Prof.dr. Jelte Rozema

Introduction

Professor Jelte Rozema is a Dutch systems ecologist and his main research is on the interactions between climate change and the biosphere, particularly in cool and cold biomes. In addition he works on developing saline culture. In a warming and salinizing world we need salt adapted crops for salinizing arable land. Thereby we save vast amounts of fresh water.

Below you will find some specific topics that Jelte is working on; for related recent papers (including pdfs) click on the Publications button and select: ‘Rozema, J.’

Two top papers are:

Jelte Rozema et al. 2002.Toward Solving the UV Puzzle. Science 296, 1621-1622

Jelte Rozema , Tim Flowers . 2008. Crops for a salinized world. Science 322:1478–1480.

Research on the on the interactions between climate change and the biosphere, particularly in cool and cold biomes has been published in : Plants and Climate Change (2006) edited by Jelte Rozema, Rien Aerts and Hans Cornelissen

Research projects

Plants and ecosystems in a warming world
In the first we study how plants and ecosystems respond to various aspects of current climate   change: the warming, increased precipitation and increased cloudiness.

Gauze is used to reduce solar radiation to mimick increased cloudiness in a tundra environment
Air inside Open Top Chambers is warmer than outside and dwarf shrubs growing in these OTCs  show us their their  longterm responses. Since temperature plays a leading role in the ecology of high arctic plants we have particular interest in the relationships of arctic tundra plants and the polar climate. Remarkably, the large geographical range of  Crowberry, Empetrum nigrum  from  The Netherlands to the Spitsbergen tundra, allows comparison of  responses at the southern and northern limit of their distribution area.
Polar bear on a field trip Northern Spitsbergen


The Spitsbergen arctic archipelago

In the treeless tundra the annual growth of Cassiope tetragona is used to reconstruct past arctic temperatures. In other words: stem length growth of this arctic bell heather represents a new climate proxy based on  correlations and the experimental response to OTC warming similar to the tree-rings in the wood of trees. Well preserved pieces of stems appear to allow temperature reconstructions on a millennial rather than centennial time scale.
See Jelte Rozema, Stef Weijers, Rob Broekman, Peter Blokker, Bert Buizer, Chantal Werleman, Hassan el Yaqine, Hanneke Hoogedoorn, Miguel
Mayoral Fuertes  & Elisabeth Cooper. 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 Biology 15, 1703–1715

Open Top Chambers on a high arctic tundra, Ny Alesund, Spitsbergen

Plants, the Ozone Hole and oncreased solar UV-B radiation
What is the impact of enhanced UV-B, as a result of thinning of the ozone layer, on ecosystems, particularly arctic and antarctic ecosystems?
Can morphological and chemical changes in plants as a result of climate change and changes in UV-B radiation be used to reconstruct climate changes in the past?
Jelte Rozema et al. 2002. Toward Solving the UV Puzzle. Science 296, 1621-1622

• The impact of current stratospheric ozone depletion (“the ozone hole over the Antarctic”) on the biosphere as well as the possibilities to reconstruct the thickness of ozone layer and surface UV-B radiation with biological proxies are of significant scientific, political and economical relevance (Rozema et al., Science 2002). By reconstructing past UV-B and ozone we try to figure out if and how solar activity has affected the climate of the system Earth. We are currently studying UV-B absorbing compounds such as p-coumaric acid and flavonoids in extant and (sub)fossil pollen grains and spores of peat cores of the Pleistocene and Holocene. Peat cores from the Arctic and Antarctic may reveal pre-ozone hole variation of UV-B and stratospheric ozone concentrations.
• Since current ozone depletion has occurred not only over the Antarctic (since the1970ies), but more recently also over the Arctic, we carry out experimental field work in the polar summer using UV lamp systems, in order to study responses of tundra plants to enhanced UV-B radiation. This work is based in Adventdalen, Spitsbergen (Svalbard).

Adapting to a warming and salinizing world
Climate warming implies a drying and salinizing environment. We need crops to grow in a salizinizing world. How can we exploit resources in saline ecosystems in a sustainable manner? Jelte Rozema & Tim Flowers. 2008. Crops for a salinized world. Science 322:1478–1480
PhD Diana Katschnig  harvesting Salicornia europaea, drip-irrigated with Waddenzee water


PhD Diana Katschnig and PhD Arjen de Vos sampling Salicornia europaea on a salt marsh
• We need to develop  the cultivation of salt tolerant crops in saline environments. This forms part of an innovative initiative of the Faculty of Earth and Life Sciences: the Biosaline Innovation Center (BIC).
• Cultivation of salt adapted with saline water crops saves vast amounts of fresh water needed as drinking water and for industrial processes
• This work will help to identify renewable resources for the chemical industry, provide food, prevent desertification and preserve freshwater stocks as well as store atmospheric carbon dioxide.
• We successfully developed new saline crops: Seakale, Saline rucola, Saline beet. Also the cultivation of potatoes in saline arable land offers new perspectives

People and funding

S. Weijers, MSc. Reconstruction of arctic climate based on responses of tundra plants
D. A. G. Buizer MSc.  Responses of dwarf shrubs of a dune valley ecosystem to warming increasing precipitation and increased cloudiness
A. de Vos. Ecology, ecophysiology and cultivation of  halophyte crops
D. Katschnig, MSc. Adapting to a warming an salizing world: developing saline agriculture and saline crops
L. Leewis, MSc. Dynamics of the ecology of sandy beaches: adaptation to nourishments to increase coastal defense
N. de Bakker, MSc. Ozone depletion: adaptation of mosses and algae to increased UV-B
J. C. Hoek, MSc. Adapting to a warming and salizing world: developing,  and marketing practising saline agriculture

PhD Bert Buizer
 

last update: 01-09-10