Showing papers by "Thomas L. Davenport published in 2013"

Bogotá's Urban Wetlands: Environmental Issues

Abstract: INTRODUCTIONWetlands are areas that are inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions (taken from US Environmental Protection Agency Regulations). Wetlands generally include swamps, marshes, bogs, and similar areas. For years, wetlands were viewed as unproductive wastelands in many parts of the world. Their natural values were measured against the value of their use as dry land. Because the natural functions of wetlands were not well understood, the accepted practice was to drain them or fill them with soil in order to make the land more "useful" to humans. The human view of the wetlands is, on occasion, focused too narrowly on the economic value of the area. Wetlands, however, have functions that are overlooked as a vital part of the ecosystem. Wetlands are now recognized as important features in the landscape that provide numerous ecosystem services for people and for fish and wildlife. Some of these services, or functions, include protecting and improving water quality, providing fish and wildlife habitats, storing floodwaters, and maintaining surface water flow during dry periods. They are also important in enhancing the aesthetics of landscapes and are significant areas of biological productivity. These ecosystem services, considered valuable to societies worldwide, are the result of the inherent and unique natural characteristics of wetlands. However, the impacts, whether natural or anthropogenic can reduce the value of wetlands. Wetlands function like natural sponges, storing water and slowly releasing it. This process slows the water's momentum and erosive potential, reduces flood damages, and allows for ground water recharge, which contributes to base flow to surface water systems during dry periods.After being slowed by a wetland, water moves around plants, allowing the suspended sediment to drop out and settle to the wetland floor. Nutrients from fertilizer application, manure, leaking septic tanks, and municipal sewage that are dissolved in the water are often absorbed by plant roots and microorganisms in the soil. Other pollutants stick to soil particles. In many cases, this filtration process removes much of the water's nutrient and pollutant load by the time it leaves a wetland. As already mentioned, wetlands are some of the most biologically productive natural ecosystems in the world, comparable to tropical rain forests and coral reefs in their productivity and the diversity of species they support. Abundant vegetation and shallow water provide diverse habitats for fish and wildlife. Aquatic plant life flourishes in the nutrient-rich environment, and energy converted by the plants is passed up the food chain to fish, waterfowl, and other wildlife and to us as well.In recent years, wetlands have received a large amount of public attention. As a result, increased scientific study of these unique ecosystems at the global, national, state, and local levels has taken place. These studies have revealed the important biological, hydrological, terrestrial, and ecological functions wetlands perform. Knowledge of these functions has improved the recognition of wetlands as important, valuable ecosystems.In this chapter, we have examined 12 wetlands of Bogota, the largest city of Colombia. They include Santa Maria de Lago, Cordoba, Juan Amarillo, Capellania, La Vaca, el Burro, Techo, Tibanica, Jaboque, Guaymaral-Torca, La Conejera and Meandro del Say. Taken individually, they may appear to be small, but form a strong network of wetlands when taken collectively. The present-day wetlands are the remnants of a large wetland area that developed around 27,000 years ago when the Bogota basin became over-filled with sediments.Early indigenous people and Spaniard conquerors were the first human groups to interact with the magnificent wetlands of Bogota's savannah. …