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The Abundance and Diversity of Legume-Nodulating Rhizobia in 28-Year-Old Plantations of Tropical, Subtropical, and Exotic Tree Species: a Case Study from the Forest Reserve of Bandia, Senegal.

Several fast-growing and multipurpose tree species have been widely used in West Africa to both reverse the tendency of land degradation and restore soil productivity. Although beneficial effects have been reported on soil stabili- zation, there still remains a lack of information about their impact on soil microorganisms. Our investigation has been carried out in exotic and native tree plantations of 28 years and aimed to survey and compare the abundance and genetic diversity of natural legume-nodulating rhizobia (LNR). The study of LNR is supported by the phylogenetic analysis which clustered the isolates into three genera: Bradyrhizobium, Mes- orhizobium, and Sinorhizobium. The results showed close positive correlations between the sizes of LNR populations estimated both in the dry and rainy seasons and the presence of legume tree hosts. There were significant increases in Rhi- zobium spp. population densities in response to planting with Acacia spp., and high genetic diversities and richness of geno- types were fittest in these tree plantations. This suggests that enrichment of soil Rhizobium spp. populations is host specific. Theresults indicated alsothatspeciesofgenera Mesorhizobium and Sinorhizobium were lacking in plantations of non-host species. By contrast, there was a widespread distribution of Bradyrhizobium spp. strains across the tree plantations, with no evident specialization in regard to plantation type. Finally, the study provides information about the LNR communities asso- ciated with a range of old tree plantations and some aspects of their relationships to soil factors, which may facilitate the management of man-made forest systems that target ecosystem rehabilitation and preservation of soil biota.


Auteur(s) : 8. SENE G, THIAO M., SAMBA-MBAYE R., KHASA D., KANE A., MBAYE M.S., BEAULIEU M.E., MANGA A. & SYLLA S.N
Pages : 128-144
Année de publication : 2013
Revue : Microbial Ecology
N° de volume : Volume 65 Number 1
Type : Article
Mise en ligne par : MBAYE Mame Samba