Vesicular-arbuscular mycorrhizae and reclamation in Wyoming's Red Desert

This study was conducted to determine the effects of reclamation practices on the vesicular-arbuscular mycorrhizal (VAM) symbiosis in coal stripmined lands of arid southwestern Wyoming. Nondisturbed lands and irrigated reclaimed lands were surveyed for VAM fungal chlamydospore densities and infection frequencies in host plants. Occurrence of VAM fungal biomass in undisturbed horizons of three Aridisols and an Entisol varied among the four soils. Entisol chlamydospore densities did not attenuate to a depth of 140 cm. Supplemental irrigation of lands reclaimed after stripmining increased rates of VAM fungal colonization in minesoil plants. Scheduling of irrigation affected fungal colonization more than rate of irrigation or fertilization in the first year of reclamation. A functional VAM fungal biomass was indicated in the third year of reclamation by seasonality of chlamydospore densities and by high fungal infection frequencies.;A review of nutritional aspects associated with VAM plant-fungal physiology is included in the disertation. Trophic and nutritional relationships of the VAM symbiosis are represented in a matrical model to reflect symbiotic functioning. The model consists of two continua that separately relate to autotrophic and heterotrophic metabolisms involved in the symbiosis. The heterotrophic continuum is presented as a nutritional gradient in plants that regulates VAM fungal growth by limiting carbon availability. Availability of carbon in plants is depicted as ranging from total nonavailability in certain noninfected plant species to nonrestricted carbon availability in highly colonized plant species. The autotrophic continuum reflects the degree of plant dependency on mycorrhizal nutrition. The continuum is comprised of three levels of ecophysiological dependency of plants on VAM mineral nutrition. Plant species are juxtaposed within the matrical model to approximate individual plant capacity for growth of VAM fungi relative to the dependency of a particular plant species on symbiotically-derived nutrition. Responses of plants and fungi are also represented within the model to demonstrate various synecological interactions associated with the symbiosis. Commensalism is suggested to be a potential interaction common to the VAM symbiosis along with mutualistic and parasitic interactions.