Biogeosciences www.biogeosciences.net 1726-4170 1726-4189 7 3 2010 10.5194/bg-7-845-2010 http://www.biogeosciences.net/7/845/2010/ http://www.biogeosciences.net/7/845/2010/bg-7-845-2010.html http://www.biogeosciences.net/7/845/2010/bg-7-845-2010.pdf 845 857 2010-03-03 Modeling the impact of drought on canopy carbon and water fluxes for a subtropical evergreen coniferous plantation in southern China through parameter optimization using an ensemble Kalman filter W. Ju juweimin@nju.edu.cn S. Wang G. Yu Y. Zhou H. Wang International Institute for Earth System Science, Nanjing University, Nanjing, 210093, China Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China School of Geography and Oceanography, Nanjing University, Nanjing, 210093, China Soil and atmospheric water deficits have significant influences on CO₂ and energy exchanges between the atmosphere and terrestrial ecosystems. Model parameterization significantly affects the ability of a model to simulate carbon, water, and energy fluxes. In this study, an ensemble Kalman filter (EnKF) and observations of gross primary productivity (GPP) and latent heat (LE) fluxes were used to optimize model parameters significantly affecting the calculation of these fluxes for a subtropical coniferous plantation in southeastern China. The optimized parameters include the maximum carboxylation rate (<i>Vc</i>_max), the slope in the modified Ball-Berry model (<i>M</i>) and the coefficient determining the sensitivity of stomatal conductance to atmospheric water vapor deficit (<i>D</i>₀). Optimized <i>Vc</i>_max and <i>M</i> showed larger variations than <i>D</i>₀. Seasonal variations of <i>Vc</i>_max and <i>M</i> were more pronounced than the variations between the two years. <i>Vc</i>_max and <i>M</i> were associated with soil water content (SWC). During dry periods, SWC at the 20 cm depth explained 61% and 64% of variations of <i>Vc</i>_max and <i>M</i>, respectively. EnKF parameter optimization improved the simulations of GPP, LE and SH, mainly during dry periods. After parameter optimization using EnKF, the variations of GPP, LE and SH explained by the model increased by 1% to 4% at half-hourly steps and by 3% to 5% at daily time steps. Further efforts are needed to differentiate the real causes of parameter variations and improve the ability of models to describe the change of stomatal conductance with net photosynthesis rate and the sensitivity of photosynthesis capacity to soil water stress under different environmental conditions. Aalto, T., Ciais, P., Chevillard, A., and Moulin, C.: Optimal determination of the parameters controlling biospheric CO₂ fluxes over Europe using eddy covariance fluxes and satellite NDVI measurements, Tellus 56B, 93–104, 2004. Arrian, M. A., Black, T. A., Barr, A. G., Javis, P. G., Massheder, J. M., Versghy, D. L., and Nesic, Z.: Effects of seasonal and interannual climate variability on net ecosystem productivity of boreal deciduous and conifer forests, Can. J. Forest Res., 32, 878–891, 2002. Baldocchi, D. A.: comparative study of mass and energy exchange rates over a closed C₃ (wheat) and an open C₄ (corn) crop: II, CO₂ exchange and water use efficiency, Agr. Forest Meteorol., 67, 291–321, 1994. Barr, A. G., Black, T. A., Hogg, E. H., Griffis, T., Morgenstern, K., Kljun, N., Theede, A., and Nesic, Z.: Climatic controls on the carbon and water budgets of a boreal aspen forest, 1994–2003, Glob. Change Biol., 12, 10–16, 2006. Ball, J. T., Woodrow, I. E., and Berry, J. A.: A model predicting stomatal conductance and its contribution to the control of photosynthesis under different environmental conditions, edited by: Biggins, J., Martinus Nijhoff Publishers, Dordrecht, 221–224, 1987. Carvalhais, N., Reichstein, M., Seixas, J., Collatz, G. J., Pereira, J. S., Berbigier, P, Carrara, A., Granier, A., Montagnani, K., Papale, D., Rambal, S., Sanz, M. J., and Valentini, R.: Implications of the carbon cycle seatdy state assumption for biogeochemical modeling performance and inverse parameter retrival, Global Biogeochem. Cy., 22, GB2007, doi:10.1029/2007GB003033, 2008. Chen, J. M., Liu, J., Cihlar, J., and Goulden, M. L.: Daily canopy photosynthesis model through temporal and spatial scaling for remote sensing applications, Ecol. Model., 124, 99–119, 1999. Ciais, P., Reichstein, M., and Viovy, N.: Europe-wide reduction in primary productivity caused by the heat and drought in 2003, Nature, 437, 529–533, 2005. Dang, Q. L., Margolis, H. A., Coyea, M. R., Sy, M., and Collatz, G. J.: Regulation of branch-level gas exchange of boreal tress: roles of shoot water potential and vapour pressure difference, Tree Physiol., 17, 521–535, 1997. Evenson, G.: The ensemble Kalman filter: theoretical formulation and practical implementation, Ocean Dynam., 53, 343–367, 2003. Farquhar, G. D., Caemmerer, S. V., and Berry, J. A.: A biochemical-model of photosynthetic CO₂ assimilation in leaves of C-3 Species, Planta, 149, 78–90, 1980. Grainer, A., Reichstein, M., Bréda, N., Janssens, I. A., Ealge, E., Ciais, P., Grünwald, T., Aubinet, M., Berbigier, P., Bernhofer, C., Buchmann, N., Facini, O., Grassi, G., Heinesch, B., Ilvesniemi, H., Keronen, P., Knohl, A., Köstner, B., Lagergren, F., Lindroth, A., Longdoz, B., Loustau, D., Mateus, J., Montagnani, L., Nys, C., Moors, E., Papale, D., Peiffer, M., Pilegaard, K., Pita, G., Pumpanen, J., Rambal, S., Rebmann, C., Rodrigues, A., Seufert, G., Tenhunen, J., Vesala, T., Wang, Q.: Evidence for soil water control on carbon and water dynamics in European forests during the extremely dry year 2003, Agr. Forest Meteorol., 143, 123–145, 2007. Grant, R. F., Black, T. A., Gaumont-Guay, D., Klujn, N., Barrr, A. G., Morgentern, K., and Nesic, Z.: Net ecosystem productivity of boreal aspen forests under drought and climate change: Mathematical modelling with Ecosys, Agr. Forest Meteorol., 140, 152–170, 2006a. Grant, R. F., Zhang, Y., Yuan, F., Wang, S., Handson, P. J., Gaumont-Guay, D., Chen, J., Black, T. A., Barr, A., Baldocchi, D. D., and Arain, A.: Modelling water stress effects on CO₂ and energy exchange in temperate and boreal deciduous forests, Ecol. Model., 196, 289–312, 2006b. Gu, F. X., Yu, G. R., Wen, X. F., Tao, B., Li, K. R., and Liu, Y. F.: Drought effects on carbon exchange in a subtropical coniferous plantation in China, J. Plant Ecol.,(in chinese with english abstract), 32(5), 1041–1051, 2008. Hogg, E. H., Saugier, B., Pontailler, J. Y., Black, T. A., Chen, W., Hurdle, P. A., Wu, A.: Response of trembling aspen and hazelnut to vpour pressure deficit in a boreal deciduous forest, Tree Physiol., 20(11), 725–734, 2000. Hollinger, D. Y. and Richardson, A. D.: Uncertainties in eddy covariance measurements and its application to physiological models, Tree Physiol., 25, 873–885, 2005. Huang, M., Ji, J. J., Li, K. R., Liu, Y. F., and Yang, F. T.: The ecosystem carbon accumulation after conversion of grasslands to pine plantations in subtropical red soil of South China, Tellus B, 59, 439–448, 2007. Infante, J. M., Damesin, C., Rambal, S., and Fernandez-Ales, R.: Modelling leaf gas exchange in holm-oak trees in southern Spain, Agr. Forest Meteorol., 95, 203–223, 1999. Ju, W. M., Chen, J. M., Black, T. A., Barr, A. G., Liu, J., Chen, B.: Modelling multi-year coupled carbon and water fluxes in a boreal aspen forest, Agr. Forest Meteorol., 140, 136–151, 2006. Keenan, T., García, R., Friend, A. D., Zaehle, S., Gracia, C., and Sabate, S.: Improved understanding of drought controls on seasonal variation in Mediterranean forest canopy CO₂ and water fluxes through combined in situ measurements and ecosystem modelling, Biogeosciences, 6, 1423–1444, 2009. Kljun, N., Black, T. A., Griffis, T. J., Barr, A. G., Gaumont-Guay, D., Morgentern, K., McCaughey, J. H., and Nesic, Z.: Response of net ecosystem productivity of three boreal forest stands to drought, Ecosystems, 10, 1039–1055, 2005. Lasslop, G., Reichstein, M., Kattge, J., and Papale, D.: Influences of observation errors in eddy flux data on inverse model parameter estimation, Biogeosciences, 5, 1311–1324, 2008. Lawlor, D. W.: The effects of water deficit on photosynthesis, in: Environmental and Pant Metabolism-Flexibility and Acclimation, edited by: Smirnoff, N., Bioscience Scientific Publishers, Oxford, 129–160, 1995. Leuning, R.: A critical appraisal of a coupled stomatal photosynthesis model for C$_3 $ plants, Plant Cell Environ., 18, 339–357, 1995. Liu, M., He, H. L., Yu, G. R., Luo Y. Q., Sun, X. M., and Wang, H. M.: Uncertainty analysis of CO₂ flux components in sub-tropical evergreen coniferous plantation, Science in China D: Earth Science, 52(2), 257–268, 2008. Liu, Y. F., Yu, G. Y., Wen, X. F., Wang, Y. H., Song, X., Li, J., Sun, X. M., Yang, F. T., Chen, Y. R., and Liu, Q. J.: Seasonal dynamics of CO$_2 $ fluxes from subtropical plantation coniferous ecosystem, Science in China Series D: Earth Science, 49 Supp~II, 99–109, 2006. Mo, X. G., Chen, J. M., Ju, W. M., and Black, T. A.: Optimization of ecosystem model parameters through assimilating eddy covariance flux data with an ensemble Kalman filter, Ecol. Model., 217, 157–173, 2008. Moradkhani, H., Sorooshian, S., Gupta, H. V., and Houser, P. R.: Dual-state-parameter estimation of hydrological models using ensemble Kalman filter, Adv. Water Res., 28, 135–147, 2005. Owen, K. E., Tenhunen, J., Reichstein, M., Wang, Q., Falge, E., Geyer, R., Xiao, X., Story, P., Ammann, C., Arain, A., Aubinet, M., Aurela, M., Bernhofer, C.: Lining flux network measurements to continental scale simulations: ecosystem carbon dioxide exchange capacity under non-water-stressed conditions, Glob. Change Biol., 13, 1–27, 2007. Parton, W. J., Scurlock, J. M. O., Ojima, D. S., Gilmanov, T. G., Scholes, R. J., Schimel, D. S., Kirchner, T., Menaut, J. C., Seastedt, T., Moya, E. G., Kamnalrut, A., and Kinyamario, J. I.: Observations and modeling of biomass and soil organic-matter dynamics for the grassland biome worldwide, Global Biogeochem. Cy., 7, 785–809, 1993. Rambal, S., Ourcival, J. M., Joffre, R., Mouillot, F., Nouvellon, Y., Reichstein, M., and Rocheteau, A.: Drought controls over conductance and assimilation of a Mediterranean evergreen ecosystem: scaling from leaf to canopy, Glob. Change Biol., 9, 1813–1824, 2003. Reichestein, M., Tenhumen, J., Roupsard, O., Ourcival, J. M., Rambal, S., Miglietta, F., Peressotti, A., Pecchiari, M., Tirone, G., and Valentini, R.: Inverse modeling of seasonal drought effects on canopy CO₂/H₂0 exchange in three Mediterranean ecosystems, J. Geophys. Res., 108, D23, 4726, doi:10.1209/2003JD003430, 2003. Reichstein, M., Tenhunen, J. D., Roupsard, O., Ourcival, J. M., Rambal, S., Miglietta, F., Peressotti, A., Pecchiari, M., Tirone, G., and Valentini, R.: Severe drought effects on ecosystem CO₂ and H₂O fluxes at three Mediterranean evergreen sites: revision of current hypotheses?, Glob. Change Biol., 8, 999–1017, 2002. Richardson, A. D., Mahecha M. D., Falge E., Kattge, J., Moffat, A. M., Papale, D. Reichstein, M., Stauch, V. J., Braswell, B. H, Churkina, G., Kruuft, B., and Hollinger, D. Y.: Statistical properties of random CO2 flux measurement uncertainties inferred from model residuals, Agr. Forest Meteorol., 148, 38–50, 2008. Rodrigues-Iturbe, I., Ecohydrology: a hydrologic perspective of climate-soil-vegetaion dynamics, Water Resour. Res., 36, 3–9, 2000. Santaren, D., Peylin, P., Viovs, N., and Ciais, P.: Optimize a process-based ecosystem model with eddy-covariance flux measurement: a pine forest in southern France, Glob. Biogeochem. Cy., 21, GB2013, doi:10.1029/2006GB002834, 2007. Sala, A. M. and Tenhunen, I. D.: Simulations of canopy net photosynthesis and transpiration in Quercus ilex L under the seasonal drought, Agr. Forest Meteorol., 78, 203–222, 1996. Song, X., Yu, G. R., Liu, Y. F., Sun, X. M., Lin, Y. M., and Wen, X. F.: Seasonal variations and environmental control of water use efficiency in subtropical plantation, Science in China Series D, 49, Supp II, 119–126, 2006. Sun, X., Wen, X. F., Yu, G. R., Liu, Y. F., and Liu, Q. J.: Seasonal drought effects on carbon sequestration of a mid-subtropical planted forest of southeastern China, Science in China Series D: Earth Science, 49 Supp II 110–118, 2006. Tuzet, A., Perrier, A., and Leuning, R.: A coupled model of stomatal conductance, photosynthesis and transpiration, Plant Cell Environ, 26, 1097–1116, 2003. Wang, Y. P. and Leuning, R.: A two-leaf model for canopy conductance, photosynthesis and partitioning of available energy I: Model description and comparison with a multi-layered model, Agr. Forest Meteorol., 91, 89–111, 1998. Wang, Y. P., Baldocchi, D., Leuning, R., Falge, E., and Vesal, T.: Estimating parameters in a land-surface model by applying nonlinear inversion to eddy covariance flux measurements from eight FLUXNET sites, Glob. Change Biol., 13, 652–670, doi:10.1111/j.1365-2486.2006.01225.x, 2007. Wen, X. F., Yu, G. R., Sun, X. M., Li, Q. K., Liu, Y. F., Zhang, L. M., Ren, C. Y., Fu, Y. L. and Li, Z. Q.: Soil moisture effect on the temperature dependence of ecosystem respiration in a subtropical Pinus plantation of southeastern China, Agr. Forest Meteorol., 137, 166–175, 2006. Wilson, K. B., Baldochii, D. D., and Hanson, P. J.: Spatial and seasonal variability of photosynthetic parameters and their relationship to leaf nitrogen in a deciduous forest, Tree Physiol., 20, 565–578, 2000. Wolf, A., Akshalov, K., Saliendra, N., Johnson, D. A., and Laca, E. A.: Inverse estimation of Vcmax, leaf area index, and the Ball-Berry parameter from carbon and energy fluxes, J. Geophys. Res., 111, D08S08, doi:10.1029/2005JD005927, 2006. Yu, G. R., Fu, Y. L., Sun, X. M., Wen, X. F., and Zhang, L. M.: Recent progress and future directions of ChinaFlux, Science in China Series D, 49, Supp~II, 1–23, 2006. Zierl, B.: A water balance model to simulate drough in forested ecossyetm and its application to entire forested area in Switerland, J. Hydrol., 242, 115–136, 2001.