Diversity of arbuscular mycorrhizal fungi in undisturbed forest, slash-and-burn field, and monoculture forest of Indo-Burma megadiverse region

Abstract

Conversion of pristine forests to agricultural lands is one of the leading causes of biodiversity loss worldwide. To assess the impact of such forest disturbance on microbial diversity, we investigated the diversity of arbuscular mycorrhizal fungi (AMF) in the rich forests of Karbi Anglong hills of Assam, a biodiversity hotspot part of Indo-Burma region. AMF spore diversity was assessed in distinct study sites with different intensities of disturbances that encompassed a pristine undisturbed forest (UF), slash-and-burn field (SBF), and monoculture forest (MF). A total of 35 arbuscular mycorrhizal (AM) fungal species belonging to 9 genera were isolated. Species forming glomoid spores were dominant in all the three sites followed by acaulosporoid spores. Highest spore density was found in UF and lowest in MF. Multivariate analyses revealed similarity in UF and SBF. It was found that in MF, AMF diversity was significantly modified and reduced, resulting in an ecological degraded ecosystem. Our results show that natural UF and SBF contained similar and a high AM fungal diversity. The AM fungal diversity is not significantly affected by the slash-and-burn agricultural land use practices practised by the ethnic hilly tribes and, therefore, could be a component of a tropical forest “conservation-agriculture matrix.” Also because of the high generic and species diversity found, this region can be considered as AMF hotspot and a priority place for conservation.