Current and past master theses

For more information see Faculty website.

2018-2019

Testen van lokale houtsoorten voor gitaarbouw (i.s.m. Centrum voor Muziekinstrumentenbouw)

Pieter Goovaerts

Veel musici geloven dat de beste klassieke en akoestische gitaren gemaakt zijn van tropisch hout. Maar deze exotische houtsoorten (bv. rozenhout, mahonie, ebbenhout enz.) worden steeds schaarser en duurder, aangezien veel van deze bossen nu worden beschermd en hun handel wordt beperkt door internationale verdragen (bv. CITES).  Bovendien is het hout soms illegaal gekapt uit tropische regenwouden met ernstige gevolgen voor het milieu.

Het Leonardo Guitar Research (LGR) project is opgezet om de mogelijkheden te onderzoeken voor het bouwen van gitaren met duurzaam lokaal hout. Het project is een pan-Europees project met bijdragen van instrumentenscholen en professionele gitaarmakers in heel Europa, waaronder het Centre of Musical Instrument Building (CMB) in België.

Door middel van een uitgebreid onderzoeksprogramma heeft het LGR-project aangetoond dat lokale, duurzame Europese houtsoorten kunnen worden gebruikt om gitaren te maken die evenwaardig zijn wat betreft geluid als tropische houtgitaren. Dit is gedemonstreerd in talloze blinde testen met professionele gitaristen, muzikanten en publiek.

De hamvraag is: welke lokale houtsoorten zijn het meest vormstabiel onder spanning voor het vervaardigen van de nek van de gitaar? En hoe verhouden ze zich tot de meest gebruikte tropische houtsoorten?

 

Morfologische verschillen tussen herkomst van spork van verschillende breedtegraden (i.s.m. Kristine Vander Mijnsbrugge) 

Lise De Clerck

In noordelijke herkomsten van Populus trichocarpa werd vastgesteld dat in de dormante vegetatieve knoppen een groter aantal bladeren aanwezig waren in vergelijking met herkomsten van deze soort die een meer zuidelijke herkomst hebben (Mc Kown et al. 2014). Dit kan erop wijzen dat de soort aangepast is aan een korter groeiseizoen en ervoor zorgt dat er in de lente snel heel wat bladeren kunnen ontplooien zodat het “vergroenen” van de kroon in de lente heel snel kan plaats vinden. Zo wordt de beperkte tijd voor groei zo productief mogelijk ingevuld.

Bij een herkomstproef (common garden) aan het INBO werd vastgesteld dat een noordelijk herkomst van spork (Frangula alnus) vroeger uitliep in het voorjaar tov een lokale herkomst (wat tegen de verwachting in was). Ook een zuidelijke herkomst liep vroeger uit (zoals verwacht).

Aan het INBO zijn momenteel potplanten aanwezig van de spork herkomstproef, die werden gestekt van een aantal moederplanten van de drie hierboven vermelde herkomsten (Scandinavisch, Vlaams en Italiaans). We hebben dus genetisch identieke planten die als herhalingen kunnen dienstdoen, en eventueel ook in verschillende groeicondities kunnen gebracht worden om plasticiteit van bepaalde kenmerken te bestuderen. Eén voorstel is alvast om naar winterknoppen te kijken via microscopische en tomografische analyses: zijn er meer bladeren aanwezig in de knoppen van de Scandinavische herkomsten tov lokale of zuidelijke herkomsten? Bijkomende onderzoeksvragen kunnen hierbij aansluiten. Bijvoorbeeld de link tussen cambiale activiteit (cambiaal meristeem) en apicale groei (apicaal meristeem) in de drie herkomsten (zie ook Perrin et al 2017).

 

Is leaf fall related to wood formation in deciduous tree species? (i.s.m. prof. Matteo Campioli)

Mieke Decoster

Tree phenology (timing of tree life cycle events) is key to understand wood growth and the feedback of forests to the climate. Much attention has been given to tree phenology in spring (e.g. timing of leaf bud burst, flowering) while autumn phenology has been understudied. In particular, we still do not understand what determines leaf fall timing (e.g. light, temperature, precipitation) and why it is highly variable (e.g. among years/tree individuals/species/sites). Leaf fall timing is very important as it relates to wood production, seasonal gas exchange between forest and atmosphere, nutrient cycle, forest albedo, species interactions etc.

Within this thesis the relationship between wood growth in autumn, leaf aging and leaf fall, with particular emphasis on intra-seasonal wood formation, is examined. Wood samples will be taken (in experimental young trees and in mature trees in natural stands), perform anatomical wood growth analysis and measure leaf aging. Field work will be conducted in Norway, while laboratory work will take place in Gent and/or Ljubljana (Slovenia). The subject fits within the new EU project LEAF-FALL (https://www.uantwerpen.be/nl/onderzoek-en-innovatie/onderzoek-aan-uantwerpen/onderzoeksexcellentie/erc/matteo-campioli/).

 

Bestrijden van de illegale houthandel via chemische vingerafdrukken: de kracht van wiskunde en massaspectrometrie (i.s.m. prof. Willem Waegeman)

Nathalie Goeders

Het correct identificeren van soorten in de houthandel is cruciaal om illegale houthandel te bestrijden. Momenteel zijn er drie prominente technieken; isotopen-analyse, houtanatomie en DNA-analyse. Deze technieken vragen echter veel tijd en zijn vaak enkel in staat om te identificeren tot op het genus-niveau. Een nieuwe techniek gebruikt ‘Direct Analysis in Real Time – Time of Flight Mass Spectrometry’ om de verhandelde soort op een snelle manier te identificeren. Een stukje hout wordt in een verhitte helium gasstroom geplaatst waarbij de moleculen in het hout geionizeerd worden. Het verkregen chemische mass-spectrum (chemische fingerprint) van het hout is uniek voor de soort en kan gebruikt worden om de soort identificeren. De student geeft toegang tot meer dan 600 mass-spectra om zich er mee vertrouwd te maken. De student zal bepalen welke voorbewerkingen op deze data nodig zijn en zal daarna een model opstellen die het mogelijk maakt de soorten te onderscheiden op basis van hun chemisch patroon. Hierbij zal de student gebruik maken van chemometrische methoden en machine learning. Specifieke clustering- en classificatie-algoritmen zullen geimplementeerd worden.

 

Fungal susceptibility of bio-based building materials (i.s.m. prof. Nathan Van Den Bossche en prof. Marijke Steeman)

Vincent Broekaert en Kevin Van Vossel

Bio-based materials are gaining in importance as they play a huge role in sustainable development. Wood and wood-engineered products as well as isolation materials made from flax, hemp, etc. are increasingly used in the construction sector. These materials originate from renewable resources and are often biodegradable. This biodegradability can cause serious problems when bio-based materials are exposed to moisture and temperature conditions that are favourable for fungi. Fungi often occur in buildings when there are moisture problems, caused for example by construction errors, and lead to million euros of damage to buildings every year. Invasion by fungi can lead to aesthetical damage and to real degradation of bio-based building materials. 
 However, there is not much information available about the fungal susceptibility of bio-based materials. It is therefore eminent that thorough research is conducted so bio-based materials can be optimally implemented. During the course of this master thesis, data will be gathered concerning the fungal susceptibility of bio-based building materials. By making use of databases containing information about real life damage cases as well as databases containing data from laboratory and field experiments, a clear overview will be given regarding the fungal susceptibility of a variety of bio-based building materials. This will provide us with more insight into these materials and will improve their implementation in the construction sector..

2017-2018

Pith-to-bark profiles of wood characteristics to quantify wood technological properties as well as growth strategies of tropical trees

Siebe Puynen

Tropische bossen spelen een belangrijke rol als ecosysteemdienstenleverancier: koolstofopslag, grondstofvoorziening, voedselbron, en meer. Een belangrijke vraag is echter hoe de tropische bossen zullen evolueren in de toekomst, onder meer in functie van een veranderend klimaat? Het voorspellen hiervan vereist een goed begrip van groei, houtvorming en houtkwaliteit in functie van de tijd. Hiervoor worden vaak destructieve bemonsteringen uitgevoerd, maar boorkernen bieden een groot potentieel om op een snelle manier verschillende karakteristieken van een houtsoort in kaart te brengen.

Dit thesisproject draagt bij tot tot een beter begrip van groei en houtkwaliteit van een aantal Zuid-Amerikaanse houtsoorten en dat aan de hand van boorkernen. Door het opmeten van houtkenmerken zoals groeiringbreedte, vatoppervlakte, en andere, kan niet alleen groei en groeistrategie worden ingeschat, maar kunnen er eveneens belangrijke houttechnologische eigenschappen aan gekoppeld worden, zoals densiteit en dimensionele stabiliteit. Op die manier worden boorkernen niet alleen gevaloriseerd als archieven van groei, maar ontsluiten ze ook belangrijke informatie betreffende houtkwaliteit.

 

Effects of Vegetation Management on Wood Properties and Plant Water Relations of Four Conifer Species in the Pacific Northwest of the USA (i.s.m. prof. Carlos A. Gonzalez-Benecke)

Joyce Aernouts

The forests of the Pacific Northwest are highly productive, but competition from vegetation can reduce tree survival and negatively impact the growth of planted Douglas-fir (Pseudotsuga menziessi (Mirbel) Franco), as well as other Pacific Northwest conifer species (Chen, 2004). Treatments for managing forest vegetation are widely used all over the world. One of the most common tools for reducing vegetative competition are herbicides. It has been shown that intensive silviculture can be applied at any time during the rotation, but the effects on conifer growth are greatest when the treatments occured during the establishment state after harvest or natural disturbances (Lautenschlager & Sullivan, 2002). Wagner & Robinson (2006) said that it is crucial to know the best timing and minimum duration of vegetation control to achieve maximum yields, better known as the critical period (CP).

 The Vegetation Management Research Cooperative is a group of private companies, public land management agencies, and scientists from Oregon State University that study forest regeneration. The Critical Period Threshold (CPT) study series deals with vegetation management specifically and was established with 4 goals:

1.  to analyse the effects of continuous vegetation management treatments (weed control) on stand productivity and vegetation community dynamics.

2. to determine the number of years of vegetation control required to maximize seedling growth.

3. to determine the level of growth loss that could result from delaying vegetation control for one or two years.

4. to compare the response of different crop-tree species to vegetation management treatments.

 

Charcoal as an archive of Central African forest history

Andreas Popelier

Tropical forests play a major role in the changing Earth system. They acted as net carbon sinks over the last four decades. However, a key question is how long the tropical forest carbon sinks will persist in the future? Predicting the fate of the sink depends upon understanding the complex relation between forest dynamics and candidate drivers. To do so, scientists have used (1) short-term ecological data spanning only the last few decades, but also (2) paleoecological records providing longer-term perspectives. 

This thesis research project will contribute to reconstructing Holocene African forest dynamics. The best archives of vegetation history are undoubtedly fossil plant remains, with pollen as a well-known example. However, lakes with stratified sediment layers are absent in large parts of central Africa, which limits the use of pollen analysis. We therefore focus on a complementary archive. Charcoal is inert and can be found in any soil type as a “witness” of forest fire. Wood-anatomical features are preserved during charcoalification, enabling taxonomic identification using standardized criteria (IAWA), transparent protocols and thin sections of reference wood samples (Xylarium of the Royal Museum for Central Africa, Tervuren).

During this project, the candidate will get a chance to collect charcoal samples from central D.R.Congo. These fragments will be radiocarbon dated (14C), described anatomically and identified using different imaging techniques. Radiocarbon dates and identifications will provide insight in past forest structure and evolution and the results will be compared with those from other palaeo-proxies.  

 

Deep learning toegepast op CT-scans van boorkernen van bomen om ringgrenzen te annoteren (i.s.m. prof. Francis wyffels)

Wout Sartrys

Tropische bossen beslaan 7 tot 10 % van de totale bosoppervlakte maar omvatten 40 tot 50 % van de koolstof in vegetatie (Lewis et al. 2009), en zorgen op die manier voor een belangrijke koolstofopslag (Pan et al. 2011) maar zijn eveneens van uitzonderlijk belang voor een waaier aan ecosysteemdiensten met maatschappelijk belang. De druk op tropische bossen is echter enorm en het is dus belangrijk om kennis te vergaren over het gedrag van tropische bomen en hun respons op klimaatverandering. Bomen archiveren het klimaat in hun groeiringen en kunnen daarom beschouwd worden als natuurlijke archieven. De klassieke aanpak, het opmeten van ringbreedtes en deze gebruiken als proxy voor klimaat, is moeilijker in de tropen dan in de gematigde streken. Om die reden wordt gezocht naar andere mogelijke proxies, en densiteit is er mogelijks één van. Met dat doel voor ogen worden boorkernen gescand met X-stralen tomografie en geconverteerd naar densiteitsprofielen. In dit onderzoek wordt nagegaan of het annoteren van de jaarringgrenzen en het extraheren van de densiteistinformatie kan gebeuren m.b.v. deep learning. Er wordt zowel gewerkt op boorkernen van bomen uit gematigde en tropische streken.

 

The knowledge gap that might not be one: forgotten climate data from the Luki and Yangambi forestry stations (Democratic Republic of the Congo) (i.s.m. dr. Koen Hufkens)

Innocent Banzi Ngulu-Kulu

During the 1930’s-1960, the Yangambi Research Institute and the Luki Forestry station were renowned research facilities that are now protected biosphere reserves and important pools of biodiversity and carbon. After decolonisation in 1960, unfortunately, unpublished historical scientific data have been scattered. Recently, an inventory has been made of all the material available in Belgium concerning forestry, botanical and ecological experiments (Coppieters 2013). All this data is archived in the State Archives of Belgium. In collaboration with the INERA (Institut National pour l'Etude et la Recherche Agronomiques) institute in the Democratic Republic of the Congo and the Royal Museum of Central Africa, we search for valorisation of these data within the recently started COBECORE project (www.cobecore.org). For decades, this information has been unavailable for the scientific community, but is still underexplored. The goal is to search for valuable climate data and to explore documents in the archive that have not been profoundly viewed for 60 years. Modern data analysis after digitisation is vital to initiate new specialised international research using these climate datasets.

 

Analysis of the influence of physical and anatomical features in drying of tropical hardwood species

Rachel Saman

 

2016-2017

Profiles of wood density and conducting tissue as functional traits of Entandrophragma spp. from the Central African rainforest

Maarten Devriendt

Functional traits in wood can help explain the responses of trees to human induced stress, which are increasingly important in the light of climate change and the raising human population. Therefore, research is done in the Democratic Republic of Congo in one of the largest tropical rainforest of the world. The focus of the study are profiles of wood density and conducting tissue to obtain ecological information about the investigated species of Entandrophragma during ontogeny. Wood density profiles from pith to bark did not show particular increasing- or decreasing trends, although differences between species and between sites could be noticed. In Luki, the average wood density is found to be higher than in Yangambi, except for E. angolense.  Clearly, the size of conduits elements increase with an increase of total tree height, both in Yangambi and Luki. By using profiles of conduit elements from pith to bark, a power function could be fitted between the size of the conduit elements and cambial age (as approximation of the number of growth rings). Therefore, xylem tapering for E. angolense is confirmed. Further, the concept of predicting height by the size of conduit elements is illustrated. Different wood anatomical traits could be linked with each other. From pith to bark, an increase in size of conduit elements is accompanied with a decrease in the number of vessels compensating in a fluctuating but rather equal conduit area, which can be linked with the almost constant average wood density.

 

Herstellen gemengde bossen sneller na droogtestress? (i.s.m. prof. Kris Verheyen & dr. Margot Vanhellemont)

Laura Massart

Bosbeheerders worden gestimuleerd om homogene bossen om te vormen naar gemengde, structuurrijke bossen. Om deze ‘nieuwe’ bossen goed te kunnen beheren, hebben beheerders echter nog nood aan informatie over en inzicht in het functioneren van gemengde bossen. In deze thesis onderzoek je hoe de groei van eik of den reageert op droge jaren, in relatie met de diversiteit van zijn buurbomen. Is de veerkracht/weerstand tegen droogtestress hoger als de eik/den omringd wordt door meer soorten? Je neemt groeiringstalen bij eik en/of den in bosreservaten in Nederland en/of Vlaanderen en identificeert droge jaren met behulp van lokale klimaatgegevens. Vervolgens meet je de groeiringen: de groeiringbreedte (Lintab) en verschillen in houtdensiteit (X-ray tomografie). Deze groeiringkenmerken gebruik je om de groei voor, tijdens en na de droge jaren met elkaar te vergelijken.

 

2015-2016

Innovatieve veenvervangers met ziekteonderdrukkende eigenschappen voor de productie van duurzame substraten op basis van lokale plantenvezels: proof of concept

Miet Poppe

Simulating the behaviour of historical valuable timber structures - A case study on wooden mills (i.s.m. prof. Wim Van Paepegem)

Sebastian Ablorh

There is a current code of practice to maintain as much as historical valuable timber as possible whilst ensuring both human safety as well as structural integrity. A wooden post mill – constructed using Quercus robur and/or Quercus petraea wood -  is an example of a structure that should remain safe and functional with minimal loss of valuable material.
This study focuses on creating a computational tool to model deterioration in the structure of a post mill and assess the replacement of elements, thus preventing unnecessary loss of valuable timber. The post is determined to be the critical structural element, both due to its structural and financial importance. The zone at the saddle experiences high stresses and failure is likely to occur here.
Deterioration was modelled in the outer ring of a basic model, created for the post. The width of the degraded ring and the degree of residual strength were investigated. The stability was investigated for a mill both in and out of service, and for both average and Eurocode strength values. All cases were able to tolerate a certain amount of deterioration. The Abaqus model proved to be useful, provided that adequate input is given.

 

Climate response of Terminalia superba from the Mayumbe forest (Democratic Republic of the Congo): intra-annual stable isotope analysis in tree rings (i.s.m. prof. Pascal Boeckx)

Mirvia Angela Rocha Vargas

Dendrochronology is applied to assess the response of trees in a changing environment. For tropical dendrochronology, the ring formation is predominantly caused by seasonal variation of rainfall especially in Central Africa, remains understudied in this context, based on the ring formation caused by the seasonal variation of rainfall. The study of

δ13C and δ18O from cellulose of tree rings are an important part of dendrochronology studies because they contain continuous historical records of its variation over the years due to physiological processes affected by weather conditions. With the δ13C and δ18O composition, it could be possible to get an idea of the balance between stomatal conductance, photosynthetic rate, source water and CO2 uptake due to the variation of weather conditions, such as rainfall and temperature.

Stable isotopes composition (δ13C and δ18O) of the intra-annual cellulose sections extracted from the tree rings (2013-2014 and 2014-2015) was analyzed for three Terminalia superba trees (Tree A, B and C) from different sites in the Luki reserve, Mayombe, Democratic Republic of the Congo. This thesis is an exploratory study to perceive a possible climate and/or physiological response to changes in weather conditions.

 

2014-2015

Intra-annual wood formation in tropical forests: case-study in the Mayombe forest, west of the Democratic Republic of Congo

Selwin Maginet

Intra-annual wood formation has hardly been studied in tropical regions. In the Reserve of Luki (Mayombe forest), selected trees were marked monthly (cambial pinning method) during one year. Moreover, some trees were equipped with dendrometers. The purpose of this work is to study detailed tree growth, and the impact of the climate on wood formation, through a combination of wood anatomy, 3D X-ray tomography and Near infrared (NIR) imaging.

 

To burn or not to burn: transition from savannah to forest in the 'mis en défens' in Manozonzi (Bas - Congo province in the Democratic Republic of Congo)

Victor Deklerck

The regular burning of forests and savannahs is a tradition in most of the African countries. In the province Bas Congo in the Democratic Republic of Congo this practice was stopped in 2005 over 88 ha. This changing landscape is quantified through measurements in permanent sample plots, wood samples and tree-ring analyses. The influence on forest structure and the stocking of carbon is also evaluated and these data will be used for the ongoing REDD+ - readiness project.  
This study is a collaboration between Woodlab, WWF Belgium, WWF DRC, RMCA, INERA and ERAIFT.

 

2013-2014

Evaluation of population dynamics based on growth ring analyzes of trees from the Guyana Basin

Daan Temmerman

Sustainable forest management in the tropics is sometimes hampered by limited understanding of the precise growth patterns of the trees. In the temperate and boreal areas, tree ring analyzes based on drill cores are useful to understand the population dynamics. The question is whether this analog growth ring analysis is possible (at all) for several tree species from the tropical forest? The study is focused on a selection of tree species occurring  in the Guyana basin. Its aim is to determine whether annual ring patterns, driven by seasonal influences, allow to determine the age of trees accurately, therefore permitting this analog sampling technique to be used as an aid for sustainable forest management in the Guyana basin. The study also considers whether it can be a way to identify climatic changes.

 

Natural durability and sawing efficiency for a few specific valuable timber species growing in the Guyana Basin, and the possible influence on felling age

Pepijn 't Hooft

Wood samples will be tested on their durability against wood-destroying fungi using biological tests. These wood samples are selected from pith to bark taken from stem discs collected in Surinam. This allows examining the variability in durability. Correlation between durability, color and age will also be part of this work.

 

2011-2012

Calorific and structural characterization of tropical timber species

Tom De Mil

The objective of this dissertation is the energetic valorization of tropical wood residues (sawdust, sapwood, etc.) resulting from sawmill activities like in Surinam. Density measurements, chemical analysis and calorific determination techniques are being used to investigate relations between extractives, calorific value and density. Moreover, the use of more advanced methods like Near Infrared Imaging and X-ray computed tomography will reveal structural traits of these species.

 

Non-destructive testing for bio-energetic characterization of native woody biomass

Hans Van Lommel

Due to a rising energy demand and declining supply of fossil fuels the interest in biomass increased in recent decades. Woody biomass can help in order to meet the rising energy need and to reduce the concentration of CO2 in the atmosphere. In this thesis state-of-the-art, non-destructive methods are used for biomass characterization of different provenances. What are the differences between different clones of short rotation coppice; is this similar for poplars from agroforestry; is the energetic content of sessile oak coppice larger than that of pedunculate oak; and how can tension wood influence the energetic content?