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Northern Arizona University (2006)

Functions of arbuscular mycorrhizal fungi at ecosystem and community scales in semi-arid environments

Chaudhary V Bala

Titre : Functions of arbuscular mycorrhizal fungi at ecosystem and community scales in semi-arid environments

Auteur : V Bala Chaudhary

Université de soutenance : Northern Arizona University

Grade : Master of Science (MS) 2006

Résumé
This thesis describes two studies that examine functions of arbuscular mycorrhizal (AM) fungi at community and ecosystem scales in a semi-arid ecosystem in southern Utah. Chapter I introduces AM fungi which form symbiotic, often-mutualistic relationships with a majority of higher plants in dryland ecosystems. In chapter II, we examine the relative contributions of plant, biological soil crust (BSC), and AM fungal communities to soil stability. We utilized two separate but complementary research approaches which allowed us to both study the basic biology of the system as well as understand how organisms interact to influence an important ecosystem service. First, we compared plant, BSC, and AM fungal abundance across a gradient of soil stability levels in a semi-arid shrublands. Second, we used this information and a structural equation modeling approach to test hypothesized causal effects of the three types of communities on both surface and subsurface stability. We present quantitative models that demonstrate how plants, BSCs, and AM fungi work together to influence soil stability in semi-arid shrublands. This research highlights the need for a holistic approach to erosion control. In chapter III, we conducted two independent experiments, one in the greenhouse and one in the field, to examine the relationship between AM fungi and several non native and native plant species. Arbuscular mycorrhizal fungi can promote, inhibit, or have no influence on the success of non-native plant invasibility. Because AM associations vary greatly along the mutualism-parasitism continuum, species-specific empirical research is needed to determine the nature of these associations. Our experiments demonstrated an antagonistic relationship between several non-native invasive plant species and local AM fungi. Consequently, there may be a potential role for AM fungi in invasive species control. Chapter IV illustrates a decision tree designed to help ecosystem managers decide if the addition of supplemental AM fungi will facilitate restoration success. It also describes the logical progression of the tree and highlights how information from each chapter of this thesis specifically helps land managers determine the best course of action regarding the restoration of mycorrhizal symbioses.

Annonce : Worlld Cat

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