What's at Stake at Ragged Mountain

One of the main reasons so many people are opposed to a huge (and, arguably, unnecessary) expansion of the Ragged Mountain Reservoir is that it will result in the loss of up to 60,000 trees over 200 acres of biologically-rich forest at the Ragged Mountain Natural Area. New & enlarged roads would have to be built through the Natural Area in order to construct the I-64 embankment and other components of the reservoir expansion project, resulting in a significant level of forest fragmentation. The City's newly-adopted water supply plan does call for a modest expansion of the Ragged Mountain Reservoir, but one that (at least at the outset) does not require an embankment at I-64 and impacts far fewer forested acres.

If you have never been out to the Ragged Mountain Natural Area, please consider heading over there for a hike on one of the beautiful fall days that lies ahead. I have hiked the reservoir trail dozens of times over the years and it's a lovely way to "get away from it all" while staying quite close to home. The Ivy Creek Foundation manages the Ragged Mountain Natural Area for the City of Charlottesville and describes the area thusly:

The Ragged Mountain Natural Area near Charlottesville, Virginia, is a beautiful 980-acre forest of mature oak, hickory, poplar, pine, and maple trees with two lakes and more than four miles of shoreline. Seven miles of trail lead through majestic forest, along rugged terrain, and through areas rich with wildlife and offer a unique opportunity for wilderness hiking within minutes of town.

The area is rich in birdlife with native woodpeckers, yellow-bellied sapsuckers, and northern flickers in the winter. In the spring, keep an eye out for songbirds migrating through such as blue-winged and Tennessee warblers. Fall brings the migrant blackpoll and bay-breasted warblers as well as hermit thrush. Nesting neotropical songbirds include pine, yellow-throated, and yellow warblers, northern parula, yellow-breasted chat, chipping and field sparrows, and red-eyed and yellow-throated vireos are best seen in early spring before the foliage gets too heavy.

Other wildlife includes the upland chorus and northern cricket frogs are in residence here, as is the American toad and spring peeper. Several species of bats are known to hunt insects here including eastern pipistrelle, evening bat, and bag brown bat. Many, many species of mammals live here. Among the large mammals, the white-tailed deer is particularly abundant. Occasional visits by black bear and sightings of bobcat are also not uncommon.

A more thorough description of flora and fauna that can be found at the Ragged Mountain Natural Area can be seen here.

A guide for local birders, published by the Monticello Bird Club in 2003, notes that one of the reasons the Ragged Mountain Natural Area is such an inviting habitat for wildlife (and birds in particular) is the fact that the forest there is largely intact. I quote:

Fertile soils and relative non-disturbance for the past 100 years have produced a mature oak-poplar forest with shaded ravines, fern-dappled coves, and abundant wildlife.... A 2002 study of the effects of forest fragmentation on nesting success of songbirds in 8 sites in the Piedmont found Ragged Mountain to be the most productive for Wood Thrushes with 64 nests and the greatest number of fledglings. Dr. Etterson of the Smithsonian Center for Migratory Birds attributes the success to the relative maturity of the intact forest at Ragged Mountain.

If there's any doubt as to the myriad benefits of preserving as much forest habitat (and specifically, contiguous forest habitat) as possible, check out the following passages from the "Biological Resources and Biodiversity" section of Albemarle County's own 2006 Comprehensive Plan:

Habitat Fragmentation

The major causes, world-wide, for the reduction of species are destruction and fragmentation of habitat. Other causes include introduction of exotic and non-native species and over-exploitation.

Here, we are concerned with fragmentation, which is of particular concern to Albemarle. Fragmentation is the carving-up of habitats into ever-smaller areas, with the accompanying lack of connections, called “corridors,” among the fragments. While fragmentation is known to be biologically and ecologically destructive to biodiversity, the prediction of effects with a high degree of certainty can be problematical, requiring expert assessment.

Benefits of Unbroken Habitats

Conventional wisdom dictates that the more contiguous a habitat or ecosystem, the greater number and variety of birds, animals, and plants it will support. Also, it is often assumed that unbroken habitats provide continuous protective pathways for the safe movement or migrations of animals or expansions of plants. These statements, however, can be misleading, as they apply mainly to species that are at least somewhat obligate to the habitat or ecosystem in question. Whereas fragmentation can be devastating to those species, it can also actually increase the total number of species. But the downside to that apparent benefit is that those latter species are likely to be what ecologists call “weedy” or “opportunistic,” and hence undesirable (for example the cowbird, which is a nest parasite on warblers and other birds and is a major factor in their decline.)

Forests, in particular, are an important asset for Albemarle. Many birds, mammals, reptiles, amphibians, and aquatic species depend upon this dominant habitat for their survival. Additionally, the protection afforded by the forest’s leafy canopy helps improve air quality and modulates microclimate. Forested areas also protect and maintain the purity of groundwater and stream and river water. Forests serve as filters to trap sediment and absorb pollutants from overland runoff. Loss of topsoil and silt into surface waters can smother the gravel bottoms that are breeding habitats of most of our stream fishes and the aquatic insect larvae that are the food for these fishes. Forests along rivers and streams help make waterways livable for many species. For example, many shrubs, grasses, and vines grow well in moist and fertile soils of large unbroken forested areas, but may not do well elsewhere. Plant material falling into the water also provides a food source. Shade from the tree canopy helps maintain a low water temperature, and tree roots help stabilize the bank and provide shelter.

Finally, forests contribute to Albemarle’s natural beauty, complement the cultural resources of the area and enhance the County as a desirable place to live, recreate, and visit.

Effect of Habitat Fragmentation on Species

The decline of many plant and animal species in Albemarle can be attributed to large-scale tree clearing, or by development activities such as woodland subdivisions, power lines, and roads. The habitat fragments that these activities produce differ from the original habitat in two important ways:

1) the center of a fragmented area is closer to the fragment’s edge;
2) the amount of edge relative to the amount of interior habitat is dramatically increased.

Because of fragmentation, the center of the habitat is closer to the edge, which exposes the species within to increased predation and competition. Furthermore, the habitat’s edge represents a dynamic environment into which many other species can invade. Thus, fragmentation not only increases the number of predators within the edge, but some of these predators compete for the same food supply as species within the habitat. For instance, predatory animals may decimate insect and amphibian populations in edge areas.

Forest fragmentation also reduces the ability of a species to move freely across a habitat to forage, to find mates, or to disperse to neighboring habitats. The resulting isolation and reduced population numbers may, in turn, lead to loss of genetic variability, which reduces a species’ viability and its ability to deal with environmental fluctuations, disease and predation. Also, many plant species that rely on animals to transfer seeds are also affected, which can have widespread ecosystem consequences.

The interactive sequence of events described in the preceding paragraph is termed an “environmental cascade,” which does not end at the level of the habitat. Some regional effects of forest clearing and fragmentation, for example, include changes in reflected solar radiation, air and soil temperature, wind, and incidence of fire. Plant cover offers shade and protection of soils, particularly in forest communities, which maintain relatively cool, moist, and shaded environments during spring and summer days, and trap heat during the night. Effects of largescale clearing and development are currently having nation-wide to global ramifications, with marked changes in species diversity and ecosystem services.

Very well-said.

For all of these reasons and more, I have long believed we need a water supply solution that provides enough water for human consumption and improves the ecology of our rivers and streams, but not at the expense of substantial and avoidable destruction & fragmentation of forest habitat. In my opinion, the water supply plan adopted by City Council last week strikes a much better balance in this regard than the plan from 2006 that it replaced.