Taxonomy and Ecology Of Inland Sand Dune ... - Mycorrhizae

18Tinker, 1983; Adelman and Morton,1986).To establish a stable basis of VAMfungal classification we need moreinformation about ecological,morphological, and biological traits atthe species level. Harley and Smith(1983) point out that taxonomic systemsbased on host relationships cannot beused since the hosts for many VAMfungi are geographically wide-rangingand taxonomically diverse.II. VAM FUNGAL ECOLOGYMycorrhizal fungi may play animportant role in plant ecology. VAMor ectomycorrhizal (ECM) fungi arecommonly associated with wild plants.Both mycorrhizal types modifycompetition; they can colonize the entirenatural community, and 40-60 % ofgross photosynthesis can be lost to thefungal mycelium (Stribley et al., 1980).VAM fungi are the most common andthe most abundant type of mycorrhizalfungi. They exhibit a wide range ofassociations, and they probably are theleast physiologically specialized. VAMfungi can colonize rhizoids of bryophytegametophytes, rhizoids and roots ofseedless vascular plants (Lycophyta andPterophyta), and the roots of mostfamilies of gymnosperms andangiosperms (Harley and Smith, 1983).However, not all plants are mycorrhizal.VAM fungi are rare or absent in somefamilies, e.g., Cruciferae (=Brassicaceae), Chenopodiaceae,Caryophyllaceae, and Cyperaceae(Hirrel et al., 1978). Greenhousedemonstrations of monoculturalinoculum of VAM fungi showed generalnon-specificity with plant root systems(Gerdemann and Trappe, 1974; Harleyand Smith, 1983). In contrastmycorrhizal host specificity is commonin ectomycorrhizal fungi (Harley andSmith, 1983) and, to some extent, inmycorrhizal orchids (Warcup, 1981).However, in a recent study McGonigleand Fitter (1990) presented evidence thatVAM fungal associations in the field canexhibit some degree of ecologicalspecificity.VAM fungi are found in tropical toalpine plants, and fungal development isstrongly temperature dependent. The