Department or Program

Environmental Studies


Japanese knotweed (Fallopia japonica) is an aggressive invasive plant that spreads via several mechanisms making it hard to control. Currently, little is known about Japanese knotweed invasion in riparian habitats. A total of 46 soil samples from both invaded and uninvaded sites (32 total locations) along the Saco River in Maine and New Hampshire were examined to see whether physical and chemical characteristics were similar among knotweed-invaded sites and what may lead to successful establishment by knotweed. The majority of sites were dominated by medium-grained sand, but there were no differences in the soil texture at invaded and uninvaded sites. Similarly, knotweed has invaded sites with a range of slopes in multiple aspect directions with no slope or aspect being preferentially invaded. Japanese knotweed has invaded sites with limited shade qualities or with mainly deciduous trees, both of which may help with its growth. Inside patches, the percent carbon and nitrogen decreased, while 𝛿13C became more positive with increasing soil pH; these trends were not observed outside of the invaded patches. There was more Ca, K, Mg, Zn, and Mn available inside knotweed patches than outside of it. Once normalized for OM, no difference was found between these elements inside and outside of the patch, revealing that OM may be important in knotweed growth. Overall, it appeared that Japanese knotweed invasion is possible in a variety of physical settings and has no clear impact on a site’s physical characteristics but that it may alter a site’s biological and chemical properties.

Level of Access

Restricted: Embargoed [Open Access After Expiration]

First Advisor

Holly Ewing

Date of Graduation


Degree Name

Bachelor of Arts

Number of Pages


Components of Thesis

1 pdf file

Open Access

Available to all.