title: External hyphal production of vesicular-arbuscular mycorrhizal fungi in pasture and tallgrass prairie communities.
abstract: External hyphae of vesicular-arbuscular mycorrhizal (VAM) fungi were quantified over a growing season in a reconstructed tallgrass prairie and an ungrazed cool-season pasture. In both sites, hyphal lengths increased throughout the growing season. Peak external hyphal lengths were 111 m cm-3of soil in the prairie and 81 m cm-3of soil in the pasture. These hyphal lengths calculate to external hyphal dry weights of 457 μg cm-3and 339 μg cm-3of soil for prairie and pasture communities, respectively. The relationships among external hyphal length, root characteristics, soil P and soil moisture were also determined. Measures of gross root morphology [e.g., specific root length (SRL) and root mass] have a strong association with external hyphal length. Over the course of the study, both grassland communities experienced a major drought event in late spring. During this period a reduction in SRL occurred in both the pasture and prairie without a measured reduction in external hyphal length. Recovery for both the pasture and prairie occurred not by increasing SRL, but rather by increasing external hyphal length. This study suggests that growth is coordinated between VAM hyphae and root morphology, which in turn, are constrained by plant community composition and soil nutrient and moisture conditions.
authors.affiliation: Environmental Research Division, Argonne National Laboratory, 9700 S. Cass Avenue, 60439, Argonne, IL, USA.
authors.forename: R M
authors.initials: RM
authors.lastname: Miller
authors.affiliation: Environmental Research Division, Argonne National Laboratory, 9700 S. Cass Avenue, 60439, Argonne, IL, USA.
authors.forename: J D
authors.initials: JD
authors.lastname: Jastrow
authors.affiliation: Biological Sciences Department, The University of Illinois at Chicago, 60680, Chicago, IL, USA.
authors.forename: D R
authors.initials: DR
authors.lastname: Reinhardt
keywords: External hyphae; Grasslands; Mycorrhiza; Root morphology; Soil moisture