JULIE D SCHOLES J.Scholes at sheffield.ac.uk
Thu May 30 17:45:16 EST 1996



Applications are invited for the above post to work with Dr Malcolm 
Press and Dr Julie Scholes on a three year project to study the 
response of rain forest tree seedlings to light and nutrients.  
Applications in the form of a CV with two referees should be sent to 
the Director of Human Resource Management, The University of 
Sheffield, Western Bank, Sheffield S10 2TN.

Salary will be in the range stlg14,317 - stlg15,986 per annum

Closing date for applications 20 June 1996 (Ref R915)

Responses of dipterocarp rain forest tree seedlings to high light: a 
role for nitrogen?

Dipterocarps dominate both the lowland tropical rainforests of S.E. 
Asia, where they can account for up tp 80% of the canpoy trees, and 
also the international hardwood timber trade.  Thus they are 
important both ecologically and commercially.  Dipterocarps produce 
seeds with little or no dormancy, and it is the seedling stage of the 
lifecycle which can survive for long periods of time, often many 
years, on the rain forest floor, where levels of light are very low.  
The growth of these seedlings is stimulated by the creation of gaps 
in the canopy, either resulting from tree falls or logging, which can 
result in up to a 25 times increase in light.  Tropical rainforests 
are biologically diverse, and large numbers of dipterocarp species 
co-exist.  Species- specific responses to light by the seedlings may 
be critical in determining the success of individuals, since many are 
damaged by high levels of light.  This project will examine how three 
contrasting dipterocarp species, which differ in their degree of 
shade tolerance and their ability to tolerate large and sudden 
increases in light, respond to gap creation, at a physiological and 
biochemical level.  Specifically we will determine differences in the 
ways in which light energy is either used or dissipated by seedlings. 
Nitrogen is an important component of the photosynthetic apparatus 
responsible for these processes, and we will determine the extent to 
which the supply of this element may enhance the ability of the 
seedlings to protect themselves against high levels of light.  By 
performing experiments at a forest site in Sabah, Malaysian Borneo 
(Danum Valley Field Centre) and in contrlled environment conditions 
in Sheffield this project will yield important information about the 
mechanistic basis of species-specific responses to light by 
dipterocarp seedlings and the role of nitrogen in determining these 
responses.  This information will be valuable both with respect to 
understanding how light controls regeneration in gaps in the forest 
and also for the management of tropical forests.

The successful candidate will spend time both in Sheffield and in 
Borneo.  Although the precise time to be spent in each location is 
flexible, we envisage that it will be approximately 2-4 months in the 
field (probably 2 visits), with remaining time in Sheffield.

The project involves studies of plant ecophysiology and biochemistry. 
Our initial preference is for somebody with a more biochemical 
background, however candidates with a background in ecophysiology 
should not be put off from applying.
       Experience in SOME of the following techniques would be 
Gas exchange (IRGA and oxygen electrode)
Chlorophyll fluorescence measurements
Pigment analysis (use of an HPLC)
Nutrient analysis
Plant growth
Tropical ecophysiology

The successful applicant will join a lively group studying plant 
ecophysiology and biochemistry, and will be expected to work closely 
with two Ph.D students working on the environmental physiology of 
dipterocarps, and using the same field sites.  The field station in 
Sabah is comfortable and well equiped and previous experience of the 
tropic (although desirable) is not a pre-requisite.

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