Seasonal leaf dynamics for tropical evergreen forests in a process-based global ecosystem model. De Weirdt, M., Verbeeck, H., Maignan, F., Peylin, P., Poulter, B., Bonal, D., Ciais, P., & Steppe, K. Geoscientific Model Development, 5(5):1091-1108, 2012.
abstract   bibtex   
The influence of seasonal phenology on canopy photosynthesis in tropical\nevergreen forests remains poorly understood, and its representation in\nglobal ecosystem models is highly simplified, typically with no seasonal\nvariation of canopy leaf properties taken into account. Including\nseasonal variation in leaf age and photosynthetic capacity could improve\nthe correspondence of global vegetation model outputs with the wet-dry\nseason CO2 patterns measured at flux tower sites in these forests. We\nintroduced a leaf litterfall dynamics scheme in the global terrestrial\necosystem model ORCHIDEE based on seasonal variations in net primary\nproduction (NPP), resulting in higher leaf turnover in periods of high\nproductivity. The modifications in the leaf litterfall scheme induce\nseasonal variation in leaf age distribution and photosynthetic capacity.\nWe evaluated the results of the modification against seasonal patterns\nof three long-term in-situ leaf litterfall datasets of evergreen\ntropical forests in Panama, French Guiana and Brazil. In addition, we\nevaluated the impact of the model improvements on simulated latent heat\n(LE) and gross primary productivity (GPP) fluxes for the flux tower\nsites Guyaflux (French Guiana) and Tapajos (km 67, Brazil). The results\nshow that the introduced seasonal leaf litterfall corresponds well with\nfield inventory leaf litter data and times with its seasonality.\nAlthough the simulated litterfall improved substantially by the model\nmodifications, the impact on the modelled fluxes remained limited. The\nseasonal pattern of GPP improved clearly for the Guyaflux site, but no\nsignificant improvement was obtained for the Tapajos site. The seasonal\npattern of the modelled latent heat fluxes was hardly changed and\nremained consistent with the observed fluxes. We conclude that we\nintroduced a realistic and generic litterfall dynamics scheme, but that\nother processes need to be improved in the model to achieve better\nsimulations of GPP seasonal patterns for tropical evergreen forests.
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 title = {Seasonal leaf dynamics for tropical evergreen forests in a process-based global ecosystem model},
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 year = {2012},
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 pages = {1091-1108},
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 abstract = {The influence of seasonal phenology on canopy photosynthesis in tropical\nevergreen forests remains poorly understood, and its representation in\nglobal ecosystem models is highly simplified, typically with no seasonal\nvariation of canopy leaf properties taken into account. Including\nseasonal variation in leaf age and photosynthetic capacity could improve\nthe correspondence of global vegetation model outputs with the wet-dry\nseason CO2 patterns measured at flux tower sites in these forests. We\nintroduced a leaf litterfall dynamics scheme in the global terrestrial\necosystem model ORCHIDEE based on seasonal variations in net primary\nproduction (NPP), resulting in higher leaf turnover in periods of high\nproductivity. The modifications in the leaf litterfall scheme induce\nseasonal variation in leaf age distribution and photosynthetic capacity.\nWe evaluated the results of the modification against seasonal patterns\nof three long-term in-situ leaf litterfall datasets of evergreen\ntropical forests in Panama, French Guiana and Brazil. In addition, we\nevaluated the impact of the model improvements on simulated latent heat\n(LE) and gross primary productivity (GPP) fluxes for the flux tower\nsites Guyaflux (French Guiana) and Tapajos (km 67, Brazil). The results\nshow that the introduced seasonal leaf litterfall corresponds well with\nfield inventory leaf litter data and times with its seasonality.\nAlthough the simulated litterfall improved substantially by the model\nmodifications, the impact on the modelled fluxes remained limited. The\nseasonal pattern of GPP improved clearly for the Guyaflux site, but no\nsignificant improvement was obtained for the Tapajos site. The seasonal\npattern of the modelled latent heat fluxes was hardly changed and\nremained consistent with the observed fluxes. We conclude that we\nintroduced a realistic and generic litterfall dynamics scheme, but that\nother processes need to be improved in the model to achieve better\nsimulations of GPP seasonal patterns for tropical evergreen forests.},
 bibtype = {article},
 author = {De Weirdt, M. and Verbeeck, Hans and Maignan, Fabienne and Peylin, P. and Poulter, B. and Bonal, Damien and Ciais, Philippe and Steppe, K.},
 journal = {Geoscientific Model Development},
 number = {5},
 keywords = {FR_GUY,GF_GUY}
}

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