Title

Assessing the ecological implications of arbuscular mycorrhizal fungal colonization of the invasive shrub amur honeysuckle (Lonicera maackii)

Date of Award

2013

Degree Name

M.S. in Biology

Department

Department of Biology

Advisor/Chair

Advisor: Carl F. Friese

Abstract

The introduction of non-native, invasive plants has significantly reduced the biodiversity of native plants and altered ecosystem processes and successional trajectories in novel environments. The invasive shrub Amur honeysuckle (Lonicera maackii) has negatively impacted the biodiversity and ecological balance of Eastern Deciduous Forests by reducing the growth and reproduction of native forbs, tree seedlings, and overstory trees. Previous research on the competitive success of L. maackii has focused on allelopathy and competition for light and below-ground resources. However, the disruption of native mycorrhizal networks by L. maackii is one potential mechanism that has been unexplored. We examined the vesicular arbuscular mycorrhizal colonization in L. maackii roots compared to a random sample of native control roots. Contrary to a reduction in mycorrhizae, the total mycorrhizal colonization levels in L. maackii roots were significantly higher than native roots in April and June. Additionally, arbuscular colonization, the site of nutrient exchange, was significantly higher in L. maackii across all months of the study; in April, arbuscular colonization was 4.1 times greater in L. maackii roots than control roots. Arbuscular colonization levels also peaked earlier in L. maackii roots than in native roots, which may be explained by L. maackii's extended leaf phenology. These findings suggest that the high arbuscular colonization in L. maackii likely provides a significant benefit of increased nutrients to this invasive shrub and perhaps a competitive advantage over native plants. Additionally, these results complicate the potential role of allelopathy as a competitive mechanism -- the allelochemicals must negatively affect the surrounding native plants, without disrupting the mycorrhizal network that these native plants and L. maackii depend on. The high arbuscular colonization of L. maackii is ecologically significant and likely an important mechanism enabling L. maackii to out-compete native plants.

Keywords

Vesicular-arbuscular mycorrhizas, Invasive plants Biological control Research, Honeysuckles Ecology, Caprifoliaceae Ecology, Forest ecology, Amur honeysuckle; arbuscular mycorrhizal fungi; arbuscules; invasive species; Lonicera maackii; mycorrhizal colonization

Rights Statement

Copyright 2013, author

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