Zoek medewerkers/organisaties dr. UGW Sass-Klaassen
Naamdr. UGW Sass-Klaassen

OmschrijvingUniversitair Hoofddocent
OrganisatieDepartement Omgevingswetenschappen
OrganisatieeenheidBosecologie en -beheer
Telefoon+31 317 486 364
Telefoon secretariaat+31 317 486 195
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BezoekadresDroevendaalsesteeg 3a
PostadresPostbus 47
Reguliere werkdagen
Ma Di Wo Do Vr
  • Honorary professor Tree Biology and Dendroecology - Eberswalde University for Sustainable Management HNEE
    jan 2020 - Nu

    teaching of 2 course modules at the HNEE


Understanding tree growth in relation to environmental factors – this is my passion! Dendrochronology (tree ring research) sounds like a very specific discipline, but it can be widely applied on trees in temperate, boreal, arctic, and tropical ecosystems and for answering fundamental and applied questions ranging from mechanism of water transport in trees and shrubs to effects of climate change on tree growth and wood quality.

The DendroLab of FEM is my arena to conduct research together with colleagues of various research disciplines and teach students about mechanisms and dynamics in wood formation in response to climate as well as to unravel environmental information (climate, flooding, burial) stored in tree-ring width and wood structure.

Examples of questions we addressed in International as well as student projects are: How Spanish was the Spanish Armanda? (Provenancing of ship timber from Iberian shipwrecks) What is the age of tropical giants and arctic dwarfs shrubs? (Age detection and growth trajectories of tropical tree species and Arctic shrubs). “Trojan horses – bark beetles invading the Netherlands (dating exit holes made by invasive insects); Pope in trouble – no regeneration in Frankincense forests in Ethiopia (Population dynamics of Boswellia papyrifera).




Team member of & Loglife-experiment: Decomposition patterns in coarse wood of 20 European and exotic tree species. Together with Hans Cornelissen (VU) and  Mariet Hefting (UU) and numerous experts on wood, soil, animals ...

Floods and sandstorms - Precision of dendrogeomorphic markers in trees.

This project systematically investigates the factors and mechanisms responsible for changes in tree-ring width and wood anatomy as a result of flooding and sand burial. Experiments are performed to determine the precision of dendrogeomorphic markers. Results from these experiments will be applied in reconstructing flooding and sand deposition and erosion events from trees in situ.

With Paul Copini, Jan den Ouden & Frits Mohren

InputDrought - Increasing the potential of economically valuable tree species to survive drought by choosing the optimal provenance.

Climate change is confronting forestry with new challenges as tree species with the ability to acclimate to exacerbated climate conditions have to be identified. The ideal future forest would consist of species coping well with increasing drought and concurrently provide timber of high economic value.

With Britta Eilmann, Jan den Ouden, Paul Copini, Sven de Vries (Alterra), Frank Sterck & Frits Mohren

ForSEAdiscovery - Application of ecological wood anatomy for provenancing oak and pine wood from Atlantic Iberia.

Unprecedented demands on Iberian oak and pine forests led by increase of ships building in the Age of Discovery (16th to 18th centuries) caused intensive forest logging practices over Iberian Peninsula. 

We study xylem structure of Iberian pine and oak species intensively used for shipbuilding, to accomplish already existing time-series and use them for provenancing of ship timber. State-of-the-art approaches will be used to build long time-series from anatomical features and to compute site specific wood-anatomical markers for each study site. Analyses of ship timber will be carried out following the same approach. Provenancing will be done by statistic comparison of time series gained from ship timber with existing and newly developed reference records built up in this study. In addition, samples from living trees and shipwrecks will undergo genetic analyses in order to identify species used for specific parts of the ships.

With Linar Akhmetzyanov, Jan den Ouden & Frits Mohren and colleagues from Spain, Portugal, France, Great Britain.

STReESS – Studying Tree Responses to extreme Events: a SynthesiS

In this EU COSt Action with34 participating countries we work on response of European tree species to extreme climate conditions. Experts from dendrochronology, wood anatomy, ecophysiology and forest ecology and management regulary meet and develop new research ideas.


Coordinator FEM22306 Forest resources and sustainable management systems.

Learning and experiencing Forest ecosystems, relevance of wood- its structure and properties, certification and conservation. Including excursions to forests, enterprises, research institutes.     

Course awarded with best education price in 2014 and 2015.

Lecturer FEM10306 - ecology of Forests.

Learning about wood formation from cell to tree and tree-ring research - methods & applications!   


BSc - MSc - theses & Internships on Wwood science and Dendrochronology

  • FEM-10306 - Ecology of Forests
  • FEM-22306 - Forest Resources
  • FEM-50403 - Capita selecta Forest Ecology and Forest Management - open for individual projects
  • FEM-80424 - MSc Thesis Forest Ecology and Forest Management
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