Geology topics

Petra Bohall Wood

Publications and source records attributed to Petra Bohall Wood.

22 records · Page 2Linked to original sources

USGS2010

Maintenance of Eastern hemlock forests: Factors associated with hemlock vulnerability to hemlock woolly adelgid

Eastern hemlock (Tsuga canadensis [L.]) is the most shade-tolerant and long-lived tree species in eastern North America. The hemlock woolly adelgid (Adelges tsugae) (HWA), is a nonnative invasive insect that feeds on eastern hemlock and Carolina hemlock (Tsuga caroliniana Engelm.). HWA currently is established in 17 eastern states and is causing tree decline and wide-ranging tree mortality. Our data from West Virginia and Pennsylvania suggest that hemlock crown vigor (a ranking of amount of live crown) relates to a predictable pattern of hemlock vulnerability at light and moderate levels of HWA infestation. We found that crown variables, such as live crown ratio and crown density and transparency, are accurate predictors of hemlock decline; more vigorous trees appear to be less vulnerable to HWA. Thus, silvicultural thinning treatments may be a means for reducing stand densities and increasing crown vigor in colder areas where climate may slow HWA spread.

Conference Paper↗

USGS2009

Recovery distances of nestling Bald Eagles banded in Florida and implications for natal dispersal and philopatry

I used band recovery data to examine distances between banding and recovery locations for 154 nestling Florida Bald Eagles and discuss the implications for understanding natal dispersal and philopatry in this species. Band recoveries occurred in 23 U.S. states and five Canadian provinces between 1931–2005. Recovery distance from the natal nest averaged longer for the youngest age classes (ANOVA: F = 3.59; df = 5, 153; P = 0.005), for individuals banded in earlier decades ( F = 1.94; df = 5, 153; P = 0.093), and for the months of May through October ( F = 3.10; df = 12, 153; P < 0.001). Of 35 individuals classed as mature (≥3.9 yr old when recovered; range 3.9–36.5 yr), 31 were located within Florida, which suggested a strong degree of philopatry to the natal state. Among 21 mature eagles of known sex with known banding and recovery locations in Florida, females, particularly younger birds, had longer recovery distances ( N = 9, mean = 93 km, SE = 22.4) than did males ( N = 12, mean = 31 km, SE = 5.3; t = 2.67, df = 19, P = 0.026). The records examined here suggest a high degree of philopatry and relatively short natal dispersal distances, particularly in male Bald Eagles.

Journal of Raptor Research↗

USGS2009

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.

West Virginia↗

USGS2008

Hemlock ecosystem monitoring in southern West Virginia

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 ecosystem response to invasion by the hemlock woolly adelgid (HWA). Hemlock vigor and degree of adelgid infestation were quantified in 1998-2007, vegetation structure and composition were sampled in 1999 and 2007, and avian populations were sampled 1999-2007. The HWA was detected on eight of 36 sampling plots in 2004 and 22 of 36 by 2007. Now that most of the monitoring plots are infested with HWA and the literature suggests that tree mortality can occur within four to six years (McClure 1991), we expect hemlock mortality to ensue. In this paper, we summarize data collected pre-infestation and during the initial stages of infestation.

West Virginia↗