sampled natural forest, forest plantations, agricultural
fields of agroforestry farms, agricultural
fields
with traditional farming and eroded soil on the slopes of Mount Elgon, Kenya. We hypothesised that
microbial decomposition capacity, biomass and diversity (1) decreases with intensified cultivation; and
(2) can be restored by soil and land management in agroforestry. Functional capacity of soil microbial
communities was estimated by degradation of 31 substrates on Biolog EcoPlatesTM. Microbial community
composition and biomass were characterised by phospholipid fatty acid (PLFA) and microbial C and N
analyses. All 31 substrates were metabolised in all studied soil types, i.e. functional diversity did not
differ. However, both the substrate utilisation rates and the microbial biomass decreased with
intensification of land use, and the biomass was positively correlated with organic matter content.
Multivariate analysis of PLFA and Biolog EcoPlateTM data showed clear differences between land uses,
also indicated by different relative abundance of PLFA markers for certain microorganism groups. In
conclusion, our results show that vegetation and land use control the substrate utilisation capacity and
microbial community composition and that functional capacity of depleted soils can be restored by active
soil management, e.g. forest plantation. However, although 20–30 years of agroforestry farming practises
did result in improved soil microbiological and chemical conditions of agricultural soil as compared to
traditional agricultural
fields, the change was not statistically significant.