When you step outside, whether heading for your car or for a walk around the block, you expect to be able to breathe the air. When planting flowers in the window box or tomatoes in the raised bed in your backyard, you expect those plants to grow, flower and produce seeds or fruit. When perusing the grocery shelves, you expect to find fresh produce, and affordable fish and meat. When you turn on the tap, you expect to be able to drink the water.
Ecosystem services are the processes through which natural ecosystems, and the plants, animals and microbes that live in those environments, sustain human life. Ecosystem services produce goods, timber, fibers, medicines and fuels. Ecosystem services even conduct life-support activities, like filtering water and recycling all kinds of wastes. The natural services that for millennia have purified the water and air, supported the growth and reproduction of food plants, controlled pests and even moderated the weather and its impacts are declining rapidly. Land clearing for agriculture, industry and mining, and development is affecting ecosystems worldwide. As habitats become fragmented, with only pockets left here and there, the services those natural systems provide become less effective. Tom Lovejoy, Chief Biodiversity Advisor at the World Bank, says other natural services, like waste decomposition and flood control, are often overlooked. Technology may duplicate these services temporarily, but it's doubtful that technological advances will be able to continually compensate for the large-scale loss of natural services. Although it is difficult to put a price tag on a wetland, forest or river, the "price" for failing to protect or nurture these natural services could be daunting. As we populate the planet, nature's services will become even more essential to humans and worthy of protection from even those who never leave the cities.
Wetlands: water purification system and natural flood control
Most wetlands are linked intricately with our groundwater and surface water supplies. By the end of the 20th century, the United States had lost about 30 percent of its historic wetlands to draining, development, and agriculture. Over 85 percent of the inland surface water was controlled artificially and more than half the nation's fish populations were suffering from the effects of water pollution and high temperatures. Yet, wetlands continue to provide crucial ecological services, including filtering and conserving water, flood control, and shelter and food for fish and wildlife. Wetlands also help maintain cycles essential for life on earth, such as the carbon, methane, nitrogen, and sulfur cycles. Resource managers now realize that preservation and restoration of wetlands and natural waterways may be a more cost effective means of maintaining drinking water quality than expensive water treatment technologies.
Today, New York City faces such a choice. The City' s clean, clear water, which originates in the Catskill Mountains, is in jeopardy of failing drinking water standards. After exploring the technological and natural options for filtering water, New York City chose a watershed protection approach that preserves and restores nature' s services. It's a choice that will affect every New Yorker, as well as the state's rural residents.
Communities across the nation and worldwide are facing similar choices between protecting natural resources that provide services humans need or implementing expensive technological solutions. The city of Arcata, California, rejected a costly plan to pipe waste from the community's wastewater treatment plant across Humboldt Bay, and dump it directly into the Pacific Ocean. Instead, they chose the natural processes provided by wetlands to filter their wastewater. The Arcata Marsh and Wildlife Sanctuary was created in 1981 and wastewater treatment was added in 1986. Both humans and wildlife benefit from the wetland's water purification and habitat services.
In Tulsa, Oklahoma, residents and businesses located on the Arkansas River floodplain were experiencing devastating floods every decade. In addition to loss of human life, thousands of buildings were damaged, with millions of dollars lost in 1976 and 1984 Memorial Day floods. Tulsa decided to quit battling nature and responded by moving vulnerable buildings out of the floodplain. Managers opted for a watershed-wide approach to storing and draining the vast amounts of stormwater runoff produced during heavy rains. In essence, wetlands were allowed to become wetlands once more. As a result, Tulsa's flood insurance rates have dropped by 25 percent and are now among the lowest in the nation. The tradeoffs for protecting natural system functions often can be win-win situations, as seen by Tulsa's lower insurance rates and less flood damage when floodplains are protected from human development.
Forests: our carbon reserves
Natural services provided by forests go beyond shade, timber, and wildlife habitat. The vast tracts of deciduous and evergreen trees that cover more than 25 percent of the ice-free land on the planet help stabilize landscapes by protecting soils and retaining moisture. Although forests today cover only about half what they did historically, they remain major sites for carbon storage, are important for nutrient cycling and help moderate local and regional climate through rainfall. Carbon-storing forests may even moderate global warming.
Boreal, tropical and temperate forests store 1,200 gigatons (billion tons) of carbon in their plants and soils. Compare that with the 750 gigatons stored in the earth's atmosphere. Even the urban forests of Chicago, with their 50.8 million trees, are estimated to store approximately 155,000 tons of carbon per year. US Department of Agriculture scientists calculate that converting the 22 million acres of marginal cropland and pasture in the southern United States to forest would increase carbon storage in the region by 32 million tons per year. This could offset 3 percent of the country's annual carbon dioxide emissions. When forests are burned, carbon is released to the atmosphere. Researchers estimate that the yearly worldwide releases of atmospheric carbon from the burning of forests are increasing even more rapidly than the amount of atmospheric carbon released from the burning of fossil fuels.
We lose a lot more than carbon storage when we clearcut forests. Huge amounts of soil are lost when forests are cleared and erosion escalates. In Nepal, where trees are needed to stabilize steep slopes, between 30 to 75 tons of soil wash from each hectare of cleared land each year. Nepal may contribute as much as 240 million cubic meters of soil each year to neighboring India's lowlands and waterways. In Africa, the deforestation of Ethiopia's forests from about 10 percent of land cover to only 3 percent has resulted in topsoil flowing from the country's high lands into the Blue Nile River. There, it silts up the Roseires Dam, hundreds of miles downriver in Sudan.
Forests also help regulate the water cycle when tree roots soak up rainfall; stems, trunks and roots slow runoff; and tree leaves release water back into the atmosphere. In addition, plant and animal biodiversity depends on intact, mature forests. In some cases, even human health may rely on that biodiversity. Many medicines have been isolated from plant compounds. Deforestation can contribute to a resurgence or redistribution of infectious disease, when the ecosystem processes that allow natural pest control are disturbed. In South America, insecticide-resistance, declining investments in public health programs and forest clearing have contributed to a resurgence in malaria. Malaria-carrying mosquitoes are normally consumed by a wide variety of reptiles, birds, bats and fish. Forest clearing removes habitat for these creatures, but clears the way for standing water where mosquitoes can breed freely.
Forecasting the future of nature's services
If current trends continue, humans could dramatically and irreparably alter the planet's remaining natural ecosystems within decades. To determine what should be saved or restored now, politicians and resource managers need to know how their actions (or failure to act) may affect the future. Although actually forecasting specifics is currently difficult, modeling the activities within small-scale geographic regions that provide a series of services is feasible. Forecasting can determine at what point an ecosystem's ability to provide services may break down. The Institute for Ecological Economics, at the University of Maryland, is trying to give decision-makers an idea of how today's activities might affect the Patuxent River, which flows into Chesapeake Bay, tomorrow. By developing new software and tools, researchers hope to improve the predictive ability of models that integrate watershed ecosystems with their human occupants.
The precision of future forecasting is dependent on the data gathered today. New technologies are helping gather and analyze the vast amount of information necessary to understand nature's services. Computer models can simulate some ecological conditions and economic projections, but integrating long-term environmental scenarios with economic behaviors and consequences is still in the development stage. Ecosystem model development has been going on for decades. A watershed model, like the Patuxent Landscape Model (PLM), utilizes environmental data from a number of studies of the Patuxent River watershed in Maryland. This river drains into Chesapeake Bay. Currently, the PLM ecosystem model can simulate "what if" scenarios, but human behavior must be input, rather than modeled internally. The ability to integrate economic factors, such as transportation, land use changes or landowner behavior is still under development.
Global changes, from climate warming and sea level rise, to shifts in land use and population growth, will affect the flow of ecosystem goods and services. Reliable forecasting of how these changes will alter the supply and flow of ecosystem benefits requires extensive taxonomic, ecologic, economic and sociologic understanding. Accurate forecasting models require, not only understanding how the ecosystem works, but also placing a value on its functions and products, as well as predicting how things might change over time. Long-term data and strategies for future monitoring of both the environment and the economy are needed to provide an index of change.
Probably the best-known example of forecasting based on computer modeling is the weather. Predictions of local weather conditions often are fairly accurate. Longer-term forecasts, for even the next week, are less accurate. And when it comes to predicting the next year's weather, the Farmer's Almanac is probably consulted as often as the National Weather Service. Scientists are not deterred, however, and forecasting tools that integrate societal aspects, like food production and health, are probably just on the horizon. A recently developed model that examines the effects of climate change on rice production offers detailed scenarios of how increased carbon dioxide levels and temperature could affect major rice-producing countries in Asia. Such forecasting could give governments and farmers time to adapt their planting dates, experiment with rice varieties, and research other cropping practices to accommodate long-term changes in weather and climate.
Forecasting human health epidemics, based on weather patterns, has the potential to give governments and public health workers up to a year to get ready for a predicted disease. Climatic forecasting for southern Africa, which is affected significantly by the Pacific's El Niño and La Niña events, could help predict droughts and floods. Droughts in Mozambique have been associated with cholera, dysentery and plague. In 1995, La Niña-caused flooding in Mozambique and South Africa spurred upsurges in malaria. Researchers at the Liverpool School of Tropical Medicine note that much of the environmental information needed to develop a weather and malaria model is already available. Satellite imagery, and meteorological and climate data can provide the rainfall, temperature and humidity information most critical to predicting malaria epidemics. Such early warning systems will have to be extremely reliable. The price of a false prediction, in terms of both resources and credibility, would be substantial. On the other hand, reliable malaria forecasting warning systems could give public health workers time to budget and order drugs and insecticides, as well as launch a public health education campaign.
Forecasting the future is mostly still in the future. But, the data-gathering and technology development conducted today will help create reliable models for future forecasting.
