptake of glucose, xylose, galacturonic acid and rhamnose were identified and characterized.

    Roots in the tundra : relations between climate warming and root biomass and implications for vegetation change and carbon dynamics
    Wang, Peng - \ 2016
    Wageningen University. Promotor(en): Frank Berendse, co-promotor(en): Monique Heijmans; Liesje Mommer. - Wageningen : Wageningen University - ISBN 9789462578609 - 168
    roots - biomass - climatic change - vegetation - carbon - global warming - tundra - ecosystems - decomposition - siberia - wortels - biomassa - klimaatverandering - vegetatie - koolstof - opwarming van de aarde - toendra - ecosystemen - decompositie - siberië

    Global climate has been warming up for the last decades and it will continue in this century. The Arctic is the part of the globe that warms fastest and is more sensitive to climate warming. Aboveground productivity of Arctic tundra has been shown to increase in response to warmer climates. However, belowground responses of tundra vegetation are still unclear. As the major part of plant biomass in tundra lies belowground, it is pivotal to investigate changes in the belowground parts of tundra vegetation for our understanding of climate warming effects on tundra ecosystems.

    To get a general idea of how belowground plant biomass may change in a warmer climate, we synthesized published data on the belowground biomass of tundra vegetation across a broad gradient of mean annual air temperature from −20 to 0 °C. We found that aboveground biomass of tundra biomass indeed increases with mean annual temperature as well as summer air temperature, while belowground biomass did not show a significant relationship with temperature. The increases in the aboveground biomass were significantly larger than belowground biomass, resulting in reduced below/above ratios at higher temperatures. The shifted biomass allocation with temperature can influence the carbon dynamics of tundra ecosystems. Future tundra studies need to focus more on the species or functional type composition of belowground biomass and species or functional type specific belowground responses to climate warming.

    To determine the seasonal changes and vertical distribution of root biomass of different plant functional types, we sampled roots at a Siberian tundra site in the early and late growing season, from vegetation types dominated by graminoids and shrubs respectively. We distinguished the roots of graminoids and shrubs, and found that shrub roots grew earlier and shallower than graminoid roots, which enables shrubs to gain advantage over graminoids at the early growing season when nutrient pulses occur during snowmelt and soil thaw. The deeper roots of graminoids can help them to be more competitive if climate warming induces more nutrient release in the deeper soil.

    In a soil thawing and fertilization experiment, we further investigated the effects of increased thawing depth and nutrient supply in the upper soil, which can be the consequences of climate warming, on root biomass and its vertical distribution. In this study we distinguished between the roots of grasses, sedges, deciduous shrubs and evergreen shrubs. The study was done in a moist tussock tundra site with similar abundance of the different plant functional types. We found that only sedges benefited from the increased thawing depth, probably through their deepest root distribution among the four functional types, while the shrubs, which were shallower-rooted, benefited from the increased nutrient availability in the upper soil. The deep-rooted grasses had the highest plasticity in vertical root distribution, which enabled them also to benefit greatly from the fertilization. Our results show that tundra plants with different rooting strategies can show different responses to climate warming dependent on the relative warming impacts on the nutrient supply in shallow and deeper soil layers. This insight can help to predict future tundra vegetation dynamics.

    The carbon balance of tundra ecosystems also depends on the decomposition of plant litter, particularly the root litter, which may account for a larger part of annual litter input than leaf litter in tundra ecosystems. Vegetation shifts also change litter quality which ultimately influences carbon dynamics. To investigate the differences in the decomposition of leaves and roots of graminoids and shrubs, we performed a litter transplant experiment. We found that although the decomposability of leaf litter did not differ between the graminoid and shrub, root decomposability might be lower for the shrub. However, this cannot be extrapolated to the overall decomposition in different vegetation types, as these different plant communities differ in rooting depths. We also found evidence of home-field advantage in the decomposition in Arctic tundra, and we show that the early stage of litter decomposition at our research site could be driven by the phosphorus concentration of the litter. To get a full understanding of the carbon balance of tundra ecosystems, much more efforts are needed to quantify litter input and decomposition.

    In this thesis we show that belowground parts, which account for a major part of plant biomass in tundra, can show a different response to climate warming from aboveground parts. Belowground responses to climate warming can have crucial impacts on the competitive balance between tundra plants, and consequently result in vegetation shifts in tundra. Such shifts in species composition can have large effects on carbon dynamics through altered input and decomposability of plant litter, particularly root litter.

    Remote sensing of land use and carbon losses following tropical deforestation
    Sy, V. de - \ 2016
    Wageningen University. Promotor(en): Martin Herold, co-promotor(en): Jan Clevers; L. Verchot. - Wageningen : Wageningen University - ISBN 9789462578036 - 142
    remote sensing - tropical forests - land use - carbon - losses - environmental degradation - forest monitoring - remote sensing - tropische bossen - landgebruik - koolstof - verliezen - milieuafbraak - bosmonitoring

    The new Paris Agreement, approved by 195 countries under the auspice of the United Nations Framework Convention on Climate Change (UNFCCC), calls for limiting global warming to “well below" 2°Celsius. An important part of the climate agreement relates to reducing emissions from deforestation and forest degradation, and enhancing carbon stocks (REDD+) in non-Annex I (mostly developing) countries. Over the last decades the growing demand for food, fibre and fuel has accelerated the pace of forest loss. In consequence, tropical deforestation and forest degradation are responsible for a large portion of global carbon emissions to the atmosphere, and destroy an important global carbon sink that is critical in future climate change mitigation.

    Within the REDD+ framework, participating countries are given incentives to develop national strategies and implementation plans that reduce emissions and enhance sinks from forests and to invest in low carbon development pathways. For REDD+ activities to be effective, accurate and robust methodologies to estimate emissions from deforestation and forest degradation are crucial. Remote sensing is an essential REDD+ observation tool, and in combination with ground measurements it provides an objective, practical and cost-effective solution for developing and maintaining REDD+ monitoring systems. The remote sensing monitoring objective for REDD+ is not only to map deforestation but also to support policy formulation and implementation. Identifying and addressing drivers and activities causing forest carbon change is crucial in this respect. Despite the importance of identifying and addressing drivers, quantitative information on these drivers, and the related carbon emissions, is scarce at the national level.

    The main objective of this thesis is to explore the role of remote sensing for monitoring tropical forests for REDD+ in general, and for assessing land use and related carbon emissions linked to drivers of tropical deforestation in particular. To achieve this, this thesis investigates the following research questions:

    What is the current role and potential of remote sensing technologies and methodologies for monitoring tropical forests for REDD+ and for assessing drivers of deforestation?

    What is the current state of knowledge on drivers of deforestation and degradation in REDD+ countries?

    What are land use patterns and related carbon emissions following deforestation, capitalising on available land use and biomass remote sensing data?

    The research conducted in this PhD thesis contributes to the understanding of the role of remote sensing in forest monitoring for REDD+ and in the assessment of drivers of deforestation. In addition, this thesis contributes to the improvement of spatial and temporal quantification of land use and related carbon emissions linked to drivers of tropical deforestation. The results and insights described herein are valuable for ongoing REDD+ forest monitoring efforts and capacity development as REDD+ moves closer to becoming an operational mitigation mechanism.

    Carbonizing forest governance: analyzing the consequences of REDD+ for multilevel forest governance
    Vijge, M.J. - \ 2016
    Wageningen University. Promotor(en): Arthur Mol, co-promotor(en): Aarti Gupta. - Wageningen : Wageningen University - ISBN 9789462576445 - 178
    forest policy - governance - deforestation - environmental degradation - forests - carbon - bosbeleid - governance - ontbossing - milieuafbraak - bossen - koolstof

    Carbonizing forest governance:

    Analyzing the consequences of REDD+ for multilevel forest governance

    Marjanneke J. Vijge

    Despite the fifty years of global action to combat deforestation and forest degradation, the world is still losing its forests at great scale. A recent governance initiative that has raised high expectations to address global deforestation is Reducing Emissions from Deforestation and forest Degradation (REDD+), negotiated under the United Nations Framework Convention on Climate Change (UNFCCC). The idea of REDD+ is to compensate developing countries for their forest-related carbon emission reductions. Through REDD+, forests are governed for their carbon content. I therefore see REDD+ as the embodiment of what I call a “carbonization” of forest governance. This thesis analyzes the consequences of carbonization for multilevel forest governance. It studies whether carbonization leads to 1) a simplification of forest governance through a prime focus on carbon, or a focus on multiple carbon and non-carbon benefits; 2) a centralization or dispersion of authority; 3) a privileging of scientific knowledge—what I call a technicalization—or a diversity in the production and use of knowledge; and 4) a primary reliance on market instruments—what I refer to as marketization—or reliance on a mix of market and non-market instruments. I discuss whether REDD+ can be seen as a case of increased homogenization of environmental governance through simplification, centralization, technicalization, and/or marketization.

    The research questions are as follows:

    1. How does the carbonization of forest governance manifest itself at different levels, and with what consequences for multilevel forest governance?

    2. What does this analysis of the consequences of carbonization reveal about the prospects of a homogenization of environmental governance?

    This thesis uses discourses as proxies for how and with what consequences the carbonization of forest governance manifests itself. The thesis analyzes how REDD+ is being framed by policy actors and practitioners, and operationalized in policy, institutional and project developments and design. Triangulation of data is established through reliance on qualitative and quantitative research methods, including semi-structured interviews, surveys, reviews of primary and secondary literature, and direct and participant observation during field visits, project meetings and conferences.

    Chapter 2 analyzes how carbonization manifests itself in UNFCCC policy debates and developments surrounding measuring, reporting and verification (MRV) systems that are centrally implicated in REDD+. This chapter shows that at the global level, REDD+ is framed as a mechanism to facilitate results-based compensation for carbon emission reductions, to be measured through national, state-based, expert-led MRV systems. The chapter argues that this may well induce a simplified focus on carbon, a technicalization of forest governance, and a centralization of authority in national state agencies responsible for measuring and accounting for forest carbon units. This might marginalize non-carbon forest services and empower certain groups of actors such as technical experts at the cost of, for example, local communities. Who will be empowered through REDD+, however, ultimately depends on the context-specific operationalization and implementation of REDD+ at the national and local level.

    Chapter 3 contains an in-depth case study of how carbonization manifests itself in the Green India Mission (GIM), the cornerstone of India’s national REDD+ strategy. The chapter shows that the GIM frames REDD+ as an opportunity to synergistically generate carbon and non-carbon benefits, and promote a further devolution of authority in Indian forest governance to local communities. Chapter 3 nevertheless concludes that this is not likely to be realized without significant investments in benefit-sharing mechanisms and biodiversity and community-based monitoring systems in India.

    Chapter 4 presents the in-depth case study of the first REDD+ pilot project in India. The chapter analyzes the prominence of REDD+-related discourses among stakeholders and in project design. The chapter shows that the manifestation of carbonization at project level can be very different from the dominant framing of REDD+ at the global level as a carbon-centric, centralized and technocratic mechanism. The project case study shows how the carbonization of forest governance might become a vehicle to generate multiple carbon and non-carbon benefits, diversify the production and use of knowledge and the types of actors involved therein, disperse authority among actors involved in forest governance, and diversify reliance on both market- and fund-based finances.

    Chapter 5 contains a cross-country comparative analysis of the prominence of REDD+-related discourses among national policy actors and in national REDD+ policy documents of seven countries: Cameroon, Indonesia, Nepal, Papua New Guinea, Vietnam, Peru and Tanzania. The chapter shows that though REDD+ is mostly framed as a mechanism to generate carbon and non-carbon benefits, most countries pay very little attention to non-carbon monitoring. Almost all countries lay out detailed plans to diversify the production and use of knowledge through the involvement of local communities in REDD+ MRV systems, but currently lack the institutional capacity to implement such plans. Almost all REDD+ policy documents plan for a national state agency to account for and distribute REDD+ payments. There is, however, strikingly little discussion of how to finance REDD+. The chapter argues that a simplification, a centralization and, to a lesser extent, a technicalization of national forest governance are possible consequences of carbonization.

    The concluding chapter shows that carbonization of forest governance manifests itself differently at different levels of governance, with varying consequences for multilevel forest governance. Though homogenization does not yet occur, it may happen in the long run due to the centralization of authority that countries envision in accounting for and distributing REDD+ payments, as well as countries’ capacity gaps in non-carbon and community-based monitoring, which make a simplification and technicalization of national forest governance possible consequences of REDD+. In answering the second research question regarding the prospects of a homogenization of environmental governance, the case of REDD+ shows that developing countries retain authority to design policies, but in diversified ways. I argue that though diversity in policies and practices exist, this goes hand in hand with—and sometimes even flows from—efforts to homogenize in order to measure and regulate environmental outcomes at central (global and/or national) levels. As such, the challenges facing global environmental governance lie not only in measuring and controlling environmental outcomes, but also in managing the diversity and fragmentation that arise from these efforts.

    Complementary surface charge for enhanced capacitive deionization
    Gao, X. ; Porada, S. ; Omosebi, A. ; Liu, K.L. ; Biesheuvel, P.M. ; Landon, J. - \ 2016
    Water Research 92 (2016). - ISSN 0043-1354 - p. 275 - 282.
    Amphoteric Donnan model - Capacitive deionization - Enhanced salt removal - Extended working voltage window - electrodes - carbon - desalination - water treatment - ionization - elektrodes - koolstof - ontzilting - waterzuivering - ionisatie

    Commercially available activated carbon cloth electrodes are treated using nitric acid and ethylenediamine solutions, resulting in chemical surface charge enhanced carbon electrodes for capacitive deionization (CDI) applications. Surface charge enhanced electrodes are then configured in a CDI cell to examine their salt removal at a fixed charging voltage and both reduced and opposite polarity discharge voltages, and subsequently compared to the salt removal of untreated electrodes. Substantially improved salt removal due to chemical surface charge and the use of a discharge voltage of opposite sign to the charging voltage is clearly demonstrated in these CDI cycling tests, an observation which for the first time validates both enhanced CDI and extended-voltage CDI effects predicted by the Donnan model [Biesheuvel et al., Colloids Interf. Sci. Comm., 10.1016/j.colcom.2015.12.001 (2016)]. Our experimental and theoretical results demonstrate that the use of carbon electrodes with optimized chemical surface charge can extend the CDI working voltage window through discharge voltages of opposite sign to the charging voltage, which can significantly enhance the salt adsorption capacity of CDI electrodes. Thus, in addition to carbon pore size distribution, chemical surface charge in carbon micropores is considered foundational for salt removal in CDI cells.

    Soil organic matter in the Netherlands : Quantification of stocks and flows in the top soil
    Conijn, J.G. ; Lesschen, J.P. - \ 2015
    Wageningen : Plant Research International, Business Unit Agrosystems Research (Report / Plant Research International 619) - 50
    soil organic matter - carbon - nutrient balance - arable farming - arable land - netherlands - organisch bodemmateriaal - koolstof - voedingsstoffenbalans - akkerbouw - bouwland - nederland
    Soil organic matter (SOM) and especially decreasing SOM are since many decades on the agenda of different stakeholders due to the importance of SOM for various issues ranging from local crop profitability to global climate change. Globally large amounts of organic carbon are stored in the soil and changes in the amount of SOM may sequester or release CO2 from/into the atmosphere. The global stock of soil organic carbon (SOC) in the upper 100 cm equals roughly two times the amount of carbon in the atmosphere and soil respiration equals circa ten times the release of carbon by burning fossil fuels. Other functions of SOM with a (more) local dimension relate to e.g. soil fertility, soil structure, soil erosion, regulation of soil water flows, plant productivity and maintenance of soil biodiversity. Declining SOM is considered as one of the most serious processes of soil degradation and has been identified as one of the main soil threats. Next to positive effects, decomposition of SOM may also have adverse effects by enhancing N2O and CH4 emissions, and releasing nutrients of which part is leached to surface and ground waters. In the Netherlands, the “Technische Commissie Bodem” (TCB) gives advice to the government on soil related issues and has recently developed an advice for the Dutch government on the effects of future trends (such as the biobased economy, climate change, safeguarding food productivity, water management) on soil functioning. As part of the information gathering underlying this advice, the TCB asked Plant Research International and Alterra to conduct a literature research of (a) SOM stocks, flows and recent trends, (b) variation and uncertainty in the data and (c) determination of areas of having/reaching low SOM levels in the Netherlands. In this study we have focussed on the top soil of 0-30 cm and mainly on soils under agricultural use. SOM in deeper soil layers may be important (e.g. globally the layer 30-100 cm contains approximately an equal amount of SOC as compared to the 0-30 cm layer), but due to lack of data this fell outside the scope of this study. The findings of this study have been presented to the working group “Koolstofstromen” of the TCB in three separate sessions in 2013-2014.
    KringloopWijzer moet inspireren
    Haan, M.H.A. de; Aarts, H.F.M. - \ 2015
    Grondig : vakblad voor de cumelasector, specialisten in groen, grond en infra (2015)5. - ISSN 2210-3260 - p. 40 - 41.
    akkerbouw - kringlopen - stikstofkringloop - veehouderij - milieueffect - gewasopbrengst - mineralenopname - bemesting - fosfaat - koolstof - arable farming - cycling - nitrogen cycle - livestock farming - environmental impact - crop yield - mineral uptake - fertilizer application - phosphate - carbon
    De komende jaren moeten melkveehouders verplicht gaan werken met de KringloopWijzer. Dat heeft als doel ze bewuster te maken van hun bedrijfsprestaties en de manier waarop ze de mineralenstroom kunnen sturen. In dit artikel leggen de grondleggers van het systeem uit hoe de KringloopWijzer werkt en waarom dit voor loonbedrijven van belang is.
    Plantsensoren geschikt gemaakt voor toepassing op tuinbouwbedrijf : de pratende plant rukt op
    Steppe, K. ; Heuvelink, E. ; Kierkels, T. - \ 2015
    Onder Glas 12 (2015)11. - p. 20 - 21.
    tuinbouw - glastuinbouw - sensors - fotosynthese - droogte - gewassen, groeifasen - stengels - waterbalans - koolstof - suikers - gewasmonitoring - horticulture - greenhouse horticulture - sensors - photosynthesis - drought - crop growth stage - stems - water balance - carbon - sugars - crop monitoring
    De ontwikkeling van geavanceerde sensoren zorgt ervoor dat er steeds meer aan de plant te meten valt. Dat leidt tot nieuwe inzichten in het functioneren, die op termijn kunnen worden vertaald in aanbevelingen voor teeltmaatregelen. Een meer directe spin-off is dat de plantsensoren geschikt worden gemaakt voor toepassing op het tuinbouwbedrijf. Als middel om snel stress te detecteren, nog voor je het met het blote oog ziet.
    Fine scale ecohydrological processes in northern peatlands and their relevance for the carbon cycle
    Nijp, J.J. - \ 2015
    Wageningen University. Promotor(en): Frank Berendse; Sjoerd van der Zee, co-promotor(en): Juul Limpens; Klaas Metselaar. - Wageningen : Wageningen University - ISBN 9789462575837 - 202
    ecohydrologie - veengebieden - koolstofcyclus - koolstof - klimaat - neerslag - droogte - bodem - ecohydrology - peatlands - carbon cycle - carbon - climate - precipitation - drought - soil
    A review of blue carbon in the Netherlands
    Tamis, J.E. ; Foekema, E.M. - \ 2015
    Den Helder : IMARES (Report / IMARES C151/15) - 29
    carbon - marine environment - coastal areas - biodiversity - carbon sequestration - climatic change - north sea - wadden sea - netherlands - koolstof - marien milieu - kustgebieden - biodiversiteit - koolstofvastlegging - klimaatverandering - noordzee - waddenzee - nederland
    Blue carbon (the carbon stored in marine and coastal ecosystems – in biomass, buried in sediments and sequestered from the atmosphere and ocean) is considered as an issue of interest regarding its potential as a climate change mitigation measure in the OSPAR maritime area (OSPAR, 2015). Because blue carbon has not yet been properly explored in the North East Atlantic, OSPAR requested the Dutch government to provide information about blue carbon in the Netherlands and opportunities to enhance blue carbon in the Netherlands.
    Tot de bodem uitzoeken : micro-organismen beïnvloeden plantengroei
    Beintema, N. ; Groenigen, J.W. van - \ 2015
    WageningenWorld (2015)2. - ISSN 2210-7908 - p. 10 - 15.
    bodembiologie - bodembeheer - organische stof - aardwormen - bodemkwaliteit - organisch bodemmateriaal - koolstof - micro-organismen - bodemvruchtbaarheid - gewasbescherming - plantenontwikkeling - soil biology - soil management - organic matter - earthworms - soil quality - soil organic matter - carbon - microorganisms - soil fertility - plant protection - plant development
    Per vierkante meter bodem leven honderden wormen en insecten samen met kilometers aan schimmeldraden, vele miljoenen aaltjes en miljarden bacteriën. Onderzoek maakt steeds meer duidelijk van het precaire evenwicht ondergronds, en de grote invloed daarvan op het leven bovengronds. Het levert nieuwe strategieën op voor gewasbescherming.
    Verwijderen gewasbeschermingsmiddelen : duurproef actief koolfilter
    Ruijven, J.P.M. van; Staaij, M. van der; Os, E.A. van; Beerling, E.A.M. - \ 2015
    glastuinbouw - gewasbescherming - milieueffect - chemische bestrijding - lozing - oppervlaktewaterkwaliteit - oxidatie - koolstof - actieve kool - filters - greenhouse horticulture - plant protection - environmental impact - chemical control - disposal - surface water quality - oxidation - carbon - activated carbon - filters
    Met de aankomende verplichting tot het toepassen van zuiveringstechnieken voor het verwijderen van gewasbeschermingsmiddelen uit glastuinbouw lozingswater in gedachten, worden in het IDC Water verschillende technieken op effectiviteit onderzocht. Eerdere (kortdurende) proeven hebben goede resultaten laten zien van de combinatie geavanceerde oxidatie met actief koolstof.
    Dynamics in organic matter processing, ecosystem metabolism and trophic sources for consumers in the Mara River, Kenya
    Masese, F.O. - \ 2015
    Wageningen University. Promotor(en): K.A. Irvine, co-promotor(en): M.E. McClain; G.M. Gettel. - Leiden : CRC Press/Balkema - ISBN 9781138028159 - 195
    organische stof - ecosystemen - landgebruik - ecosysteemdiensten - rivieren - meren - koolstof - stikstof - visserij - aquatische ecologie - organic matter - ecosystems - land use - ecosystem services - rivers - lakes - carbon - nitrogen - fisheries - aquatic ecology

    To properly conserve, restore and manage riverine ecosystems and the services they provide, it is pertinent to understand their functional dynamics. However, there is still a major knowledge gap concerning the functioning of tropical rivers in terms of energy sources supporting riverine fisheries. I reviewed the anthropogenic influences on organic matter processes, energy sources and attributes of riverine food webs in the Lake Victoria basin, but also expanded the review to incorporate recent research findings from the tropics. Contrasting findings have been presented on the diversity of shredders and their role in organic matter processing in tropical streams. Recent tropical research has also highlighted the importance of autochthonous carbon, even in small forested streams. However similar studies are very limited in Afrotropical streams making it difficult to determine their place in emerging patterns of carbon flow in the tropics.

    This study was conducted in the Mara River, which is an important transboundary river with its headwaters in the Mau Forest Complex in Kenya and draining to Lake Victoria through Tanzania. In its headwaters, the basin is drained by two main tributaries, the Amala and Nyangores Rivers which merge in the middle reaches to form the Mara River mainstem. The overall objective of this dissertation was to better understand the functioning of the Mara River by assessing the spatio-temporal dynamics of organic matter sources and supply under different land-use and flow conditions and the influence of these dynamics on energy flow for consumers in the river. I collected benthic macroinvertebrates from open- and closed-canopy streams and classified them into functional feeding groups (FFGs) using gut content analysis. In total, I identified 43 predators, 26 collectors, 19 scrapers and 19 shredders. Species richness was higher in closed-canopy forested streams where shredders were also the dominant group in terms of biomass. Seven shredder taxa occurred only in closed-canopy forested streams highlighting the importance of maintaining water and habitat quality, including the input of leaf litter of the right quality, in the studied streams. The findings suggest that Kenyan highland streams harbor a diverse shredder assemblage contrary to earlier findings that had identified a limited number of shredder taxa.

    I subsequently used the composition of invertebrate functional feeding groups (FFGs) and the ecosystem process of leaf breakdown as structural and functional indicators, respectively, of ecosystem health in upland Kenyan streams. Coarse- and fine-mesh litterbags were used to

    compare microbial (fine-mesh) with shredder + microbial (coarse-mesh) breakdown rates, and by extension, determine the role of shredders in litter processing of leaves of different tree species (native Croton macrostachyus and Syzygium cordatum and the exotic Eucalyptus globulus). Breakdown rates were generally higher in coarse- compared with fine-mesh litterbags for the native leaf species and the relative differences in breakdown rates among leaf species remained unaltered in both agriculture and forest streams. Shredders were relatively more important in forest compared with agriculture streams where microbial breakdown was more important. Moreover, shredder mediated leaf litter breakdown was dependent on leaf species, and was highest for C. macrostachyus and lowest for E. globulus, suggesting that replacement of indigenous riparian vegetation with poorer quality Eucalyptus species along streams has the potential to reduce nutrient cycling in streams.

    To study organic matter dynamics is these streams, I assessed the influence of land use change on the composition and concentration of dissolved organic matter (DOM) and investigated its links with whole-stream ecosystem metabolism. Optical properties of DOM indicated notable shifts in composition along a land use gradient. Forest streams were associated with higher molecular weight and terrestrially derived DOM whereas agriculture streams were associated with autochthonously produced and low molecular weight DOM and photodegradation due to the open canopy. However, aromaticity was high at all sites irrespective of catchment land use. In agricultural areas high aromaticity likely originated from farmlands where soils are mobilized during tillage and carried into streams and rivers by runoff. Gross primary production (GPP) and ecosystem respiration (ER) were generally higher in agriculture streams, because of slightly open canopy and higher nutrient concentrations. The findings of this study are important because, in addition to reinforcing the role of tropical streams and rivers in the global carbon cycle, they highlight the consequences of land use change on ecosystem functioning in a region where land use activities are poised to intensify in response to human population growth.

    Lastly, I used natural abundances of stable carbon (δ13C) and nitrogen (δ15N) isotopes to quantify spatial and temporal patterns of carbon flow in food webs in the longitudinal gradient of the Mara River. River reaches were selected that were under different levels of human and mammalian herbivore (livestock and wildlife) influences. Potential primary producers (terrestrial C3 and C4 producers and periphyton) and consumers (invertebrates and fish) were collected

    during the dry and wet seasons to represent a range of contrasting flow conditions. I used Stable Isotope Analysis in R (SIAR) Bayesian mixing model to partition terrestrial and autochthonous sources of organic carbon supporting consumer trophic groups. Overall periphyton dominated contributions to consumers during the dry season. During the wet season, however, the importance of terrestrially-derived carbon for consumers was higher with the importance of C3 producers declining with distance from the forested upper reaches as the importance of C4 producers increased in river reaches receiving livestock and hippo inputs. This study highlights the importance of large mammalian herbivores on the functioning of riverine ecosystems and the implications of their loss from savanna landscapes that currently harbour remnant populations.

    The results of this dissertation contribute data to discussions on the effects of land use change on the functioning of upland streams and food webs in savanna rivers with regard to carbon flow and the vectoring role played by large mammalian herbivores as they transfer terrestrial organic matter and nutrients into streams and rivers. This study also provides information and recommendations that will guide future research and management actions for the sustainability of the Mara River and linked ecosystems in the Lake Victoria basin.

    The dynamics of oil accumulation in Scenedesmus obliquus
    Breuer, G. - \ 2015
    Wageningen University. Promotor(en): Rene Wijffels, co-promotor(en): Dirk Martens; Packo Lamers. - Wageningen : Wageningen University - ISBN 9789462572348 - 268
    algen - stikstof - uithongering - triacylglycerolen - productiviteit - fotosynthese - koolstof - tussenmuren - oliën - algae - nitrogen - starvation - triacylglycerols - productivity - photosynthesis - carbon - partitions - oils

    .Abstract long

    Global demands for food and biofuels increase rapidly, together with an increase of concerns for depleting fossil resources and climate change. New sustainable sources of vegetable oil, from now on referred to as triacylglycerol (TAG), are therefore highly desired. Arable land to produce these TAGs is however limited. Microalgae have the potential to achieve much higher TAG productivities than commonly used terrestrial plants and can be cultivated on non-arable land. Microalgae are therefore often considered as a promising alternative natural-source of TAGs. Microalgae can accumulate up to 50% of their weight as TAGs, but only do so in response to nitrogen starvation. At the same time, nitrogen starvation also affects many other cellular processes, including photosynthesis. At the start of the work presented in this thesis, little was known about the quantitative aspects of photosynthesis and TAG production during nitrogen starvation. This contributed to a large uncertainty in what could be expected from microalgae. This thesis therefore provides a quantitative understanding of the microalgal response to nitrogen starvation, that can be used to understand and optimize TAG production.

    The differences between microalgae species in their response to nitrogen starvation are characterized. It was found that the difference in the response to nitrogen starvation between microalgae could be characterized in 1) how long the species could retain their photosynthetic efficiency during nitrogen starvation, 2) how much the species could in increase in biomass concentration in the absence of a nitrogen source, and 3) which fraction of the newly made biomass constitutes of TAG. The microalga species S. obliquus was chosen as the most suitable species for TAG production and used in all further studies.

    It is quantified how process conditions, such as the light intensity, pH, and temperature, influence TAG production during nitrogen starvation in S. obliquus. It was found that TAG could be produced in the ranges pH 5-9, temperature of 20-35°C, and incident light intensity of 200-1500 µmol m-2 s-1. The light intensity did not affect the maximum TAG content. The light intensity did, however, have a major effect on the photosynthetic efficiency. Suboptimal pH values and temperatures resulted in both a reduction in photosynthetic efficiency and reduction in maximum TAG content.

    It was found that during nitrogen starvation, at best approximately half of the biomass produced during nitrogen starvation is TAG. Large amounts of starch were produced simultaneously. This simultaneous starch and TAG production was therefore investigated in more detail. It was investigated how the carbon partitioning ratio (the ratio between fatty acid and starch synthesis rates), and the photosynthetic efficiency during nitrogen starvation, are influenced by the light intensity during nitrogen starvation and by the photoacclimated state at the onset of nitrogen starvation. It was found that the ratio between starch and fatty acid synthesis strongly correlated to the extent of nitrogen starvation, quantified as the biomass nitrogen content. Immediately after nitrogen depletion, mostly starch was made, but when nitrogen starvation progressed, this ratio shifted in favour of fatty acid synthesis. When nitrogen starvation progressed further, only fatty acids were made. Hereafter, the initially accumulated starch was degraded while fatty acid synthesis continued. The effects caused by the photoacclimated state persisted during nitrogen starvation. This did however not affect the photosynthetic efficiency or the carbon partitioning ratio during nitrogen starvation. The light intensity during nitrogen starvation had a major impact on the photosynthetic efficiency, but only a minor impact on the carbon partitioning ratio.

    Because large amounts of starch are produced during nitrogen starvation in wild-type S. obliquus, it is investigated how starchless mutants of S. obliquus can be used to improve TAG production. The carbon-partitioning of the wild-type and the slm1 starchless mutant of S. obliquus are therefore compared. It was found that the starchless mutant diverted all photosynthetic capacity, that was used for starch synthesis in the wild-type, towards TAG synthesis. This resulted in much higher TAG accumulation rates during initial nitrogen starvation. Furthermore, it was found that the efficiency of photosynthesis was not negatively affected in this starchless mutant. Altogether, the TAG yield on light increased by 51%.

    Using these insights, a mechanistic model was developed that describes photosynthesis and carbon partitioning during nitrogen starvation. The model was validated using experimental data from both the wild-type and starchless mutant of S. obliquus. This model was used to investigate how TAG production could be improved by advances in reactor design and strain improvement. Projections are made for productivities that seem feasible when various technologies are implemented in the microalgal cultivation process, using S. obliquus as a case-study.

    Finally, the findings of this thesis are used to evaluate the outcomes of techno-economic and life cycle analysis (LCA) studies that investigated the cost-price and net energy ratio of microalgal products, mostly biodiesel. It was found that the biomass productivity and biochemical composition associated with the cultivation of microalgae are large uncertainties in the input values for these studies. Several scenarios for microalgal cultivation are therefore presented based on the findings of this thesis. For each scenario, productivities, biochemical compositions, and nutrient requirements are provided that can be used as more realistic input values for techno-economic and LCA studies. It was concluded that the TAG productivity is commonly overestimated by 3 to 6-fold. According to these studies, approximately half of the costs and energy are used in the cultivation step. It was therefore concluded that these techno-economic and LCA studies underestimate the cost-price and energy consumption by 2 to 3.5-fold. The future improvements in productivity that might seem feasible according to the model simulations, could potentially improve the productivity such that it approaches the productivity that is commonly assumed as the base-case in current techno-economic and LCA studies. These advances in productivity can help to reduce the cost-price and specific energy consumption, but in addition, a reduction in costs and energy consumption of photobioreactors is needed before microalgal TAG production can be commercialized.

    Carbon debt : inzichtelijk maken van maatschappelijke risico's van het opnemen van carbon debt vereisten
    Nabuurs, G.J. ; Croezen, H. ; Arets, E.J.M.M. - \ 2014
    Wageningen : Alterra, Wageningen-UR (Alterra-rapport 2525)
    koolstof - kooldioxide - koolstofvastlegging - schuld - biomassa - hout - bio-energie - risicobeheersing - duurzaamheid (sustainability) - energiecentrales - biobased economy - carbon - carbon dioxide - carbon sequestration - debt - biomass - wood - bioenergy - risk management - sustainability - power industry - biobased economy
    In het Energieakkoord is afgesproken dat meestook van biomassa in kolencentrales niet meer wordt dan 25 PetaJoule. Als onderdeel van de totale biomassa is zo’n 3,5 miljoen ton hout nodig. De mee te stoken biomassa zal aanvullend op de NTA8080-eisen moeten voldoen aan ‘duurzaamheidseisen voor koolstofschuld, indirecte landgebruikseffecten (ILUC) en duurzaam bosbeheer (FSC)’. In dit rapport wordt verkend, in hoeverre de duurzaamheidseisen genoemd in het Energieakkoord, risico’s op een carbon debt al uitsluiten en welke biomassa-stromen additioneel uitgesloten worden door een carbon debt eis. Ook zijn mogelijke procesrisico’s geïdentificeerd die discussie over carbon debt kan opleveren voor de verdere uitwerking van de afspraken uit het Energieakkoord.
    Replacement of soybean meal in compound feed by European protein sources : effects on carbon footprint
    Boer, H.C. de; Krimpen, M.M. van; Blonk, H. ; Tyszler, M. - \ 2014
    Lelystad : Wageningen UR Livestock Research (Livestock research report 819) - 46
    eiwitbronnen - voedingswaarde - koolstof - emissie - voer - varkens - eiwitleverende planten - sojabonen - protein sources - nutritive value - carbon - emission - feeds - pigs - protein plants - soyabeans
    The overall aim was to investigate if soybean products from South American can be replaced by protein sources produced in Europe in a sustainable way. Based on data from literature, and based on the systematics of the FeedPrint programme, the nutritional value and the carbon footprint (CFP) of these protein sources is determined. These protein sources are used in feed optimizations of a starter diet for pigs, thereby maintaining the nutritional value of the diet. Subsequently, the CFP of the grower diet is calculated. The results and conclusions will be discussed in this report.
    The sensitivity of tropical forests to climate variability and change in Bolivia
    Seiler, C. - \ 2014
    Wageningen University. Promotor(en): Pavel Kabat, co-promotor(en): Ronald Hutjes; Bart Kruijt. - Wageningen : Wageningen University - ISBN 9789461739230 - 157
    tropische bossen - klimaatverandering - gevoeligheid - klimaat - remote sensing - koolstof - bolivia - tropical forests - climatic change - sensitivity - climate - remote sensing - carbon - bolivia
    The potential of carbon sequestration to mitigate against climate change in forests and agro ecosystems of Zimbabwe
    Mujuru, L. - \ 2014
    Wageningen University. Promotor(en): Rik Leemans, co-promotor(en): Marcel Hoosbeek. - Wageningen : Wageningen University - ISBN 9789461739285 - 209
    koolstofvastlegging - klimaatverandering - bossen - agro-ecosystemen - mitigatie - koolstofvastlegging in de bodem - koolstofcyclus - koolstof - zimbabwe - carbon sequestration - climatic change - forests - agroecosystems - mitigation - soil carbon sequestration - carbon cycle - carbon - zimbabwe

    Climate change adversely affects human livelihoods and the environment through alteration of temperatures, rainfall patterns, sea level rise and ecosystem productivity. Developing countries are more vulnerable to climate change because they directly depend on agriculture and natural ecosystem products for their livelihoods. Mitigation of climate change impacts includes practices that can store carbon (C) in soil and biomass thus, reducing concentrations of atmospheric carbon dioxide (CO2) and other greenhouse gasses. In addition, planted and natural forests that store large amounts of C, can become key resources for mitigating and reducing vulnerability to climate change, whilst infertile agricultural soils require large amounts of chemical and/or organic fertilisers to improve productivity. Increasing awareness about climate change mitigation has led to realisation of a need for sustainable land management practices and promoting soil C sequestration to reduce the greenhouse effects.

    The C storage potential of agricultural soils is compounded by conventional tillage practices, covering large areas with only small portions of fields dedicated to conservation farming practices. Maintaining soil and crop productivity under these agricultural systems becomes a major challenge especially in rain-fed arid and semi-arid regions, characterised by long annual dry spells. Conservation tillage practices, such as no-till and reduced tillage, have been reported to increase soil organic carbon (SOC) stocks in agricultural systems as they reduce soil disturbance, whereas conventional tillage has been criticised for causing soil C losses, accelerating soil erosion and displacing of soil nutrients, despite benefits, such as reduced soil compaction, weed control and preparation of favourable seedbed, which have been reported under conventional tillage. The identification of appropriate agricultural management practices is critical for realisation of the benefits of Soil C sequestration and reducing emissions from agricultural activities.

    This thesis was planned to improve our understanding on how tillage, fertilisation, tree planting or natural forest conservation can enhance C sequestration and thus mitigate climate change. The main goal was to quantify the influence of tillage, fertilisation and plantation forestry practices on C and N dynamics in bulk soil and density separated soil organic matter (SOM) fractions relative natural forest. Tillage treatments under reduced tillage (RP), no tillage (DS) and conventional tillage (CT) were compared with natural forests (NF) in sandy Haplic Arenosols and clayey Rhodic Ferralsols. Impacts of fertilisation were assessed from three fertility treatments; unfertilised control (control), nitrogen fertiliser (N Fert) and nitrogen fertiliser plus cattle manure (N Fert + manure) in conventionally tilled fields on Arenosols (sandy soil) and Luvisols (clayey soil) along two soil fertility gradients. Similarly, C and N storage in tree farming was studied using a Pinus patula chronosequence. Soil sampling followed randomised complete block design with four replications in agricultural systems and two replicates in each plantation age stands and natural forest. Sodium polytungstate (density 1.6 g cm-3) was used to isolate organic matter into free light fraction (fLF), occluded light fraction (oLF) and mineral associated heavy fraction (MaHF). Carbon an N were analysed by dry combustion and C and N stocks calculated using bulk density, depth and C and N concentration. The RothC model was used to match density separated fractions with conceptual model pools for agricultural and natural forest soils.

    Findings from tillage studies showed significantly larger C and N stocks in natural forests than tillage systems despite the open access use of the natural forests. The C and N stocks were significantly lower in sandy than clayey soils. At 0–10 cm depth, SOC stocks increased under CT, RP and DS by 0.10, 0.24, 0.36 Mg ha−1yr−1 and 0.76, 0.54, 0.10 Mg ha−1yr−1 on sandy and clayey soils respectively over a four year period while N stocks decreased by 0.55, 0.40, 0.56 Mg ha−1yr−1 and 0.63, 0.65, 0.55 Mg ha−1yr−1 respectively. Under prevailing climatic and management conditions, improvement of residue retention could be a major factor that can distinguish the potential of different management practices for C sequestration.

    Among the fertility treatments, there were significantly higher SOC and TON stocks under N Fert and N Fert + manure at 0-10 cm soil depth in Luvisols. Although this effect was not significant at 20-30 cm and 30-50 cm depth. On Arenosols, N Fert had highest C and N at all depths except at 0-10 cm. The storage of C and N on Luvisols, followed: control < N Fert < N Fert + manure whereas Arenosols had control < N Fert + manure < N Fert. Compared with control, N Fert and N Fert + manure enhanced fLF C on homefields and outfields by 19%, 24% and 9%, 22% on Luvisols and 17%, 26% and 26%, 26% respectively on Arenosols. Homefields on Luvisols, under N Fert and N Fert + manure had similar equilibrium levels, which were 2.5 times more than control.

    Forests play a major role in regulating the rate of increase of global atmospheric CO2 storing C in soil and biomass although the C storage potential varies with forest type and plant species composition. In this research, storage of C and N were highest in moist forest and lowest in the Miombo woodland. In both natural and planted forests, above ground tree biomass was the major ecosystem C pool followed by forest floor’s humus (H) layer. The mineral soil had 45%, 31% and 24% of SOC stored at the 0–10, 10–30 and 30–60 cm soil depths respectively. Stand age affected C and N storage significantly having an initial decline after establishment recovering rapidly up to 10 years, after which it declined and increased again by 25 years. Average soil C among the Pinus compartments was 12 kg m-2, being highest at 10 years and lowest in the 1 year old stands. Organic N was also highest at 10 years and least at 25 years. The proportional mass of fLF and oLF in Miombo woodlands was similar while the other stands had higher fLF than oLF. The highest LF was in the moist forest. In the Pinus patula stands the fLF C contributed between 22−25%, the oLF C contributed 8−16% and MaHF C contributed between 60−70% to total SOC. Carbon in MaHF and oLF increased with depth while the fLF decreased with depth in all except the 1 and the 10 year old stands. Conversion of depleted Miombo woodlands to pine plantations can yield better C gains in the short and long run whilst moist forests provide both carbon and biodiversity. Where possible moist forests should be conserved and enrichment planting done in degraded areas to sustain them and if possible the forests can be considered as part of future projects on reduced emission from deforestation and degradation (REDD+). It is believed that REDD+ can promote both conservation and socio economic welfare, including poverty alleviation by bringing together the development of the forest and climate change link in African forests and woodlands. The focus on the monetary valuation and payment for environmental services can contribute to the attraction of political support for soil conservation. Developing countries therefore, need to formulate enabling economic and institutional land management policies that have positive impacts on poverty alleviation, food security and environmental sustainability.

    Soil C models are used to predict impacts of land management on C storage. The RothC 2.63 model was used for estimating SOC stock under selected land management practices on the clayey and sandy soils of Zimbabwe. There is greater potential to store more C in clayey soils than sandy soils and in practices that receive more organic inputs. Results show that the RothC model pool of HUM + IOM is related to the measured MaHF from density fractionation and that the model can be used to estimate SOC stock changes on Zimbabwean agricultural and forest soils. The relationship between equilibrium levels estimated by the RothC model and those estimated using the Langmuir equation was good. A 1.5˚ C rise in temperature was found to cause the A and B systems on clayey soils to sequester more C. The results also show that, when holding all the other factors constant, the model is sufficiently sensitive to a rise in temperatures with sandy soils reaching an equilibrium much earlier than clayey soils. The modelling approach represents one of the most promising methods for the estimation of SOC stock changes and allowed us to evaluate the changes in SOC in the past period on the basis of measured data. However, since the data were obtained from short term experiments (4−9 years), further ground validation can be hampered by the lack of long-term experimental trials in the southern African region. The deficiency of adequate experimental sites also limits further work on model uncertainties. The understanding soil quality and dynamics however, helps to design sustainable agricultural systems, while achieving the urgently needed win-win situation in enhancing productivity and sequestering C.

    Unravelling changes in soil fertility of agricultural land in The Netherlands
    Reijneveld, J.A. - \ 2013
    Wageningen University. Promotor(en): Oene Oenema; Aad Termorshuizen. - Wageningen : Wageningen UR - ISBN 9789461737793 - 227
    bodemvruchtbaarheid - landbouwgrond - organisch bodemmateriaal - bodemonderzoek - koolstof - fosfor - nederland - soil fertility - agricultural land - soil organic matter - soil testing - carbon - phosphorus - netherlands

    Keywords:

    Soil fertility, soil test, phosphorus, soil organic matter, soil organic carbon, fertilization recommendation, data base, the Netherlands

    On fertile soils, high-yielding crop production systems can be built which are indispensable both for profitable farming and for feeding the steadily increasing world population. With its high soil fertility, agriculture in the Netherlands is one of the most productive in the world. The high soil fertility is partly inherited from sea and rivers, partly it is men-made through manure and fertilizer applications. However, from the 1980s manure and fertilizer applications are limited through governmental regulations.

    This thesis aims to increase the understanding of spatial variations and changes over time in soil fertility of farmers’ fields in the Netherlands during the last century. More specifically, it addresses the following research questions: i) which changes have taken place in soil organic matter (SOM) and soil phosphorus (P) contents in the period 1970 to 2000s, ii) will mean soil P status develop towards the optimal agricultural range, with a small standard deviation when virgin soil is cultivated with high craftsmanship?, iii) how did herbage quality respond to changes in mean soil fertility in dairy farming, iv) what are farmers’ perceptions and concerns regarding soil fertility?, and v) how to improve the usability of fertilization recommendations, using new knowledge? A large data base of a laboratory for routine soil, manure, herbage tests (BLGG) was analysed statistically, and a questionnaire was conducted.

    Results show that the mean SOM content of mineral soils remained stable during the last decades, despite worldwide reports about declining SOM contents, and concerns expressed by farmers. Restrictions on the use of animal manure did not yet have an effect on dairy farms; soil P status of grassland and mineral content of herbage remained within the optimal range during the last few decades, but crude protein decreased. Soil P status on arable land increased until the 2000s, partly to above agronomical optimal ranges. Risk avoidance seems a decisive factor for pursuing these higher statuses, stressing the need for improved recommendations. Since implementing new insights proves hard, a three-step schedule for incorporating results of novel soil tests into fertilization recommendations is suggested. Farmers endorse the importance of soil fertility and SOM, and P status should be monitored, including anticipated information about soil structure and soil life.

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