Competing roles of rising CO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; and climate change in the contemporary European carbon balance

Harrison, Giles; Jones, Chris D.; Hughes, John

doi:10.5194/bg-5-1-2008

Cited by 32 publications

(17 citation statements)

References 51 publications

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“…Understanding and quantifying biogeochemical feedbacks that may modify the CO 2 -fertilisation effect in terrestrial ecosystems are key steps in understanding and predicting the future sink strength of the biosphere and thus atmospheric CO 2 concentration (Thompson et al 2004;Harrison et al 2008) and in assessing the impact of global change on managed (e.g. Kimball et al 2002) and natural ecosystems (Nowak et al 2004).…”

Section: Introductionmentioning

confidence: 99%

The rate of progression and stability of progressive nitrogen limitation at elevated atmospheric CO2 in a grazed grassland over 11 years of Free Air CO2 enrichment

et al. 2010

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A decline in the availability of nitrogen (N) for plant growth (progressive nitrogen limitation or PNL) is a feedback that could constrain terrestrial ecosystem responses to elevated atmospheric CO 2 . Several long-term CO 2 enrichment experiments have measured changes in plant and soil pools and fluxes consistent with PNL but evidence for PNL in grasslands is limited. In an 11 year Free Air CO 2 Enrichment (FACE) experiment on grazed grassland we found the amount of N harvested in aboveground plant biomass was greater at elevated CO 2 but declined over time to be indistinguishable from ambient after 5 years. Re-wetting after a major drought resulted in a large input of N from mineralisation and a return to a higher N harvested under elevated CO 2 followed by a further decline. Over these two periods the amount of N in soil significantly increased at elevated CO 2 . Data from mesocosms introduced into the rings at intervals, and therefore having different lengths of exposure to CO 2 , showed plant N availability declined at elevated CO 2 reaching a new equilibrium after 6 years of exposure. We conclude that the availability of N for plants in this grassland is dynamic but the underlying trend at elevated CO 2 is for PNL.

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Section: Introductionmentioning

confidence: 99%

The rate of progression and stability of progressive nitrogen limitation at elevated atmospheric CO2 in a grazed grassland over 11 years of Free Air CO2 enrichment

et al. 2010

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“…They do not account, however, for changes in environmental factors, and they only simulate aboveground biomass and need to be complemented by soil models, soil data and/or biomass expansion factors (BEF) to produce complete carbon budgets. • Process models such as ORCHIDEE, JULES, LPJ, BIOME-BGC or EuroBiota (Milne & Van Oijen, 2005;Zaehle et al, 2006Zaehle et al, , 2007Harrison et al, 2008;Luyssaert et al, 2010) rely on a set of equations describing eco-physiological processes such as photosynthesis, respiration and transpiration. As opposed to empirical models, process models are arguably more realistic for long simulations during which climate and [CO 2 ] change, because they explicitly account for the complex effect of these forcing variables on ecosystems, and their interactions.…”

Section: Introductionmentioning

confidence: 99%

Reconstruction and attribution of the carbon sink of European forests between 1950 and 2000

et al. 2011

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European forests are an important carbon sink; however, the relative contributions to this sink of climate, atmospheric CO2 concentration ([CO2]), nitrogen deposition and forest management are under debate. We attributed the European carbon sink in forests using ORCHIDEE-FM, a process-based vegetation model that differs from earlier versions of ORCHIDEE by its explicit representation of stand growth and idealized forest management. The model was applied on a grid across Europe to simulate changes in the net ecosystem productivity (NEP) of forests with and without changes in climate, [CO2] and age structure, the three drivers represented in ORCHIDEE-FM. The model simulates carbon stocks and volume increment that are comparable - root mean square error of 2 m3 ha_1 yr_1 and 1.7 kg C m_2 respectively - with inventory-derived estimates at country level for 20 European countries. Our simulations estimate a mean European forest NEP of 175 ± 52 g C m_2 yr_1 in the 1990s. The model simulation that is most consistent with inventory records provides an upwards trend of forest NEP of 1 ± 0.5 g C m_2 yr_2 between 1950 and 2000 across the EU 25. Furthermore, the method used for reconstructing past age structure was found to dominate its contribution to temporal trends in NEP. The potentially large fertilizing effect of nitrogen deposition cannot be told apart, as the model does not explicitly simulate the nitrogen cycle. Among the three drivers that were considered in this study, the fertilizing effect of increasing [CO2] explains about 61% of the simulated trend, against 26% to changes in climate and 13% only to changes in forest age structure. The major role of [CO2] at the continental scale is due to its homogeneous impact on net primary productivity (NPP). At the local scale, however, changes in climate and forest age structure often dominate trends in NEP by affecting NPP and heterotrophic respiration. (Résumé d'auteur

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“…Estimating C stocks and changes, especially at finer spatial scales, requires the use of refined estimates of D b , which can be obtained using the types of landscape-scale models described in this paper. It is at these scales that many spatially distributed land-atmosphere interaction models such as JULES operate (Harrison et al, 2008).…”

Section: Stock Estimationmentioning

confidence: 99%

“…Dawson and Smith (2007) suggest that much of the error associated with carbon stock inventory in soils can be traced back to uncertainties in D b estimates, prompting further investigation into the methods for deriving these estimates. Furthermore, soil carbon content plays a crucial role in spatially distributed, integrated land-atmosphere process models such as JULES (Harrison et al, 2008). There is evidence that improvements to the soil C component in these types of models increases their response sensitivity to changes in soil stocks and processes.…”

Section: Introductionmentioning

confidence: 99%

Modelling soil bulk density at the landscape scale and its contributions to C stock uncertainty

et al. 2013

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Soil bulk density (D_b) is a major contributor to uncertainties in landscape-scale carbon and nutrient stock estimation. However, it is time consuming to measure and is, therefore, frequently predicted using surrogate variables, such as soil texture. Using this approach is of limited value for estimating landscape-scale inventories, as its accuracy beyond the sampling point at which texture is measured becomes highly uncertain. In this paper, we explore the ability of soil landscape models to predict soil D_b using a suite of landscape attributes and derivatives for both topsoil and subsoil. The models were constructed using random forests and artificial neural networks.

Using these statistical methods, we have produced a spatially distributed prediction of D_b on a 100 m × 100 m grid, which was shown to significantly improve topsoil carbon stock estimation. In comparison to using mean values from point measurements, stratified by soil class, we found that the gridded method predicted D_b more accurately, especially for higher and lower values within the range. Within our study area of the Midlands, UK, we found that the gridded prediction of D_b produced a stock inventory of over 1 million tonnes of carbon greater than the stratified mean method. Furthermore, the 95% confidence interval associated with total C stock prediction was almost halved by using the gridded method. The gridded approach was particularly useful in improving organic carbon (OC) stock estimation for fine-scale landscape units at which many landscape–atmosphere interaction models operate

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Competing roles of rising CO<sub>2</sub> and climate change in the contemporary European carbon balance

Cited by 32 publications

References 51 publications

The rate of progression and stability of progressive nitrogen limitation at elevated atmospheric CO2 in a grazed grassland over 11 years of Free Air CO2 enrichment

The rate of progression and stability of progressive nitrogen limitation at elevated atmospheric CO2 in a grazed grassland over 11 years of Free Air CO2 enrichment

Reconstruction and attribution of the carbon sink of European forests between 1950 and 2000

Modelling soil bulk density at the landscape scale and its contributions to C stock uncertainty

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