Effect of land use system on Arbuscular Mycorrhiza fungi in Maasai Mara ecosystem, Kenya

Abstract

Arbuscular mycorrhiza fungi (AMF) diversity and inoculums potential were assessed in different land use systems (protected and unprotected grassland and woodland, intensified monocropping systems and subsistence farming systems) in dry and wet region of Maasai Mara ecosystems (MME) during dry and wet season (November, 2009 and April, 2010). AMF spore were assessed in field and trap cultures (sorghum) using morphological tools. AMF inoculums potential were assessed using undisturbed soil cores planted with sorghum and cow pea. A total of 15 AMF species, dominated by species belonging to genus Acaulospora and Scutellospora were recorded across the MME. Wet region recorded high spore density and species richness in trap cultures. Human related disturbances caused by overgrazing and deforestation outside protected core altered AMF species composition in grassland, and negatively affected AMF species richness in woodland and grassland in the dry region. Similarly, intensified agriculture declined AMF diversity in dry region, but was unaffected in the wet region. Among different cropping systems, subsistence farming systems had higher AMF diversity and species numbers. This study demonstrates that human disturbances in natural ecosystems and intensified agricultural systems have adverse effects on AMF community especially in regions with semi-arid climatical conditions in Savannah ecosystems.

Composition and spore abundance of arbuscular mycorrhizal fungi in sweet potato producing areas in Uganda

“…The six AMF genera identified in this study were present in all the AEZs and CTs but differences in their spore production were not significant. The AMF genera observed in this study were lower than 12 isolated in Sudan (76), 15 in Ethiopia (24), 15 in Southern China (77), 9 in Ethiopia (73) but higher than the 4 to 5 genera isolated in Kenya (23,28,34) and 4 in Rwanda (78). This may be due to variances in edaphic conditions and the cropping systems of the study sites.…”

“…Similarly, the dominance of Scutellospora and Acaulospora had been reported earlier in Western Kenya (29). Sporulation of genus Acaulospora was high in acidic soils (26,30), increasing their dominance in soils of a pH range of 5.51 to 6.77 (28). Castillo et al (31) reported high sporulation of Acaulospora spp.…”

“…Less frequently cultivated fallow fields always have higher spore abundance than fields under frequent conventional cultivation (23). In the drier areas of the Maasai-Mara Ecosystem in Kenya, maize and wheat monocrops recorded significantly lower AMF diversity, species richness, and spore density in the wet and dry season than the maize-bean intercrops dominated by Scutellospora and Acaulospora species (28). Similarly, the dominance of Scutellospora and Acaulospora had been reported earlier in Western Kenya (29).…”

“…The limited occurrence of Gigaspora spp. In various ecosystems compared to other AMF genera has been confirmed by their low density reported by Schalamuk et al (33) Jefwa et al (34), and Muchane et al (28).…”

“…Most importantly, the soil pH was within a favorable range (5.85-6.64) for fungi and supported sporulation of especially, Glomus, Scutellospora, Entrophospora, and Archaeospora, and negatively affected the sporulation of Acaulospora and Gigaspora. Earlier, Muchane et al (28) reported that AMF were favored by pH 5.51 to 6.67, while Dobo et al (73) reported pH 6.18 to 6.28 to increase AMF sporulation in agricultural soils. However, it was expected that Acaulospora spp.…”