Temporal Patterns of Woody Species Diversity in a Central Appalachian Forest from 1856 to 1997

Abstract

This study examined the composition of woody species in a mixed mesophytic forest in the central Appalachian region with respect to both time and different disturbance regimes. Species composition and diversity were assessed from 1856 to 1997 on a tract of land that currently is part of the Fernow Experimental Forest in north-central West Virginia. Additionally, the effect of different silvicultural disturbances are described using inventory data from four silvicultural demonstration areas initiated in 1948. These areas included a commercial clearcut, diameter- limit harvesting, single-tree selection, and an area that has not been artificially manipulated since initial logging around the turn of the century (ca 1907). Witness tree data from early land surveys (1856 and 1915) conducted in the same watershed were used to gain some insight into species frequency prior to and after initial logging. A forest inventory conducted in 1922 provided a more detailed description of the vegetation in the vicinity of the post-1948 stand data. The Shannon-Weiner Diversity Index was calculated based on species importance values for all time periods and management activities. Detrended correspondence analysis was used to assess differences in composition related to time and management activity. Data from old-growth (1856), early second-growth (1915 and 1922), and more mature second-growth stands were well separated in ordination space. A decline in species diversity from a high in 1922 to a low in 1997 appears to be driving this separation. Diversity declined primarily due to a reduction in evenness, which was significantly correlated with increasing importance of Acer saccharum. Relative A. saccharum importance is increasing in both the overstory and understory for all disturbance regimes. The increasing dominance of this species with time, regardless of stand age or disturbance regime evaluated, may be unprecedented and suggests new silvicultural techniques are needed to maintain the diversity of central Appalachian forests.