Ozflux08 meeting Overview Introduction – ARC NESS Plenary – OzFlux network – updates, research activities, science highlights Discussion – Funding – NCRIS AEOS concept Opportunities.
Download ReportTranscript Ozflux08 meeting Overview Introduction – ARC NESS Plenary – OzFlux network – updates, research activities, science highlights Discussion – Funding – NCRIS AEOS concept Opportunities.
Ozflux08 meeting Overview Introduction – ARC NESS Plenary – OzFlux network – updates, research activities, science highlights Discussion – Funding – NCRIS AEOS concept Opportunities for OzFlux Key science questions – OzFlux issues QC, data repository, biomass estimates, soil respiration 2007 conference OzFlux network http://www.cmar.csiro.au/ar/lai/ozflux/ Existing network •Initiated by CSIRO (Leuning, Finnagan, Cleugh, Raupach, etc.) extended by Universities •Limited capacity •Adhoc and uncoordinated •Some sites in under-represented biomes (savanna, broadleaf evergreen) Preston - Urban NCRIS To date: – Exposure draft – Strategic roadmap – Feedback June 2006 – Discussion paper NCRIS 1 of 16 priorities – second tier Next – Workshops – Appoint facilitator for investment – Further scoping by Sept 2006 NCRIS Opportunities for Ozflux: – Objective “Develop Australia’s research capabilities in areas that support world-class research and contribute to achieving national policy goals including environmental sustainability” – Scope Identified the AEON concept as having some similarities with TERN “8.3 recognise that there needs to be debate about whether it is appropriate of viable to include atmospheric fluxes and biogeochemical cycles” Appear to be continually marginalised We need to argue that from a ‘sustainability’ approach we can not assess ecosystem function and change without C and N etc. – Science questions We need to identify key research questions that ‘Ozflux’ can address AEOS: An Australian Earth Observing System to monitor and manage Australia’s terrestrial water, ecosystem and climate resources Objective: Rapid delivery of data and products needed to wisely and sustainably use our terrestrial biosphere resources, and to manage the impacts of climate variability and change Features: Enhanced climate observations Fluxes, concentrations & stores of key entities Radiation, wind, water, CO2 and non-CO2 gases, aerosols Integrate satellite data and models: – “spatialisation” of in-situ network – near-real time monitoring – marine and terrestrial Uses: Real-time environmental monitoring National carbon and water budgeting - NRM National Observing System Terrestrial Space • Enhances and integrates current networks (Ozflux, BoM) Existing sensors and products • New monitoring sites AEOS: An Australian Earth Observing System to monitor and manage Australia’s terrestrial water, ecosystem and climate resources New sensors (AATSR, FLORA) Networked Data Acquisition and Distribution Backbone Operational Integration System Locally operated nodes Standardised protocols Fast data transfer Data Assimilation Centre Data acquisition and processing Data archiving and distribution Modelling Clients: ACCESS WRON Towards a terrestrial observing network: in situ monitoring 1. Meteorology: – – Wind, RH and T Soil moisture and temp. 2. Radiation – – Short and long wave Downwelling and outgoing 3. Flux towers – Mobile and fixed 4. Scalars of interest: – – – Greenhouse gases Dust .... AEOS Concept : Integrated Earth Observation System for Data Integration & Predictive Modeling Historical and real-time Climate Products in situ observatns Real-time Satellite Observations Data & Model Integration System Foreign Available near real-time data sources MODIS, ALOS, ENVISAT, NPOESS 20+ year Satellite data timeseries archive ~25 Terabyte Web-based Data & Product Delivery System New Australian Sensors on Foreign Platforms Uses: •Real-time environmental monitoring •Carbon Budgeting • National Water Budgeting • CSIRO Climate • Flagships Networked X-Band stations Past Proposal for Ozflux Proposal was University based – Monash Uni (Beringer et al.) 22 Investigators, 14 Institutions ARC funding sought for Universities only through LIEF $1.41 Million total included 30% University contribution New network designed to capture geographical and ecosystem variability including human disturbed landscapes Constrained by investigator and institution locations and interests Opportunities Limitations (CSIRO) – Not core business – Applications/stakeholder focused – Constraints in working with Universities Current – Australian Research Council (ARC) Networks – Earth system network (Pitman, et al.) Terrestrial node (Beringer, et al.) Coordinate larger scale initiatives Facilitate interaction and collaboration (interagency) – TWP-ICE (regional flux estimates). Twr clusters, aircraft, etc. Pending - ARC Centres of excellence – Eucalyptus! (Adams, Beringer, et al.) – Climate impacts: risks and opportunities (Lynch, Beringer, et al.) – Savanna landscapes (Bowman, Hutley, et al. Future - National Collaborative Research Infrastructure Strategy – $100 million per year program – Ozflux mentioned as priority for building capacity – Cross institutions Vision for a Biosphere Observing Network Objectives 1. Determine the exchanges of energy, carbon (CO2) and water and how these vary spatially and temporally in response to environmental changes and disturbance. 2. Understand the biological and climatic processes that control carbon and water exchanges 3. Parameterise and evaluate ecosystem, land surface and hydrological models. 4. Compare NEP from towers inventory and other biometric techniques. 5. Use the knowledge from objectives 1-4, combined with existing landuse, aircraft, satellite, atmospheric concentration data and along with state-of-the-art data assimilation and multiple constraint methods to provide regional and national estimates of the carbon and water cycling in Australian ecosystems on various time scales. 6. Build expertise and collaborations in global change science Research Activities Supported Most regional flux networks confined to quantification, variability, processes, scaling and integration through modelling Observations: Flux towers, aircraft, satellite. Concentrations (LOFLO). Other trace gases (FTIR). Land surface, land cover, vegetation properties, physical and biological variables. Potential supersites? Models: SVAT, physiological, hydrological, biogeochemical (isotopes). Net fluxes (comparisons tower versus accounting). Response processes Data Assimilation/Fusion: Assimilate diverse information Carbon and water budgets regionally resolved (soil water - GEWEX). Model inversions (IPILPS). Ecosystem response to climate and human activities Predictive Models: Carbon and water source/sink projections, response to policy scenarios, verification of outcomes Adapted from GCP Policy relevance of flux studies Disturbance studies – Fire, land clearing, urbanisation, and grazing Greenhouse science – Carbon balance, non-CO2 trace gases, aerosols, Mitigation strategies, etc. Agricultural studies – Wheat, Rice, Cereals, Grains and pathogens/disease, biomass energy crops Hydrological studies - Desertification, Water balance, supply, Salinity/Erosion Predictive Modelling (earth system, land surface, biogeochemical, ecophysiological, hydrological, etc.) Regional network functions Site specific process oriented Intra network synthesis – climate, substrate, and functional type gradients Cross network comparisons Annual accounting – Carbon and water balance Enhancing network utility and synergies Observational/process focus Elevated CO2 studies Experimental Warming Studies Disturbance studies Biosphere-Atmosphere Stable Isotope Studies Network scaling (chamber, aircraft, boundary layer budgets) Non-CO2 trace gasses and aerosols (VOC’s, CH4, N2O, etc.) Carbon stocks and turnovers – Roots, Tubers, and Soil Organic Matter studies Nutrient cycling Biometric/inventory approaches to carbon balance We propose to add seven new long-term flux towers to the existing 4-5 to gain a critical mass for a nation-wide network. The new sites have been chosen to represent major landscape types across the country or sites that have been subject to human disturbance (land area estimates from NLWRA, 2001). These include; 1. Urban (Melbourne) – Monash University. 2. Bluegum plantation forest (W. Australia) UWA. 3. Native tussock / hummock grassland (Pilbara, WA) (UWA). 12.8% of native vegetation has been modified by humans following European settlement - urbanisation. Eucalyptus globules plantations now cover more than 150,000 Ha in Australia. One of the largest of the major vegetation groups (1,756,104 km2). 4. Upland wet eucalypt forest (Atherton) – James Cook University. Comprises 30,232km2. Confined to the wetter areas or climatic refuges. 5. Acacia Woodlands/scrub (Tennant Creek) – Northern Territory University and University of Technology, Sydney. Comprises 560,649 km2. 6. Open eucalypt woodland NSW. (Murrumbidgee Basin, 7. Agricultural land (WA) – Murdoch University. 982,051 km2 of native Kyeamba Creek ) – Monash/Melbourne University. The Murrumbidgee is now only 14% woody nearly all of which is in the hills/mountains. 650mm rainfall. vegetation has been modified by human practices following European settlement, especially agriculture. Network site selection Aim to: 1. the range of bioclimates across the continent - wet/dry (8 and 10), tropical (4 and 9), semi-arid (3), arid (5), temperate (1,6), mediterranean (2,7), cool (11); 2. major ecosystem types including a range of functional groups – Evergreen forest (2,4,9,11), woodland (5,6), savanna, (8,10), grassland (3,7); 3. a range of important anthropogenic landscapes (1,2,7) (e.g. cropping, fire, grazing); 4. sites important in carbon sequestration activities (2,7,8,11) ; 5. an east-west transect from NSW coast inland across the Murray Darling region (6,11); 6. a north-south transect from Darwin to Alice Springs along a rainfall gradient (5,8,10); 7. and sites that link with international programs (6-GEWEX, 9-Int Canopy Crane Network). http://www.clw.csiro.au/research/landscapes/interactions/ ozflux/monitoringsites/tumbarumba/pictures/index.html Measurements Variables Eddy-covariance (EC) fluxes, above canopy Carbon dioxide flux Latent heat flux Sensible heat flux Momentum flux Fluxes or storages below EC level CO2 air column storage (where appropriate) Sensible and latent heat air column storage (where appropriate) Aboveground biomass heat storage (where appropriate) Soil heat flux at the soil surface Soil carbon dioxide efflux (Methods to be developed by a working group to consider coverage of spatial and temporal variability) Radiation Net above canopy (using a network standard 4-way radiometer set (downwelling and upwelling shortwave radiation, and downwelling and upwelling longwave) plus an integrated net radiometer) Down- and up-welling photosynthetically active radiation (PAR), above canopy Net below canopy where a significant canopy exists Fraction of PAR absorbed by the vegetation (fPAR) using at least three ground-level PAR sensors where a significant canopy exists Diffuse and Direct beam PAR radiation Meteorology, canopy above Air temperature and relative humidity (shielded) Wind speed and direction Meteorology canopy within Air temperature and relative humidity (shielded) Meteorology, other Barometric pressure Rainfall Soil Soil temperature profile (2, 5, 10, 20, 50, 100 cm, 2 replicate profiles) Soil moisture profile (by depth to at least 50 cm, or, where the roots go deeper, to the rooting depth, 3-6 depths, 3 replicate profiles) Water table depth (peatlands ? Howard Springs Virginia Park Characteristic Howard Springs, NT Virginia Park, Qld 12 17' 24"S¸ 131 5' 24" E 19 53' 00" S, 146 33' 14" E Mean annual rainfall (mm) 1750 667 Mean annual temperatures (max/min, oC) 31.9 / 23.2 30.1 / 17.1 Sands, sandy loams, red Kandosol Sandy-loam, Alfisol Vegetation type Open-forest savanna Low open-woodland savanna Canopy species Eucalyptus tetrodonta, E. miniata, Erythrophleum chlorostachys, Terminalia ferdinandiana E. crebra, E. drepanophylla Sorghum spp., Heteropogon contortus Aristida spp., Eriachne spp 14-16 5-8 Stem density (per ha) 500-700 20-30 LAI, wet season (overstorey/understorey) 0.9 / 1.4 0.3 / 1.0 LAI, dry season (overstorey/understorey) 0.6 / 0.02 0.3 / 0 Vacant crown land Pastoral lease Location Soil texture Understorey species Stand height (m) Land use PROJECT 3.2: NET ECOSYSTEM EXCHANGE OF CARBON, HEAT AND WATER IN A TROPICAL RAINFOREST. Dr Mike Liddell Chemistry Department James Cook University CAIRNS THE CAPE TRIB FLUX SITE Satellite Imagery Cape Tribulation LANDSAT 80m resolution ASTER DEM 30m resolution THE CANOPY CRANE Dec. 1998 Liebherr construction crane Height 48.5m Complex mesophyll vine forest 25m canopy Pristine lowland rainforest, high species diversity ( 79 tree spp. in 1ha) Leaf area index 2003 4 EC flux equipment mounted at 45m (Campbell sonic, LiCOR IRGA) RAINFALL Assoc. Prof. Steve Turton (CRC-TREM, JCU TESAG) BOM Data Daily Rainfall at Cape Tribulation (Jan 1, 2001 - 31 May 2002) 2001 strongly 2002 seasonal 2003 Mean3903 Annual average rainfall approx. 3500mm, 70% falls between December and April. 200 January mean daily temperature is near 28C and 800 July mean daily temperature is arounddrought 22C. occurred in A substantial 150 2002, 2003 with essentially no wet season in 2002 - 2003. 600 Rainfall mm Rainfall (mm) 1000 100 400 50 200 0 0 1 24 47 70 93 116 139 162 185 208 231 254 277 300 323 346 369 392 415 438 461 484 507 0 2 Mar01 4 6 8 Days July01 Nov01 Month 10 12 May22 Carbon stocks Variable Frequency Aboveground biomass by species, including overstorey biomass (basal area, sapwood area, stem density) and understorey biomass (shrubs, herbs, moss). Root biomass Surface detrital C including standing dead trees, coarse and fine woody debris, and forest floor organic layers Mineral soil C (to the depth of parent material) - Biomass would be measured only once, and then combined with measurements of growth rate. Ecosystems with rapidly changing biomass may need additional measurements Once, at the start Site history Species composition Canopy height Clumping index Specific leaf area Foliar element size Spatial variability in fPAR Leaf area index Rooting depth Date of budbreak Profiles (sampled by depth to at least 50 cm, but where the roots go deeper, to the rooting depth) of: o soil texture o bulk density o soil coarse fragment fraction o water retention characteristics (field capacity, wilting point) o pH o Cation exchange capacity o N total, extractable P and K o % base saturation o 13C (where possible) o Mineralisable N (To be established) Once as part of installation - Once per year - Annually Vegetation Soil Once At least at the start and end of the experiment, but annually for disturbed sites For mature sites at start and end of experiment, but more frequently for regrowth and deciduous. Annually (coniferousevergreen) or seasonally (deciduous) Once Annually Component Carbon FluxesBalance Variable Frequency Soil carbon dioxide efflux (Methods to be developed by a working group to consider coverage of spatial and temporal variability Aboveground growth increment (dendrometers) Frequent (eg monthly) to cover seasonal variation. Seasonally with dendrometers or at end of experiment with increment cores Frequent(eg monthly) to monitor production and mortality of fine roots Seasonally for sites with canopy Annually or from re-measurement of C stocks Annually 7 times per year Foliar nutrients (total N, P, K) 13C & 18O in leaves and wood Annually or seasonally Maximum stomatal conductance In situ photosynthetic light response curves (i.e., quantum efficiency and Vmax). In situ A/Ci curves Pre-dawn and mid-day water potential Once Once Once During significant drought periods Fine root phenology/turnover (to be established) Litterfall Overstory mortality Decomposition (litter and roots) 13C, 18O in CO and 2H in water vapour 2 VEGETATION ECOPHYSIOLOGY Other Partners OzFlux Determine the exchanges of energy, CO2 and water and how these vary spatially across Australian ecosystems and temporally from hourly to decadal scales. Quantify the seasonal and inter-annual variability and dynamics due to environmental changes (vegetation structure and phenology, droughts, heat spells, El Nino, growing season length) along with the role of disturbance (fire, agriculture and urbanisation). Understand the biological & climatic processes that control carbon and water exchanges (including components). Parameterise, evaluate and improve models - ecosystem, land surface and hydrological. Evaluate techniques - NEP from towers with inventory and other biometric techniques. Estimate the total potential for carbon uptake in Australian ecosystems on regional and national scales. Build expertise and collaborations in global change science to meet increasing demand for these skills. Research Priorities We will provide a major contribution to the National Research Priority of ‘An environmentally sustainable Australia’ through three priority goals. 1) Water – a critical resource: We will assess the role of climate variability on water fluxes and the impact on water supplies in vegetated catchments for an understanding of sustainable water management. Impact of salinity on ecosystem-atmosphere system will be investigated. 2) Reducing and capturing emissions in transport and energy generation: We will determine the role of Australian ecosystems in carbon sequestration and their likely response to climate change, climate variability and to human and natural disturbances. 3) Sustainable use of Australia’s biodiversity: We will provide a comprehensive understanding of the interplay between natural and human systems with regard to the provision of ecosystem services (water and carbon). Policy need for Flux networks Policymakers & Managers Research Results Flux Network Management Stakeholder issues Other research & programs Mitigation Adaptation Adapted from US CCRI Stakeholders Australian and State Governments (including AGO) CRC Greenhouse Accounting Bureau of Meteorology Forest agencies and companies Emissions trading industry Primary producers (agriculture, pastoralists, etc.) Land management authorities (water, soil, air) Wider scientific community Broader public Overall Objective To meet the needs of all Australians for the meteorological information, understanding and services that are essential for their safety, security and general well-being and to ensure that meteorological data and knowledge are effectively applied to Australia’s national and international goals. http://ngs.greenhouse.gov.au/index.html Goals of the National Greenhouse Strategy To limit net greenhouse gas emissions, in particular to meet our international commitments. To foster knowledge and understanding of greenhouse issues. To lay the foundations for adaptation to climate change. Reducing emissions of greenhouse gases, consistent with the Kyoto Protocol, has been identified by governments as the most important area for action. Australian Greenhouse Office http://www.greenhouse.gov.au/index.html Identify the key policy issues in greenhouse action; Reduce the growth in national greenhouse emissions; Improve sustainable energy services; Improve knowledge base on climate change; Evaluate and report on Australia’s progress towards the Kyoto target; Our mission is to provide research outputs for greenhouse emissions accounting at the national and project level. Ozflux is Policy relevant in; Quantifying effect of land management practices Contribution of non-CO2 gases Validation of IPPC or national emission factors Biomass for bioenergy Multiple constraint models of national carbon accounting http://www.greenhouse.crc.org.au/ Conclusions Need to incorporate human-environment paradigm Must be done at regional scales (not just global integration) Need to enhance network utility Need two-way interaction with Stakeholders A successful network will be ‘pitched’ to policy makers and managers Network is more than just collecting towers What is an isotope? Elements are defined by the number of protons (Z) in their nucleus. The mass number (A) of an element is equal to the sum of both protons and neutrons (N) in the nucleus, or A = N + ZA single element can have two or more mass numbers due to differences in the number of neutrons that can occur in the nucleus. These different forms of a single element are called isotopes. While protons have a positive charge, neutrons have no charge, so the number of neutrons does not affect the charge of a molecule. Some isotopes are stable, while others are radioactive and release particles and energy to decay into a more stable form.Elements usually have a common isotope that is the form most often found in nature. Because carbon, oxygen, and hydrogen are the elements that make up all organic matter, biologists are often interested in the isotopes of these elements. Each has common and rare forms. For instance, 98.8% of carbon atoms contain 6 protons and 6 neutrons with a mass number of 12; the notation for this form is 12C. 1.1% of carbon has 6 protons and 7 neutrons, noted as 13C. Similarly, 99.98% of hydrogen is found as 1H, but two stable isotopes and one radioactive isotope are known. 99.6% of oxygen is 16O, in addition there are three stable isotopes and five radioactive isotopes. Nitrogen, an important plant nutrient, is also of interest to biologists. It is found as 99.6% 14N and 0.4% 15N.How common are stable isotopes? A brief listing of the stable isotopes and their abundances for the elements most commonly used in global change research would include:ElementIsotopeAbundance (%)Hydrogen1 H99.9852 H0.015Carbon12 C98.8913 C1.11Nitrogen14 N99.6315 N0.37Oxygen16 O99.75917 O0.03718 O0.204Sulfur32 S95.0033 S0.7634 S4.2236 S0.014Strontium84 Sr0.5686 Sr9.8687 Sr7.0288 Sr82.56Isotopes influence the physical and chemical properties of matter. For instance, 12CO2 will behave differently than 13CO2 during certain processes and chemical reactions. Light isotopes form weaker chemical bonds than heavy isotopes, so light isotopes are somewhat more chemically reactive. Molecules containing light isotopes also evaporate and diffuse more quickly than their heavier counterparts. Therefore an evaporating liquid will contain more of the light isotope in the gas phase, and more of the heavy isotope in the liquid phase.Isotopic fractionation occurs when isotopes are partitioned differently between two phases or two substances. If we understand the processes underlying fractionation, we can use isotopes to determine how plants, animals, and whole ecosystems function. We can gain information from isotopes that naturally occur in the environment in studies of natural abundance, or we can artificially apply isotopes in high concentrations to use them as tracers. http://basinisotopes.org/basin/tutorial/measurements.html Measuring stable isotopes ons are accelerated through a vacuum tube and subjected to a magnetic field that causes io mation about the Stable Isotope Ratio Facility for Environmental Research (SIRFER) here a How does natural variation in stable isotopes come about? Variations in the abundances of stable isotopes among different compounds arise because the chemical bonding is stronger in molecules containing heavier isotopic forms, making it more difficult to break up the molecule in a chemical reaction (often termed kinetic fractionation), or because of differences in the physical properties of molecules containing heavier isotopic forms (often termed diffusive and equilibrium fractionation). With kinetic fractionation, the rate of an enzymatic reaction is faster with substrates that contain the lighter isotopic form than in reactions involving the heavier isotopic form. As a consequence, there will be differences in the abundances of the stable isotopes between substrate and product. Such differences will occur unless, of course, all of the substrate were consumed, in which case there would be no difference in the isotopic composition of substrate and product. Expression of a significant kinetic fractionation in most biological reactions involves substrates at branch points in metabolism, such as the initial fixation of CO2 in photosynthesis. Equilibrium fractionation events reflect the observation that during equilibrium reactions, such as the equilibration of liquid and gaseous water, molecules with the heavier isotopic species are typically more abundant in the lower energy state phase. Diffusive fractionation events reflect the observation that heavier isotopic forms diffusive more slowly than lighter isotopic forms. What is the natural range of isotopic variation in nature? The natural variations in isotopic abundance can be large, including the that found for materials frequently of interest in global changes studies: waters, greenhouse gases, and biological materials. As a starting point, note that some atmospheric gases, such as CO2, N2, and O2, exhibit limited variation, while N2O and CH4 exhibit wide isotopic variation. The larger isotopic ranges in the latter two gases reflects both significant isotopic fractionation by microbes as well as different biological substrates which are used to produce these gases. How are isotopes affected by plant processes? Stable isotopes are a useful tool in plant physiology and ecology because isotopic fractionation occurs during both photosynthesis and transpiration - the basic physiological processes responsible for plant growth. PhotosynthesisPhotosynthesis converts CO2 in the atmosphere to carbohydrates, the building blocks of plant material. We can consider photosynthesis in two steps: 1) CO2 enters the leaf from the atmosphere and 2) it is fixed into carbohydrates in a process known as carboxylation. Isotopic discrimination occurs during both steps:In step 1, CO2 diffuses into leaves through adjustable pores on the leaf surface, or stomates. During diffusion, fractionation occurs as the heavier 13CO2 molecules diffuse more slowly. Thus, the air outside the leaf is slightly enriched in 13CO2, and the air inside the leaf pore space is depleted in 13CO2. The discrimination value for diffusion of CO2 is 4.4‰.In step 2 carboxylation occurs, but the details of carboxylation are different for two major pathways of photosynthesis that are found in plants. The most common pathway is called C3 photosynthesis, because the intermediate molecule in the process has three carbon atoms. In C3 plants, CO2 binds to the enzyme Rubisco (RuBP carboxylase,). This enzyme preferentially binds to 12CO2 if the concentration of CO2 is high and many molecules are available. The concentration of CO2 inside the leaf (noted as ci) depends on the rate of photosynthesis and the opening of the stomatal pores, which in turn influences isotopic discrimination. To understand this, consider the extreme case of complete closure of the stomates, so that no additional CO2 can diffuse into the leaf. In this case all of the CO2 present inside the pore space must be used in photosynthesis, and Rubisco has no "choice" about whether to bind to 12CO2 or 13CO2. Therefore, discrimination by carboxylation is zero. However, the diffusional discrimination value of 4.4‰ still applies - the carbohydrates produced inside this closed leaf will carry this signature. Because d13C of the atmosphere is equal to about -8‰, the plant material in this hypothetical case will equal -8 - 4.4 = -12.4‰.Conversely, consider that the stomates are fully open. In this case ci approaches the concentration of CO2 in the atmosphere, noted as ca (ci is always lower than ca). The discrimination by diffusion becomes insignificant, but carboxylation becomes very important. Rubisco can now "choose" from many CO2 molecules, and will preferentially bind to 12CO2. The carbohydrates produced by this process will carry the signature of the maximum discrimination of Rubisco, about 30‰. Adding in atmospheric d, the biomass be -38‰.In reality, plants fall between these extreme cases of fully closed and fully open stomates. Typical d values for C3 plants are -21 to -35‰.We can predict the photosynthetic discrimination of plants because the relationship between ci, ca, and discrimination has been expressed mathematically: 13D = a + (b - a)*ci/ca where D is discrimination, a is the diffusional discrimination (4.4) and b is the discrimination by carboxylation (30). Thus, the isotopic composition of the plant material contains information about ci/ca, which is controlled by the rate of photosynthesis anddegree of stomatal opening, or stomatal conductance. There is a less common, but still important type of photosynthesis called C4 photosynthesis, after the four carbon intermediate molecule. This pathway arose because Rubisco will bind to oxygen as well CO2, especially under high temperatures. This process is called photorespiration, and it is undesirable because plants cannot use oxygen for photosynthesis, and actually must release CO2 to remove oxygen from the pathway. High CO2 concentrations inhibit photorespiration, and it is likely that C3 photosynthesis evolved when the CO2 concentration in the atmosphere was much higher than it is today. As the concentration in the atmosphere dropped and photorespiration became more problematic, a new type of photosynthesis arose.C4 photosynthesis limits photorespiration by separating the site of CO2 fixation from the leaf pore space, where the oxygen concentration is very high. In the cells surrounding the pore space (mesophyll cells), CO2 is accepted not by Rubisco, but by a different enzyme called PEP carboxylase that does not bind to oxygen. It is converted to the 4 carbon intermediate malate and transported to special cells that surround the plant's vascular (circulatory) system. These cells are called bundle sheath cells. In these cells, malate is converted back to CO2 and is fixed by Rubisco in the C3 photosynthetic pathway. Because the concentration of CO2 in bundle sheath cells is so high, photorespiration is minimized.So why don't all plants use C4 photosynthesis? The extra steps of fixing, transporting, and re-fixing CO2 cost energy. C4 plants are restricted to environments and ecosystems where they have some competitive advantage over their neighbors by expending extra energy on an alternative method of photosynthesis. Because photorespiration is dependent on temperature, C4 plants often (but not always) occur in warm climates, where up to 50% of the carbon fixed by C3 plants can be wasted as photorespiration. Some ecosystems, such as certain grasslands, are dominated by C4 plants, while others contain only a small component of plants using the C4 pathway.Whether a plant is a C3 or C4 type is extremely important isotopically. Bundle sheath cells are almost impermeable to diffusion, similar to the example of closed stomates discussed above. Recall that if all of the available CO2 is fixed by Rubisco there cannot be discrimination. Plants vary in their capacity to seal CO2 inside the bundle sheath without leakage, which can affect discrimination. This effect as also been described mathematically: 13D = a + (b4 - b3f a)*ci/ca This equation is similar to the equation given for C3 plants but has some extra terms. b4 is the discrimination of PEP carboxylation of 5.7‰, far lower than the value for Rubisco, or b3, of 30‰. f is the fraction of CO2 that leaks out of the bundle sheath cells; this value is typically near 0.2. Thus, we can also use isotopic discrimination to gain information on ci/ca and the factors that control it in C4 plants, which are more enriched in 13C than C3 plants. Typical d values for C4 plants are -12 to -15‰.Oxygen isotopes in CO2 are also subject to diffusional fractionation, but once inside the leaf, oxygen in water can exchange readily with oxygen in CO2 due to the presence of an enzyme called carbonic anhydrase. Only about 1/3 of CO2 that diffuses into a C3 leaf is actually fixed in photosynthesis - the remainder diffuses back out and influences the oxygen isotope composition of atmospheric CO2. We can calculate an "apparent" discrimination against 18O in photosynthesis of C3 plants, which is not entirely based on an actual discrimination because of the exchange with leaf water: 18D = Ra/RA - 1 = â + cc(dc - da)/(ca-cc) where Ra is the ratio of 18O/16O in atmospheric CO2, RA is the ratio of 18O/16O in the net flux of CO2 into the leaf, and cc is the CO2 concentration in the chloroplast (which is generally lower than ci). â is average fractionation during diffusion from the air into the leaf chloroplast, the site of photosynthesis. This is dominated by the diffusion from the atmosphere into leaf pore space, which is theoretically 8.8‰ based on the differences in diffusivity between C16O2 and C18O2. However, there is some influence by other fractionation factors such CO2 entering solution, so â is more accurately about 7.4‰. 18D is highly variable across a range of ecosystems - it can vary from -20 to +32‰. This is because da and dc, the d values for 18O/16O in the atmosphere and chloroplast, respectively, are highly variable. We will discuss the factors that control them in the next sections.ReferencesEhleringer, J.R., T.E. Cerling, M.D. Dearing. 2002. Atmospheric CO2 as a global change driver influencing plant-animal interactions. Integrative and Comparative Biology 42: 424-430.Farquhar, G. D. 1983. On the nature of carbon isotope discrimination in C4 species. Aust J Plant Physiol 10: 205-226.Farquhar, G. D., J. R. Ehleringer, and K. T. Hubick. 1989. Carbon isotope discrimination and photosynthesis. Annual Review of Plant Physiology and Plant Molecular Biology 40: 503-537.Farquhar, G. D., and J. Lloyd. 1993. Carbon and oxygen isotope effects in the exchange of carbon dioxide between plants and the atmosphere. Transpiration and EvaporationWater that enters an ecosystem through rain can leave through several mechanisms. It can runoff the surface, flow through the soil and enter groundwater, or it can evaporate. Soil evaporation is generally confined to the first few centimeters of soil; however, plant roots can reach depths of many meters to remove water from far below the surface. This water evaporates out of leaves and returns to the atmosphere in the process of transpiration. The combination of evaporation from the soil surface and transpiration from plant leaves is called evapotranspiration.Water may contain isotopes of both hydrogen and oxygen - the light isotope of hydrogen is 1H (usually abbreviated as H) and the heavy stable isotope is 2H (abbreviated as D for deuterium). The light isotope of oxygen is 16O, while the most common heavy stable isotope is 18O. Recall that lighter isotopes evaporate more quickly than heavier ones, so that there is more of heavy isotope in the liquid phase and more of the lighter isotope in the gas phase. This is called an equilibrium effect. It can be described by an equilibrium fractionation factor, or a*: a* = RL/Rv where R is the ratio of the amount heavy isotope/light isotope, L refers to the liquid phase, and v refers to the vapor phase.As we discussed in the section on photosynthesis, light isotopes also diffuse more quickly than heavy isotopes. This is called a kinetic effect, and it can be described by a kinetic fractionation factor, ak: ak = D/D' = g/g' where D is the diffusion coefficient of the light isotope and D' is the diffusion coefficient of the heavy isotope (ak = 1.025 for H/D and 1.0285 for 16O/18O).A diffusion coefficient is a constant that quantifies differences in diffusion rates among various molecules. We can describe differences in diffusion rates through any substance, including the stomates of plants, so we can also express ak as the ratio of the stomatal conductance of a light isotope (g)/stomatal conductance of a heavy isotope (g'). This will be useful later in our calculations. Both equilibrium and kinetic effects are involved in transpiration. Water molecules evaporate into the leaf pore space from xylem, the conduits that transport water from the soil to the leaves, and then diffuse into the atmosphere. The rate of plant transpiration depends on the stomatal conductance and the dryness of the air relative to the leaf pore space, as expressed by the difference between vapor pressure inside the leaf (ei) and outside the leaf (ea): E = g(ei - ea) where E is transpiration and g is stomatal conductance. Let us define E as the transpiration rate of water containing light isotopes only. We can also describe the transpiration rate of water containing heavy isotopes: E' = g'(Rvei-Raea) where Rv is the ratio of the heavy and light isotopes of water vapor in the leaf pore space, and Ra is the ratio of heavy and light isotopes of water vapor in the air outside the leaf. By combining these two equations, we can describe the ratio of heavy to light isotopes in transpired water (recall that ak = g/g' and a* = RL/Rv): E'/E = RT = (1/ak) * (RLei/a* - Raea)/(ei - ea) There is no fractionation during transport of the water from the soil to the leaves. Therefore RT is the isotopic composition of the plant's source of water. It can be measured by sampling the water in stem xylem. If RT is known, we can rearrange the equation to predict the enrichment of 18O and D that occurs in leaves:RL = a*[akRT(ei-ea/ei) + Ra(ea/ei)] This leaf water is used in photosynthesis to build plant tissues; therefore all plant material carries the isotopic signature of the water source in addition to the evaporative enrichment influenced by the vapor pressure in the air. How are isotopes affected by plant processes?Ecosystem carbon balance: respiration Stable isotopes may be used to understand the processes that affect photosynthesis on a whole ecosystem scale. Since plants preferentially use 12CO2 in photosynthesis, the CO2 left behind in the atmosphere is enriched in 13CO2. At the same time, plants and all other organisms in the ecosystem are always respiring, or using oxygen and producing CO2 to maintain metabolic processes. It is commonly assumed that there is no fractionation during respiration, so the CO2 that is respired from organisms has the same isotope ratio as the live tissue. Photosynthetic discrimination dominates in the daytime, while respiration dominates at night - this produces a diurnal variation in d13C of ambient CO2.For C3 plants, respired CO2 is very depleted in 13C, with d on the order of -22 to -35‰. Because respired CO2 and CO2 left behind in atmosphere after photosynthesis have different isotope ratios, the isotopic composition of CO2 entering and leaving ecosystems can provide information on the balance of photosynthesis and respiration, so that we can better make predictions about how each parameter will change in the future. For instance, respiration is largely regulated by temperature, whereas photosynthesis is affected by light, temperature, drought, and many other factors.Organisms that live in the soil also respire. Soil organisms range from bacteria and fungi to fauna such earthworms, nematodes, and even mammals. The plant litter that falls on to the soil surface is consumed by many types of organisms, which release CO2 in the process. The chemical components of plant material are not consumed at the same rates, as some are more difficult to digest than others. These chemical substances, which include sugars, lipids, lignin, and cellulose, generally have different isotope ratios within a single plant. Therefore the carbon isotope ratio of CO2 emitted from the soil can be complex, and may change over time.What is a Keeling Plot?We can determine the isotope ratio of respired CO2 from the soil or from whole ecosystems with Keeling plots. To construct a Keeling plot you must capture CO2 samples during a period when the CO2 concentration is changing over time. At the night when photosynthesis has ceased, the CO2 concentration above the soil or the plant canopy increases as the ecosystem respires. During this time you can plot the isotope ratio of sampled CO2 on the y-axis, and the inverse of the CO2 concentration, 1/CO2, on the x-axis. This should create a straight line because of the mixing of respired and atmospheric CO2. If the CO2 concentration is near the atmospheric value of 365 ppm, then the sample mostly contains atmospheric CO2, and d13C is near -8‰. When the CO2 concentration rises above the atmospheric concentration, it contains a larger proportion of respired CO2, which has a more negative carbon isotope ratio.The equation for a straight line is: y = intercept + slope*x The intercept is the value of y when x if zero. The intercept of a Keeling plot is the isotope ratio of respiration in the absence of dilution by atmospheric CO2. If CO2 is sampled at the soil surface, the Keeling intercept is the isotope ratio of soil respiration; if it's sampled in the plant canopy the intercept is the isotope ratio of ecosystem respiration. It is also possible to sample CO2 higher in the troposphere, where the carbon isotope ratio represents an entire region. A sample Keeling plot is shown here.We can also generate Keeling plots for d18O in CO2. We have described the photosynthetic discrimination of CO2 with respect to oxygen isotopes and the effect of the exchange of oxygen with leaf water. Leaf water is highly enriched in 18O due to equilibrium fractionation in evaporation. Water in other plant parts such as stems and roots is not enriched, rather it has the same isotopic composition of the source of water in the soil. The CO2 that is respired from these plant parts will equilibrate with this water, and also have the same isotope composition as the water source, which is depleted in 18O. Soil respired CO2 also equilibrates with soil water; it is generally affected by the water at about 5-15 cm depth; above 5 cm CO2 leaves the soil too rapidly to exchange with water, and below 15 cm isotopic exchange is negated by diffusional effects as the CO2 molecules move upwards. At 5 - 15 cm depth, soil water is generally depleted in 18O due to the isotopic composition of precipitation discussed below.Because of the differences in discrimination of 18O during photosynthesis and respiration, the oxygen isotope information contained in CO2 fluxes from ecosystems can be used to separate these two components. The differences in oxygen discrimination between respiration and photosynthesis are larger than the differences in carbon discrimination, which are generally quite small are require sophisticated instrumentation to detect. However, d18O can be more temporally and spatially variable than d13C due to environmental influences on precipitation and atmospheric water vapor. The choice of isotope is dependent on the ecosystem and the question of interest.ReferencesBoutton TW. 1996. Stable carbon isotope ratios of soil organic matter and their use as indicators of vegetation and climate change. in Mass Spectrometry of Soils, edited by T.W. Boutton, and S. Yamasaki, pp. 47-83, Marcel-Dekker, New York.Bowling DR., Tans PP, Monson RK. 2001. Partitioning net ecosystem carbon exchange with isotopic fluxes of CO2. Global Change Biology 7: 127-145.Flanagan LB, Ehleringer JR. 1998. Ecosystem-atmosphere CO2 exchange: interpreting signals of change using stable isotope ratios. TREE 13 (1): 10-14.Keeling CD. 1958. The concentration and isotopic abundances of atmospheric carbon dioxide in rural areas, Geochim Cosmochim Acta. 13: 322-334.Keeling CD.1961. The concentration and isotopic abundance of carbon dioxide in rural and marine air, Geochim Cosmochim Acta. 24: 277298.Pataki DE, Ehleringer JR, Flanagan LB, Yakir D, Bowling DR, Still C, Buchmann N, Kaplan JO, Berry JA. 2003. The application and interpretation of Keeling plots in terrestrial carbon cycle research. Global Biogeochemical Cycles, 17(1).Yakir D, Sternberg LL. 2000. The use of stable isotopes to study ecosystem gas exchange. Oecologia: 123, 297-311. Simulated physiological effects on stable isotope fractionation can be evaluated at a growing number of field sites in the BASIN portfolio • SiB2 captures important diurnal, synoptic, seasonal, and interannual variations in ∆ • Model (with NDVI and weather drivers) can extend process understanding to regional and global scales • Time-varying regional simulations of ∆ may provide better constraints on CO2 inversions • Uncertainties in all terms must be quantified to make proper use of isotopic constraint for regional mass balance http://biocycle.atmos.colostate.edu/html/simple_biosphere_model__sib_.html Ameriflux Quantify magnitude of net annual CO2 exchange in major ecosystem/biome types (natural and managed) Determine response to changes in environmental factors and climate changes on CO2 fluxes Provide information on processes controlling CO2 flux and net ecosystem productivity Provide site-specific calibration and verification data for process-based CO2 flux models Address scaling issues (spatial and temporal) Quality control and quality assure data collection Coordinate the news, and exchange CO2 flux data & ecological data with other carbon flux networks CarboEurope The objectives of the CarboEurope cluster are to advance the understanding of carbon fixation mechanisms and to quantify carbon sources/sinks magnitudes of a range of European terrestrial ecosystems and how these may be constrained by climate variability, availability of nutrients, changing rates of nitrogen deposition and interaction with management regimes. Research focusing on European ecosystem is complemented by investigations of the sink strength of Amazon forests. AsiaFlux The research potential of studies of carbon dioxide, water and heat fluxes in Asia is highlighted, and the accumulation of results is enhanced. Collaborative research is improved through information interchange, and results are more widely disseminated. Results can be compared among Asian countries. Moreover, it becomes possible to understand the carbon, water and heat budgets of various land surfaces and ecosystems in the Asian monsoon climate, and of those affected by artificial activities such as biomass burning. Japanese researchers can play an important role in flux research in Asia and can help improve FLUXNET. Fluxnet-Canada Use EC to make continuous, multi-year measurements of CO2, water, and sensible heat fluxes, for mature and disturbed forest and peatland ecosystems along an east-west national transect that encompasses some of Canada's important ecoregions. We will (a) examine inter-annual variability; (b) contribution of different ecosystem (c) relationship between NPP and NEP; (d) parameterise and evaluate ecosystem and land surface climate models. Characterise relationships between climate variables (e.g., mean monthly temperature) and NEP including disturbance Compare techniques - NEP from towers with inventory and other biometric techniques. Gain better approximations of potential carbon uptake by Canadian forests and wetlands. Train highly-qualified personnel, inform policy-makers, and increase public understanding of C cycling science and issues. KoFlux Our study is to measure the energy, water and carbon dioxide flux using eddy covariance method and to simulate their exchange using dynamic global vegetation model in order to understand and predict the changing of biosphere-atmosphere interactions for a long time period in Asian deciduous forest. The Global Carbon Project - Partnerships and Stakeholders Observational Programs IGOS-P [IGCO] IGBP [ESSP] IHDP IPCC INTERNATIONAL PROTOCOLS NATIONAL / POLICY GOVERNMENT NATIONAL/REGIONAL CARBON PROGRAMS CO2 Panel [IOC-SCOR] WCRP http://www.GlobalCarbonProject.org GCP Research Goal To develop comprehensive, policy-relevant understanding of the global carbon cycle, encompassing its natural and human dimensions and their interactions. http://www.GlobalCarbonProject.org Unperturbed C Cycle Perturbed C Cycle Perception of a problem The Conceptual Framework Perceptions of human welfare Changes in institutions & technol. Atmospheric Carbon Fossil Carbon Industry Transport Populatn Solubility Pump Land Use Ecosystem Disturbances Systems Physiology Climate Change and Variabil. Biological Pump Ocean-use Systems Terrestrial Carbon Ocean/Coastal Carbon From http://www.GlobalCarbonProject.org GCP Research Goal To develop comprehensive, policy-relevant understanding of the global carbon cycle, encompassing its natural and human dimensions and their interactions. •Can not be considered only at global level of integration •Human-environment interaction regionally specific •Must therefore address regional issues in regional networks http://www.GlobalCarbonProject.org Kyeamba Creek Location: Southern New South Wales, 5 km south of Wagga Wagga. Area: 600 km . 2 Rainfall: 650 mm, grading from 600 mm in the north to 800 mm in the south. Land use Dominated by cattle grazing, limited sheep, some irrigation of crops and vegetables in the higher country. Click for large conceptual model Reference: Cresswell et al. (2001) Salinity The salinity issue in Kyeamba Creek is mainly associated with the high contributing salt load conveyed through the stream to the Murrumbidgee River. Dryland salinity also exists within the catchment as a result of local variation in the thickness of the surface alluvial aquifer (mainly along Kyeamba Creek), and due to the high salt store of the surface material at the head of streams (mainly in Livingstone Creek). Groundwater system There are two aquifers operating within Kyeamba Creek. The upper system is a surface alluvial aquifer that carries most of the main watercourses. The variability of the aquifer thickness creates local flow cells only a few kilometres long. These have local discharge areas that become saline due to evaporative concentration of near-surface water. The other aquifer is a deeper and more extensive intermediate scale fractured rock aquifer that underlies much of the area. Groundwater flow is generally northward, complementary with the direction of surface flow in the larger creeks, and the water levels in this aquifer are near the surface over the lower reaches of Kyeamba Creek near its confluence with the Murrumbidgee River. Management The two different systems require quite different approaches. In the local alluvial system, recharge reduction through the establishment of trees, for example, must be targeted at each local flow cell, rather than as a general coverage. Forestry planning is underway in this catchment, involving up to 13% of the catchment earmarked for commercial hard and softwood plantations over the next decade. If these plantations are targeted to influence local groundwater flow cells then some recovery of the present discharge sites may ensue. In the case of the largerscale flows within the deeper, more extensive fractured rock aquifer, a more general recharge reduction strategy may be required. This is unlikely to be achieved by the planned area of plantation timber, but may be positively influenced through changed cropping and grazing practices. Click for large map of groundwater discharge zones he eastern headwaters of the Murray-Darling Basin (drainage area about 1,000,000 km2). Although the basin lies within about 100 km of Australia's e m^2 (Book Book) 1E (ladysmith); 35.35S, 147.55E (Book Book) and 2001-ongoing(Ladysmith); 1985 to present (Book Book) 1-ongoing); BoM station at Wagga Wagga 15km from Kyeamba Creek (an AMS and AMO s a - incoming shortwave, screen temperature, specific humidity, wind speed and direction, su nt, fluxes tower planned for 2004, subject to funding along transect across the whole Murrumbidgee; 14 sites within the Kyeamba Creek, mobile T moisture simulations from the VB95 land surface model against observations. Proceedings of the International Congress on Modelling and Simulatio W. Western. 2003. Preparation of a climate data set for the Murrumbidgee River catchment , 2003. Gravity changes, soil moisture and data assimilation. EGS - AGU - EUG Joint Assem ung, R.I., Mills, G., Grayson, R.B., Manton, M.and T.A. McMahon, 2002. Testing the Australi b.edu.au The overarching goal of the CARBOEUROFLUX programme is to improve our understanding on magnitude, location, temporal behaviour and causes of the carbon source/sink strengths of terrestrial ecosystems which can be used to improve the negotiation capacity of the European Community in the context of the Kyoto protocol. (for further details refer to CARBOEUROFLUX web site: http://www.bgcjena.mpg.de/public/carboeur/projects/index_p.html) Within this framework we are strongly limited in two important issues. First, in identifyi and tracing individual fluxes of CO associated with photosynthetic assimilation or respiration. Second, in understandin 2 observed large inter-annual variations in the net CO exchange between land ecosystems and the atmosphere. Stable isotopes are among t few tools available to us to improve on these fronts. In the first case, by taking advantage of the specific isotopic signals associated with photosynthesis and respiration. In the second case, by using ecosystem-scale isotopic discriminations as indicators for ecophysiological response to environmental change. 2 Work Package 5 (WP5), entitled "Isotopic Studies", is one of the nine work packages of the CARBOEUROFLUX project. The general goal o WP5 is to monitor and elucidate the ecosystem-scale processes that influence spatial and temporal variations in the concentration and isoto composition of atmospheric CO at sites within the CarboEurope cluster. It should provide, therefore, the necessary basis to advance the us stable isotopes in ecosystem studies. 2 Methodology A new isotopic sampling program was developed and applied in 18 tower flux sites across Europe. In this program air samples above and within the canopy are taken in glass flasks. Analysis of these samples is used to examine the co-variations in [CO ] an stable isotopic compositions (d C and d O) in the canopy over time and space. These relationships can, in turn, be used to estimate the iso 2 13 18 signals associated with net ecosystem CO exchange and Ecosystem Discrimination. By complementing such measurements with sampling analysis of organic materials (leaf, stem and soil) we can potentially constrain the relative contributions of specific CO source or sinks in the ecosystem. 2 2 One of the common ways to use the co-variations of [CO ] and isotopes in canopy air is to apply the 'Ke 2 model' (Keeling 1958, 1961). This approach will also be used here among other data analyses. The Keeling model assumes that the observ variation in [CO ] and isotopes reflect simple mixing between a unique CO sink/source in the ecosystem and unique CO in the PBL. Accord a linear fit to the data, appropriately plotted, provides information on the isotopic signal of the CO source/sink in the system (Figure 1). 2 2 2 2 Pataki DE, Ehleringer JR, Flanagan LB, Yakir D, Bowling DR, Still C, Buchmann N, Kaplan J, Berry JA. 2003. The application and interpretation of Keeling plots in terrestrial carbon cycle research. Global Biogeochemical Cycles, 17(1). Carbon isotope discrimination by a sequence of Eucalyptus species along a subcontinental rainfall gradient in Australia Author: mIller, J. M.; Williams, R. J.; Farquhar, G. D. Source: Functional Ecology 15, no. 2 (2001): 222-232 (11 pages) 98. Ecosystem-atmosphere CO2 exchange: interpreting signals of change using stable isoto Falge, E. et al. (2002) Seasonality of ecosystem respiration and gross primary production as derived from FLUXNET measurements, Agricultural and Forest Meteorology 113 (2002) 53–74 Site Name Landcover Rainfall: annual mm Temp range: ºC Location Howard Springs* Tropical savanna (wet) 1700 20 to 33 E of Darwin, NT Cape Tribulation* Tropical rainforest 2000 20 to 40 Burdekin Delta Sugar cane 2000 Virginia Park Tropical savanna (wet/dry) Janina Group Status Contact Monash University (Melbourne) Northern Territory University Running since August 2001 data available from 1997 Jason Beringer LindsayHutley Cape Tribulation rainforest, 100 km N of Cairns, Qld 16 06' 20" S 145 22' 40" E James Cook University (Cairns) Running since January 2001 Michael Liddell 20 to 40 Coastal plain Burdekin River, Qld -19 34'S 147 24'E CSIRO Land and Water (Townsville) Running since March 2001 P.Charleswort h 700 15 to 40 40 km NE of Charters Towers, Qld 19 53' 00" S 146 33' 14" E CSIRO Land and Water (Canberra, Townsville) Running since July 2001 Ray Leuning Helen Cleugh Rangeland (dry savanna woodland) 300 0 to 40 125 km W of Bourke, NSW -30 04'36" S 144 48'11" E RSBS Australian National University (Canberra) Commenced March 2002 Chin Wong Tumbarumba Wet temperate sclerophyll eucalypt 1000 -10 to 30 Near Tumbarumba, NSW 35 39' 20.6" S 148 09' 07.5" E CSIRO Land and Water (Canberra) Running since May 2000 Ray Leuning Helen Cleugh Moanatuatua* Peat bog 1181 -3.5 to 28.8 20 km SE of Hamilton, North Island of New Zealand University of Waikato (Hamilton, New Zealand) December 1998 to December 2000 Dave Campbell Maroondah Wet temperate eucalypt forest 1700 3 to 17 Approx. 100 km NE of Melbourne, Vic. 37 34' S 145 38'E Monash University, Climatology Group August 2004 Jason Beringer Preston Urban 950 5 to 22 Melbourne, Australia Monash University Running since 2003 Jason Beringer 12° 49.428'S 131° 15.231'E Science highlights Howard Springs Howard Springs NEP -0.7 tC.ha-1.year-1 NEP -2.6 tC.ha-1.year-1 8 300 6 250 • Separate tree and grass components using neural network model. YEAR TREES (tC.ha-1.y-1) GRASS (tC.ha-1.y-1) 2001-2002 -8.6 -8.5 2002-2003 -8.5 -10.2 • Increase in grass growth produces higher fuel loads, which are burned in following years. 2 200 0 -2 150 -4 -6 -8 -10 NEP (L) GPP (L) Re (L) Rainf all (R) 100 50 -12 -14 0 2001219 2001239 2001259 2001279 2001299 2001319 2001339 2001359 2002014 2002034 2002054 2002074 2002094 2002114 2002134 2002154 2002174 2002194 2002214 2002234 2002254 2002274 2002294 2002314 2002334 2002354 2003009 2003029 2003049 2003069 2003089 2003109 2003129 2003149 2003169 • Year to year variability large and related to length and intensity of wet season, which drives changes in grass growth Daily Carbon Flux (gC.m -2.day -1) 4 NBP ~-1.5 tC.ha-1.yr-1 Daily rainfall total (mm.day -1) Inter-annual variability Virginia Park Virginia Park monitoring site - view to north-east Instrumentation Virginia Park monitoring site - view to north-west Instrument mast http://www.clw.csiro.au/research/landscapes/interactions/ozflux/monitoringsites/virginiapark/pictures/index.html Virginia Park Howard Springs 10 0 Fc (m mol m -2 -1 s ) 5 -5 -10 -15 LAI 2.3 (d) Wet season LAI 1.3 -20 10 0 Fc (m mol m -2 -1 s ) 5 -5 -10 -15 (e) Dry season LAI 0.62 LAI 0.3 -20 00:00 06:00 12:00 Time (h) 18:00 00:00 Daintree –Cape Tribulation Australian Canopy Crane (45m) platform, view to the west Soil CO2 flux: automatic closed chamber Drought effects Summation kgC/Ha/Day BOM Data 2001 2002 2003 Mean3903 1000 2001 -31 800 2002 +4 A substantial drought occurred in 2002, 2003 with essentially no wet season in 2002 - 2003. Rainfall mm 600 2003 +12 400 200 Mean Polynomial fit (6) 8 2003 Day 1 - 249 6 0 4 0 -2 CO2 Flux mmol m s -1 2 0 2 4 6 Month -2 -4 -6 -8 -10 -12 -14 -16 0 2 4 6 8 10 12 14 Hour of Day 16 18 20 22 24 8 10 12 Wallaby Creek (Maroondah) •Carbon and water balances of water catchments •Chronosequence following fire •Online Jan 2005 •Coupled with dendrochronology and wood quality studies 300 year old Canopy height 75-80m LAI ~1-2 and BA ~60 m2 80 year old Canopy height 30-50m LAI ~2-3 and BA ~30 m2 20 year old Canopy height 20-30m LAI ~3-4 and BA ~25 m2 Preston (Melbourne) • Melbourne urban planning scheme • Influence of housing density and feedbacks to local climate