SURVIVAL OF ARBUSCULAR MYCORRHIZAL FUNGI FOLLOWING RECIPROCAL TRANSPLANTING ACROSS THE GREAT-BASIN, USA

Mycorrhizal fungi are transplanted into exotic habitats to aid in agri culture and land restoration. However, different taxa have different e ffects on hosts, and little is known about their survival or spread. T he fate of arbuscular mycorrhizal fungi was examined in a reciprocal t ransplant experiment of a single host shrub species, Artemisia trident ata subspecies tridentata between two semiarid sites. The sites were l ocated near Reno, Nevada, and San Diego, California, in the western Un ited States. The experiment was a complete factorial design: two plant populations, A. tridentata ssp. tridentata from the Reno and the San Diego sites, and five fungal treatments (Acaulospora elegans from San Diego, Scutellospora calospora from Reno, a whole-soil inoculum from S an Diego, a whole-soil inoculum from Reno, and uninoculated soil). Bas ed on fluorescein isothiocyanate-labeled antiserum studies, neither fu ngus declined over three growing seasons at the site of origin with th e plant population of origin. Survival of the fungi always declined in association with the exotic host population and at the exotic site. S pore density of fungi that had been inoculated was generally very low. However, when significant differences between treatments were observe d, spore density of the fungus was higher in association with plants t hat had been inoculated with it than with uninoculated plants and the fungus had higher survivorship in the site and with the host of its or igin. Both fungi usually sporulated more often under inoculated than u ninoculated host plants. Over three growing seasons, both A. elegans a nd S. calospora survived in their sites of origin and in the exotic lo cation with both plant populations. The fungi spread throughout the ro ot systems and between plants of the different treatments. These resul ts show that, while there was higher survival by the arbuscular mycorr hizal fungi at the site and with the host of origin, these fungi survi ved and spread for at least three growing seasons, although they decli ned significantly at the exotic site and with exotic hosts.