Evaluation of Arbuscular Mycorrhizal Fungi as Potential Determinants of Medicinal Plant Community Structure in Mihintale Sanctuary, Sri Lanka

Abstract

Forests of Sri Lanka have higher density and species diversity of medicinal plants. There isan increasing world wide interest in medicinal plants due to growing recognition of naturalproducts, being non toxic having no side effects and easy availability at affordable prices.Due to an increase demand for medicinal plants and to a loss and fragmentation of naturalhabitats medicinal plants of the Sri Lanka face a threat in the wild. Almost all natural plantcommunities except few plant families contain arbuscularmycorrhizal fungi (AMF). Wehypothesized that thevaryingarbuscularmycorrhizal dependencycould have the potential todetermine medicinal plant community structure in MihintaleSanctuary, Sri Lanka.

With the objective of testing above hypothesis we conducted a study where ten medicinalplant species in undisturbed site of the MihintaleSanctuarywas randomly selected. For theestimation of the abundance of medicinal plant species, five line transect of 100 m wererandomly derived and calculations were done. Composite root samples of fine roots of eachof the ten species were taken from all five line transects. Ten replicate root samples per oneselected medicinal plant species were analysed for AMF colonization following the standardprocedures of root staining and quantification. Further, along the different points of linetransects moisture content, pH and organic carbon content were estimated. Non parametricanalysis was followed to check whether there any significant difference among selectedmedicinal plant species for the abundance and percentage AMF colonization respectively.Multivariate analysis was performed to establish the relationship with the percentagemycorrhizal colonization and species abundance.

All the ten medicinal plants species selected for the present study had AMF associations invarying colonization levels, ranged from 81.43% in Elephantopus scaber to 28.92% inMorinda coreia.There was a significant difference among selected medicinal plant species forabundance (p=0.031) and percentage AMF colonization (p=0.029). For all the testedmedicinal plants correlation studies were shown positive significant correlation at the 0.01level. The results indicated that below ground native AMF community has the potential todetermine medicinal plant community structure above ground in Mihintale Sanctuary.