A MYCORRHIZAL SURVEY OF PLANT-SPECIES COLONIZING COASTAL RECLAIMED LAND IN SINGAPORE

Coastal land reclamation in Singapore (1-degree 20') utilises sand from marine ocean beds which lacks mycorrhizal propagules. A survey of the vegetation on this ecosystem, five years after reclamation, indicated a close relationship between the absence of vesicular-arbuscular mycorrhizal fungi and the predominance of plants generally regarded as non-mycorrhizal species (Fimbristylis cymosa and Cyperus kyllinga). However, proximity and accessibility to mycorrhizal vegetation and inoculum on one side of the reclaimed area has increased the dominance of mycorrhizal species over non-mycorrhizal species in those areas. This has resulted in an interesting pattern of plant community succession as plant species diversity and mycorrhizal plant species gradually increase across the reclaimed site. Where mycorrhizal plants were prevalent, spore numbers were very low in the rhizosphere, although roots of Desmodium heterophyllum and Rhynchelytrum repens were heavily colonized by hyphae and spores of Glomus macrocarpum. However, intense hyphal colonization of the roots of most mycorrhizal plants suggests the interconnecting fungal network in the rhizosphere to be the most effective method for nutrient transfer and mycorrhizal infection in this ecosystem.