last update October 28, 2000
Mycorrhizal fungi are transplanted into exotic habitats to aid in agriculture and land restoration. However, different taxa have different effects on hosts, and little is known about their survival or spread. The fate of arbuscular mycorrhizal fungi was examined in a reciprocal transplant experiment of a single host shrub species, Artemisia tridentata subspecies tridentata between two semiarid sites. The sites were located near Reno, Nevada and San Diego, California, in the western United States. The experiment was a complete factorial design: two plant populations, A. tridentata ssp. tridentata from teh Reno and the San Diego sites, and five fungal treatments (Acaulospora elegans from San Deigo, Scutellospora calospora from Reno, a whole-soil inoculum from San Diego, a whole-soil inoculum from Reno, and uninoculated soil). Based on fluorescein isothiocyanate-labeled antiiserum studies, neither fungus declined over three growning seasons at the site of origin with the plant population of origin. Survival of the fungi always declined in association with the exotic host population at the exotic site. Spore density of fungi that had been inoculated was generally very low. However, when significant differences between treatments were observed, spore density of the fungus was higher in association wiht plants that had been inoculated with it than with uninoculated plants, and the fungus had higher survivorship in the site and with the host of its origin. Both fungi usually sporulated more often under inoculated than uninoculated host plants. Over three growing seasons, both A. elegans and S. calospora survived in their sites of origin and in the exotic location with both plant populations. The fungi spread throughout the root systems and between plants of the different treatments. These results show that, while there was higher survival by the arbuscular mycorrhizal fungi at the site and with the host of origin, these fungi survived and spread for at least three growing seasons, although they declined significantly at the exotic site and with exotic hosts.