Abstract: This study aims to examine the changes that occur in forest understory plant community as a result of the sudden and widespread death of Eastern Hemlocks ( Tsuga canadensis ) due to the Hemlock Wooly Adelgid ( Adelges tsugae ), an introduced pest. The creation of light gaps when hemlocks are defoliated may be a driver for both the loss of native hemlock-associates and the increased establishment of exotic weedy invasives. In this study, 40 plots under the categories of A) healthy hemlock, B) healthy birch, C) adelgid-killed hemlock, and D) gap, were distributed along three stream branches in an old-growth forest co-dominated by Eastern Hemlock and Yellow Birch ( Betula allegheniensis ). Data describing floristic variables (species presence and percent cover) and habitat location and conditions (e.g. distance from stream, soil pH, slope and aspect) were collected for each plot. This data was analyzed to determine whether 1) there are more invasive exotics in plots upstream and more weedy exotic and native species in gaps, 2) there is a difference in community composition under healthy hemlocks, dead hemlocks, yellow birches, and gaps, and 3) there are differences in environmental variables under trees of the above categories. This analysis is in progress and will be continued as part of a Senior Honors Thesis, but currently we've found that there are more exotic species upstream and in gaps, the species-area curves of the four plot categories are significantly different (F 3,24 = 938.5 p < 0.0001) showing different patterns in species diversity, and the soil beneath hemlocks and birches is distinctly different in variables such as pH, organic matter content, and plant nutrients. These differences suggest there will be implications for the whole community as many large hemlocks are removed.