A comparative analysis of simulated and observed photosynthetic CO2 uptake in two coniferous forest canopies.

Gross canopy photosynthesis (P(g)) can be simulated with canopy models or retrieved from turbulent carbon dioxide (CO2) flux measurements above the forest canopy. We compare the two estimates and illustrate our findings with two case studies. We used the three-dimensional canopy model MAESTRA to simulate P(g) of two spruce forests differing in age and structure. Model parameter acquisition and model sensitivity to selected model parameters are described, and modeled results are compared with independent flux estimates. Despite higher photon fluxes at the site, an older German Norway spruce (Picea abies L. (Karst.)) canopy took up 25% less CO2 from the atmosphere than a young Scottish Sitka spruce (Picea sitchensis (Bong.) Carr.) plantation. The average magnitudes of P(g) and the differences between the two canopies were satisfactorily represented by the model. The main reasons for the different uptake rates were a slightly smaller quantum yield and lower absorptance of the Norway spruce stand because of a more clumped canopy structure. The model did not represent the scatter in the turbulent CO2 flux densities, which was of the same order of magnitude as the non-photosynthetically-active-radiation-induced biophysical variability in the simulated P(g). Analysis of residuals identified only small systematic differences between the modeled flux estimates and turbulent flux measurements at high vapor pressure saturation deficits. The merits and limitations of comparative analysis for quality evaluation of both methods are discussed. From this analysis, we recommend use of both parameter sets and model structure as a basis for future applications and model development.

[1]  H. Mooney,et al.  Modeling the Exchanges of Energy, Water, and Carbon Between Continents and the Atmosphere , 1997, Science.

[2]  W. Massman,et al.  Eddy covariance flux corrections and uncertainties in long-term studies of carbon and energy exchanges , 2002 .

[3]  J. Gebel,et al.  Rapid field determination of photosynthetic capacity of cut spruce twigs (Picea abies) at saturating ambient CO2 , 1986, Trees.

[4]  Gode Gravenhorst,et al.  Determination of heat and water vapour fluxes above a spruce forest by eddy correlation , 1994 .

[5]  C. Osmond,et al.  Physiological Plant Ecology I , 1981, Encyclopedia of Plant Physiology.

[6]  P. Jarvis,et al.  Influence of crown structural properties on PAR absorption, photosynthesis, and transpiration in Sitka spruce: application of a model (MAESTRO). , 1990, Tree physiology.

[7]  K. Popper,et al.  Logik der Forschung , 1935 .

[8]  Influence of Shoot Structure on the Photosynthesis of Sitka Spruce (Picea sitchensis) , 1993 .

[9]  P. Jarvis,et al.  Photosynthesis in Sitka Spruce. VIII. The Effects of Light Flux Density and Direction on the Rate of Net Photosynthesis and the Stomatal Conductance of Needles , 1979 .

[10]  Ari Nissinen,et al.  Evaluation of six process‐based forest growth models using eddy‐covariance measurements of CO2 and H2O fluxes at six forest sites in Europe , 2002 .

[11]  D. Paslier,et al.  Net Exchange of CO2 in a Mid-Latitude Forest , 1993, Science.

[12]  D. Pury,et al.  Simple scaling of photosynthesis from leaves to canopies without the errors of big‐leaf models , 1997 .

[13]  A. Bondeau,et al.  Comparing global models of terrestrial net primary productivity (NPP): analysis of differences in light absorption and light‐use efficiency , 1999 .

[14]  Fergus L. Sinclair,et al.  Light interception and growth in agroforestry systems , 1995 .

[15]  D. Baldocchi,et al.  CO2 fluxes over plant canopies and solar radiation: a review , 1995 .

[16]  Winfried Kurth,et al.  Die Simulation der Baumarchitektur mit Wachstumsgrammatiken , 1999 .

[17]  J. Norman,et al.  Photosynthesis in Sitka spruce (Picea sitchensis (Bong.) Carr.). V. Radiation penetration theory and a test case , 1975 .

[18]  Dennis D. Baldocchi,et al.  On using eco-physiological, micrometeorological and biogeochemical theory to evaluate carbon dioxide, water vapor and trace gas fluxes over vegetation: a perspective , 1998 .

[19]  S. Long,et al.  Quantum yields for uptake of carbon dioxide in C3 vascular plants of contrasting habitats and taxonomic groupings , 1993, Planta.

[20]  E. Falge,et al.  A model of the gas exchange response ofPicea abies to habitat conditions , 1996, Trees.

[21]  Y. P. Wang,et al.  Two-dimensional needle-area density distribution within the crowns of Pinus radiata. , 1990 .

[22]  L. Wingate.  The contribution of photosynthesis and respiration to the net ecosystem exchange and ecosystem ¹³C discrimination of a sitka spruce plantation , 2003 .

[23]  R. Desjardins,et al.  Measuring nighttime CO2 flux over terrestrial ecosystems using eddy covariance and nocturnal boundary layer methods , 2001 .

[24]  Trevor Platt,et al.  Primary productivity of planet earth: biological determinants and physical constraints in terrestrial and aquatic habitats , 2001 .

[25]  P. G. Jarvis,et al.  Photosynthesis in Sitka Spruce (Picea sitchensis (Bong.) Carr.): VI. Response of Stomata to Temperature , 1975 .

[26]  Fei Liu,et al.  Model Description and Validation , 2006 .

[27]  K. Wilson,et al.  How the environment, canopy structure and canopy physiological functioning influence carbon, water and energy fluxes of a temperate broad-leaved deciduous forest--an assessment with the biophysical model CANOAK. , 2002, Tree physiology.

[28]  P. Jarvis.  The Interpretation of the Variations in Leaf Water Potential and Stomatal Conductance Found in Canopies in the Field , 1976 .

[29]  A. Ibrom,et al.  Application of a Six-Layer SVAT Model for Simulation of Evapotranspiration and Water Uptake in a Spruce Forest , 1996 .

[30]  Ü. Rannik,et al.  Productivity overshadows temperature in determining soil and ecosystem respiration across European forests , 2001 .

[31]  C. Barton.  Effects of elevated atmospheric carbon dioxide concentration on growth and physiology of Sitka spruce (Picea sitchensis (Bong.) Carr.) , 1997 .

[32]  A. I. Breymeyer,et al.  Global change: effects on coniferous forests and grasslands. , 1996 .

[33]  R. Stull.  An Introduction to Boundary Layer Meteorology , 1988 .

[34]  P. Jarvis,et al.  Stomatal responses to humidity in selected conifers. , 1986, Tree physiology.

[35]  Keith Beven,et al.  On the sensitivity of soil-vegetation-atmosphere transfer (SVAT) schemes: equifinality and the problem of robust calibration , 1997 .

[36]  H. Ellenberg.  Integrated experimental ecology;: Methods and results of ecosystem research in the German Solling project , 1971 .

[37]  P. Jarvis,et al.  Leaf Conductance as Related to Xylem Water Potential and Carbon Dioxide Concentration in Sitka Spruce , 1979 .

[38]  J. Goudriaan,et al.  SEPARATING THE DIFFUSE AND DIRECT COMPONENT OF GLOBAL RADIATION AND ITS IMPLICATIONS FOR MODELING CANOPY PHOTOSYNTHESIS PART I. COMPONENTS OF INCOMING RADIATION , 1986 .

[39]  P. Jarvis,et al.  Photosynthesis in Sitka Spruce (Picea sitchensis (Bong,) Carr.): VII. Measurements of Stomatal Conductance and 14 CO 2 Uptake in a Forest Canopy , 1976 .

[40]  P. Jarvis,et al.  Photosynthesis in Sitka Spruce (Picea sitchensis (Bong.) Carr.). II. Response to Temperature , 1972 .

[41]  A. Ibrom,et al.  A six-layer SVAT model for a simulation of water vapour and sensible heat fluxes in a spruce forest , 1997 .

[42]  Winfried Kurth,et al.  Tree and stand architecture and growth described by formal grammars. I. Nonsensitive trees , 1999 .

[43]  W. Oechel,et al.  FLUXNET: A New Tool to Study the Temporal and Spatial Variability of Ecosystem-Scale Carbon Dioxide, Water Vapor, and Energy Flux Densities , 2001 .

[44]  D. Baldocchi.  Assessing the eddy covariance technique for evaluating carbon dioxide exchange rates of ecosystems: past, present and future , 2003 .

[45]  Corinna Rebmann,et al.  Methodology for data acquisition, storage, and treatment , 2003 .

[46]  M. Fuchs,et al.  Spacial distribution of photosynthetic capacity and performance in a mountain spruce forest of northern Germany , 1977, Oecologia.

[47]  P. Jarvis.  Atmospheric carbon dioxide and forests , 1989 .

[48]  P. De Angelis,et al.  Effects of elevated (CO2) on photosynthesis in European forest species: a meta-analysis of model parameters , 1999 .

[49]  Ü. Rannik,et al.  Respiration as the main determinant of carbon balance in European forests , 2000, Nature.

[50]  N. Jensen,et al.  Two years of continuous CO2 eddy-flux measurements over a Danish beech forest , 2001 .

[51]  Stan D. Wullschleger,et al.  Biochemical Limitations to Carbon Assimilation in C3 Plants—A Retrospective Analysis of the A/Ci Curves from 109 Species , 1993 .

[52]  H. Griffiths,et al.  Water deficits: plant responses from cell to community. , 1993 .

[53]  K. Popper.  Objective Knowledge: An Evolutionary Approach , 1972 .

[54]  Paul G. Jarvis,et al.  Description and validation of an array model - MAESTRO. , 1990 .

[55]  A. Verhoef,et al.  A system to measure surface fluxes of momentum, sensible heat, water vapour and carbon dioxide , 1997 .

[56]  M. Aubinet,et al.  Long term carbon dioxide exchange above a mixed forest in the Belgian Ardennes , 2001 .

[57]  B. Medlyn,et al.  A MAESTRO retrospective , 2004 .

[58]  J. Leverenz.  Chlorophyll content and the light response curve of shade‐adapted conifer needles , 1987 .

[59]  Ying-ping Wang.  Crown structure, radiation absorption, photosynthesis and transpiration , 1988 .

[60]  Jonathan M Adams,et al.  Carbon balance gradient in European forests: Interpreting EUROFLUX , 2000 .

[61]  R. Monson,et al.  Temperature as a control over ecosystem CO2 fluxes in a high-elevation, subalpine forest , 2003, Oecologia.

[62]  J. Berry,et al.  A biochemical model of photosynthetic CO2 assimilation in leaves of C3 species , 1980, Planta.

[63]  H. Oeschger,et al.  Biospheric CO2 emissions during the past 200 years reconstructed by deconvolution of ice core data , 1987 .

[64]  P. Stenberg,et al.  Photosynthetic Light Capture and Processing from Cell to Canopy , 1995 .

[65]  Ü. Rannik,et al.  A model-based study of carbon fluxes at ten European forest sites , 2003 .

[66]  Corinna Rebmann,et al.  Spruce forests (Norway and Sitka spruce, including Douglas fir): Carbon and water fluxes, Balances, Ecological and ecophysiological determinants , 2003 .

[67]  Paul G. Jarvis,et al.  Scaling processes and problems , 1995 .

[68]  Craig Loehle,et al.  A hypothesis testing framework for evaluating ecosystem model performance , 1997 .

[69]  Ü. Rannik,et al.  Estimates of the annual net carbon and water exchange of forests: the EUROFLUX methodology , 2000 .

[70]  Yuri Knyazikhin,et al.  Small-sclae study of three-dimensional distribution of photosynthetically active radiation in a forest , 1997 .

[71]  James R. Ehleringer,et al.  Quantum Yields for CO2 Uptake in C3 and C4 Plants: Dependence on Temperature, CO2, and O2 Concentration , 1977 .

[72]  John Moncrieff,et al.  The propagation of errors in long‐term measurements of land‐atmosphere fluxes of carbon and water , 1996 .

[73]  Ü. Rannik,et al.  Carbon balance gradient in European forests: should we doubt 'surprising' results? A reply to Piovesan & Adams , 2001 .

[74]  J. Finnigan,et al.  Atmospheric Boundary Layer Flows: Their Structure and Measurement , 1994 .

[75]  Achim Grelle,et al.  Long‐term measurements of boreal forest carbon balance reveal large temperature sensitivity , 1998 .

[76]  John Moncrieff,et al.  Seasonal variation of carbon dioxide, water vapor, and energy exchanges of a boreal black spruce forest , 1997 .

[77]  Antonio Donato Nobre,et al.  Acclimation of photosynthetic capacity to irradiance in tree canopies in relation to leaf nitrogen concentration and leaf mass per unit area , 2002 .

[78]  J. William Munger,et al.  Exchange of Carbon Dioxide by a Deciduous Forest: Response to Interannual Climate Variability , 1996, Science.

[79]  D. Baldocchi,et al.  Spatial and temporal variation in respiration in a young ponderosa pine forest during a summer drought , 2001 .

[80]  R. Clement.  Mass and energy exchange of a plantation forest in Scotland using micrometeorological methods , 2004 .

[81]  A. Friend,et al.  The high‐latitude terrestrial carbon sink: a model analysis , 2000 .

[82]  W. Oechel,et al.  Seasonality of ecosystem respiration and gross primary production as derived from FLUXNET measurements , 2001 .

[83]  M. Wesely,et al.  Variability of Short Term Eddy-Correlation Estimates of Mass Exchange , 1985 .

[84]  B. Medlyn.  Physiological basis of the light use efficiency model. , 1998, Tree physiology.

[85]  N. Coops,et al.  Performance of the forest productivity model 3-PG applied to a wide range of forest types , 2003 .