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Ecosystem Change

2. How have ecosystem services and their uses changed?

  • 2.1 What are ecosystem services?
  • 2.2 What have been the changes in specific ecosystem services?
    • 2.2.1 Changes in provisioning services
    • 2.2.2 Changes in regulating services
    • 2.2.3 Changes in cultural services
  • 2.3 What are the effects of developing substitutes for ecosystem services?
  • 2.4 What is the link between biodiversity and ecosystem services?
  • 2.5 What are trade-offs or synergies between ecosystem services?

2.1 What are ecosystem services?

The source document for this Digest states:

Ecosystem services are the benefits provided by ecosystems. These include provisioning services such as food, water, timber, fiber, and genetic resources; regulating services such as the regulation of climate, floods, disease, and water quality as well as waste treatment; cultural services such as recreation, aesthetic enjoyment, and spiritual fulfillment; and supporting services such as soil formation, pollination, and nutrient cycling (See Box 2.1.)

See Box 2.1 for more information on ecosystem services :

Source & ©: MA  Millennium Ecosystem Assessment Synthesis Report (2005),
Chapter 1, p.39

2.2 What have been the changes in specific ecosystem services?

    • 2.2.1 Changes in provisioning services
    • 2.2.2 Changes in regulating services
    • 2.2.3 Changes in cultural services

The source document for this Digest states:

Human use of all ecosystem services is growing rapidly. Approximately 60% (15 out of 24) of the ecosystem services evaluated in this assessment (including 70% of regulating and cultural services) are being degraded or used unsustainably. (See Table 2.1.) Of 24 provisioning, cultural, and regulating ecosystem services for which sufficient information was available, the use of 20 continues to increase. The use of one service, capture fisheries, is now declining as a result of a decline in the quantity of fish, which in turn is due to excessive capture of fish in past decades. Two other services (fuelwood and fiber) show mixed patterns. The use of some types of fiber is increasing and others decreasing; in the case of fuelwood, there is evidence of a recent peak in use. Humans have enhanced production of three ecosystem services - crops, livestock, and aquaculture - through expansion of the area devoted to their production or through technological inputs. Recently, the service of carbon sequestration has been enhanced globally, due in part to the re-growth of forests in temperate regions, although previously deforestation had been a net source of carbon emissions. Half of provisioning services (6 of 11) and nearly 70% (9 of 13) of regulating and cultural services are being degraded or used unsustainably.

Source & ©: MA  Millennium Ecosystem Assessment Synthesis Report (2005),
Chapter 2, p.39

2.2.1 Changes in provisioning services

The source document for this Digest states:

Provisioning Services: The quantity of provisioning ecosystem services such as food, water, and timber used by humans increased rapidly, often more rapidly than population growth although generally slower than economic growth, during the second half of the twentieth century. And it continues to grow. In a number of cases, provisioning services are being used at unsustainable rates. The growing human use has been made possible by a combination of substantial increases in the absolute amount of some services produced by ecosystems and an increase in the fraction used by humans. World population doubled between 1960 and 2000, from 3 billion to 6 billion people, and the global economy increased more than sixfold. During this time, food production increased by roughly two-and-a-half times (a 160% increase in food production between 1961 and 2003), water use doubled, wood harvests for pulp and paper tripled, and timber production increased by nearly 60% (C9.ES, C9.2.2, S7, C7.2.3, C8.1). (Food production increased fourfold in developing countries over this period.)

The sustainability of the use of provisioning services differs in different locations. However, the use of several provisioning services is unsustainable even in the global aggregate. The current level of use of capture fisheries (marine and freshwater) is not sustainable, and many fisheries have already collapsed. (See Figure 2.1.) Currently, one quarter of important commercial fish stocks are overexploited or significantly depleted (high certainty) (C8.2.2).

From 5% to possibly 25% of global freshwater use exceeds long-term accessible supplies and is maintained only through engineered water transfers or the overdraft of groundwater supplies (low to medium certainty) (C7.ES). Between 15% and 35% of irrigation withdrawals exceed supply rates and are therefore unsustainable (low to medium certainty) (C7.2.2). Current agricultural practices are also unsustainable in some regions due to their reliance on unsustainable sources of water, harmful impacts caused by excessive nutrient or pesticide use, salinization, nutrient depletion, and rates of soil loss that exceed rates of soil formation

See also: Table on Trends in human use of provisioning services and their enhancement or degradation

Source & ©: MA  Millennium Ecosystem Assessment Synthesis Report (2005),
Chapter 2, p.39

2.2.2 Changes in regulating services

The source document for this Digest states:

Regulating Services: Humans have substantially altered regulating services such as disease and climate regulation by modifying the ecosystem providing the service and, in the case of waste processing services, by exceeding the capabilities of ecosystems to provide the service. Most changes to regulating services are inadvertent results of actions taken to enhance the supply of provisioning services. Humans have substantially modified the climate regulation service of ecosystems— first through land use changes that contributed to increases in the amount of carbon dioxide and other greenhouse gases such as methane and nitrous oxide in the atmosphere and more recently by increasing the sequestration of carbon dioxide (although ecosystems remain a net source of methane and nitrous oxide). Modifications of ecosystems have altered patterns of disease by increasing or decreasing habitat for certain diseases or their vectors (such as dams and irrigation canals that provide habitat for schistosomiasis) or by bringing human populations into closer contact with various disease organisms. Changes to ecosystems have contributed to a significant rise in the number of floods and major wildfires on all continents since the 1940s. Ecosystems serve an important role in detoxifying wastes introduced into the environment, but there are intrinsic limits to that waste processing capability. For example, aquatic ecosystems “cleanse” on average 80% of their global incident nitrogen loading, but this intrinsic self-purification capacity varies widely and is being reduced by the loss of wetlands.

See also: Table on Trends in human use of regulating services and their enhancement or degradation

Source & ©: MA  Millennium Ecosystem Assessment Synthesis Report (2005),
Chapter 2, p.39-46

2.2.3 Changes in cultural services

The source document for this Digest states:

Cultural Services: Although the use of cultural services has continued to grow, the capability of ecosystems to provide cultural benefits has been significantly diminished in the past century (C17). Human cultures are strongly influenced by ecosystems, and ecosystem change can have a significant impact on cultural identity and social stability. Human cultures, knowledge systems, religions, heritage values, social interactions, and the linked amenity services (such as aesthetic enjoyment, recreation, artistic and spiritual fulfillment, and intellectual development) have always been influenced and shaped by the nature of the ecosystem and ecosystem conditions. Many of these benefits are being degraded, either through changes to ecosystems (a recent rapid decline in the numbers of sacred groves and other such protected areas, for example) or through societal changes (such as the loss of languages or of traditional knowledge) that reduce people’s recognition or appreciation of those cultural benefits. Rapid loss of culturally valued ecosystems and landscapes can contribute to social disruptions and societal marginalization. And there has been a decline in the quantity and quality of aesthetically pleasing natural landscapes

See also: Table on Trends in human use of cultural services and their enhancement or degradation

Source & ©: MA  Millennium Ecosystem Assessment Synthesis Report (2005),
Chapter 2, p.46

2.3 What are the effects of developing substitutes for ecosystem services?

The source document for this Digest states:

Global gains in the supply of food, water, timber, and other provisioning services were often achieved in the past century despite local resource depletion and local restrictions on resource use by shifting production and harvest to new underexploited regions, sometimes considerable distances away. These options are diminishing. This trend is most distinct in the case of marine fisheries. As individual stocks have been depleted, fishing pressure has shifted to less exploited stocks (C18.3.1).

Industrial fishing fleets have also shifted to fishing further offshore and in deeper water to meet global demand (C18.ES). (See Figure 2.2.) A variety of drivers related to market demand, supply, and government policies have influenced patterns of timber harvest. For example, international trade in forest products increases when a nation’s forests no longer can meet demand or when policies have been established to restrict or ban timber harvest.

Although human demand for ecosystem services continues to grow in the aggregate, the demand for particular services in specific regions is declining as substitutes are developed. For example, kerosene, electricity, and other energy sources are increasingly being substituted for fuelwood (still the primary source of energy for heating and cooking for some 2.6 billion people) (C9-ES). The substitution of a variety of other materials for wood (such as vinyl, plastics, and metal) has contributed to relatively slow growth in global timber consumption in recent years (C9.2.1). While the use of substitutes can reduce pressure on specific ecosystem services, this may not always have positive net environmental benefits. Substitution of fuelwood by fossil fuels, for example, reduces pressure on forests and lowers indoor air pollution, but it may increase net greenhouse gas emissions. Substitutes are also often costlier to provide than the original ecosystem services

Source & ©: MA  Millennium Ecosystem Assessment Synthesis Report (2005),
Chapter 2, p.46

2.4 What is the link between biodiversity and ecosystem services?

The source document for this Digest states:

Both the supply and the resilience of ecosystem services are affected by changes in biodiversity. Biodiversity is the variability among living organisms and the ecological complexes of which they are part. When a species is lost from a particular location (even if it does not go extinct globally) or introduced to a new location, the various ecosystem services associated with that species are changed. More generally, when a habitat is converted, an array of ecosystem services associated with the species present in that location is changed, often with direct and immediate impacts on people (S10). Changes in biodiversity also have numerous indirect impacts on ecosystem services over longer time periods, including influencing the capacity of ecosystems to adjust to changing environments (medium certainty), causing disproportionately large and sometimes irreversible changes in ecosystem processes, influencing the potential for infectious disease transmission, and, in agricultural systems, influencing the risk of crop failure in a variable environment and altering the potential impacts of pests and pathogens (medium to high certainty) (C11.ES, C14.ES).

Source & ©: MA  Millennium Ecosystem Assessment Synthesis Report (2005),
Chapter 2, p.46

2.5 What are trade-offs or synergies between ecosystem services?

The source document for this Digest states:

Trade-offs and Synergies

The modification of an ecosystem to alter one ecosystem service (to increase food or timber production, for instance) generally results in changes to other ecosystem services as well (CWG; SG7). Trade-offs among ecosystem services are commonplace. (See Table 2.2.) For example, actions to increase food production often involve one or more of the following: increased water use, degraded water quality, reduced biodiversity, reduced forest cover, loss of forest products, or release of greenhouse gases. Frequent cultivation, irrigated rice production, livestock production, and burning of cleared areas and crop residues now release 1,600±800 million tons of carbon per year in CO2 (C26.ES). Cultivation, irrigated rice production, and livestock production release between 106 and 201 million tons of carbon per year in methane (C13 Table 26.1). About 70% of anthropogenic nitrous oxide gas emissions are attributable to agriculture, mostly from land conversion and nitrogen fertilizer use (C26.ES). Similarly, the conversion of forest to agriculture can significantly change flood frequency and magnitude, although the amount and direction of this impact is highly dependent on the characteristics of the local ecosystem and the nature of the land cover change (C21.5.2).

Many trade-offs associated with ecosystem services are expressed in areas remote from the site of degradation. For example, conversion of forests to agriculture can affect water quality and flood frequency downstream of where the ecosystem change occurred. And increased application of nitrogen fertilizers to croplands can have negative impacts on coastal water quality. These trade-offs are rarely taken fully into account in decision-making, partly due to the sectoral nature of planning and partly because some of the effects are also displaced in time (such as long-term climate impacts).

The net benefits gained through actions to increase the productivity or harvest of ecosystem services have been less than initially believed after taking into account negative trade-offs. The benefits of resource management actions have traditionally been evaluated only from the standpoint of the service targeted by the management intervention. However, management interventions to increase any particular service almost always result in costs to other services. Negative trade-offs are commonly found between individual provisioning services and between provisioning services and the combined regulating, cultural, and supporting services and biodiversity. Taking the costs of these negative trade-offs into account reduces the apparent benefits of the various management interventions. For example:

  • Expansion of commercial shrimp farming has had serious impacts on ecosystems, including loss of vegetation, deterioration of water quality, decline of capture fisheries, and loss of biodiversity (R6, C19).
  • Expansion of livestock production around the world has often led to overgrazing and dryland degradation, rangeland fragmentation, loss of wildlife habitat, dust formation, bush encroachment, deforestation, nutrient overload through disposal of manure, and greenhouse gas emissions (R6-ES).
  • Poorly designed and executed agricultural policies led to an irreversible change in the Aral Sea ecosystem. By 1998, the Aral Sea had lost more than 60% of its area and approximately 80% of its volume, and ecosystem-related problems in the region now include excessive salt content of major rivers, contamination of agricultural products with agrochemicals, high levels of turbidity in major water sources, high levels of pesticides and phenols in surface waters, loss of soil fertility, extinctions of species, and destruction of commercial fisheries (R6-Box 6.9).
  • Forested riparian wetlands adjacent to the Mississippi river in the United States had the capacity to store about 60 days of river discharge. With the removal of the wetlands through canalization, leveeing, and draining, the remaining wetlands have a storage capacity of less than 12 days discharge, an 80% reduction in flood storage capacity (C16.1.1).

However, positive synergies can be achieved as well when actions to conserve or enhance a particular component of an ecosystem or its services benefit other services or stakeholders. Agroforestry can meet human needs for food and fuel, restore soils, and contribute to biodiversity conservation. Intercropping can increase yields, increase biocontrol, reduce soil erosion, and reduce weed invasion in fields. Urban parks and other urban green spaces provide spiritual, aesthetic, educational, and recreational benefits as well as such services such as water purification, wildlife habitat, waste management, and carbon sequestration. Protection of natural forests for biodiversity conservation can also reduce carbon emissions and protect water supplies. Protection of wetlands can contribute to flood control and also help to remove pollutants such as phosphorus and nitrogen from the water. For example, it is estimated that the nitrogen load from the heavily polluted Illinois River basin to the Mississippi River could be cut in half by converting 7% of the basin back to wetlands (R9.4.5). Positive synergies often exist among regulating, cultural, and supporting services and with biodiversity conservation.

Source & ©: MA  Millennium Ecosystem Assessment Synthesis Report (2005),
Chapter 2, p.46-47


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