Stef Weijers persoonlijke pagina
Introduction
About me: I am Stef Weijers, born in august 1978 in Waalre, located in the southern Dutch province North Brabant. In the summer of 1997 I moved to Utrecht, to study Biology. During my studies I took many courses in Ecology, Palaeoecology and Geology and I got well acquainted with many scientific methods used in ecology, palynology and dendrochronology. Currently I’m working on my PhD-project on the use of annual growth parameters of the circumarctic dwarf shrub Cassiope tetragona as climate proxy.
Curriculum Vitae
January 2008: Start of Ph.D. research “Long-lived evergreen shrubs from polar ecosystems as monitors of present-day and past climate change” at the Systems Ecology Department of the VU University in Amsterdam.
- 2005-2007: Functional Application Manager at Sogeti Netherlands B.V.
- 1997-2004: Biology student at Utrecht University, specialisation in Palaeoecology and Geobiology.
Master Research projects:
Changes within a mangrove community as a proxy for palaeoprecipitation in Rookery Bay, Florida.
Supervisors: Dr. W.M. Kürschner en Dr. F. Wagner at the Laboratory of Palaeobotany & Palynology, Utrecht University, the Netherlands
Reconstruction of ENSO-related (palaeo-)precipitation in Southwest Florida from tree-rings of Taxodium distichum.
Supervisors: Dr. F. Wagner (UU) en Dr. U. Sass-Klaassen (WUR) at the Laboratory of Palaeobotany & Palynology, Utrecht University and the Forest Ecology and Forest Management Group, Wageningen University, the Netherlands
Master Thesis:
The evolutionary history of photosynthesis in terrestrial plants: a palaeoecological perspective.
Supervisor: Dr. W.M. Kürschner, Laboratory of Palaeobotany & Palynology, Utrecht University, the Netherlands
Ph.D. Project
Long-lived evergreen shrubs from polar ecosystems as monitors of present-day and past climate change, the development of a tree ring like proxy to reconstruct polar climate.
The project was funded by the Netherlands Organisation for Scientific Research (NWO) as part of the International Polar Year and is supervised by Prof. Dr. Jelte Rozema.
Summary:
The study aims to validate the use of annual growth parameters of the arctic dwarf shrubs Cassiope tetragona as proxy for past arctic summer temperatures. Dendrochronological techniques are applied in order to establish reliable growth-temperature transfer functions that allow temperature reconstruction on the high arctic archipelago Svalbard.
Subsequently climate-growth relationships are further experimentally assessed by manipulating growth in the field through warming of the tundra with Open Top Chambers (OTC’s), lowering of the Photosynthetically Active Radiation (PAR) with tents (-50%) and doubling the ambient precipitation in field sites near Longyearbyen and Ny-Ålesund in Svalbard.
Publications and abstracts
Weijers, S., Wagner-Cremer, F., Sass-Klaassen, U., Broekman, R., and Rozema, J. (in preparation) Growing degree-day sums accurately predict Cassiope tetragona growth: reconstructing past summer intensity in the High Arctic
Weijers, S., Auliaharty, L., van Logtestijn, R., and Rozema, J. (in preparation) Effects of manipulated precipitation and shading on Cassiope tetragona growth and carbon isotope discrimination: a high arctic field study.
Weijers, S., Greve Alsos, I., Bronken Eidesen, P., Broekman, R., Loonen, M.J.J.E., and Rozema, J. (submitted) No divergence in Cassiope tetragona (L.) D. Don: persistence of growth response along a latitudinal temperature gradient and under long-term experimental warming.
Buizer, B., Weijers, S., van Bodegom, P.M., Greve Alsos, I., Bronken Eidesen, P., van Rijckevorsel, J., van Breda, J., de Korte, M., and Rozema, J. (submitted) Ecological responses of Empetrum nigrum L. subspecies to experimental warming with Open Top Chambers at the northern (high arctic) and southern (atlantic) geographic range margin.
Myers-Smith, I., Forbes, B.C., Wilmking, M., Hallinger, M., Lantz, T., Blok, D., Tape, K.D., Macias Fauria, M., Sass-Klaassen, U., Lévesque, E., Boudreau, S., Ropars, P., Hermanutz, L., Trant, A., Siegwart Collier, L., Weijers, S., Rozema, J., Rayback, S.A., Schmidt, N.M., Schaepman-Strub, G., Wipf, S., Rixen, C., Ménard, C., Venn, S., Goetz, S., Andreu-Hayles, L., Elmendorf, S., Epstein, H.E., Welker, J., Grogan, P. and Hik, D. (submitted) Shrub expansion in tundra ecosystems: Dynamics, impacts and research priorities.
Weijers, S., Broekman, R., and Rozema, J. (2010) Dendrochronology in the High Arctic: July air temperatures reconstructed from annual shoot length growth of the circumarctic dwarf shrub Cassiope tetragona. Quaternary Science Reviews29, 3831-3842
Weijers, S. and Rozema, J. (2010) Annual shoot length growth of the Arctic dwarf shrub Cassiope tetragona as monitor of present-day and past climate change. In WorldDendro 2010 - The 8th International Conference on Dendrochronology – Abstracts. Eds. Mielikäinen, K., Mäkinen, H., and Timonen, M. Rovaniemi, Finland. p. 171
Rozema J., Weijers S., Broekman R., Blokker P., Buizer B., Werleman C., El Yaqine H., Hoogedoorn H., Fuertes M.M., and Cooper E. (2009) Annual growth of Cassiope tetragona as a proxy for Arctic climate: developing correlative and experimental transfer functions to reconstruct past summer temperature on a millennial time scale Global Change Biology15 1703–1715
Remie, M., Weijers, S. and van Overeem, B. (2009) Report on the 8th Winter School at Klosters. IAWA Journal, Vol. 30(1), p. 97-98
Rozema, J., Weijers, S., Buizer, B., Blokker, P., and Broekman R. (2008) Global warming: field and open top chamber studies on growth-temperature relationships of high arctic ecosystems. In Climate Change and its Implication for Ecosystem Dynamics and Functioning – Book of Abstracts. Editor Veste, M. Bielefeld, Germany. pp. 18-19
Weijers, S., Wagner, F. and Kürschner, W.M. (2003). Changes in mangrove communities as a proxy for paleosalinity in Rookery Bay, Florida. In Abstracts, Conference on organic substrates of the Fakahatchee Strand and other South Florida sites, Evolutionary Development and Human Impacts. Naples, Florida, USA.
