Date of Award

2017

Degree Type

Thesis

Degree Name

Master of Science in Environmental Science

Department

Biological, Geological and Environmental Sciences

First Advisor

Rauschert, Emily

Subject Headings

Ecology, Environmental Science

Abstract

Ranunculus ficaria L., an ephemeral perennial invasive plant brought over from Europe, is becoming widespread throughout the Northeastern United States. This herbaceous buttercup is able to create extensive dense mats that limit native species growth. Taking advantage of an early growing season and rapid reproduction rates, this species can create dense monocultures, which threatens native communities and ecosystems. Elimination of native spring ephemerals results in decreased biodiversity. A better understanding of how R. ficaria responds to site characteristics is needed to prioritize management efforts toward high-risk sites.

Ranunculus ficaria abundance and reproductive output (seed, bulbil and tuber production rates) were examined in plots spanning a disturbance gradient away from a river. Site characteristics (PAR, aspect, soil pH, soil moisture, texture and nutrient content) were investigated to examine their role in plant performance. I hypothesized that soil characteristics (pH and nutrient availability) drive R. ficaria plant performance; specifically I expected higher biomass and reproductive output to be associated with higher soil pH. I also expected reproductive output and R. ficaria biomass would be highest in moist floodplain at intermediate distances from rivers.

Many soil nutrients and characteristics were significantly related to biomass and reproductive output; specifically phosphorus, calcium and LTI (Lime Test Index) all showed significantly positive relationships with plant biomass and bulbil counts, while soil pH was significantly positively related to biomass. Bulbil and tuber counts were significantly higher in soils of high percent silt. These findings suggest that soil characteristics (pH, texture) and nutrients (P, Ca) are strongly linked to plant performance, supporting my hypothesis. Reproductive output and R. ficaria biomass were not significantly greater at intermediate distances from rivers, in contrast to my hypothesis.

A plant performance model was generated using object-based image analysis with the aim of creating an accurate classification of sites in terms of suitability for R. ficaria performance. A large scale field survey was used to assess model predictions, which were found be 68 % accurate. Overall, this study was able to expand on the current limited understanding of R. ficaria, which can prove helpful in aiding management to reduce population size and spread.

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