Hemlock ecosystem monitoring of New River Gorge National River and Gauley River National Recreation Area vegetation and bird communities: 1998–2008
We initiated a long-term hemlock ecosystem monitoring study in 1998 on the New River Gorge National River (NERI) and Gauley River National Recreation Area (GARI), in Nicholas, Fayette, and Raleigh counties, West Virginia, to quantify the effects of hemlock woolly adelgid (HWA) on forest ecosystem dynamics. Hemlock vigor and degree of adelgid infestation were sampled in each fall 1998 through 2007 except 1999 and 2005; vegetation structure and composition were sampled in summer 1999 and 2007; and avian populations were sampled each summer 1999 through 2008. HWA was first detected on sampling plots in 2004 when it was found on eight of 36 plots and reached a high of 22 plots in 2006. Although hemlock crown vigor has declined, limited hemlock mortality has occurred. Consequently, vegetation structure and bird communities have changed little. However, because the literature suggests that tree mortality can occur within four to six years of infestation, we expect hemlock mortality to ensue.