Population dynamics of sugar maple through the southern portion of its range: implications for range migration
The range of sugar maple (Acer saccharum Marsh.) is expected to shift northward in accord with changing climate. However, a pattern of increased sugar maple abundance has been reported from sites throughout the eastern US. The goal of our study was to examine the stability of the sugar maple southern range boundary by analyzing its demography through the southern extent of its distribution. We analyzed changes in sugar maple basal area, relative frequency, relative density, relative importance values, diameter distributions, and the ratio of sapling biomass to total sugar maple biomass at three spatial positions near the southern boundary of the species’ range using forest inventory data from the USDA Forest Service Forest Inventory and Analysis program over a 20 year observation period (1990–2010). We contend that the southern range boundary of sugar maple neither contracted nor expanded during this period. We speculated that biophysical changes caused by succession may provide a short-lived ameliorative barrier to a rapid southern range contraction for some species. The eclipse of some greater climate change threshold may therefore be required to realize significant range movement for mesophytic tree species.