In situ and Ex situ Conservation of Commercial Tropical Trees - ITTO

463Nevertheless, inability to form an aseptic ectomycorrhizal associationin dipterocarp species does not restrict its practical applications, since soil orspore inoculation have proven effective at the nursery or field scale. However,it is speculated that the requirement for vegetatively defined inoculant ofectomycorrhizal fungi will be evident in the future, where commercial dipterocarpplantations are to be established on various sites using clonal propagation. Effortsto successfully employ ectomycorrhizal association using vegetative inoculantare therefore crucially needed to assess the functional diversity of this group offungi. Opportunities to study this diversity are now possible by ‘cultureindependentapproaches’ using molecular techniques. These procedures allowassociations between particular species or isolates of the fungi and dipterocarpspecies or clones to be investigated. Thus, information on dominant fungalspecies that associate with particular host species/genotypes on particular sitesand also their phylogenetic relatedness may be obtained without an asepticmycorrhizal synthesis with a defined vegetative inoculant. A sequence databasefor the identification of ectomycorrhizal fungi in the temperate regions is alreadyaccessible for public use (Bruns et al. 1998), even though databases for fungicollected in tropical regions are still unavailable.Today, conserving ectomycorrhizal diversity is a crucially importantactivity due to the vast destruction of tropical rain forests through improperlogging. Forest-fire also presents a threat to the survival of these fungi in forestsoils. There is evidence indicating that the failure of dipterocarp plantationestablishment in disturbed areas may be due to absence of ectomycorrhizalpopulations. It is suggested that due to their narrower host range, the diversityof these ectomycorrhizal fungi is naturally unique and is related to their siteheterogeneity and/or their geographical distributions, paralleling the diversity oftheir host dipterocarp species. This diversity may also be similar to that occurringin rhizobia (Lie et al. 1987, Karyanto et al. in this proceeding).Arbuscular mycorrhizal fungiUnlike those in ectomycorrhizal associations, fungi belonging to the arbuscularmycorrhizal fungi (amf) have a broader host range and thus an ability to associatewith diverse groups of host plant. The ubiquity of amf is reflected by theirassociations with more than 80% of all terrestrial vascular plants species. Itwas estimated that these associations have been established 353-462 millionyears ago during land colonization by plant species. This parallel developmentbetween amf and vascular plants suggests a vital role for amf in vegetationdevelopment.