Aim The controls of gross radiation use efficiency (RUE), the ratio between gross primary productivity (GPP) and the radiation intercepted by terrestrial vegetation, and its spatial and temporal variation are not yet fully understood. Our objectives were to analyse and synthesize the spatial variability of GPP and the spatial and temporal variability of RUE and its climatic controls for a wide range of vegetation types.

/pdf/patterns-and-controls-of-the-variability-of-radiation-use-21jaykko3f.pdf

Patterns and controls of the variability of radiation use efficiency and primary productivity across terrestrial ecosystems

This paper, developed under the framework of the RECCAP initiative, aims at providing improved estimates of the carbon and GHG (CO2, CH4 and N2O) balance of con- tinental Africa. The various components and processes of the African carbon and GHG budget are considered, exist- ing data reviewed, and new data from different methodolo- gies (inventories, ecosystem flux measurements, models, and atmospheric inversions) presented. Uncertainties are quanti- fied and current gaps and weaknesses in knowledge and mon- itoring systems described in order to guide future require- ments. The majority of results agree that Africa is a small sink of carbon on an annual scale, with an average value of

/pdf/a-full-greenhouse-gases-budget-of-africa-synthesis-jhp3uq6d13.pdf

A full greenhouse gases budget of Africa: synthesis, uncertainties, and vulnerabilities

http://max2.ese.u-psud.fr/publications/KSoudaniNDVIRSE2012.pdf

Ground-based Network of NDVI measurements for tracking temporal dynamics of canopy structure and vegetation phenology in different biomes

Evaluation of MODIS gross primary productivity for Africa using eddy covariance data

Exploring the potential of MODIS EVI for modeling gross primary production across African ecosystems

. This study reports carbon and water fluxes between the land surface and atmosphere in eleven different ecosystems types in Sub-Saharan Africa, as measured using eddy covariance (EC) technology in the first two years of the CarboAfrica network operation. The ecosystems for which data were available ranged in mean annual rainfall from 320 mm (Sudan) to 1150 mm (Republic of Congo) and include a spectrum of vegetation types (or land cover) (open savannas, woodlands, croplands and grasslands). Given the shortness of the record, the EC data were analysed across the network rather than longitudinally at sites, in order to understand the driving factors for ecosystem respiration and carbon assimilation, and to reveal the different water use strategies in these highly seasonal environments. Values for maximum net carbon assimilation rates (photosynthesis) ranged from −12.5 μmol CO2 m−2 s−1 in a dry, open Millet cropland (C4-plants) up to −48 μmol CO2 m−2 s−1 for a tropical moist grassland. Maximum carbon assimilation rates were highly correlated with mean annual rainfall (r2=0.74). Maximum photosynthetic uptake rates (Fpmax) were positively related to satellite-derived fAPAR. Ecosystem respiration was dependent on temperature at all sites, and was additionally dependent on soil water content at sites receiving less than 1000 mm of rain per year. All included ecosystems dominated by C3-plants, showed a strong decrease in 30-min assimilation rates with increasing water vapour pressure deficit above 2.0 kPa.

https://horizon.documentation.ird.fr/exl-doc/pleins_textes/divers17-09/010046216.pdf

M. Muchinda

Papers

Precipitation as driver of carbon fluxes in 11 African ecosystems