Rebecca Raffo

Invasive earthworm

Wildlife Tech Class of 2015
Somers High School
Mentor: Rebecca Walling (SUNY ESF)

Project: Patterns of plant biodiversity and invasive earthworm densities at the Mianus River Gorge.

Project Status: Completed

Project Description: Since the 1700s, earthworms from Europe and, more recently, Asia have been introduced to North America and have been reproducing and expanding since.  These organisms have upset the stability of various ecosystems and negatively impact floral communities.  Becca’s study is investigating the relationship between plant diversity and the prevalence of worms in vegetation plots in conjunction with Rebecca Walling‘s M.S. work examining the impacts of exotic earthworms on soil chemistry and plant growth.

In 2013 and 2014, Rebecca conducted vegetation surveys to calculate the abundance and diversity of wildflowers and seedlings (<1 yr old) at twelve sites in Mianus River Gorge Preserve, Bedford, NY. Earthworm presence was then determined at each site using multiple methods. Worm-invaded plots doubled over the course of year from 4 to 8 plots. Rebecca compared mean stem counts of native plants with the presence or absence of earthworms and found an inverse relationship between the two in 2013 and a weaker correlation in 2014. Tsuga canadensis (Eastern Hemlock), a slow growing climax species of particular importance to the management of this preserve, showed the most severe difference between invaded and non-invaded plots. Rebecca observed a similar pattern with Quercus spp. (Oak) seedlings, another important species. Earthworms appear to be spreading throughout the preserve, and my findings indicate that invasive earthworms may play a role in the decline of native plants in this preserve and the Northeast.

Posted in WTP Techs.