Electronic Thesis and Dissertation Repository

Degree

Master of Science

Program

Biology

Supervisor

Dr. R. G. Thorn

Abstract

Common buckthorn (Rhamnus cathartica) is a competitive Eurasian woody shrub currently invading North America. Buckthorn thickets reduce native diversity and may reduce mycorrhizal diversity through the release of allelochemicals. Two aspects of buckthorn’s invasional biology are explored: 1) identifying fungi associating with buckthorn, and 2) determining buckthorn’s allelochemical impacts on arbuscular mycorrhizae in forest soils and an open-greenhouse experiment.

Twenty-three fungi were found growing on buckthorn, including Armillaria mellea s.l., Hypoxylon fuscum, H. perforatum, Nectria cinnabarina, and Cylindrobasidium evolvens. Data from invaded and uninvaded sugar maple (Acer saccharum) soils revealed that arbuscular mycorrhizal fungi (AMF) diversity fluctuated as a function of season or potting disturbance, but the presence of buckthorn had little effect on AMF development in maple roots. Buckthorn may be a mycorrhizal generalist, and changes in AMF abundance may be more influenced by underlying stochastic soil processes and aboveground plant composition than by buckthorn and its allelochemicals.


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