Publications des scientifiques de l'IRD

Bertrand I., Ehrarhdt F., Alavoine G., Joulian C., Malam Issa Oumarou, Valentin Christian. (2014). Regulation of carbon and nitrogen exchange rates in biological soil crusts by intrinsic and land use factors in the Sahel area. Soil Biology and Biochemistry, 72, p. 133-144. ISSN 0038-0717.

Titre du document
Regulation of carbon and nitrogen exchange rates in biological soil crusts by intrinsic and land use factors in the Sahel area
Année de publication
2014
Type de document
Article
Auteurs
Bertrand I., Ehrarhdt F., Alavoine G., Joulian C., Malam Issa Oumarou, Valentin Christian
Source
Soil Biology and Biochemistry, 2014, 72, p. 133-144 ISSN 0038-0717
The occurrence and diversity of biological soil crusts (BSC) a thin soil surface layer composed of phototrophic and heterotrophic microorganisms intimately associated with soil particles, are known as strong indicators of ecosystem health and sensitivity to soil surface disturbances and are key factors in the biochemical cycling of carbon and nitrogen in drylands. However, the impact of land use on C and N budgets related to BSC dynamics is poorly understood and hinders the prediction of changes in soil fertility in response to future land use scenarios. In this study, we examined the C and N exchange rates of BSC sampled along a north-south pluviometric gradient of the Sub-Sahel, which provides evidence of increasing human land pressure, leading to a gradient in fallow duration and trampling intensity. We demonstrate that the net and gross photosynthesis by BSC significantly increases with fallow duration and a reduction of trampling intensity, thus affecting BSC fine particles and relative water content. Conversely, no effect of land use was found on N fixation or mineralisation rates, which are instead regulated by the N availability within the crust. Simple statistical models were derived from the relationships between C exchange rates and BSC intrinsic characteristics related to soil surface disturbances. The proposed statistical models were tested for C gas exchange with independent data obtained from a new BSC dataset sampled in Burkina Faso and Niger. A simple equation using BSC fine particle content as a unique variable was found to explain between 60 and 70% of the gross photosynthesis. Our findings will help in mapping photosynthesis and estimating the contribution of BSC to the carbon budget at a regional scale in the dryland area of the Sahel and to further testing of land use change scenarios.
Plan de classement
Environnement, écologie générale [021ENVECO] ; Pédologie appliquée [068PEDAPP] ; Biochimie des relations sol- microorganismes vivants [074SOLMIC]
Descripteurs
SURFACE DU SOL ; CROUTE ; MICROORGANISME ; DIVERSITE SPECIFIQUE ; CYCLE BIOGEOCHIMIQUE ; CARBONE ; AZOTE ; MINERALISATION ; PHOTOSYNTHESE ; RESPIRATION ; UTILISATION DU SOL ; PRESSION FONCIERE ; JACHERE ; ENGRAIS ORGANIQUE ; TRAVAIL DU SOL
Description Géographique
BURKINA FASO ; NIGER ; SAHEL
Localisation
Fonds IRD [F B010063320]
Identifiant IRD
fdi:010063320
Contact