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

55believe the overriding factor is depth.There are simply fewer roots and,therefore, fewer mycorrhizae and fewerpropagules in soils collected from lowerdepths.Survival of VA mycorrhizal fungi andsubsequent spore germination maydepend on a species' adaptation and onthe influence of physical parameters ofthe soil such as pH (Green et al., 1976).Friese and Koske (1991) found nosignificant correlation between VAmycorrhizal fungal spore clumping andsoil pH. Bagyaraj (1991) points out thatthe interpretation of a pH effect on VAMfungal spore germination is difficultbecause many chemical properties ofsoil vary with changes in pH. Soil pHover a range of 4.8-8.0 significantlyinfluenced germination of Glomusepigaeum Daniels & Trappe spores;optimum germination occurred at pH 7(Daniels and Trappe, 1980). Myregression analysis of the MIP of the soilsurrounding O. hymenoides roots andinitial soil pH shows a significantrelationship (R 2 = 0.809). MIP valuesdecrease as initial soil pH increases.Our results indirectly support Powell andBagyaraj's (1984) conclusion that pHcan influence spore germination in VAMfungal species, and that sporegermination occurs within a range that isacceptable for plant growth. In spite ofthe significant relationship betweeninitial soil pH and MIP, I believe, again,the overriding factor is depth. Theinitial soil pH range covers less than oneorder of magnitude. As depth increases,there are fewer propagules to contributeto MIP values.For the most part, our data for VAMcolonization of plants from inland sanddunes are consistent with those datafrom maritime dune ecosystems. I foundVAM rather than ectomycorrhizaepredominate in inland dunes. Read(1989) noted that VAM rather thanectomycorrhizae predominate in drysandy ecosystems of high base status,little organic matter, and low availablephosphorus. I found that even pioneer