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Classification of ecosystem functions, goods and services
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Table 1 below provides an overview of the main functions, goods and services that can be attributed to natural ecosystems and their ecological structures and processes. The first column indicates a list of functions and the second column lists the ecological structures and processes underlying these functions. The third column provides a more detailed list with examples of specific goods and services derived from these functions (not exhaustive). In Table 1, only those goods and services are included that can be used on a sustainable basis, in order to maintain the ecosystem functions and associated ecosystem processes and structures. Given these restrictions, important non-renewable natural mineral resources like gold, iron, diamonds, and oil are excluded from this list. Furthermore, energy sources that cannot be attributed to a certain ecosystem type are excluded, e.g. wind and solar-energy. On the other hand, some non-ecosystem specific functions that can be used without (permanently) affecting the other functions, such as the use of natural waterways for transportation, is included. Also some mineral resources that are renewable within a time-frame of 100–1000 years, like sand on beaches provided by dead coral and shells, are included.
Since the use of one function may influence the availability of other functions, and their associated goods and services, the capacity of ecosystems to provide goods and services in a sustainable manner should be determined under complex systems conditions. The ecosystem processes and components described in the second column of Table 1 should, therefore, be used in dynamic modeling to make these interdependencies, and the implications for their valuation, more explicit. It should be realized that ecosystem processes and services do not always show a one-to-one correspondence: sometimes a single ecosystem service is the product of two or more processes, whereas in other cases a single process contributes to more than one service. For example, the function ‘gas regulation’ is based on biogeochemical processes (like carbon and oxygen cycling) which maintain a certain air quality but also influence the greenhouse effect and thereby climate regulating processes. Furthermore, analysis of ecosystem functions and services involves different scales, notably the physical scale of the ecosystem function itself, and the scale at which humans value the goods and services provided. It is not a necessary condition that the two correspond. When valuing ecosystem functions, these inter-linkages and scale issues should be made clear.
Table 1
Functions, goods and services of natural and semi-natural ecosystems
| Functions | Ecosystem processes | Goods and services (examples) |
| Regulation Functions Maintenance of essential ecological process and life support systems | ||
| Gas regulation | Role of ecosystems in bio-geochemical cycles (e.g. CO2/O2 balance, ozone layer, etc.) | UVb-protection by O3 (preventing disease); Maintenance of (good) air quality; Influence on climate |
| Climate regulation | Influence of land cover and biol. Mediated processes (e.g. DMS-production) on climate | Maintenance of a favorable climate (temperature., precipitation, etc), for example, human habitation, health, cultivation |
| Disturbance prevention | Influence of ecosystem structure on dampening environmental disturbances | Storm protection (e.g. by coral reefs); Flood prevention (e.g. by wetlands and forests) |
| Water regulation | Role of land cover in regulating runoff & river | Drainage and natural irrigation; Medium for transport |
| Water supply | Filtering, retention and storage of fresh water | Provision of water for consumptive use (e.g. drinking, irrigation and industrial use) |
| Soil retention | Role of vegetation root matrix and soil biota in soil retention | Maintenance of arable land; Prevention of damage from erosion/siltation |
| Soil formation | Weathering of rock, accumulation of organic | Maintenance of productivity on arable land |
| Nutrient regulation | Role of biota in storage and re-cycling of nutrients | Maintenance of healthy soils and productive |
| Waste treatment | Role of vegetation & biota in removal or breakdown of xenic nutrients and compounds | Pollution control/detoxification; Filtering of dust particles; Abatement of noise pollution. |
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2.1. Regulation functions and related ecosystem ser v ices
Natural ecosystems play an essential role in the regulation and maintenance of ecological processes and life support systems on earth. The maintenance of the earth’s biosphere as humanity’s only life support system in an otherwise hostile cosmic environment depends on a balance between many ecological processes. Some of the most important processes include the transformation of energy, mainly from solar radiation, into biomass (primary productivity); storage and transfer of minerals and energy in food chains (secondary productivity); biogeochemical cycles (e.g. the cycling of nitrogen and other nutrients through the biosphere); mineralization of organic matter in soils and sediments; and regulation of the physical climate system. All these processes, in turn, are regulated by the interplay of abiotic factors (i.e. climate) with living organisms through evolution and control mechanisms. In order for humans to continue to benefit from these functions, we need to ensure the continued existence and integrity of these natural ecosystems and processes. Because of the indirect benefits of regulation functions, they are often not recognized until they are lost or disturbed, but they are nevertheless essential to human existence on earth.
2.1.1. Gas regulation
Life on earth exists within a narrow band of chemical balance in the atmosphere and oceans, and any alterations in that balance can have positive or negative impacts on natural as well as social and economic processes. The chemical composition of the atmosphere (and oceans) is maintained by bio-geochemical processes which, in turn, are influenced by many biotic and a-biotic components of natural ecosystems. Important examples are the influence of natural biota on processes that regulate the CO2/O2 balance, maintain the ozone-layer (O3), and regulate SO x levels. The main services provided by the gas regulation function are the maintenance of clean, breathable air, and the prevention of diseases (e.g. skin cancer), i.e. the general maintenance of a habitable planet. An important issue when trying to determine the service value from this ecosystem function is the scale at which the analysis is carried out. For example, the influence of 1 hectare of ocean, or forest, as a carbon-sink is difficult to measure. However, the cumulative effect of losing 50% of the earth forest-cover, or 60% of the coastal wetlands, and the reduction of algae-productivity in large parts of the oceans due to pollution, on the gas regulation function is considerable.
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2.1.2. Climate regulation
Local weather and climate are determined by the complex interaction of regional and global circulation patterns with local topography, vegetation, albedo, as well as the configuration of, for example, lakes, rivers, and bays. Due to the greenhouse- properties of some atmospheric gases, gas regulation (see above) also plays an important role in this function, but reflectance properties of ecosystems are also important in determining weather conditions and climate at various scales.
The services provided by this function relate to the maintenance of a favorable climate, both at local and global scales, which in turn are important for, among others, human health, crop productivity, recreation and even cultural activities and identity.
2.1.3. Disturbance pre v ention
This function relates to the ability of ecosystems to ameliorate ‘natural’ hazards and disruptive natural events. For example, vegetative structure can alter potentially catastrophic effects of storms, floods and droughts through its storage capacity and surface resistance; coral reefs buffer waves and protect adjacent coastlines from storm damage. The services provided by this function relate to providing safety of human life and human constructions.
2.1.4. Water regulation
Water regulation deals with the influence of natural systems on the regulation of hydrological flows at the earth surface. This ecosystem function is distinct from disturbance regulation insofar as it refers to the maintenance of ‘normal’ conditions in a watershed and not the prevention of extreme hazardous events. Ecosystem services derived
from the water regulation function are, for example, maintenance of natural irrigation and drainage, buffering of extremes in discharge of rivers, regulation of channel flow, and provision of a medium for transportation. A regular distribution of water along the surface is, therefore, quite essential, since too little as well as too much runoff can present serious problems.
2.1.5. Water supply
This ecosystem function refers to the filtering, retention and storage of water in, mainly, streams, lakes and aquifers. The filtering-function is mainly performed by the vegetation cover and (soil) biota. The retention and storage capacity depends on topography and subsurface characteristics of the involved ecosystem. The water supply function also depends on the role of ecosystems in hydrologic cycles (see function No. 4), but focuses primarily on the storage capacity rather than the flow of water through the system. Ecosystem ser vices associated with water supply relate to the consumptive use of water (by households, agriculture, industry).
2.1.6. Soil retention
The soil retention function mainly depends on the structural aspects of ecosystems, especially vegetation cover and root system. Tree roots stabilize the soil and foliage intercepts rainfall thus preventing compaction and erosion of bare soil. Plants growing along shorelines and (submerged) vegetation in near-coastal areas contribute greatly to controlling erosion and facilitating sedimentation. The services provided by this function are very important to maintain agricultural productivity and prevent damage due to soil erosion (both from land slides and dust bowls).
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2.1.7. Soil formation
Soil is formed through the disintegration of rock and gradually becomes fertile through the accretion of animal and plant organic matter and the release of minerals. Soil-formation usually is a very slow process; natural soils are generated at a rate of only a few centimeters per century and after erosion, soil formation (or regeneration) from bedrock takes 100–400 years per cm topsoil (Pimentel and Wilson, 1997). Ecosystem services derived from soil formation relate to the maintenance of crop productivity on cultivated lands and the integrity and functioning of natural ecosystems.
2.1.8. Nutrient cycling
Life on earth depends on the continuous (re)cycling of about 30–40 of the 90 chemical elements that occur in nature. In addition tocarbon (C), oxygen (O), and hydrogen (H) (which have been discussed in the gas-, climate- and water-regulation services) the most important nutrients are nitrogen (N), sulfur (S) and phosphorous (P). Other so-called macro-nutrients are calcium, magnesium, potassium, sodium and chlorine. Furthermore, a large number of so-called trace elements are needed to maintain life, including, for example, iron and zinc. The availability of these elements is often a limiting factor to the growth and occurrence of life forms and constant (re)cycling of these nutrients is, therefore, essential. Many structural and functional aspects of natural ecosystems facilitate nutrient cycling at local and global scales. For example, soil organisms decompose organic matter thereby releasing nutrients to both local plant growth, but also to the atmosphere; algae in coastal waters perform this same function. Also, migration (of birds, fish and mammals) plays an important role in the distribution of nutrients between ecosystems.
Ecosystem services derived from nutrient cycling are mainly related to the maintenance of ‘healthy’ and productive soils. Furthermore, nutrient cycling plays an important role in the gas-, climate- and water-regulation functions.
2.1.9. Waste treatment
To a limited extent, natural systems are able to store and recycle certain amounts of organic and inorganic human waste through dilution, assimilation and chemical re-composition. Forests, for example, filter dust particles from the air, and wetlands and other aquatic ecosystems can treat relatively large amounts of organic wastes from human activities acting as ‘free’ water purification plants.
Vocabulary
waste treatment - удаление отходов, переработка мусора
dilution - растворение вредных выделений в окружающей атмосфере
assimilation – самоочищение воды
non-renewable natural resources – не возобновляемые природные ресурсы
exhaustive – исчерпывающий
nutrient cycling – круговорот питательных веществ
purification plants – очистительные сооружения
soil retention – сохранение земли
circulation patterns – режим циркуляции
capacity of ecosystems – возможность экосистем
maintenance - поддержание
habitable planet – пригодная для жизни планета
buffering – создание защитной зоны
storage capacity – вместимость хранилища
abiotic factors – абиотический фактор
arable land – пахотная земля
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abatement of noise – снижение уровня шума
Read the text again and answer the following questions:
1. What does the maintenance of earth’s biosphere depend on?
2. What are the main ecosystem processes on earth can you name?
3. What is the role of ecosystem in the ecological processes on earth?
4. What are ecological processes regulated by?
5. What does a chemical atmosphere on the planet maintained by?
6. How is water regulated on earth?
7. What does life on earth depend on?
8. What are ecosystem processes regulated by?
9. How is climate regulated on earth?
10. What is the role of migration in ecosystem?
Ocean planet in decline
Growing human numbers and growing consumption per capita are putting intense pressure on ocean coastal areas, over-consuming ocean resources, and undermining the health of the oceans themselves.
Healthy oceans are essential to a healthy terrestrial environment. The earth's great sea is the heart of the hydrological cycle - nature's solar-driven water pump. About 430,000 cubic kilometres of water evaporate from the oceans every year. Of this amount, around 110,000 cubic kilometres fall as freshwater precipitation over land, replenishing surface and ground waters and eventually completing the cycle by returning to the sea.
The ocean is also the engine that drives the world's climate, storing huge quantities of solar energy in the process. The ocean absorbs and stores carbon dioxide from the atmosphere. Since this invisible gas is one of the main agents of climate change, the ocean is an important sink that helps to modify human impacts on global climate. Ocean currents, the blue planet's super highways, transfer enormous quantities of water and nutrients from one place to another. The Gulf Stream, for instance, pushes more water from the Gulf of Mexico and the Caribbean across the Atlantic into northern Europe, than is carried by all the rivers on earth.
Human populations have a tremendous impact on the quality of coastal and oceanic environments. A full two-thirds of the world's population - 4 billion people - live within 400 kilometres of a seacoast. Just over half the world's population - around 3.2 billion people - occupy a coastal strip 200 kilometres wide (120 miles), representing only 10 per cent of the earth's land surface. With this population distribution, increasing human numbers and mounting development pressures are taking a grim toll on coastal and near-shore resources.
Of Asia's total population of 4 billion, 60 per cent live within 400 km of a coast. Roughly 1.5 billion live within 100 km of the sea. The exceptions are India, Pakistan, and, of course, the land-locked countries of Central Asia. The population of Latin America and the Caribbean is even more clustered on the coasts. The region's coastal states have a total population of around 521 million (in 2006); a full three-quarters of them live within 200 kilometres of a coast.
Among continents, only in Africa do more people live in the interior than along or near ocean coasts. But even in Africa demographic patterns are shifting. Over the past two decades, for example, Africa's coastal cities, as centers of trade and commerce, have been growing in population by 4 per cent or more a year, as they attract people from the countryside.
Over half of the world's coastlines have suffered from severe development pressures, according to a study by the World Resources Institute (WRI) in the mid-1990s. The WRI study used four key indicators to assess risk to coastal areas: cities and population density, major ports, road density, and pipeline density. According to these indicators, the coastlines of most developed countries - particularly Japan, Australia, the United States, Europe and the European part of Russia, were suffering from development pressures and loss of coastal resources. But developing countries fared little better - around virtually all urban areas, coasts were beset by a pattern of pollution and over-development.
Coastal wetlands. The world has lost half its coastal wetlands, including mangrove swamps and salt marshes. Over the past century mangrove forests have been decimated - 25 million hectares are estimated to have been destroyed or grossly degraded. In the Philippines, for instance, the mangrove area has been annihilated by development, dropping by 90 per cent - from one million hectares in 1960 to around 100,000 in 1998.
Mangrove wetlands provide a rich habitat for over 2,000 species of fish, shellfish, invertebrates and plants. Some 80 species of salt-tolerant trees currently occupy about 182,000 square kilometres of intertidal, lagoonal and riverine flatlands throughout the world.
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Seagrass beds, the underwater meadows of the ocean, have fared little better. Though no overall quantitative estimates of damage are available, these diverse ecosystems appear in retreat near virtually all inhabited coastal areas.
Coral reefs. Coral reefs, the rainforests of the sea, are also being destroyed in the name of development. Of the world's 600,000 square kilometres of reefs found in tropical and semi-tropical seas, scientists estimate that 70 per cent of them - some 400,000 square kilometres - could be lost within 40 years. Coral reefs are wonders of biological diversity, supporting upwards of one million species and providing humankind with many benefits. They buffer waves and protect shorelines from erosion; they help transfer nutrients from the land to the open ocean; they provide feeding, breeding and nursery areas for many commercially important species of fish and shellfish; and they offer scientists a pharmacopoeia of potential medicines. Yet, they are fast disappearing. In 1997, a global effort to assess the status of coral resources was carried out by Reef Check, organized by Hong Kong University. The study used professional and recreational divers to chart the health of 300 reefs in 30 countries. According to the survey, less than one-third of all reefs had healthy, living coral cover, while two-thirds were seriously degraded. The Caribbean had the lowest rate of living coral, an average of just 22 per cent. Southeast Asia was second, with only 30 per cent of its coral reefs in good to excellent condition; coral reefs in good to excellent condition must have 50 per cent or more of their area in living coral.
Another study by WRI confirmed these findings, observing that the world's most degraded reefs are in Southeast Asia and the Caribbean. In Southeast Asia, for example, one of the epicentres of coral biodiversity, more than 80 per cent of all reefs are at risk. The sea worst hit is the Caribbean. According to a team of British researchers from the University of East Anglia four-fifths of the coral on Caribbean reefs has disappeared in the past 25 years, a phenomenal rate of destruction. Their report, published in Science Magazine in 2003, cites over-fishing, rampant coastal development and pollution as the main reasons for the wholesale annihilation of reef ecosystems.
Coastal erosion. Human activities are eroding close to 70 per cent of the world's beaches at greater than natural rates. Coastlines in developing countries are suffering from serious erosion problems due to unplanned coastal construction, dredging, mining for sand, harvesting of coral reefs for building material and other activities. Erosion is particularly severe along the coasts of Nigeria, Sierra Leone, Liberia, Gambia, Benin and Togo in West Africa. Hundreds of coastal villages have been moved inland as the sea advances. In the Niger River Delta, for instance, erosion claims 400 hectares of land a year and 40 per cent of the inhabited delta could be lost in three decades.
Vocabulary
consumption per capita – потребление на душу населения
terrestrial environment – наземная среда, окружающая среда
freshwater precipitation – пресноводные атмосферные осадки
enormous quantities – огромные количества
essential – жизненно важный, необходимый
coastline – береговая линия
demographic pattern – демографическая модель
wetlands – водно-болотные угодья, сильно увлажненная местность
seagrass bed – дно, покрытое водорослями
rainforest – тропический лес
rampant coastal development – бурное (угрожающее) освоение прибрежных зон
annihilation of reef ecosystems – уничтожение экосистемы береговых вал
pharmacopoeia - фармакопея
riverine - приречная полоса, прибрежный
flatlands – равнина с плоским рельефом
breeding - разведение, размножение
nursery area - питомник
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