Index
- Introduction
- Visibility
- Natural Background Visibility
- Vegetation
- AQRV Type VISIBILITY
- AQRV Type WATER
- Pollutant Exposure Concern Thresholds
- General Information
Introduction
The James River Face Wilderness (8,903 acres) is located on the Jefferson National Forest in Virginia, between the James River on the north and Blue Ridge Parkway to the south. The elevation of the Wilderness ranges from 650 - 3073 feet. Higher elevation is characterized by steep and rugged terrain, with thin to rocky soils and numerous cliffs and bluffs. The vegetation is predominantly chestnut oak and yellow pine with a heath understory. Lower elevation is characterized by deeper soils that support white pine, hemlock and a mix of hardwood species.
Air Quality Related Values
Visibility
The scenic beauty of James River Face is one of the most important features of the wilderness. The James River, at the northern boundary of the wilderness, existed prior to the last uplift of the Blue Ridge Mountains. The uplift of the surrounding Blue Ridge Mountains in combination with the downward cutting of the River have resulted in a picturesque gorge readily viewed from the river itself and a State highway across the river. The area is characterized by steep and rugged ridges with numerous cliffs and bluffs. The most striking characteristic is frequently reported to be the expansive views offered by numerous bluffs. Closer inspection of this scenic landscape yields features of geologic interests such as Devil's Marbleyard, an impressive 8-acre boulder field on the slopes of Gunter Ridge. The mountain scenery is further enhanced by the exceptionally steep gradients present. From the James River to High Cock Knob (roughly 3 miles) the elevation rises more than 2,300 feet.
The Appalachian Trail and numerous spur trails run through the Wilderness. These trails provide the users with many views across and out from the Wilderness. James River Face is also the focus of several vantage points on the Blue Ridge Parkway which forms the southern boundary of the Wilderness.
Natural Background Visibility | ||||||
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Site Specific Rayleigh scattering coefficient: | Clearest 20% Natural | Clearest 20% 2000-2004 Baseline | Haziest 20% Natural | Haziest 20% 2000-2004 Baseline | Average Annual Natural | Annual Average 2000-2004 Baseline |
Standard Visual Range (km) | 270 | 97 | 133 | 21 | 193 | 48 |
Haze Index (dv) | 4.39 | 14.21 | 11.13 | 29.12 | 7.55 | 21.17 |
Vegetation
The rugged landscape and location of the Wilderness have resulted in a variety of environments within its boundaries. The gorge along the James River and the riparian areas along other streams provide moist to wet habitats, while the shallow soils and steep slopes on the ridges combine to make very dry environments. Elevation, which ranges from 650 feet to 3073 feet, provides even more modification of climate. These diverse habitats have been exploited by a wide variety of plants.
The gorge provides for a short passage through the Blue Ridge and connects the Great Valley with the Piedmont physiographic province. This has provided a natural dispersion route for many plants. In addition, the river has been a major travel way in historic times, so man has also been responsible for moving many plants into and through the area. This has all resulted in a tremendous diversity of vegetation in the Wilderness. About 800 species of plants have been collected here, representing almost a third of all of the species recorded in Virginia. The area has been noted for its rhododendron and azalea displays and for the Carolina hemlock. The Carolina hemlock is a tree noted for its beauty in form and lustrous color and reaches its northern terminus on the slopes of the James River gorge. Cove hardwoods dominate the moist sites, while northern red oak, chestnut oak and yellow pine are the dominate timber types through the rest of the area. Some of the driest areas are represented by the shale barrens on Hickory Stand Mountain and the boulder fields, such as Devils Marbleyard, where lichens are the dominant vegetation. Bulbous bluegrass (Poa bulbosa) and the typha-like sedge (Carex typhina) reach their westernmost limit at the gorge. Three species of plants present in the Wilderness are listed as being extremely rare. These are the clammyweed, the star-flowered Solomon's seal and the Kanakakee mallow. This diversity of vegetation provides the wilderness user a variety of experiences. Each of the habitats and each of the species of vegetation, from the unusual and rare species to the common, but dominant timber species, are important components of the diverse vegetative community which is James River Face Wilderness.
Resource Concern Thresholds
AQRV Type: VISIBILITY | ||
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Sensitive Receptor | Sensitive Receptor Indicator | Thresholds |
Natural Visibility | Light Extinction | In specific Class I areas to maintain consistency with Regional Haze implementation plans or BART, the visibility threshold for concern is not exceeded if the 98th percentile change in light extinction is <5% for each year modeled, when compared to the 20% best natural background values. |
Natural Visibility | Light Extinction | For sources generally further than 50 km from a Class I area, the visibility threshold for concern is not exceeded if the 98th percentile change in light extinction is <5% for each year modeled, when compared to the annual average natural condition value for that Class I area. |
Plume Blight | Absolute Contrast | Screening Analysis: For near field sources (within 50 km of a Class I area), no additional analysis will be requested if screening analysis of a new or modified source can demonstrate that its emissions will not cause a plume with hourly estimates of DeltaE (color difference index) greater than or equal to 2.0 or the absolute value of the contrast greater than or equal to 0.05 when modeled against natural conditions. |
Plume Blight | Absolute Contrast | Refined Analysis: No further analysis will likely be requested if a new or modified source can show that impacts from a new or modified source will stay with the threshold of DeltaE <1.0 and |C| <0.02 modeled against natural conditions. |
Plume Blight | Color Difference Index | Screening Analysis: For near field sources (within 50 km of a Class I area), no additional analysis will be requested If screening analysis of a new or modified source can demonstrate that its emissions will not cause a plume with hourly estimates of DeltaE (color difference index) greater than or equal to 2.0 or the absolute value of the contrast greater than or equal to 0.05 when modeled against natural conditions. |
Plume Blight | Color Difference Index | Refined Analysis: No further analysis will likely be requested if a new or modified source can show that impacts from a new or modified source will stay with the threshold of DeltaE <1.0 and |C| <0.02 when modeled against natural conditions. |
AQRV Type: WATER | ||
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Sensitive Receptor | Sensitive Receptor Indicator | Thresholds |
Perennial Streams | Acid Neutralizing Capacity | In perennial streams, no more than 0.1 microequivalent/liter measurable decrease in acid neutralizaing capacity is acceptable |
Perennial Streams | Chronic Acid Neutralizing Capacity | To maintain healthy biological functioning in perennial streams, the chronic acid neutralizing capacity must be >= 25 ueq/l. |
Perennial Streams | Chronic pH | To maintain healthy biological functioning, the chronic pH of perennial streams must be >= 6.0. |
Perennial Streams | Episodic Acid Neutralizing Capacity | To maintain healthy biological functioning in perennial streams, the episodic acid neutralizing capacity must be >= 0 ueq/l. |
Perennial Streams | Episodic pH | To maintain healthy biological functioning, the episodic pH of perennial streams must be >= 5.5. |
Perennial Streams | pH | In perennial streams, no more than 0.1 measurable decrease in pH is acceptable |
Pollutant Exposure Concern Thresholds | ||
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Pollutant Exposures | Level Name | Thresholds |
Nitrogen | DEPOSITION | Nitrogen deposition may be expected to cause cation leaching in soils when N levels are greater than 12 kg/ha/yr. Below 5 kg/ha/yr, negative effects to soil and vegetation are not expected |
Nitrogen | EXCEEDANCE | The Deposition Analysis Threshold for nitrogen deposition below which estimated impacts from a source are considered negligible is 0.010. kilograms/hectare/year. |
Ozone | W126 | Biomass reduction of ozone sensitive species may occur when the W126 ozone metric (for April-September) is ≥ 14.5 ppm-hours. This should be evaluated in conjunction with the N100 value. |
Ozone | N100 | Biomass reduction of ozone sensitive species may occur when the number of hours from APRIL-SEPTEMBER with an ozone concentration greater than or equal to 0.100ppm equals or exceeds 4. This should be evaluated in conjunction with the W126 value. |
Sulfur | DEPOSITION | Sulfur deposition may be expected to cause cation leaching and increased aluminum toxicity in soils when levels are greater than 20 kg/ha/yr. At 5 kg/ha/yr or below, sulfur negative effects to soil and vegetation are not expected. |
Sulfur | EXCEEDANCE | The Deposition Analysis Threshold for sulfur deposition below which estimated impacts from a source are considered negligible is 0.010 kg/ha/yr. |
General Information | |
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State(s): | Virginia |
County(s): | Bedford, Rockbridge |
Forest Service Administrative Unit(s): | Southern Region (Region 8) -- Jefferson National Forest |
Size: | 8886 acres |
Elevation Range: | 650 - 3,073 feet |
Image(s): | https://www.wilderness.net/images/ |
Detailed wilderness information: | https://www.wilderness.net |
GIS Map/Official Boundary: | https://www.wilderness.net/NWPS/ |
updated: 02/28/13