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| Current research | People & Contacts | Student Opportunities | Facilities | Reports, Publications & News | Seminars | Annual Report Appendices

Environmental Biology

We are studying fundamental aspects of plant growth and adaptive responses to environmental stresses and environmental variation, including global climate change.

 

 

We seek to identify how plants sense variations in their environments, how this information is transmitted and how it is integrated into responses that impact on plant morphogenesis and architecture, resource acquisition and use for growth.

This information will be key to the engineering of plants tailored to specific environments and to an intelligent management of biological diversity in environments of the future.

Our research integrates across levels of biological organisation, from sub-cellular structures to the whole plant, even to the canopy. We combine molecular-genetic approaches, with developmental and biophysical approaches, along with mathematical modelling so as to examine and quantify the interplay of genetic and physiological mechanisms and their modulation by the environment, towards identifying strategies for improved plant stress tolerance and growth efficiency.


Current Research

Professor Graham Farquhar's team: Coordination of CO2 fixation and transpiration in plants - Biophysics of CO2 and water exchange between plants-soil and atmosphere.

We seek to understand and model interactions between plants and their environment, with an emphasis on mechanisms involved in scaling up from cell to whole plant and ecosystem. Our studies combine practical experimentation in the laboratory and the field with an extensive use of biophysical and stable isotope ratio techniques, to mechanistic mathematical modelling.

Dr John Evans's team: Physiology of photosynthesis; interactions with nitrogen.

We study leaf physiology, relating anatomy and protein allocation to photosynthesis. We are also examining whole plant responses to rising CO2 concentration, particularly the effect on symbiotic nitrogen fixation.

Dr Josette Masle's team: Molecular- and eco- physiology of root:shoot communication, stress sensing and plant development under abiotic stresses.

Roots have evolved sensitive sensing mechanisms of variations in their environment and effective local and long-distance signalling mechanisms. We study the sensing and signalling in plants of root mechanical impedance, a condition inevitably associated to soil drought. We examine the developmental and functional responses it triggers in roots and leaves, their regulation and adaptive significance. Our studies combine molecular genetics and genomic approaches to developmental biology and whole plant physiology.

Dr Michael Roderick's team:  We seek to understand interactions between water, carbon, energy ad the environment.  

Our current emphasis is onthe physical aspects of water movement at scales ranging from plant cells to the globe.  OUr studies combine practical experimentation in the field with satellite remote sensing and mathematical modelling.

 

Prof Roderick Dewar's team: We are applying the concepts and tools of statistical mechanics to several problems in environmental biology and beyond.

Concepts such as Maximum Relative Entropy and Maximum Entropy Production help us to understand the behaviour of plants, ecosystems, the climate and other complex systems from a novel statistical perspective. Our work aims to incorporate these ideas into mathematical models to make better predictions of how these systems will evolve in the future.


Reports, Publications and News

TECHNICAL & OTHER REPORTS

Technical Report:  The Global Water Atlas  

Technical Report:  Maximum Entropy Production (MEP) & the Earth's Climate

Technical Report Diagrams: MEP

Technical Report:  LWA 49

Technical Report:  CSIRO Land and Water Science Report 26/07

Proceedings of Australian Academy of Science National Committee for Earth System Science Workshop  22-23 November 2004 "Pan evaporation:  An example of the detection and attribution of trends in climate variables."

  • The pan evaporation paradox – an overview of the scope of the problem.
    Graham D. Farquhar & Michael L. Roderick pp 20-21
  • An analysis of pan evaporation changes in relation to possible explanatory factors. Michael L. Roderick & Graham D. Farquhar pp 79-81

Global Change Newsletter 69, 32-23 "Evaporative demand: Does it increase with global warming?"  Roger M Gifford, Michael L Roderick and Graham D Farquhar

PUBLICATIONS

For publications in previous years please refer to the appendices sections in the Annual Reports listed under Publications on the main RSBS page.

BIBLIOGRAPHIES

Global Dimming-Brightening and Pan Evaporation Bibliography

POSTERS

Evaporative Demand and Water Resources under a Changing Climate.  PDF

          Roderick ML, Farquhar GD, Hobbins MT and Lim WH.

Is there a tradeoff between nitrogen invested in cell walls and photosynthesis?  PDF

Harrison MT, Edwards EJ, Farquhar GD, Nicotra AB and Evans JR.

Do temperature-based parameterizations of evaporative demand force overestimates of mid-latitude continental drying? PDF

Hobbins M, Farquhar G and Roderick M.

A detailed examination of oxygen isotopes toincrease the precision of leaf water modelling.  PDF

Clayton SJ, Sutart-Williams H, Harrison MT and Farquhar GD.

Carbon and oxygen isotopes: a tool to analyze the fluxes of CO2 and H2O between plants and atmosphere.  PDF

Ripullone F, Borghetti M, Cernusak L, Matsuo N, Stuart-Williams H, Wong SC, and Farquhar GD.

One-Dimesional Non-Steady-State Leaf Water Enrichment.  PDF

Cuntz M, Ogee J, Farquhar GD, Peylin P and Cernusak L.

Variation in the isotopic composition of organic matter allocated from the leaves to the roots of trees - effects of photosynthetic and post-photosynthetic carbon isotope fractionaltion.  PDF

Gessler A, Keitel, C, Kodama N, Brandes E, & Farquhar GD.

Using a Half-century of Mis-diagnosis to Make Bad Predictions about Future Drought Trends. PDF

Hobbins, M, Roderick M and Farquhar G.

NEWS

PRESS

ABC TV's Catalyst Programme 03 May 07:  Drought Wheat - getting more crop per drop

  • Transcript and on-line video of the story can be found here.

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People and Contacts


ANU - RSB - Environmental Biology Staff Directory

Prof Graham Farquhar's Team

Name Role Phone Email
Prof Dewar, Roderick Professor +61 2 6125 2447 Send email
Prof Farquhar, Graham Distinguished Professor
(Group Leader)
+61 2 6125 3743 Send email
Mr Groeneveld, Peter Technical Officer +61 2 6125 4194 Send email
Ms McCarthy, Michelle Group Administrator +61 2 6125 5052 Send email
Dr Stuart-Williams, Hilary Research Officer +61 2 6125 2099 Send email
Dr Wong, Chin Research Officer +61 2 6125 0320 Send email

Dr John Evans' Team

Name Role Phone Email
Dr Evans, John Senior Fellow +61 2 6125 4492 Send email
Mr Harrison, Matthew PhD Student +61 2 6125 4892 Send email
Mrs McCaffery, Stephanie Technical Officer +61 2 6125 4492 Send email
Dr Tazoe, Youshi Postdoctoral Fellow +61 2 6125 8144 Send email

Dr Josette Masle's Team

Name Role Phone Email
Mr David, Rakesh PhD Student +61 2 6125 2406 Send email
Ms Landgren, Emma Technical Officer +61 2 6125 0123 Send email
Dr Liang, Lu Postdoctoral Fellow +61 2 6125 2404 Send email
Dr Masle, Josette Fellow +61 2 6125 4410 Send email
Mr Pai, James Technical Assistant +61 2 6125 0123 Send email
Dr Qiu, Deyun Postdoctoral Fellow +61 2 6125 2406 Send email
Mr Schulze, Keith PhD Student +61 2 6125 2406 Send email
Mr Zsögön, Agustin PhD Student +61 2 6125 2406 Send email

Dr Michael Roderick's Team

Name Role Phone Email
Mr Donohue, Randall PhD Student +61 2 6125 8273 Send email
Mr Lim, Wee PhD Student +61 2 6125 2406 Send email
Dr Roderick, Michael Professor +61 2 6125 5589 Send email
Mr Van Niel, Thomas PhD Student +61 2 6125 6705  

Visiting Fellows

Name Role Phone Email
Dr Bathellier, Camille Visiting Fellow +61 2 6125 0213 Send email
Dr Bloomfield, Keith Visiting Fellow +61 2 6125 3547 Send email
Prof Cowan, Ian Visiting Fellow    
Dr Keitel, Claudia Visiting Fellow +61 2 6125 3696 Send email
Prof Kriedemann, Paul Adjunct Professor +61 2 6125 4407 Send email
Prof Lloyd, Jon Visiting Fellow +61 2 6125 2469 Send email

Prof Paltridge, Garth

Visiting Fellow    
Dr Sherwin, William Visiting Fellow   Send email

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Postal Address:

Research School of Biological Sciences
The Australian National University
GPO Box 475
Canberra ACT 2601

Fax:

(02) 6125 4919

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Student Opportunities

Prospective PhD Students in this group

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Facilities

Facilities within the group include staff and workshops for experimental design and making supporting equipment, as well as four (4) stable isotope mass spectrometers in the stable isotope facility.

Professor’s Farquhar lab has developed analytical techniques for stable isotope research in plants (C, O and H) and is running a stable isotope facility with four isotope ratio mass spectrometers. Analysis using these machines is available on a contract basis or for cooperative research, both inside and outside ANU.

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Seminar Series

A weekly seminar series is presented by group members, visitors and invited speakers.

When:        Every Wednesday (unless otherwise notified)
Where:       Robertson Seminar Room, RSBS, ANU

                  (Map: http://campusmap.anu.edu.au/largemap.asp - Bldg 46, E4)

Time:          4pm

Contact:     For more information on these seminars, contact Prof Roderick Dewar  

                   on 6125-2447 or Roderick.Dewar@anu.edu.au

LATEST SEMINAR :

The seminar series takes a break over July and restarts on 05 August 2009.

Wednesday 26 August 2009

Speaker:   Dr Thomas Lennie

                  Functional Ecology Group, Research School of Biology

                  

Venue:        Robertson Seminar Room

Discussing: The effects of solutes on the phase behaviour of phospholipid

                     embranes

Synopsis:   Severe dehydration is lethal for most biological species; however, there are a number of organisms which have evolved mechanisms to avoid damage during dehydration. One of these mechanisms is the accumulation of small solutes (e.g. sugars), which have been shown to preserve membranes by inhibiting deleterious phase changes at low hydration. Specifically, sugars reduce the gel to fluid phase transition temperatures of model lipid/water mixtures.

However, there is debate about the precise mechanism, the resolution of which hinges on the location of the sugars. An experimental investigation into the effects of small solutes on the phase behaviour of phospholipid membranes is presented in order to help identify the mechanisms by which solutes facilitate desiccation (and freezing) tolerance.

PREVIOUS SEMINARS :

Wednesday 01 July 2009

Speaker:   Dr John Evans

                  Environmental Biology Group, Research School of Biology

                  

Venue:        Robertson Seminar Room

Discussing: Resistances along the CO2 diffusion pathway inside leaves

Synopsis:    CO2 faces a series of resistances while diffusing between the substomatal cavities and the sites of carboxylation within chloroplasts. The absence of techniques to measure the resistance of individual steps makes it difficult to define their relative importance. Resistance to diffusion through intercellular airspace differs between leaves, but is usually of minor importance. Leaves with high photosynthetic capacity per unit leaf area reduce mesophyll resistance by increasing the surface area of chloroplasts exposed to intercellular airspace per unit leaf area, Sc. Cell walls impose a significant resistance and could account for more than 50% of the total resistance. Most of the remaining resistance is imposed by one or more of the three membranes as mesophyll resistance can be altered by varying the expression of cooporins.

Wednesday 17 June 2009

Speaker:   Prof Fred Chow

                  Photobioenergetics Group, Research School of Biology

 

Discussing: Chasing the Elusive Cyclic Electron Flow in Leaf Segments

Synopsis:   The main function of photosynthetic membranes is to store light energy in ATP and NADPH, which are used in the ratio of 3:2 in carbon assimilation.  The membranes have four protein complexes and other smaller components to perform the task.  Photosystem II (PS II) splits water into oxygen, electrons and protons.  The electrons flow through PS II, the cytochrome bf complex and PS I in series (linearly) to give NADPH.  The protons, deposited in a reservoir (the lumen), drive nature’s tiny motor, the ATP synthase, to form ATP.  Linear electron flow alone, however, does not provide a sufficient supply of ATP in the required ratio of three ATP to two NADPH molecules for carbon assimilation, let alone additional ATP for other processes such as on-going repair of inevitably-photodamaged PS II.  Therefore, cyclic electron flow around PS I occurs to deposit more protons in the lumen, at an efficiency of two protons per photon, compared with 1.5 protons per photon in linear electron flow.  Because no net product is formed in cyclic electron flow, quantification of the flow rate has been difficult.  This talk reports on our attempt to quantify cyclic electron flow in leaf segments under varied environmental conditions, as part of a broader investigation to probe the four photosynthetic membrane protein complexes in situ in leaves.


Wednesday 10 June 2009

Speaker:   Dr Nikolaos Fylass

                  School of Geography, University of Leeds,
                  Visiting Fellow, Functional Ecology Group, RSB

                  

Discussing: Variation of foliage properties and plant functional types across

                    the Amazon Basin

Synopsis:   We analysed 1040 individual trees, positioned in 63 plots across the Amazon Basin, for a set of biochemical and structural traits. The amount of variation attributed to the taxonomic affinity and/or the location of the tree was estimated in order to quantify the phylogenetic and the environmental influence on these characters. In general intrinsic values of most trait pairs coordinate, although different species were found to be located at discrete locations along a common axis of coordination. Additionally, growth environment was found to substantially modify inter-relationships between key traits with the environmental effect of trait variation to a large degree predictable from observed edaphic and climatic variables. A three-way ordination incorporating species traits, plot level species abundances and soil/climatic conditions will be described. This analysis not only allowed the intensity of plant trait/environment associations to be quantified (through a mutual linkage to a plot level species abundance table) but also through cluster analysis for four discrete tropical forest functional types to be identified.


Wednesday 27 May 2009

Speaker:   Assoc Prof Owen Atkin

                  Functional Ecology Group, Research School of Biological Sciences
                  

Discussing: Impacts of thermal history on metablic scaling

Synopsis:    Using data from a wide range of biomes, a growing number of studies have shown that inter-specific variations in plant metabolic rates (e.g. photosynthesis and respiration) are linked to variations in related functional traits (e.g. tissue chemistry and/or area/mass relationships).  Such studies have shown that while overall trends are held across biomes, there is also evidence that there is considerable scatter in such relationships.  Given the importance of such scaling relationships for predicting shifts in vegetation patterns and changes in carbon fluxes between plants and the atmosphere, it is essential that the importance of individual climate parameters (e.g. temperature) in determining variations in functional trait scaling relationships be quantified.  In this seminar, I present data on the impact of sustained changes in growth temperature on rates of respiration, photosynthesis and associated plant functional traits.  The mechanisms underpinning thermal acclimation of respiration to sustained changes in growth temperature will be discussed. I show that in addition to altering the phenotype of individual plants, changes in growth temperature can alter scaling relationships used to predict rates of leaf and root respiration. This finding provides a framework via which thermal history can be better accounted for in coupled global climate-vegetation models.

Wednesday 15 May 2009

Speaker:   Prof Marilyn Ball

                  Functional Ecology Group, Research School of Biological Sciences
                  

Discussing: Nitrogen fertilisation increases tree mortality under hot, dry

                    conditions

Synopsis:    Field-based  experiments conducted on eucalypt and mangrove species showed greater mortality of nitrogen fertilised trees when water was limiting under hot, dry conditions. Fertilising with nitrogen had no effect on hydraulic characteristics of twigs, but stimulated leaf area growth.  Increasing atmospheric CO2 concentration around the eucalypts induced greater hydraulic conductance at the root/shoot junction, but the inhibition by nitrogen of root penetration into the soil led to enhanced death of the tree seedlings with the rapid onset of hot, dry weather conditions in summer. These results have far reaching implications for responses of forests to combined effects of increasing nutrient loads and climate change.


Wednesday 06 May 2009

Speaker:   Robert K. Niven
                  School of Aerospace, Civil and Mechanical Engineering,

                  UNSW@ADFA, Canberra
                  

Discussing: A Derivation of the Maximum Entropy Production Principle

                    and Various Applications

Synopsis:    The maximum entropy principle (MaxEnt) of Jaynes is used to derive a conditional, local formulation of the "maximum entropy production'' (MEP) principle [1], which states that a flow system with variable flow(s) or gradient(s) will converge to a steady state position of maximum production of thermodynamic entropy. The analysis provides a steady state analogue of equilibrium thermodynamics, applicable to many complex flow systems including heat-induced (B'enard) convection, the Earth climate circulatory system, turbulent fluid flow, biochemical reactions and ecological systems. The analysis involves the synthesis of traditional engineering control volume analysis with a MaxEnt analysis, using a local "flux entropy" defined on the set of instantaneous fluxes through a fluid element. The analysis reveals a very different manifestation of the second law of thermodynamics in flow systems, which explains the formation of complex non-equilibrium systems, including life.
The seminar will examine both the theoretical derivation and its application to various flow systems in thermodynamics, engineering and biological science.  The seminar is to be presented in an invited lecture to the 10th Joint European Thermodynamics Conference (Journées Européennes de Thermodynamique Contemporaine), to be held in Copenhagen, 22–24 June 2009.
[1] R.K. Niven (2009) http://arxiv.org/abs/0902.1568


Wednesday 22 April 2009

Speaker:   Dr Charles Lineweaver

                  RSES, RSAA & Planetary Scienec Institute, ANU

                  

Discussing: Life, gravity and the second law of thermodynamics

Synopsis:   We review the cosmic evolution of entropy and the gravitational origin of the free energy required by life. All dissipative
structures in the universe including all forms of life, owe their existence to the fact that the universe started in a low entropy state
and has not yet reached equilibrium. The low initial entropy was due to the low gravitational entropy of the nearly homogeneously
distributed matter and has, through gravitational collapse, evolved gradients in density, temperature, pressure and chemistry. These
gradients, when steep enough, give rise to far from equilibrium dissipative structures (e.g., galaxies, stars, black holes, hurricanes
and life) which emerge spontaneously to hasten the destruction of the gradients which spawned them. This represents a paradigm
shift from “we eat food” to “food has produced us to eat it”.

Lineweaver CH & Egan CA. 2008. Physics of Life Reviews 5:225-242.


Wednesday 15 April 2009

Speaker:      Mr Keith Schulze

                     Environmental Group, RSBS

DiscussingEvaluating the short-term regulatory effects of the ERECTA gene in

                     Arabidopsis

The ERECTA gene, known widely for its effects in the Landsberg erecta ecoptype of Arabidopsis, plays an important role in many
developmental processes ranging from early vegetative to late reproductive development. Recently Masle et al. (2005) showed ER
to be an important regulator of Transpiration Efficiency in Arabidopsis and that er mutants display various morphological changes
in leaf development and anatomy, which explain in part the differences observed in TE. However, the study was unable to
exclude more direct short-term regulatory effects of the gene, and the authors suggest some data to support this.

The objective of this study is to separate those short-term direct effects of the ER gene from its long-term effects, on TE and the
overall leaf organogenesis.  In order to do this, a series of transgenic inducible ER silencing plant lines have been developed.
The focus of my work so far has been on the developmental effects of the gene throughout leaf development, from leaf initiation in
the Shoot Apical Meristem to the mature leaf. The aim is to identify where and when the gene might specify the anatomical differences
observed in the mature leaves of er mutants.


Wednesday 08 April 2009

Speaker:     Dr Suan Chin Wong

                    Environmental Biology Group, RSBS

                  

Discussing: Humidity in the Intercellular Space of Leaves Does Not Saturate at

                    High Transpiration Rate

The conductance to diffusion of water from a leaf, mainly stomatal, is calculated as the transpiration rate, E, divided by the leaf-to-air humidity difference,
with the humidity inside the leaf taken as the saturated humidity. This conductance to diffusion of water is then used to calculate the conductance to diffusion of CO2,
and from the measured assimilation rate and external concentration of CO2 the concentration of CO2 inside the leaf can in turn be calculated.

Canny & Huang (2006) recently described observations of the cell-area-fraction of EM sections of leaf discs equilibrated at various relative humidity (RH). 
They suggested that the vapour pressure could be around 20% less than the saturation value when plants are stressed.
Jarvis & Slatyer (1970), using a nitrous oxide diffusion technique, suggested that RH of intercellular space could be as low as 70% when transpiration rate was high.
 
Our recent gas exchange measurements showed that RH in the intercellular space of cotton leaves could be as low as 90% at high transpiration rate. 
The method involved using a double-sided clamp-on leaf chamber. CO2 concentration on one side of an amphi-stomatal leaf was adjusted so that assimilation
rate was equal to zero.  We used the difference of the sub-stomatal CO2 concentrations of the two surfaces at various air humidities to determine the degree
of saturation of the intercellular space.

The underlying mechanism of humidity response of stomatal conductance will also be discussed.


Wednesday 01 April 2009

Speaker:     Ms Foteini Hassiotou

                    University of Western Australia,
                    Visiting Scholar Environmental Biology Group, RSBS

                  

Discussing: CO2 diffusion into sclerophylls: anatomical and physiological
                     aspects


Leaf structure impacts on the diffusion of CO2 into the leaf. In the present
study, the genus Banksia, displaying a diversity of leaf anatomies, has been
chosen as model group to examine the effects of sclerophyllous traits on CO2
diffusion and photosynthesis. Firstly, the effect on diffusion of stomatal
crypts relative to stomata will be presented. Stomatal crypts are
depressions of the abaxial leaf surface where stomata are located in some
sclerophylls. A function other than transpiration reduction will be proposed
for stomatal crypts and evidence supportive of this function will be shown.
Secondly, diffusion in the mesophyll of these species will be examined.
Mesophyll conductance estimated using the fluorescence method will be
presented for a range of species which vary in leaf dry mass per area (an
indicator of leaf structure) and correlated with cell wall thickness. The
dependence of mesophyll conductance on irradiance and CO2 in sclerophylls
will be discussed. Results from the fluorescence method will be compared
with preliminary results from the C isotope discrimination method.


Wednesday 18 March 2009

Speaker:     Dr Youshi Tazoe

                    Environmental Biology Group, RSBS
                   
                  

Discussing: Carbon isotope discrimination and photosynthesis : Mesophyll conductance to CO2 in a C3 plant and CO2 leakiness from the bundle sheath cells in a C4 plant

Measuring carbon isotope discrimination during CO2 exchange helps us to know the flow of CO2 inside leaves. In C3 plants, diffusion of CO2 into leaves is restricted not only by stomata but also by the intercellular airspaces and liquid phase into chloroplasts, which was defined as the mesophyll conductance to CO2 diffusion (gm). However, little is known on whether gm changes with respect to photon flux density (PFD) and CO2 partial pressure (pCO2).

In this study, the effects of PFD and/or pCO2 on gm were examined in wheat leaves using a membrane inlet mass spectrometer. Measurements were made in 2% O2 to reduce the fractionation associated with photorespiration. In wheat, gm was independent of PFD between 200 and 1500 mmol m-2 s-1 and was independent of pCO2 between 80 and 500 mbar.

In C4 plants, CO2 is concentrated around Rubisco in the bundle-sheath (BS) cells by a CO2-concentrating mechanism. Some CO2 concentrated by this mechanism leaks back to mesophyll cells or intercellular spaces and the ratio of the rate of CO2 leakage from BS cells to the rate of CO2 fixation by PEPC was defined as the CO2 leakiness (f), which has been estimated by measuring carbon isotope discrimination during CO2 exchange. Although f remains constant over a wide range of CO2 and temperatures, f shows a tendency to increase when measured at low PFDs (40-240 mmol m-2 s-1). How f increases at low PFDs is unknown. In this study, we examined the changes in f when PFD was transiently changed using Flaveria bidentis (NADP-ME type, dicot). When PFD was transiently changed from high (2000 mmol m-2 s-1) to low (300 mmol m-2 s-1), f changed quickly from 0.3 to 0.8 before decreasing to 0.5 after 90 min. When PFD was changed from low to high, f reduced from 0.5 to 0.3.

 

Wednesday 11 March 2009

Speaker:     Dr Caille Bathellier

                    Universite de Paris-Sud,

                    Visiting Fellow, Environmental Biology Group, RSBS
                   
                  

Discussing: An isotopic approach to root respiratory metabolism in French bean

C3 photosynthesis discriminates against 13C so that plant organic matter is on average 13C-depleted by 20‰ compared to atmospheric CO2. However, other post-photosynthetic discriminations (e.g. during dark respiration) occur that may modify the δ13C of plant organic matter. While leaf dark respiration has been shown to produce 13C-enriched CO2, root respiration, though poorly documented, seems to produce 13C-depleted CO2. In the present study, the origin of the 13C-natural abundance in respired CO2 of intact bean roots was investigated in relation to substrate availability under continuous darkness. In contrast to leaves, root-respired CO2 is 13C-depleted as compared to sucrose, and the 13C-signal does not correlate at all with the respiratory quotient (that is, the type of respired substrates). Such an isotopic divergence between leaves and roots appears when leaves turn to autotrophy. Isotopic labeling data demonstrate that the 13C-depletion in respired CO2 is caused by both the contribution of the pentose phosphate pathway (PPP) to the CO2 efflux (22%), and the quasi-stochiometric relationship between the PDH and the Krebs cycle fluxes. Under continuous darkness, the relative PPP flux is kept constant and the consumption of (13C-depleted) lipids compensates for the decrease of the flux associated with the Krebs cycle. Such a pattern results in an invariant δ13C of respired CO2. Taken as a whole, it is concluded that, unless the 13C photosynthetic fractionation varies at the leaf level, the root 13C-signal does not change under natural environmental conditions throughout a circadian day/night cycle, thereby buffering isotopic daily variations in ecosystems.


Wednesday 25 February 2009

Speaker:     Mr Wee Ho Lim

                    Environmental Biology Group, RSBS
                   
                  

Discussing: What do climate models tell us about our water availability in the

                    past and future?

What will happen to water availability in the future? Will it remain the same or will it change?
What do the climate models say about it? We used climate model simulations from 20 different models
submitted to the IPCC 4th Assessment Report to compile maps for the globe and for Australia
showing precipitation, evaporation and their difference (i.e. runoff) for
the historic period (1970-1999) and for the future (2070-2099). This talk
will summarise the results.


Wednesday 18 February 2009

Speaker:     Dr Mark G. Tjoelker

                    Dept of Ecosystem Science and Management,

                    Texas A&M University
                   
                  

Discussing: Plant respiration and temperature: Acclimation and adaptation in a

                    warming world

The temperature response of plant respiration is a fundamental relationship in the global carbon cycle. The patterns and mechanisms of short-term temperature acclimation and long-term climatic adaptation of respiration remain poorly understood, but are important in constraining respiratory carbon flux with climate warming. A plant trait-based approach using nitrogen may be useful in quantifying general predictive relationships of leaf and whole-plant respiration across diverse plant taxa and in informing the debate concerning metabolic scaling theory.


Wednesday 11 February 2009

Speaker:     Associate Professor William Sherwin

                    School of Biological, Earth and Environmental Sciences, UNSW

                    Visiting Fellow, Environmental Biology Group, RSBS
                                      

Discussing: Genes are Information – Who would have guessed?

Everyone knows that genes are information, so it comes as a shock to realise that over 50 years of knowledge about the flow of computer information has rarely been applied directly to genes.    We quantify genetic biodiversity using Shannon's information index.  Simulations, and trials on a diverse array of species, from birds to snails to flies to trees, shows that the information approach vastly improves genetic assessment of dispersal between populations – a vital tool for conservation management.    The hierarchical information approach also adapts well to analysis of variation within populations, linkage between DNA sequence elements, and other genetical and ecological tasks.   Sherwin WB, Jabot F, Rush R,  Rossetto M 2006 Measurement of biological information with applications from genes to landscapes  Molecular Ecology 15:2857-2869. Rossetto M, Kooyman R, Sherwin WB, Jones R. 2008.  Dispersal limitations, rather than bottlenecks or habitat specificity, can restrict the distribution of rare and endemic rainforest trees.  Amer. J Bot  95(3): 321–329.


Click here for details of other previous seminars.

 

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