Ecophysiological modeling of the climate imprint on photosynthesis and carbon allocation to the tree stem in the North American boreal forest

Gennaretti, Fabio; Gea‐Izquierdo, Guillermo; Boucher, Étienne; Berninger, Frank; Arseneault, Dominique; Guiot, Joël

doi:10.5194/bg-2017-51

Cited by 5 publications

(27 citation statements)

References 40 publications

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“…5). These climate-growth relationships have previously been reported for the Canadian boreal forest (e.g., Drobyshev et al 2010;Walker and Johnstone 2014;Girardin et al 2016;Gennaretti et al 2017). High summer temperatures in the previous growing season can restrict carbon reserve accumulation, which shapes early wood development the next growing season (Fritts 1976;Skomarkova et al 2006;Campioli et al 2011).…”

Section: A Shift In Tree Response To Climate In the 1980ssupporting

confidence: 72%

Paludification reduces black spruce growth rate but does not alter ecophysiological mechanisms in Canadian boreal forested peatlands

Beaulne

Boucher

Garneau

et al. 2020

Preprint

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Background Paludification is widespread in the boreal biome, inducing tree growth decline in forested peatlands following the development of thick organic layers over the mineral soil. However, the ecophysiological processes involved remain poorly documented and little is known about the interactions between tree growth mechanisms and site conditions in these ecosystems. We investigated changes in stem growth and main ecophysiological processes in a black spruce forested peatland in eastern Canada by combining peat-based and tree-ring stable isotope analyses. These were conducted at three sampling sites located along a paludification gradient with different peat thicknesses.Results Organic layer thickening induces black spruce growth decline without altering tree ecophysiological mechanisms. A 40% increase in water use efficiency, or the ratio of carbon assimilated to water losses, was observed at the three sites from 1920 to the 1980s, but did not translate into enhanced tree growth. A clear shift in the 1980s revealed a decline in black spruce sensitivity to climate and rising atmospheric CO2 concentration, regardless of the organic layer thickness. Water table reconstructions revealed an important drawdown in the last few decades at the three sites, but we found no evidence of an influence of water table variations on stem growth.Conclusions This study shows that paludification induces black spruce growth decline without altering tree metabolism in boreal forested peatlands. This underlines that changes in water use efficiency are decoupled from changes in carbon allocation, which are constrained by site, or even tree-specific strategies to access water and nutrients from belowground. Our findings indicate that dynamic changes in edaphic conditions need to be considered in process models. Otherwise, failing to account for the degree of paludification can lead to misleading forest productivity predictions and result in considerable overestimations of aboveground carbon stocks from trees in the boreal regions.

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Section: A Shift In Tree Response To Climate In the 1980ssupporting

confidence: 72%

Paludification reduces black spruce growth rate but does not alter ecophysiological mechanisms in Canadian boreal forested peatlands

Beaulne

Boucher

Garneau

et al. 2020

Preprint

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“…Up to now, MAIDEN has been applied in the Mediterranean (Gea-Izquierdo et al, 2015) and temperate regions (Misson, 2004;Boucher et al, 2014), in the Eastern Canadian taiga (Gennaretti et al, 2017) and in Argentina (Lavergne et al, 2017). Currently, there are two versions of the model from Gea-Izquierdo et al (2015), developed for the Mediterranean forests, and Gennaretti et al (2017) for boreal tree species. A unified version from those two versions has also been developed by Fabio Gennaretti (unpublished).…”

Section: The Maiden Modelmentioning

confidence: 99%

“…In this study, all tests have been conducted using the unified version of MAIDEN. This unified version gives the opportunity to choose between the version from Gennaretti et al (2017) and from Gea-Izquierdo et al (2015) and, if needed, to test equations from both versions to evaluate their impact. However, here, only the version from Gennaretti et al (2017) is used as it is the most adapted to the selected sites.…”

Section: The Maiden Modelmentioning

confidence: 99%

“…Dstem is assumed to be proportional to tree-ring growth so that we can build simulated tree-ring index time series and compare it with tree-ring width (hereafter TRW) observations (Sect. 2.3.1) (Gea-Izquierdo et al, 2015;Gennaretti et al, 2017).…”

Section: The Maiden Modelmentioning

confidence: 99%

“…From this network, we have only selected sites from Nicault et al (2014) and Boucher et al (2017) ending at least in 2000, with an expressed population signal (defined as the amount of variance of a population chronology infinitely replicated explained by a finite subsample; Buras, 2017) equal to or above 0.8 and replication equal to or above 15. We have also kept the site from Gennaretti et al (2017) as a control site. At the end of the selection process, we get twenty-one sites (Fig.…”

Section: Study Sitesmentioning

confidence: 99%

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Application and evaluation of the dendroclimatic process-based model MAIDEN during the last century in Canada and Europe

Rezsöhazy¹,

Goosse²,

Guiot³

et al. 2019

Preprint

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Abstract. Tree-ring archives are one of the main sources of information to reconstruct climate variations over the last millennium with annual resolution. The links between tree-ring proxies and climate have usually been estimated using statistical approaches, assuming linear and stationary relationships. Both assumptions may be inadequate but this issue can be overcome by ecophysiological modelling based on mechanistic understanding. In this respect, the model MAIDEN (Modeling and Analysis In DENdroecology) simulating tree ring growth from daily temperature and precipitation, considering carbon assimilation and allocation in forest stands, may constitute a valuable tool. However, the lack of local meteorological data and the limited characterisation of tree species traits can complicate the calibration and validation of such complex model, which may hamper paleoclimate applications. The goal of this study is to test the applicability of the MAIDEN model in a paleoclimate context using as a test case tree ring observations covering the twentieth century from twenty-one Eastern Canadian taiga sites and three European sites. More specifically, we investigate the model sensitivity to parameters calibration and to the quality of climatic inputs and evaluate the model performance using a validation procedure. We also examine the added value of using MAIDEN in paleoclimate applications compared to a simpler tree-growth model, VS-Lite. A bayesian calibration of the most sensitive model parameters provides good results at most of the selected sites with high correlations between simulated and observed tree-growth. Although MAIDEN is found to be sensitive to the quality of the climatic inputs, simple bias-correction and downscaling techniques of these data improve significantly the performance of the model. The split-sample validation of MAIDEN gives encouraging results but requires long tree-ring and meteorological series to give robust results. We also highlight a risk of overfitting in the calibration of model parameters that increases with short series. Finally, MAIDEN has shown higher calibration and validation correlations in most cases compared to VS-Lite. Nevertheless, this latter model turns out to be more stable over calibration and validation periods. Our results provide a protocol for the application of MAIDEN to potentially any site with tree-ring width data in the extratropical region.

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Testing the performance of dendroclimatic process-based models at global scale with the PAGES2k tree-ring width database

et al. 2021

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Tree-rings are one of the most commonly used proxies for reconstructing past climates at annual resolution. The climate information is generally deduced from tree-rings using statistical relationships, but the assumed linearity and stationarity may be inadequate. Process-based models allow for non-stationarity and non-linearity; however, many challenges are associated with their application for global scale reconstructions. In this study, we aim to test the feasibility of using the mechanistic model MAIDEN at the global scale for paleoclimate data assimilation based reconstructions by applying it to the PAGES2k tree-ring width database. We also compare its performance with the simpler model VS-Lite, often used in global applications. Both models are skillful in terms of calibration and verification correlations for a similar number of sites (63 and 64 for VS-Lite and MAIDEN, respectively). VS-Lite tends to perform better for sites where the climate signal in tree-rings is strong and clear.

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Ecophysiological modeling of the climate imprint on photosynthesis and carbon allocation to the tree stem in the North American boreal forest

Cited by 5 publications

References 40 publications

Paludification reduces black spruce growth rate but does not alter ecophysiological mechanisms in Canadian boreal forested peatlands

Paludification reduces black spruce growth rate but does not alter ecophysiological mechanisms in Canadian boreal forested peatlands

Application and evaluation of the dendroclimatic process-based model MAIDEN during the last century in Canada and Europe

Testing the performance of dendroclimatic process-based models at global scale with the PAGES2k tree-ring width database

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