Eastern Hemlocks (Tsuga canadensis) are foundation species, which are known to have a large influence on the species composition and ecosystem dynamics. The purpose of this study was to understand how rodent species richness and composition differed among different hemlock treatments consisting of intact forest, logged forest, and invaded hemlock stands in the Harvard Forest of Petersham, MA. Sherman live traps were arranged on 7x7m grids covering 0.49ha in four different hemlock treatments that were established in 2003: 1) the logged treatment, where commercial trees were removed 2) the girdled treatment, where the hemlocks were girdled using a chainsaw, thus killing the trees, and mimicking the effects of the woolly adelgid, an invasive insect 3) the hemlock control which is where hardwoods are at least 70% hemlocks, and 4) the hardwood control, where other hardwood species are dominate. Animals were marked and recaptured from June-July. Using Schnabel methods for population estimate, there appeared to be a shift in the population from more abundant Gapper’s Red-backed vole, Clethrionomys gapperi in the logged and girdled treatments to white footed and deer mice (Peromyscus spp) in the hemlock and hardwood control plots. This shift in population may indicate that hemlocks support Peromyscus spp over voles. The species richness and overall population dynamic of these rodents surveyed may lead to a greater understanding as to the potential affect they may have on the seed dispersal in these plots and could account for many interactions between the vegetation and the animals also present.