Bertin, Robert .
Seventy years of change in the flora of one New England County.
The vascular flora of Worcester County, Massachusetts was examined in detail over the past two decades. The current flora was compared to the flora represented in a set of systematic herbarium collections made in the same county, primarily from the late 1920s to early 1950s. The county comprises 60 towns, covers 4090 square km, and ranges in elevation from 57 m to 610 m. The major terrestrial vegetation zones are central hardwoods/hemlock/white pine and transition hardwoods/hemlock/white pine. Because town was the most detailed location specified for most of the historical collections, this was taken as the standard sampling unit, and the number of towns in which a species was recorded was taken as a measure of that speciesí frequency in the historical and current sampling. Historical comparisons reveal large changes in the frequencies of many species. Many alien species have increased dramatically in abundance. These include many invasive species (e.g. Euonymus alata, Elaeagnus umbellata, Acer platanoides), but also many aliens of roadsides, lawns and other ruderal habitats (e.g. Arabidopsis thaliana, Draba verna, Oxalis dillenii). A few alien species have declined, especially those associated with old-fashioned or herbal gardens (Inula helenium, Carum carvi) and some species associated with agriculture (Sinapis arvensis, Anthemis cotula). Numerous native species have declined, including multiple species in the Orchidaceae and Ophioglossaceae, and certain species associated with open habitats (Cirsium pumilum, Pedicularis canadensis, Liatris scariosa), which have become less widespread with abandonment of agriculture. A few native species have increased, most associated with disturbed habitats (e.g. Galium aparine, Triodanis perfoliata) . Species near the southern end of their New England ranges on average have tended to decline relative to those near the northern end of their New England ranges. Analyses currently under way are attempting to evaluate the relative contribution of climate change, habitat affiliation and sampling protocols to this north/south difference.
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1 - College of The Holy Cross, Department of Biology, Worcester, Massachusetts, 01610, USA
land use change
alien plant species
Presentation Type: Poster:Posters for Topics
Location: Hall A/Convention Center
Date: Monday, August 2nd, 2010
Time: 5:30 PM