Ph.D. Studentship
Assessing Constraints on Tree-line Advance Due to Nutrient Availability
Schools of Biology and Biosciences
University of Nottingham
Application Deadline: Wednesday, 28 June 2006
Anticipated Start Date: Monday, 1 January 2007
For further information, please contact:
Peter D. Crittenden
E-mail: pdc [at] nottingham.ac.uk
The Schools of Biology and Biosciences at the University of Nottingham
invite applications for a Ph.D. programme assessing constraints on
tree-line advance due to nutrient availability. This studentship is
funded by the European Commission via the Quantifying the Carbon Budget
in Northern Russia (CARBO-North) project.
Project Description:
Global warming will be marked at high latitudes due to feedbacks from
loss of snow and ice cover. One biological response to a warming trend
will be northward tree-line advance. However, tundra soils are infertile
and plant growth is primarily limited by the availability of nitrogen;
this project will examine the extent to which tree-line advance might be
constrained by availability of soil nitrogen and phosporus. Experiments
will be conducted in controlled environments to examine effects of
increased growing season temperature and N enrichment on tree seedling
growth and nitrogen acquisition, and on soil nitrogen transformations,
in both cases using intact soil cores collected at tundra sites close to
tree-line. 15N-labelled ammonium and nitrate will be added to the cores
to simulate nutrients release from the snowpack in spring. Subsequent
distribution of labelled nitrogen (15N) between different soil and plant
fractions at the end of the growth period will be used to assess
temperature sensitivity of plant growth and microbial processing of soil
N. In addition, representative tundra and forest ecosystems close to
tree-line will be audited for total N and P content. Nutrient deficits
in tundra, compared to forest, will be used to calculate annual N and P
increment rates necessary to achieve equivalence (i.e., for tundra to
develop into forest). These rates will be compared with predicted
increases in nutrient deposition by precipitation, dry deposition, and
nitrogen fixation to assess the likelihood of a nutrient limitation to
tree-line advance.
The project is part of an international collaboration (CARBO-North)
funded by European Commission 6th Framework Program to produce regional
carbon budgets for Northeast European Russia under present and future
climate scenarios. The research involves field work in the Russian
Arctic with a multinational research team. Funding for this studentship
is subject to final completion of contract negotiations in Brussels.
This is a three-year Ph.D. programme supervised by Peter Crittenden (an
ecophysiologist in the School of Biology), Scott Young (a soil scientist
in the School of Biosciences), and Tarmo Virtanen (an ecologist in the
Department of Biological and Environmental Sciences, University of
Helsinki). The person appointed should have a 1st class honours degree
(or equivalent) in plant sciences, biology, environmental science, soil
science, or allied subject and will be self-motivated and enthusiastic
about field work in remote areas.
Applicants should send a letter and CV (including names of two academic
referees) by Wednesday, 28 June to:
Peter D. Crittenden
School of Biology
University of Nottingham
Nottingham NG7 2RD
UK
E-mail: pdc [at] nottingham.ac.uk
Phone: 44 (0) 115 9513211
Fax: 44(0) 115 9513251
http://www.nottingham.ac.uk/life-env/