Date of Award

12-2007

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Forest Resources

Advisor

Shelburne, Victor B

Abstract

The spread of invasive plants is one of the most challenging ecological problems in the 21st century, causing a $35 billion loss per year to the economy in the United states alone. More than 85% of woody invasive species were introduced originally for ornamental and landscape use. As a result, over the last few decades, perennial woody invaders have appeared in fence rows, rights-of-way, old fields, understories, and the canopies of eastern forests of the United States. Besides the information about the geographical distribution, general biological characteristics, and response to herbicides, very little information is available on the occurrence and abundance of these invasive plants in relation to landscape variables, and historical land use. The objective of this study was to identify landscape variables that were correlated with occurrence and percent cover of woody invasive species. We examined the distribution and abundance of woody invasive plants in the Clemson Experimental Forest, situated in the Southern Inner Piedmont of South Carolina in relation to landscape variables and historical land use. GPS locations of woody invasive, slope gradient, landform index, aspect, overstory canopy cover, woody invasive species cover, and dominant tree vegetation were recorded for 175 invaded ON road plots and 175 paired 150 feet OFF road plots throughout the Clemson Experimental Forest. Ligustrum sinense, Lonicera japonica, and Rosa multiflora were the most frequent woody invasives. The Friedman Test and GLIMMIX procedure were used to identify factors predicting woody invasive presence. Slope gradient, overstory canopy, and near or ON road were significant factors associated with presence or absence of woody invasive species. Occurrence and abundance of invasive iii species were associated with low slope gradient, lower overstory canopy, and roadside habitats as compared with higher slope gradient and higher overstory canopy associated with the absence of invasive species. The land use history was studied from the aerial photographs of the area to determine if the change in land use caused the spread of the invasive species. Major land use changes, occurring on the area during the last several decades, furnished a favorable situation for the spread of invasive species. These results add to our understanding of factors promoting plant invasions. Because the control of woody invasive species in natural areas is a time- and resource-intensive task, this information may be used to direct conservation efforts by efficiently predicting and managing biological invasions.

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Agriculture Commons

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