Ecology And Environment

How Construction and the Built Environment can both Benefit and Harm the Natural



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"How Construction and the Built Environment can both Benefit and Harm the Natural"
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In these days of ever-expanding suburban sprawl, it might seem that construction would only harm the natural environment. However, as usual, there is another side to the story. While it is true that a large warehouse-type structure or paved parking lot, by its sheer extent of coverage of what was once the habitat of plants and animals, is probably more harmful than beneficial, this is one extreme on the spectrum of construction types.

One of the most basic types of beneficial construction is that which is built to mitigate the harmful effects of another construction. For example, by tunneling through a mountainside, a highway avoids the need to rearrange the natural topography. Delicate mountain plants that grow on rock faces can continue to grow right up to the edge of the tunnel, instead of losing precious habitat to grading and paving. Similarly, elevated highways in mountainous terrain allow for the safe movement of wildlife beneath them, rather than subjecting them to the risks of crossing over the highway.

One of the more common types of construction specifically for the benefit of the environment is the building of artificial reefs. Reefs are important feeding and/or spawning grounds for certain fishes and other marine wildlife, and artificial reefs allow some of these to expand into areas where they otherwise could not have lived. In some areas, offshore oil rigs have had the same effect.

The case of the bluebird gives an example of similar nature. Bluebirds are a grassland species, but nest in hollow trees. Obviously, hollow trees are much harder to come by on grassland than in the woods. But many conservation-minded people in bluebird country now maintain "bluebird trails" - that is, a string of nest boxes, often mounted on fence-posts in the open grassland. This provides many more nesting locations than the bluebirds could ever find if they had to rely solely on hollow trees. Another example is the chimney swift. Originally, it, too, most likely nested in hollow trees; but with the clearing of forest land for agriculture, there soon were not enough such trees left. Fortunately, the trees were replaced by chimneys, which served the bird's purposes nicely, and nowadays, the chimney swift is believed to nest solely in chimneys and similar built structures, having abandoned hollow trees entirely.

More often, the beneficial effects of construction are incidental, and may occur only after the harmful effects. One example of this would be underground mines. Tailings build up around the mine entrance, burying soils and vegetation, and depending on their mineral content, possibly leaching toxic substances into the groundwater. But after the mine is played out, the abandoned mine-shafts may become homes for bats or other cave-roosting wildlife. For safety, the entrance may be bared to keep out curious humans, while still allowing bats free passage in and out.

A similar case is the open-pit quarry. While the rock is being mined, this construction is harmful, in that it strips away vegetation, alters topography and soil structure, and may contribute to sedimentation of nearby streams. But once quarrying has ceased, depending on the water table, some old quarries fill with water and can become ponds or lakes where there was no pond or lake before.

Generally speaking, any construction must be considered in context. Take, for example, wind farms. Acres and acres of spinning windmills generate electricity in some regions. Some people have criticized these as being a hazard to birds, which may be killed by the spinning blades; and also as using up land that would otherwise be valuable habitat for other wildlife. But when the wind farm is considered in context, a different picture emerges. Suppose, instead of wind power, the city used a coal-fired power plant. This is still the most common type of power plant. A coal-fired power plant not only releases greenhouse gases into the atmosphere, but its complex of buildings is even less amenable to wildlife habitat than the wind farm. Seen in this light, the wind farm, even with its problems, is still the better alternative.

Then there is the case of the construction of a fish hatchery. With fishery stocks in decline in all the world's oceans, hatchery fish, it can be argued, serve to bolster populations and prevent them disappearing entirely. The same can be said for any construction built expressly for conservation purposes: provided it is carefully planned, its benefit to the environment probably outweighs its cost in terms of habitat loss and energy usage.

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