Abstract

Rapid colonization by invasive plants can lead to failures of wetland restoration, particularly in forested wetlands where mature plant communities are slow to develop. To develop more effective methods for reducing the spread of invasive plants, I tested the hypothesis that planting native shrubs during the early stages of wetland creation can provide an alternative to herbicides by enhancing competition for light and other resources with invasive herbaceous plants, such as Phalaris arundinacea (reed canary grass). Planting native shrub live stakes in two created forested wetlands in Western New York State, USA, increased overall native herbaceous plant cover and biodiversity relative to plots without shrubs over a four-year period. Invasive species richness was lowest in plots containing Cephalanthus occidentalis, while other planting combinations showed lower invasive species richness but less difference in invasive species richness relative to neighboring plots without shrubs. This finding was confirmed in a controlled greenhouse experiment, where shrubs limited growth of P. arundinacea, without negative reciprocal effects on the shrubs. One mechanism for the reduction in invasive plant cover was likely the significantly reduced light availability beneath shrubs. Shrub health varied among species over time, with a substantial reduction in survivorship following a winter with extreme low temperatures. Overall health was highest for the winter-hardy shrub species C. occidentalis. All species tested had higher survival rates and health assessment when planted in single-species plots rather than in combination with other shrub species and plantings in varying hydrological settings indicated that C. occidentalis and Cornus amomum drier soil than Salix sericea. This work shows the potential for native live stakes to deter pernicious invaders such as P. arundinacea and enhance the success of wetland restoration projects, but that plantings must be selected to ensure survival in variable hydrological and climate conditions.

Publication Date

7-19-2016

Document Type

Thesis

Student Type

Graduate

Degree Name

Environmental Science (MS)

Department, Program, or Center

Thomas H. Gosnell School of Life Sciences (COS)

Advisor

Anna Christina Tyler

Advisor/Committee Member

Elizabeth N. Hane

Advisor/Committee Member

Karl Korfmacher

Campus

RIT – Main Campus

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