Malam Issa O., Trichet J., Défarge C., Couté A., Valentin Christian. (1999). Morphology and microstructure of microbiotic soil crusts on a tiger bush sequence (Niger, Sahel). In :
Valentin Christian (ed.), Poesen J. (ed.). The significance of soil, water and landscape processes in banded vegetation patterning. Catena, 37 (1-2), p. 175-196. ISSN 0341-8162.
Titre du document
Morphology and microstructure of microbiotic soil crusts on a tiger bush sequence (Niger, Sahel)
Année de publication
1999
Auteurs
Malam Issa O., Trichet J., Défarge C., Couté A., Valentin Christian
In
Valentin Christian (ed.), Poesen J. (ed.), The significance of soil, water and landscape processes in banded vegetation patterning
Source
Catena, 1999,
37 (1-2), p. 175-196 ISSN 0341-8162
Microbiotic crusts resulting from the colonization of soil surfaces by communities of microorganisms dominated by cyanobacteria, eucaryotic algae or lichens are widespread in arid and semi-arid regions. In the 'tiger bush' of Niger (Sahel) microbiotic crusts occur in bare bands between densely vegetated bands. The tiger bush soils are sandy loams with pH 4.7-6.5. Three different microbiotic crusts are recognised, forming strips parallel to the vegetation banding. They are all formed mainly by filamentous cyanobacteria dominated by Schizothrix. Other important genera are Scytonema, Lyngbya, Nostoc, and Phormidium. The filamentous microorganisms trap sand particles and finer particles stick on the filament surfaces. These effects enhance coil cohesion and resistance to erosion. Soil porosity is also increased by the microbial cover, with additinal pores delineated by filaments on the surfaces of crusts and porous organic bodies derived from microbial remains at depth. The microbiotic crusts are essential components of the tiger bush ecosystem. Water leaving the lower sides of vegetated bands results inplant decay, and on the upslope sides vegetation grows because of increased water supply. Microbial covers help resist erosion, and increase water and nutrient retention, thus providing substrates for the expansion of plants form adjacent vegetated bands. (Résumé d'auteur)
Plan de classement
Formations végétales [082VEGET02]
Descripteurs
FORMATION VEGETALE ; DYNAMIQUE DE VEGETATION ; SURFACE DU SOL ; CROUTE ; MICROBIOLOGIE DU SOL ; MICROORGANISME ; MICROMORPHOLOGIE ; POROSITE ; ANALYSE PHYSICOCHIMIQUE ; CARACTERISTIQUE HYDRIQUE ; BROUSSE TIGREE
Localisation
Fonds IRD [F A010018923]
Identifiant IRD
fdi:010018927
