CHANGES IN THE FLORA OF THE MOUNT HOLYOKE RANGE, HAMPSHIRE CO., MASSACHUSETTS OVER THE PAST 150 YEARS (1860-2010)

The current (2010) flora of the Mount Holyoke Range was compared to a flora compiled from herbarium specimens collected between 1860 and 1952. Losses and additions were examined for families and for rare and introduced species. The patterns of loss were compared to other recent floras from Massachusetts. In addition, the potential impacts of global warming on species distribution and spring flowering phenology were examined. The historic flora consisted of 370 species, all but 8 of which were native. The current flora of 834 taxa more than doubled that previously recorded, with introduced species showing the largest percent increase. About 10.7% of the native plants from the historic flora were not re-located; thus, lower than the 20-44% loss of natives in other Massachusetts floras from urban or suburban areas but similar to the loss from the non-urban Harvard Forest flora. Nevertheless, the patterns of loss were similar for all areas, with rare species and families such as the Orchidaceae, Saxifragaceae, and Ophioglossaceae exhibiting the largest fraction of species lost. The similarity in pattern suggests that region-wide factors, such as successional processes, habitat loss, and habitat fragmentation are not confined to areas that are more heavily impacted by human development. Another region-wide factor impacting regional floras could be global warming. Between the periods 1863-1935 and 1994-2008, the spring-quarter temperature in the Amherst, MA area increased 0.8 degrees C. This increase was correlated with a significant reduction in species with northern distributions and with an advance in average flowering date of 5.4 days. The number of species with earlier flowering dates was significant, with 71% of the 38 species examined blooming earlier now than historically.