Effects of soil physical and chemical parameters, and farm management practices on arbuscular mycorrhizal fungi communities and diversities in coffee plantations in Colombia and Mexico

Arbuscular mycorrhizal fungi (AMF) are essential for growth of coffee plants in acidic and phosphate deficient soils in Central and South America. We investigated the species richness of Glomeromycotean fungi in 9-13 years old coffee plantations in Colombia and Mexico. Fungal species richness was related to physical and chemical soil factors, soil aggregate stability, and farm management practices. Using morphological spore characteristics 85 AMF species were found. AMF species similarity within the plantations was 62-73 %, and the most regularly AMF species found in both countries were: Acaulospora mellea, Acaulospora spinosa, Ambispora fennica, Diversispora aurantia, Dominikia aurea, Glomus brohultii, Rhizoglomus clarum and Rhizoglomus intraradices. In both countries species richness was differently influenced by agronomic management intensity and soil parameter. In Colombia, where soils were more fertile with higher organic matter and soil pH than in Mexico, soil parameter explained the variations in species diversity, while in Mexico, agronomic management intensities explained the variations in species richness among sites. Soil aggregate stability slightly explains the AMF species richness in Colombia and Mexico. It can be concluded that the Glomeromycotean species richness is very high in older coffee plantations in Colombia and Mexico, and that agronomic inputs have positive effects on species richness in very acidic soils with lower organic matter contents, while in more fertile soils like in Colombia, soil parameter define more the AMF richness.