The African contribution to the global climate-carbon cycle feedback of the 21st century

Friedlingstein, Pierre; Cadule, Patricia; Piao, S. L.; Ciais, Philippe; Sitch, S.

doi:10.5194/bg-7-513-2010

Cited by 11 publications

(9 citation statements)

References 25 publications

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“…As previously mentioned, the African vegetation contributes 38% of the global climate-carbon cycle feedback, mostly coming from its savanna comprised mainly of woodlands (Friedlingstein et al, 2010).…”

Section: Relationships Between Lsp and Rainfall Parametersmentioning

confidence: 94%

Large‐scale prerain vegetation green‐up across Africa

Adole

Dash

Atkinson

2018

Global Change Biology

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Information on the response of vegetation to different environmental drivers, including rainfall, forms a critical input to ecosystem models. Currently, such models are run based on parameters that, in some cases, are either assumed or lack supporting evidence (e.g., that vegetation growth across Africa is rainfall-driven). A limited number of studies have reported that the onset of rain across Africa does not fully explain the onset of vegetation growth, for example, drawing on the observation of prerain flush effects in some parts of Africa. The spatial extent of this prerain green-up effect, however, remains unknown, leaving a large gap in our understanding that may bias ecosystem modelling. This paper provides the most comprehensive spatial assessment to-date of the magnitude and frequency of the different patterns of phenology response to rainfall across Africa and for different vegetation types. To define the relations between phenology and rainfall, we investigated the spatial variation in the difference, in number of days, between the start of rainy season (SRS) and start of vegetation growing season (SOS); and between the end of rainy season (ERS) and end of vegetation growing season (EOS). We reveal a much more extensive spread of prerain green-up over Africa than previously reported, with prerain green-up being the norm rather than the exception. We also show the relative sparsity of postrain green-up, confined largely to the Sudano-Sahel region. While the prerain green-up phenomenon is well documented, its large spatial extent was not anticipated. Our results, thus, contrast with the widely held view that rainfall drives the onset and end of the vegetation growing season across Africa. Our findings point to a much more nuanced role of rainfall in Africa's vegetation growth cycle than previously thought, specifically as one of a set of several drivers, with important implications for ecosystem modelling.

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Section: Relationships Between Lsp and Rainfall Parametersmentioning

confidence: 94%

Large‐scale prerain vegetation green‐up across Africa

Adole

Dash

Atkinson

2018

Global Change Biology

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“…We suggest that the observed decreasing trend in the contribution of R SOC to T SOC pool with increasing precipitation was mainly the result of more frequent fire events characteristic of savanna ecosystems. Global coupled climate carbon cycle model simulations predict net losses in SOC stocks in West Africa as a result of increased heterotrophic soil respiration and reduced precipitation (Friedlingstein et al, 2010). These models have identified that SOC losses will be more significant in humid coastal regions, while SOC pools will show lower susceptibility in more arid regions.…”

Section: Significance Of the Findings For Soil Carbon Studies In Tropmentioning

confidence: 99%

Variation in soil carbon stocks and their determinants across a precipitation gradient in West Africa

Saiz

Bird

Domingues

et al. 2012

Global Change Biology

125

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We examine the influence of climate, soil properties and vegetation characteristics on soil organic carbon (SOC) along a transect of West African ecosystems sampled across a precipitation gradient on contrasting soil types stretching from Ghana (15°N) to Mali (7°N). Our findings derive from a total of 1108 soil cores sampled over 14 permanent plots. The observed pattern in SOC stocks reflects the very different climatic conditions and contrasting soil properties existing along the latitudinal transect. The combined effects of these factors strongly influence vegetation structure. SOC stocks in the first 2 m of soil ranged from 20 Mg C ha À1 for a Sahelian savanna in Mali to over 120 Mg C ha À1 for a transitional forest in Ghana. The degree of interdependence between soil bulk density (SBD) and soil properties is highlighted by the strong negative relationships observed between SBD and SOC (r 2 > 0.84). A simple predictive function capable of encompassing the effect of climate, soil properties and vegetation type on SOC stocks showed that available water and sand content taken together could explain 0.84 and 0.86 of the total variability in SOC stocks observed to 0.3 and 1.0 m depth respectively. Used in combination with a suitable climatic parameter, sand content is a good predictor of SOC stored in highly weathered dry tropical ecosystems with arguably less confounding effects than provided by clay content. There was an increased contribution of resistant SOC to the total SOC pool for lower rainfall soils, this likely being the result of more frequent fire events in the grassier savannas of the more arid regions. This work provides new insights into the mechanisms determining the distribution of carbon storage in tropical soils and should contribute significantly to the development of robust predictive models of biogeochemical cycling and vegetation dynamics in tropical regions.

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“…Modeling studies suggest large differences in different approaches used to obtain estimates of global GPP (Anav et al 2013), largely controlled by seasonal, decadal and longer time variability and change in different regions, globally (Ahlström et al 2015). Many studies have estimated GPP in key regions of the world: for example, Lee et al (2013) estimated GPP in Amazonia using Greenhouse gases Observing SATellite (GOSAT) measurements; Liu et al (2014) estimated GPP in China using five GPP models and Moderate Resolution Imaging Spectroradiometer (MODIS) observations; Jung et al (2008) estimated GPP in Europe (EU) using terrestrial ecosystem models; Nightingale et al (2008) and Chen et al (2011) estimated GPP in the USA using MODIS observations; and Friedlingstein et al (2010) estimated GPP in the Sahel region of Africa using ORCHIDEE model. In spite of this large body of research, there is limited information on the relative contributions of these regions to the seasonal, inter-annual and longer time variability of total global GPP.…”

Section: Introductionmentioning

confidence: 99%

Regional contribution to variability and trends of global gross primary productivity

Chen

Rafique

Asrar

et al. 2017

Environ. Res. Lett.

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Terrestrial gross primary productivity (GPP) is the largest component of the global carbon cycle and a key process for understanding land ecosystems dynamics. In this study, we used GPP estimates from a combination of eight global biome models participating in the Inter-Sectoral Impact-Model Intercomparison Project phase 2a (ISIMIP2a), the Moderate Resolution Spectroradiometer (MODIS) GPP product, and a data-driven product (Model Tree Ensemble, MTE) to study the spatiotemporal variability of GPP at the regional and global levels. We found the 2000-2010 total global GPP estimated from the model ensemble to be 117 ± 13 Pg C yr −1 (mean ± 1 standard deviation), which was higher than MODIS (112 Pg C yr −1 ), and close to the MTE (120 Pg C yr −1 ). The spatial patterns of MODIS, MTE and ISIMIP2a GPP generally agree well, but their temporal trends are different, and the seasonality and inter-annual variability of GPP at the regional and global levels are not completely consistent. For the model ensemble, Tropical Latin America contributes the most to global GPP, Asian regions contribute the most to the global GPP trend, the Northern Hemisphere regions dominate the global GPP seasonal variations, and Oceania is likely the largest contributor to inter-annual variability of global GPP. However, we observed large uncertainties across the eight ISIMIP2a models, which are probably due to the differences in the formulation of underlying photosynthetic processes. The results of this study are useful in understanding the contributions of different regions to global GPP and its spatiotemporal variability, how the model-and observational-based GPP estimates differ from each other in time and space, and the relative strength of the eight models. Our results also highlight the models' ability to capture the seasonality of GPP that are essential for understanding the inter-annual and seasonal variability of GPP as a major component of the carbon cycle.

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The African contribution to the global climate-carbon cycle feedback of the 21st century

Cited by 11 publications

References 25 publications

Large‐scale prerain vegetation green‐up across Africa

Large‐scale prerain vegetation green‐up across Africa

Variation in soil carbon stocks and their determinants across a precipitation gradient in West Africa

Regional contribution to variability and trends of global gross primary productivity

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