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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    ThinkForest: Science insights to the European Green Deal and forests
    Palahí, M. ; Potočnik, J. ; Nabuurs, G.J. ; Bauhus, J. ; Hetemäki, Lauri - \ 2020
    Wageningen University & Research
    biobased economy - renewable energy - forestry - wood - climate - Europe
    Our May ThinkForest webinar focused on:
    - What are the main objectives of the Green Deal and how do these relate to the forest-based sector?
    - How is the forest-based sector in general viewed in the Green Deal?
    - What are the strengths and weaknesses of the Green Deal proposal from ecological, economic and social sustainability perspectives?

    Speakers included:
    Marc Palahí, European Forest Institute (5:34)
    Janez Potočnik, ThinkForest president (12:52)
    Gert-Jan Nabuurs, Wageningen University, IPCC Lead Author (24:47)
    Jürgen Bauhus, University of Freiburg (45:30)
    Lauri Hetemäki, European Forest Institute (1:05:18)
    Stedelijk groen helpt tegen klimaatverandering
    Spijker, J.H. ; Lerink, Bas - \ 2020
    Vakblad Natuur Bos Landschap (2020)163. - ISSN 1572-7610 - p. 21 - 24.
    biobased economy - green infrastructure - biomass - wood - trees - carbon sequestration - towns
    In het klimaatakkoord is de rol die stedelijk groen kan spelen voor de klimaatopgave onderbelicht. Dat is jammer, omdat de oppervlakte van steden, dorpen en infrastructuur in Nederland aanzienlijk is. En het aardige van stedelijk groen is dat dit naast het vastleggen van CO2, ook kan bijdragen aan aanpassing aan klimaatverandering: wateropvang bij piekbuien en verkoeling van de stad tijdens hittegolven.
    De keerzijde van houtstook in open haarden en kachels
    Hein, L.G. - \ 2018
    Milieu (2018)9. - ISSN 0920-2234 - p. 41 - 45.
    biomass - biobased economy - wood - stoves - heat - bioenergy - biofuels
    Het toenemende gebruik van conventionele open haarden en houtkachels levert geen bijdrage aan de
    vermindering van de opwarming van de aarde. Voor het klimaat is het beter het huis te ver warmen
    met de cv-ketel. Daarentegen leveren pelletkachels wel klimaatwinst ten opzichte van de cv-ketel.
    Verder worden voor alle vormen van houtstook de gezondheidseffecten van fi jnstof uit deze bronnen,
    zeker ook voor de stoker zelf, sterk onderschat. Een eerste, voorlopige inschatting is dat het stoken
    van hout jaarlijks leidt tot 900 à 2700 voortijdige sterfgevallen in Nederland. Tenslotte lijken de emis-
    sies van houtstook in de Nederlandse emissieregistratie sterk onderschat te worden. Aanvullende
    maatregelen voor het tegengaan van het stoken van hout zijn wenselijk vanuit zowel gezondheids- als
    klimaatperspectief.
    De toekomst van hout in de biobased economy
    Annevelink, E. ; Harmsen, P.F.H. ; Spijker, J.H. - \ 2018
    Vakblad Natuur Bos Landschap 15 (2018)141. - ISSN 1572-7610 - p. 7 - 11.
    biobased economy - hout - biobrandstoffen - biomassa - hernieuwbare energie - materialen uit biologische grondstoffen - cellulose - lignine - vezels - biobased economy - wood - biofuels - biomass - renewable energy - biobased materials - cellulose - lignin - fibres
    De laatste jaren is de biobased economy sterk gegroeid door allerlei activiteiten, variërend van fundamenteel onderzoek naar nieuwe biobased toepassingen, tot het op commerciële schaal vervaardigen van biobased producten. Welke kansen biedt dit voor hout en houtige biomassa en wat zijn de verwachte effecten op de houtmarkt?
    Innovatieve technologie in beheer en oogst van houtige biomassa : eindrapportage
    Raa, Rik te; Pfau, S. ; Clerkx, A.P.P.M. ; Massop, Hans ; Hissink, H.J. - \ 2017
    BTG Biomass Technology Group - 57
    bio-energie - biobased economy - biobrandstoffen - hout - biomassa productie - bosbeheer - bioenergy - biobased economy - biofuels - wood - biomass production - forest administration
    Sustainable woodfuel for food security : A smart choice: green, renewable and affordable
    Sooyeon, Laura Jln ; Schure, J.M. ; Ingram, V.J. ; Yoo, Byoung Il ; Reeb, Dominique ; Xia, Zuzhang ; Perlis, Andrea ; Nordberg, Mats ; Campbell, Jeffrey ; Muller, Eva - \ 2017
    FAO - ISBN 9789251099629 - 35
    biobased economy - biofuels - bioenergy - wood - biomass - heat - biobased economy - biobrandstoffen - bio-energie - hout - biomassa - warmte
    With food insecurity, climate change and deforestation and forest degradation remaining key global issues, this paper highlights the role of sustainable woodfuel in improving food security. Food insecurity and a high dependence on woodfuel as a primary cooking fuel are characteristics common to vulnerable groups of people in developing regions of the world.With adequate policy and legal frameworks in place, woodfuel production and harvesting can be sustainable and a main source of green energy. Moreover, the widespread availability of woodfuel, and the enormous market for it, presents opportunities for employment and for sustainable value chains, providing further rationale for promoting this source of energy. This paper explains how sustainable woodfuel is closely linked to food security and provides insights in how the linkages could be strengthened at all stages of woodfuel production, trade and use.
    Publishable version of Compendium on research results on agro and forest-biomass side-streams : Deliverable 1.1. EU-Horizon2020 project AGRIFORFALOR, Project ID: 696394
    Hendriks, C.M.A. ; Lambrecht, E. ; Nabuurs, G.J. ; Gellynck, X. ; Welck, H. - \ 2016
    European Commission - 25
    biomass - bioenergy - sustainability - biobased economy - residual streams - wood - agricultural wastes - organic wastes - chemical industry - projects - biomassa - bio-energie - duurzaamheid (sustainability) - biobased economy - reststromen - hout - agrarische afvalstoffen - organisch afval - chemische industrie - projecten
    AGRIFORVALOR aims to close the research and innovation divide by connecting practitioners from agriculture and forestry to research and academia as well as with associations and clusters, bio-industry, policy makers; business support organisations, innovation agencies and technology transfer intermediaries in multi-actor innovation partnership networks. The focus of the project is on the transfer of know-how and information to enable and support farmers and foresters to exploit existing research results and facilitate the capture of grass root ideas for bio-industry development.
    In the project, practitioners in the field of biomass side-streams are united in three Biomass Innovation Design Hubs, piloted in Spain (Andalucía), Hungary and Ireland. In each of these hubs, existing research results and good practices on valorisation of biomass side-streams from agro and forest will be shared and matched with the specific needs and potentials; new grass-roots ideas collected and developed; and dedicated innovation support applied to further deploy selected topics which are dealt with by multi-actor innovation partnership groups.
    Plan van aanpak voor houtmobilisatie bij particuliere boseigenaren
    Clerkx, A.P.P.M. ; Reumerman, Patrick ; Schelhaas, M. ; Raa, Rik te - \ 2016
    Enschede : BTG Biomass Technology Group - 28
    bosbezit - particulier eigendom - hout - bosproducten - houtkap - twente - forest ownership - private ownership - wood - forest products - logging - twente
    In Nederland bestaat 11% van het oppervlak uit bossen. Deze bossen vervullen belangrijke functies, zoals recreatie, bron van biodiversiteit en leverancier van grondstoffen voor bioenergie en de bioeconomie. Daarnaast passen bossen in de cultuur en tradities van Nederland. De houtoogst in Nederland is laag – ongeveer de helft van de jaarlijkse bijgroei – en redelijk constant. Diverse (overheids)acties in de afgelopen 20 jaar hebben hier geen verandering in gebracht. Het is belangrijk om de houtoogst te verhogen vanwege de positieve effecten op de staat van het Nederlandse bos en vanwege de toekomstige grotere vraag naar hout. Uit een recente enquête onder particuliere boseigenaren in Twente is gebleken dat de helft van deze eigenaren – goed voor 2/5 van het bos in Twente – niet oogst. Daarnaast is ook gebleken dat een belangrijk deel van deze eigenaren bereid is te oogsten als de omstandigheden zouden verbeteren. In dit Plan van Aanpak zijn een aantal acties opgesteld met als doel de houtmobilisatie onder particuliere eigenaren te verhogen.
    Evaluatie van de ecologische effectiviteit van de houtconstructies in de Snelle loop
    Verdonschot, R.C.M. ; Brugmans, Bart ; Moeleker, Mieke ; Verdonschot, P.F.M. - \ 2016
    H2O online (2016)27 juli.
    ecologie - waterlopen - noord-brabant - hydrologie - macrofauna - monitoring - bemonsteren - hout - aquatische ecosystemen - dood hout - ecology - streams - noord-brabant - hydrology - macrofauna - monitoring - sampling - wood - aquatic ecosystems - dead wood
    In de Snelle Loop zijn in 2012 verschillende typen houtconstructies aangebracht. Waterschap Aa en Maas en studenten van de HAS Hogeschool in Den Bosch verrichten sindsdien jaarlijks fysisch-chemische, hydromorfologische en biologische metingen. In deze studie zijn de tot nu toe verzamelde gegevens over de effecten op de levensgemeenschap na drie jaar geëvalueerd. Het hout bleek effect te hebben op de levensgemeenschap, maar grote jaarlijkse verschillen lieten zien dat met name effecten op een groter schaalniveau een sturende rol spelen. Er worden aanbevelingen gedaan voor de opzet van monitoring om onderscheid te kunnen maken tussen effecten op verschillende schaalniveaus
    Markers inside wood : tree rings as archives of insect outbreaks, drift-sand dynamics, and spring flooding
    Copini, P. - \ 2015
    Wageningen University. Promotor(en): Frits Mohren, co-promotor(en): Ute Sass-Klaassen; Jan den Ouden. - Wageningen : Wageningen University - ISBN 9789462574861 - 192
    acer palmatum - quercus robur - hout - insectenplagen - jaarringen - uitbraken (ziekten) - inundatie - houtanatomie - bomen - acer palmatum - quercus robur - wood - insect pests - growth rings - outbreaks - flooding - wood anatomy - trees

    MARKERS INSIDE WOOD – TREE RINGS AS ARCHIVES OF INSECT OUTBREAKS, DRIFT-SAND DYNAMICS AND SPRING FLOODING

    Trees are long-living organisms that record ecologically relevant information in their xylem that can be accessed by dendrochronology, the study of tree rings. Specific environmental events like frost, fire, floods, burial or wounding may drastically alter the anatomy of tree rings and consequently may leave markers inside trees. These wood-anatomical markers have shown a high potential for studying past environmental events with an annual or even intra-annual temporal resolution. In this thesis, the temporal resolution of wood-anatomical markers was studied to date wounds made by invasive Anoplophora beetles. In addition, the accuracy of dating drift-sand dynamics and spring flooding events was studied using wood-anatomical changes, which were expected to occur after drastic changes in the stem and root environment. It was hypothesised that all these wood-anatomical markers can be used with an intra-annual resolution. Field studies in combination with experiments were used to study tree growth and the formation of wood-anatomical markers in Japanese maple (Acer palmatum Thunb.) and pedunculate oak (Quercus robur L.).

    It was shown that wounds in Japanese maple can be assigned to three different phases related to tree-ring development: (1) wounds that originated during dormancy are located at the tree-ring boundary; (2) wounds that originated during the growing season are located within the tree ring. If wound-xylem formation was observed locally around the wound (3), it could either imply that the wound originated at the very end of the growing season or just before the onset of radial growth or during dormancy when temperature was high. Dating wounds caused by the formation of exit holes has proved to be very significant in fighting invasive insect outbreaks. By pinpointing the exact year and season when Anoplophora beetles emerged, it can be substantiated whether exit holes in imported trees were formed at the location of import. This knowledge can subsequently be used to draw up customised eradication measures and allocate proper surveillance plans and population dynamics can be reconstructed.

    Living trees in drift-sand areas may contain burial or exposure signals even if the sand under which they were buried has long since disappeared. Anatomical changes in pedunculate oak trees due to burial are not a result of physical changes in the stem environment that directly affect the cambium. Instead they are most likely the result of adventitious root formation that transforms lower parts of the stem into root, and concomitantly induces a change from stem to root anatomy. As the formation of a wood-anatomical marker caused by burial can be delayed by many years or might be entirely absent, depending on the formation of adventitious root formation, its presence only allows for an estimate on minimum burial age.

    Flood rings containing anomalously small earlywood vessels in pedunculate oak are formed in response to spring flooding within a narrow time window related to cambial phenology. They can be induced if a flooding event has occurred for at least two weeks during spring. The extreme reduction in vessel size is a consequence of a delay in vessel formation due to anoxic conditions related to flooding. Flood rings however, provide only limited information on the duration of flooding, as the flooding may have lasted for months (during winter) before it is recorded.

    It is concluded that the origin of wood-anatomical markers largely determines the temporal resolution. Markers induced by wounding or flooding show a high intra-annual temporal resolution and immediate effect on tree functioning, whereas burial might not be recorded three years after the triggering events. The different wood-anatomical markers addressed in this thesis illustrate the relevance of studying the mechanism behind the formation of markers for correct interpretation of the specific triggering factor as well as their temporal resolution. Only with this knowledge it becomes possible to reliably use wood-anatomical markers as archives to understand and reconstruct dynamics in geomorphic, entomologic, pathogenic or climatic factors.

    Lignin solubilisation and gentle fractionation in liquid ammonia
    Strassberger, Z. ; Prinsen, P. ; Klis, F. van der; Es, D.S. van; Tanase, S. ; Rothenberg, G. - \ 2015
    Green Chemistry 17 (2015). - ISSN 1463-9262 - p. 325 - 334.
    technical lignins - renewable chemicals - catalysts - extraction - conversion - fuels - kraft - wood - purification - valorization
    We present a simple method for solubilising lignin using liquid ammonia. Unlike water, which requires harsh conditions, ammonia can solubilise technical lignins, in particular kraft lignin. A commercial pine wood Kraft lignin (Indulin AT) was solubilized instantaneously at room temperature and 7–11 bars autogeneous pressure, while a commercial mixed wheat straw/Sarkanda grass soda lignin (Protobind™ 1000) was solubilized within 3 h at ambient temperature, and 30 min at. 85 °C. Hydroxide salts were not required. Wheat straw, poplar and spruce organosolv lignins, as well as elephant grass native lignin (MWL) were also solubilized, albeit at lower values. Different sequences of solubilisation and extraction were tested on the Protobind™ 1000 lignin. The remaining lignin residues were characterized by FTIR, size exclusion chromatography (SEC), elemental analysis (ICP), 2D-NMR and 31P NMR. Liquid ammonia is not an innocent solvent, as some nitrogen was incorporated in the residual lignin which then rearranged to higher molecular weight fractions. Nevertheless, the mild solubilisation conditions make liquid ammonia an attractive candidate as a solvent for lignin in future biorefinery processes.
    Boom geeft chemie nieuw leven
    Gosselink, Richard - \ 2014
    biopolymers - lignin - separation technology - wood - papermaking - energy saving - biobased chemistry - biobased economy
    Fractionation of five technical lignins by selective extraction in green solvents and characterization of isolated fractions
    Boeriu, C.G. ; Fitigau, F. ; Gosselink, R.J.A. ; Frissen, A.E. ; Stoutjesdijk, J.H. ; Peter, F. - \ 2014
    Industrial Crops and Products 62 (2014). - ISSN 0926-6690 - p. 481 - 490.
    antioxidant activities - structural features - alcell(r) lignin - molecular-weight - kraft lignin - solubility - spectroscopy - prediction - ethanol - wood
    Lignins from softwood, hardwood, grass and wheat straw were fractionated by selective extraction at ambient temperature using green solvents like acetone/water solutions of 10, 30, 50, 70 and 90% (v/v) acetone and ethyl acetate. A comparison between the isolated fractions and unfractionated lignins was made in terms of extraction yield, lignin solubility factor, molecular weight distribution and functional group composition. Low molecular weight (LMW) lignin fractions with narrow dispersity are obtained by extraction with ethyl acetate and acetone–water solution containing 30% acetone, with yields depending on the type and the functional group content of lignins. A significant amount (56%) of the organosolv hardwood lignin with low molecular weight (Mw = 1868 g/mol) and low dispersity was isolated from ethyl acetate. Insoluble fractions with very high molecular weight (Mw between 10 and 17 kg/mol) are obtained in low yield from acetone–water solutions with 50, 70 and 90% acetone. LMW lignins are in general less condensed and have lower aliphatic hydroxyl content than parent lignins while the HMW fractions have a higher content of condensed hydroxyls. Principal component analysis on the chemical composition of lignins and isolated fractions determined from 31P NMR data showed the high heterogeneity of the technical lignins. Partial least squares models based on FT-IR spectral data were developed to predict the functional group content determined by quantitative 31P NMR analysis of technical lignins and lignin fractions. This approach can be used to develop simple, rapid and accurate analytical tools to monitor and control the selective fractionation of lignin.
    Mobilization of biomass for energy from boreal forests in Finland & Russia under present sustainable forest management certification and new sustainability requirements for solid biofuels
    Sikkema, R. ; Faaij, A.P.C. ; Ranta, T. ; Heinimö, J. ; Gerasimov, Y.Y. ; Karjalainen, T. ; Nabuurs, G.J. - \ 2014
    Biomass and Bioenergy 71 (2014). - ISSN 0961-9534 - p. 23 - 36.
    environmental impacts - wood - bioenergy - resources - fuel - alternatives - procurement - potentials - countries - products
    Forest biomass is one of the main contributors to the EU's renewable energy target of 20% gross final energy consumption in 2020 (Renewable Energy Directive). Following the RED, new sustainability principles are launched by the European energy sector, such as the Initiative Wood Pellet Buyers (IWPB or SBP). The aim of our study is the investigation of the quantitative impacts from IWPB's principles for forest biomass for energy only. We deploy a bottom up method that quantifies the supplies and the costs from log harvest until forest chip delivery at a domestic consumer. We have a reference situation with existing national (forest) legislation and voluntary certification schemes (scenario 1) and a future situation with additional criteria based on the IWPB principles (scenario 2). Two country studies were selected for our (2008) survey: one in Finland with nearly 100% certification and one in Leningrad province with a minor areal share of certification in scenario 1. The sustainable potential of forest resources for energy is about 54 Mm3 (385 PJ) in Finland and about 13.5 Mm3 (95 PJ) in Leningrad in scenario 1 without extra criteria. The potential volumes reduce considerably by maximum 43% respectively 39% after new criteria from the IWPB, like a minimum use of sawlogs, stumps and slash for energy, and by an increased area of protected forests (scenario 2A Maximum extra restrictions). In case sawlogs can be used, but instead ash recycling is applied after a maximum stump and slash recovery (scenario 2B Minimum extra restrictions), the potential supply is less reduced: 5% in Finland and 22% in Leningrad region. The estimated reference costs for forest chips are between €18 and €45 solid m-3 in Finland and between €7 and €33 solid m-3 in the Leningrad region. In scenario 2A, the costs will mainly increase by €7 m-3 for delimbing full trees (Finland), and maximum €0.3 m-3 for suggested improved forest management (Leningrad region). In scenario 2B, when ash recycling is applied, costs increase by about €0.3 to €1.6 m-3, depending on the rate of soil contamination. This is an increase of 2%, on top of the costs in scenario 2A.
    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.
    Woodfuel for urban markets in the Congo Basin: a livelihood perspective
    Schure, J.M. - \ 2014
    Wageningen University. Promotor(en): Bas Arts, co-promotor(en): Freerk Wiersum; P. Levang. - Wageningen : Wageningen University - ISBN 9789461737717 - 186
    hout - markten - stadsomgeving - brandhout - brandstofgewassen - huishoudens - afrika - energie - ontwikkelingslanden - biobased economy - wood - markets - urban environment - fuelwood - fuel crops - households - africa - energy - developing countries - biobased economy
    Hout is de belangrijkste energiebron van huishoudens in sub-Sahara Afrika en het gebruik van houtskool in stedelijke gebieden groeit. Deze dissertatie maakt deel uit van een nieuwe generatie van houtenergie-studies sinds de begin jaren 2000. De hernieuwde interesse komt voort uit de erkenning, dat handel in houtenergie mogelijk bijdraagt aan het oplossen van armoede en energieproblemen. Waar in het verleden houtenergie- studies zich nog voornamelijk concentreerden op het kappen voor eigen huishoudelijk gebruik en productievraagstukken, is er nu meer aandacht voor de rol van stedelijke vraag en commercie. Dit omvat het potentieel van houtenergie als bron van inkomsten. Omdat houtenergie-studies zich traditioneel meer gericht hebben op de kwetsbare droge en semi-aride gebieden in de wereld, is er weinig informatie over het karakter en het ontwikkelingsperspectief van de handel in Afrika’s tropische humide bos regio’s. Deze dissertatie analyseert houtenergie als een bron van levensonderhoud in de context van stedelijke brandhoutbevoorrading in het Kongobekken.
    Opportunities and applications of dendrochronology in Africa
    Gebrekirstos, A. ; Bräuning, A. ; Sass-Klaassen, U. ; Mbow, C. - \ 2014
    Current Opinion in Environmental Sustainability 6 (2014). - ISSN 1877-3435 - p. 48 - 53.
    climate-growth relationships - tree-rings indicate - tropical forest - stable-carbon - rainfall variability - precipitation signal - isotope ratios - west-africa - dynamics - wood
    Partly due to severe lack of instrumental climate data, the drivers of the African climate, their interactions and impacts are poorly understood. The paper demonstrates the prospects and applications of dendroecological and stable isotope techniques, such as to reconstruct climate variability, trends and atmospheric circulation patterns, to fill the knowledge gap in ecosystem productivity and hydrological cycle in different climatic zones of Africa. We summarize the contribution of tree-ring analyses to validation of climate and hydrological models for improved scenarios, and to identify agroforestry species with the ability to acclimate to exacerbated climate conditions. A high number of African tree species shows datable annual tree rings and may reach multi century age. To advance dendrochronology in Africa, collaborative efforts in capacity building of African universities and research organizations are needed.
    Frankincense tapping reduces the carbohydrate storage of Boswellia trees
    Mengistu, T. ; Sterck, F.J. ; Fetene, M. ; Bongers, F. - \ 2013
    Tree Physiology 33 (2013)6. - ISSN 0829-318X - p. 601 - 608.
    tropical forest - swiss treeline - rubber trees - pinus-cembra - wood - sink - photosynthesis - limitation - papyrifera - ecology
    Carbohydrates fixed by photosynthesis are stored in plant organs in the form of starch or sugars. Starch and sugars sum to the total non-structural carbohydrate pool (TNC) and may serve as intermediate pools between assimilation and utilization. We examined the impact of tapping on TNC concentrations in stem-wood, bark and root tissues of the frankincense tree (Boswellia papyrifera (Del.) Hochst) in two natural woodlands of Ethiopia. Two tapping treatments, one without tapping (control) and the other with tapping at 12 incisions, are applied on experimental trees. Trees are tapped in the leafless dry period, diminishing their carbon storage pools. If storage pools are not refilled by assimilation during the wet season, when crowns are in full leaf, tapping may deplete the carbon pool and weaken Boswellia trees. The highest soluble sugar concentrations were in the bark and the highest starch concentrations in the stem-wood. The stem-wood contains 12 times higher starch than soluble sugar concentrations. Hence, the highest TNC concentrations occurred in the stem-wood. Moreover, wood volume was larger than root or bark volumes and, as a result, more TNC was stored in the stem-wood. As predicted, tapping reduced the TNC concentrations and pool sizes in frankincense trees during the dry season. During the wet season, these carbon pools were gradually filled in tapped trees, but never to the size of non-tapped trees. We conclude that TNC is dynamic on a seasonal time scale and offers resilience against stress, highlighting its importance for tree carbon balance. But current resin tapping practices are intensive and may weaken Boswellia populations, jeopardizing future frankincense production.
    Distinct roles of carbohydrate esterase family CE16 acetyl esterases and polymer-acting acetyl xylan esterases in xylan deacetylation
    Koutaniemi, S. ; Gool, M.P. van; Juvonen, M. ; Hinz, S.W.A. ; Schols, H.A. ; Tenkanen, M. - \ 2013
    Journal of Biotechnology 168 (2013)4. - ISSN 0168-1656 - p. 684 - 692.
    eucalyptus-globulus labill - trichoderma-reesei - alpha-glucuronidase - schizophyllum-commune - catalytic-properties - purification - aspen - mode - wood
    Mass spectrometric analysis was used to compare the roles of two acetyl esterases (AE, carbohydrate esterase family CE16) and three acetyl xylan esterases (AXE, families CE1 and CE5) in deacetylation of natural substrates, neutral (linear) and 4-O-methyl glucuronic acid (MeGlcA) substituted xylooligosaccharides (XOS). AEs were similarly restricted in their action and apparently removed in most cases only one acetyl group from the non-reducing end of XOS, acting as exo-deacetylases. In contrast, AXEs completely deacetylated longer neutral XOS but had difficulties with the shorter ones. Complete deacetylation of neutral XOS was obtained after the combined action of AEs and AXEs. MeGlcA substituents partially restricted the action of both types of esterases and the remaining acidic XOS were mainly substituted with one MeGlcA and one acetyl group, supposedly on the same xylopyranosyl residue. These resisting structures were degraded to great extent only after inclusion of a-glucuronidase, which acted with the esterases in a synergistic manner. When used together with xylan backbone degrading endoxylanase and ß-xylosidase, both AE and AXE enhanced the hydrolysis of complex XOS equally.
    Hout verstoken toch niet zo klimaatneutraal
    Arets, Eric - \ 2013
    wood - combustion - sustainability - environmental impact - carbon dioxide - emission - biobased economy
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