Earthworms introduced to formally glaciated parts of North America have the potential to adversely affect forested habitats across the region. In order to investigate potential impacts of earthworms on plant diversity in a New England forest, we documented the biomass of invasive earthworms and tallied plant diversity at Ice Glen preserve in the western Massachusetts town of Stockbridge. Given the profound role of earthworms as ecosystem engineers, we investigated whether mean invasive earthworm biomass was correlated with plant species diversity (richness and phylogenetic diversity). We found that a high biomass of invasive earthworms coincided with reduced total plant phylogenetic diversity and species richness, in addition to reduced richness of native plants, and increased abundance of non-native plants. This study provides insight into the potential impacts of introduced earthworms on forest plants in New England.

We surveyed plant diversity in the tidal fresh, brackish and salt marshes of the 10-km long Saco River estuary in southern Maine. We also investigated possible relationships between shoreline development in the estuary, nitrogen levels in marsh sediments, and marsh plant species composition. Plant species cover was determined in 1 m² quadrats along transects in sixteen marsh study sites, and land cover was mapped in a 100-m buffer around each site. Nitrogen content (total nitrogen, nitrate and ammonium) of marsh sediments was measured at ten sites. Marsh porewater salinities were determined to range from 0.2±0.1 to 18.6±2.9 ppt (mean±1 SE), with species diversity the greatest in marshes where salinity was less than 8 ppt. We identified 72 vascular plant species in the estuary's marshes, including ten that are listed as threatened or of special concern in the state of Maine. Ordination results showed that the extent of development along the shoreline correlated with the variation in plant species abundance at tidal marsh sites. The proportion of high intensity development also correlated negatively (r_s(16) =-0.571, p=0.021) with plant diversity as measured by the Shannon Wiener index. Nitrogen levels in marsh sediments did not explain these results. The results of this study establish a baseline for future studies of tidal marsh plant communities in the Saco River estuary, and show that the extent of shoreline development may influence tidal marsh plant diversity, even across a salinity gradient.

Chromosome numbers are reported for 133 individuals of 41 taxa and cultivars and four hybrids in the goldenrod genus Solidago from Canada, the United States and botanical gardens in Europe. With the exception of first reports, all of the reports confirm previously published reports. First reports are for the following: Solidago juliae, 2n=36, Texas; S. radula, 2n=36, Arkansas, Texas; S. mexicana, 2n=36, Louisiana, Texas; S. velutina ssp. californica, 2n=36, California.