ARBUSCULAR MYCORRHIZAL FUNGI AND SOIL NUTRIENTS ASSOCIATED WITH FOUR FERN SPECIES IN TWO ECOSYSTEMS IN OAXACA, MEXICO

The abundance and richness of arbuscular mycorrhizal fungi (AMF) and arbuscular mycorrhizae (AMs) in the roots of four fern species (Cheilanthes myriophylla, Ch. bonariensis, Blechnum appendiculatum and Adiantum capillus-veneris) were examined in relation to soil fertility in February and December. The ferns were evaluated in two ecosystems in Oaxaca, Mexico: Ch. myriophylla and Ch. bonariensis in semiarid tropical scrub, and B. appendiculatum and A. capillus-veneris in cloud forest. The rhizospheric soil of the four fern species had higher AMF spore abundance and richness than fern-free soil. A total of 13 genera and 32 morphospecies of AMF were recorded. Glomus morphospecies were detected in both ecosystems, whereas Racocetra, Scutellospora, Diversispora, Gigaspora and some morphospecies of Acaulospora and Funneliformis were unique to the cloud forest. The low arbuscular mycorrhization in the ferns was attributed to the high levels of organic matter, total N and inorganic P; AMs were more active in Ch. bonariensis, a semiarid tropical scrub species, suggesting that AMs are regulated by the availability of soil resources and the type of fern. The four species form reservoirs of AMF in the soil, suggesting that the ferns could generate native inocula useful for environmental restoration in their respective ecosystems.