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Research about Shenandoah National Park

Source-linked reports with geographic coverage including Shenandoah National Park.

47 records · Page 3Linked to original sources
USGS2001

Water-quality data of soil water from three watersheds, Shenandoah National Park, Virginia, 1999-2000

Data on the chemical composition of soil-water samples were collected quarterly from three watersheds in Shenandoah National Park, Virginia, from September 1999 through July 2000. The soil-water samples were analyzed for specific conductance and concentrations of sodium, potassium, calcium, magnesium, ammonium, chloride, nitrate, sulfate, acid-neutralizing capacity, silica, and total monomeric aluminum. The soil-water data presented in this report can be used to support water-quality modeling of the response of streams to episodic acidification. Laboratory analytical data as well as laboratory quality-assurance information also are presented.

Virginia↗
USGS1999

Assessment of landscape correlates of Eastern hemlock decline due to hemlock woolly adelgid

Eastern hemlock ( Tsuga canadensis ) is in decline throughout its range in the eastern US due to infestation by an exotic insect pest, the hemlock woolly adelgid ( Adelges tsugae ). In Shenandoah National Park, the hemlock woolly adelgid (HWA) rapidly killed many stands of hemlock after first appearing in the late-1980’s, while having only minor impact in other stands. At present, few investigators have examined the mechanisms that produce this discontinuous impact, although landscape factors are predicted to play a major role (Orwig and Foster, 1998: Perry 1988). In an effort to address possible landscape correlates to hemlock decline, we conducted a preliminary analysis of 5 years of hemlock health estimates in comparison to measures of terrain, stand isolation, and potential dispersal corridors at the stand level. We found that elevation, slope, light conditions, and distance to streams all exhibited relatively strong correlation with hemlock decline, although the relationship varied by year. In addition, there appears to be some evidence of spatial autocorrelation in decline, suggesting that similar environmental conditions are either controlling the adelgid or making hemlock stands more susceptible to HWA. We are using the results of this preliminary analysis to guide more detailed efforts aimed at modeling hemlock stand vulnerability as a result of site, landscape, and regional factors.

Virginia↗
USGS1995

The association of water chemistry variables and fish condition in streams of Shenandoah National Park (USA)

As part of the “Shenandoah National Park: Fish in Sensitive Habitats” (SNP:FISH) project, the blacknose dace ( Rhinichthys atratulus ) was utilized as an indicator species to assess the susceptibility of the ichthyofaunal community of Shenandoah National Park (USA) to acidification. Water chemistry (ANC, conductivity, pH, and concentrations of Ca 2+ , Mg 2+ , Na + , K + , Cl − , NO 3 − , SO 4 2− , and SiO 2 ) was sampled every three months over the course of 3 1/4 years which represents the probable maximum lifetime of R atratulus. Condition factors (K=[g/mm 3 ] * 10 6 ) were calculated for samples of fish (age class 2+ yr; n=370) from nine montane, second/third order streams representing a range of ANCs. A principle components regression was performed on factor scores from a principle components analysis of the water chemistry variables and fish condition factor. Two factors, one associated with stream water ANC and ion concentrations, and another associated with SO 4 2− concentration, collectively explained 84% of the variance in condition factor. The influence of variables other than water chemistry upon R atratulus K is addressed. The results show that environmental chemistry is highly associated with the K of R atratulus.

Shenandoah National Park↗
USGS1989

Vegetation alteration along trails in Shenandoah National Park, Virginia

Most studies in the USA of vegetation alteration and human impact along trails have been located in large western wilderness areas. The objective of this study was to determine vegetation changes occurring along trails in an eastern ecosystem supporting second-growth deciduous forest. The location of this study was Shenandoah National Park in Virginia, which has a long history of trail use by humans. Located in different sections of the park, ten trails were chosen as study areas. In each, transects were established to measure ground flora in trailside, transition, and undisturbed areas perpendicular to the trail. Field data were collected on frequency, life-form, and percent cover for ground flora of 25 cm or less in height. Cover and species diversity increased toward the trail in eight out often cases. Competition for light and resistance to trampling were thought to influence the occurrence of plants along the transect. Plants found along the trail border were represented by low growthforms, early blooming, or graminoid characteristics, and hemicryptophyte, therophyte, or chamaephyte life-forms. Plants found in the undisturbed zone were represented by scattered cover and frequency, woody growth forms or delicate herbaceous forms, and phanerophyte or geophyte life-forms.

Virginia↗
USGS1988

Runoff for selected sites in Shenandoah National Park, Virginia, July 18, 1981, through July 17, 1982

Estimates of runoff for 56 sites within the Shenandoah National Park were made by the U.S. Geological Survey for the Direct/Delayed Response Project that is being conducted by the U.S. Environmental Protection Agency. The purpose of that project is to determine the long-term effects of acidic deposition on surface-water chemistry. Runoff was estimated for the period July 18,1981, through July 17,1982 during which periodic water-quality samples were collected for a study by the U.S. Geological Survey to determine the sensitivity of the area to the current input of acid deposition. The runoff values and waterquality samples will be used by the U.S. Environmental Protection Agency (EPA) to determine chemical budgets for 56 watersheds in the Park. The runoff estimates were determined by a graphical-correlation procedure. Six discharge measurements at each site were made when waterquality samples were collected; these were then correlated with the concurrent recorded discharges at one of 13 nearby streamflow-gaging stations. The mean discharge at the gaging station for the subject period was transferred through the relation line to estimate the mean discharge and runoff at the waterquality sampling site. The runoff estimates during the study period ranged from 10.9 to 38.7 inches. The accuracy of the method was evaluated by treating 13 nearby gaging stations as if they were water-quality sampling sites. A comparison of estimated and recorded runoff for the same period showed differences ranging from 28.2 to 49.5 percent, with an absolute average of 14.7 percent.

Virginia↗
USGS1969

Ancient lavas in Shenandoah National Park near Luray, Virginia

In the Blue Ridge Province of northern Virginia, Maryland, and southern Pennsylvania, Lower Cambrian beds are underlain by a thick sequence of greenstone and interbedded sedimentary rocks known as the Catoctin Formation. An area near Luray, Va., was studied to determine the thickness of the formation, its relationship to overlying and underlying rocks, and the original nature of the lavas from which the Catoctin greenstone was derived. There the Catoctin Formation lies unconformably on granitic rocks. Its basal sedimentary layer ranges from a few inches to 150 feet in thickness and contains pebbles of underlying basement rocks. The erosion surface beneath the Catoctin is irregular, and in several places, hills as much as 1,000 feet high were buried beneath the Catoctin lavas. No important time break is indicated between the deposition of the Catoctin Formation and the overlying Cambrian sediments. The original Catoctin lavas were basaltic and were probably normal plateau basalts. Columnar joints, amygdules, sedimentary dikes, flow breccias low-dipping primary joints, and other primary structures are well preserved.

Virginia↗
USGS1961

The trout fishery in Shenandoah National Park

Populations of brook trout in streams of Shenandoah National Park were reduced drastically early in the past decade by a succession of unusually severe droughts and floods. The drying of stream beds, predation, and scouring were principal factors in the loss of fish. The park was closed to fishing in 1954 and 1955 to protect survivors. The small numbers of survivors quickly repopulated the streams after drought conditions abated. The stocking of hatchery-reared fingerling trout in selected waters failed to augment the recovery of populations. Survival and growth of young, wild trout were especially good. Their redistribution through miles of previously dry streams was rapid. The park was opened again to fishing in 1956 under regulations which restrict the take but afford an increase in sporting opportunity. Two streams were placed under fishing-for-fun-only regulations in 1961. The welfare of the trout populations is dependent mostly on the weather cycle . Fish may be abundant in wet years but very scarc e in dry ones. Thus, the stream must be managed a s marginal for trout.

Virginia↗