Growth dynamics and associated mycorrhizal fungi of little bluestem grass [Schizachyrium scoparium (Michx.) Nash] on burned and unburned sand prairies

Abstract

SUMMARYWP examined the influence of burning on little bluestem grass productivity and its vesicular‐arbuscular mycorrhizal (VAM) fungal associates in a sand prairie community over (bar growing seasons (1586‐4). Above‐and below‐ground productivity was higher on the burned sites than on the unhurried sites. Percent VAM funga1 colonization levels were significantly burned sites than on the unburned sites. In contrast, early in the growing season, colonized and specific rout lengths were longer on the burned site than on the unburned sites but differences were not always significant. Roots of plants on the burned sites supported more fungal biomass than roots on the unburned sites especially during the early growing season. However, colonization d:it;i suggest that the fungi were unable to keep up with the greater below‐ground production of plants on the burned prairies. Mycorrhizal inoculum potential levels of little bluestem rooi zone and randomly collected soil and VAM fungal spore densities were lower on the burned sites than the unburned sites during the year of the burn. Above‐ and below‐ground tissue samples showed significantly higher concentrations and accumulations of several inorganic, nutrients on the burned site early and later in the growing season.However, in contrast, plants on the unburned sites had greater nutrient‐use efficiencies for several nutrients than plants on the burned sites. Lower nutrient‐use efficiencies of plants on burned sites may in pan be due to the onset of harsher environmental conditions during the growing season and/or to associated VAM fungi‐ VAM fungi associated with plants on the burned sites are likely a carbon drain on these plants, supporting greater fungal biomass, and hence, plants on burned sand prairie sites may not benefit from their VAM fungal association especially early in the growing season.