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Title:Invasion of Alliaria petiolata on a small fragmented central Illinois woodland: a test of the novel weapons hypothesis
Author(s):Rose, Scott
Advisor(s):Endress, Anton G.
Department / Program:Natural Res & Env Sci
Discipline:Natural Res & Env Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
Degree:M.S.
Genre:Thesis
Subject(s):Alliaria petiolata
garlic mustard
allelopathy
novel weapons
Abstract:Invasive species are the second leading threat to biodiversity in the U.S. and are considered the greatest threat to North American deciduous forest. Plant species richness is changing in many woodland communities as invasive species alter survival, fecundity, and regeneration of native species. Several hypotheses seek to explain the success of invasive species in their new range. The Novel Weapons hypothesis suggests invasive plants secrete allelopathic chemicals that are relatively ineffective against co-evolved neighbors in their native range, but deleteriously alter the fitness of neighboring plants in the novel range. For at least two decades, Alliaria petiolata (Bieb.) Cavara & Grande), a European biennial herb, has been a serious invader of natural areas and woodland communities of North America. Spatiotemporal changes within the herbaceous groundlayer and a microbial community assessment were analyzed in Collins Woods, a fragmented Illinois woodland. Across an eight-year interval, plant species richness increased despite A. petiolata becoming a dominant species within the community. Results of the microbial analyses were variable depending on invasion and spatial considerations. Native seed germination experiments indicate species-specific tolerance to changing soil characteristics may influence plant community structure. The total above-ground plant biomass differed significantly between plots with and without A. petiolata, but the above-ground biomass of native plant species was not affected by the presence of A. petiolata. The results of this study are partially consistent with a combination of direct and indirect allelopathic impacts of A. petiolata but other mechanisms may explain changes of native plant community in this small woodland.
Issue Date:2012-05-22
URI:http://hdl.handle.net/2142/30936
Rights Information:Copyright 2012 Scott Rose
Date Available in IDEALS:2012-05-22
Date Deposited:2012-05


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