@article{fdi:010018927, title = {{M}orphology and microstructure of microbiotic soil crusts on a tiger bush sequence ({N}iger, {S}ahel)}, author = {{M}alam {I}ssa, {O}. and {T}richet, {J}. and {D}{\'e}farge, {C}. and {C}out{\'e}, {A}. and {V}alentin, {C}hristian}, editor = {}, language = {{ENG}}, abstract = {{M}icrobiotic 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. {I}n the 'tiger bush' of {N}iger ({S}ahel) microbiotic crusts occur in bare bands between densely vegetated bands. {T}he tiger bush soils are sandy loams with p{H} 4.7-6.5. {T}hree different microbiotic crusts are recognised, forming strips parallel to the vegetation banding. {T}hey are all formed mainly by filamentous cyanobacteria dominated by #{S}chizothrix$. {O}ther important genera are #{S}cytonema$, #{L}yngbya$, #{N}ostoc$, and #{P}hormidium$. {T}he filamentous microorganisms trap sand particles and finer particles stick on the filament surfaces. {T}hese effects enhance coil cohesion and resistance to erosion. {S}oil 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. {T}he microbiotic crusts are essential components of the tiger bush ecosystem. {W}ater leaving the lower sides of vegetated bands results inplant decay, and on the upslope sides vegetation grows because of increased water supply. {M}icrobial covers help resist erosion, and increase water and nutrient retention, thus providing substrates for the expansion of plants form adjacent vegetated bands. ({R}{\'e}sum{\'e} d'auteur)}, keywords = {{FORMATION} {VEGETALE} ; {DYNAMIQUE} {DE} {VEGETATION} ; {SURFACE} {DU} {SOL} ; {CROUTE} ; {MICROBIOLOGIE} {DU} {SOL} ; {MICROORGANISME} ; {MICROMORPHOLOGIE} ; {POROSITE} ; {ANALYSE} {PHYSICOCHIMIQUE} ; {CARACTERISTIQUE} {HYDRIQUE} ; {BROUSSE} {TIGREE}}, booktitle = {{T}he significance of soil, water and landscape processes in banded vegetation patterning}, journal = {{C}atena}, volume = {37}, numero = {1-2}, pages = {175--196}, ISSN = {0341-8162}, year = {1999}, DOI = {10.1016/{S}0341-8162(99)00052-1}, URL = {https://www.documentation.ird.fr/hor/fdi:010018927}, }