ARBUSCULAR MYCORRHIZAL FUNGI ABUNDANCE AND DIVERSITY ACROSS DIFFERENT LAND-USE TYPES IN JABI TEHNAN WOREDA WESTERN GOJAM, ETHIOPIA

Abstract

Arbuscular mycorrhizal fungi (AMF) are ubiquitous soil organisms. They form symbioses with majority of terrestrial plants and contributor to mineral and water uptake, plant biodiversity, productivity, ecosystem stability and function. However, AMF community structure and function are affected by land use and land cover changes. This necessitates the exploration of the AMF land- use change association within selected agro-ecosystems in the country. To this end, a site was selected at Jabi Tehnan woreda with eight (8) land use types to identify spore density (population), root colonization and diversity of AMF. The data showed that spore density of the different cropping systems varied significantly within and between land uses types ranging from 104 spores/100gm soil from Eucalyptus (E.globulus) mono (tree) cropping to 929 spores/100gm soil for mixed cropping system (cabbage+sunflower+maize). All plants formed AM symbiosis except cabbage (Brassica oleraceae).The AM fungal colonization pattern showed variations among the roots of the cropping types ranging from 22% (teff and eucalyptus) up to 73.4% from sunflower/maize/ (mixed crop). A total of 8 AMF genera and 43 morphospecies were identified from the different cropping systems of which the highest number of species was recorded from the genus Acaulospora(14 species), followed by the genera Glomus (9 species) and Scutellospora (7 species), Funneliformis (5 species), Claroideoglomus (3 species), Gigaspora(3), Entrophosphora and Paraglomuswith one species each. Based upon Importance Value, no dominant AMF species were recorded across all the land use types. However, three common AMF species: Funneliformis geosporum (34%), Acaulospora rehmii (27%) and Glomus clarum (26%) were found comparatively with high importance value respectively. Although the genera Acaulospora and Glomus contained large number of species, they did not have dominant species distributed across the land use types. In this study, AMF species diversity was much lower in tree-based cropping system (Eucalyptus) or mixed croton+juniperus plantation than in the annual cropping systems (monocrops, mixed crops).The study showed that intensive land use (cropping) produced more spores than the relatively stable ecosystems of trees indicating that disturbance enhances sporulation. In addition to this a better picture of the land use change could be revealed if the frequency of sampling was increased. The data show a link between spore density, mycorrhization and species diversity in relation to physico-chemical characteristics at P< 0.05. The data on AMF population and diversity was based on soil samples which could help in revealing spore density but not necessarily species diversity. So it is necessary to conduct pot culture for several months to bait as many species as possible.