Ecosystem services

Ecosystem services are the means by which societal benefits and support are provided by ecosystems. Such benefits and support are also known as natural capital. They include climate regulation, water availability, the maintenance of wildlife and their habitats, fodder, and the production of raw materials such as wood, fiber, medicines, and a range of foods. All are fundamental components in people-environment relationships, given their necessity for human well-being, and all contribute to the provision and/or maintenance of global resources.

Background

Ecosystem services are closely linked with biogeochemical cycles and energy transfer. In biogeochemical cycles nutrients are continuously transferred between the constituent parts of the Earth’s surface: rocks, soils, water (freshwater and marine), plants, animals, and the atmosphere. These processes are vital in energy transfers within food chains and webs. The spatial and temporal distribution of these processes is determined to a large extent by climatic characteristics but also influences global climate via the carbon cycle. Such processes affect the quality of the “commons” (air, water, oceans), the maintenance of which is essential to human well-being. These processes also control the natural capital that accrues within all ecosystems and that are used for society’s needs. Ecosystem services underpin all human activity through the continuous generation of resources and the environmental processes that are essential to that generation. Inevitably, ecosystem services are complex, are under pressure from a growing global population, and require careful management. The Millennium Ecosystem Assessment (MEA), compiled as a collaborative effort by 1,360 scientists worldwide between 2001 and 2005, summarizes the state of and major trends in global ecosystems and their services under the four headings used below.

Supporting Services

The primary supporting services are nutrient cycling, soil formation, and primary production. Nutrient, or biogeochemical, cycling involves the transfer of elements and compounds within and between the biosphere (organisms and their environment), atmosphere, and pedosphere (soils). They consist of pools or stores between which fluxes occur. For example, in the carbon cycle the major pools are living organisms, dead organic matter, the oceans, and the atmosphere. Fluxes occur between these pools at rates that vary according to factors such as climate. Nutrient cycles also link the inorganic and organic components of the environment and operate at various spatial and temporal scales. For example, photosynthesis, respiration, and decomposition link microbes, plants, and animals with water, soils, and the atmosphere through carbon, hydrogen, nitrogen, phosphorus, and many other elemental cycles. Most major nutrients—carbon is the most obvious example—have a pool in the atmosphere and are thus an influence on climate. These are gaseous biogeochemical cycles. Those nutrients without an atmospheric pool—for example, phosphorus, iron, and calcium—are sedimentary biogeochemical cycles.

Soil formation involves the breakdown of solid bedrock into small particles by biological, chemical, and physical processes known collectively as weathering. Dead organic matter from microbes, insects, and pioneer plants is mixed with the particles to create new habitats for organisms; this aids water retention, which continues the weathering process and contributes to the release of nutrients for use by plants. Many factors—the most important being climate—influence the processes and rates of soil formation, water availability, and degree of acidity or alkalinity.

Primary production is the amount of organic matter produced per unit area per unit time by organisms that can photosynthesize (green plants on land and algae in the oceans). These organisms have the ability to absorb solar energy and convert it to chemical energy through the generation of complex organic compounds such as sugars and carbohydrates. Although less than 1 percent of the solar energy that reaches Earth is used in photosynthesis, this small amount fuels the biosphere. Primary production is the first stage in energy transfer through ecosystems and is thus the basis of all food chains and webs. All animals, including humans, depend on primary production for survival—not only for food and shelter but also for a wide range of goods, including fiber, wood, and medicine. Rates of primary production (primary productivity) are influenced by environmental factors such as water availability, annual temperature regimes, soil types, and nutrient availability. Nutrient cycling, soil formation, and primary production are vital for the ecosystem services described below.

Provisioning Services

Provisioning services encompass food, wood, fiber, genetic resources, fuel, and fresh water. Primary production on land and in the oceans underpins the generation and replenishment of many resources on which humanity depends. Apart from fossil fuels, these are all renewable resources and are all organic or biological in origin. The provision of fresh water is renewable but is inorganic in essence, though influenced by ecosystem (biological) characteristics.

Global food production is a vast enterprise that essentially processes carbon and is a major generator of wealth. It involves crop and animal agriculture at various scales (subsistent or commercial); may have a fossil-fuel subsidy, as in the case of “industrialized” agriculture; and requires a reliable supply of fresh water. A proportion of this is used as animal feed to create secondary products such as meat and milk products. These and other crops, including cotton fiber, are produced on millions of square kilometers of cropland.

An increasing proportion of crop production—notably that of corn, soybean, and canola—is used to generate biofuels, while several crops are grown specifically as biofuels. However, the value of growing materials to use as biofuels is controversial because the crops take up land that could be used for food production. For instance, a great amount of land is dedicated to pastures that support a large population of cattle and sheep.

Fish derived from inland and marine waters form an important component of human diets. Humans are responsible for the overwhelming majority of consumption of produced fish; the remainder is processed for animal feed. However, the global fishing industry is facing problems because fish stocks have been seriously depleted. The reduction or loss of this service illustrates the difficulties that arise when conservation and management are inadequate: Marine ecosystems are altered and social consequences arise.

The world’s natural forests and plantations are another major resources with a host of uses, the most important of which are used as materials for construction, furniture, fencing, pulp and paper, garden products, and fuel. Forests are also a source of other resources, including nuts, berries, fodder, and game. However, the loss of forest cover because of agriculture, logging, and poor management reduces the capacity of the terrestrial biosphere to store carbon. FAO indicates that between 1990 and 2005 carbon stocks in forest biomass decreased by 1.1 billion metric tons of carbon annually; this reflects the impairment of an ecosystem service.

The organisms in the world’s ecosystems contain a wealth of genetic resources with vast potential. Biodiversity prospecting is the term given to programs designed to tap this resource by identifying species and screening them for useful properties such as crop protection chemicals and pharmaceuticals. A variety of prescription medicines are plant-based, including the widely used aspirin, while the bacterium Bacillus thuringiensis is the basis of insect pest control in a range of crops. The bacterium itself is produced as a commercial spray, but the gene component responsible for insect mortality has been identified and inserted into a number of crops, notably cotton and maize, so that these genetically modified varieties produce their own insecticide. As further advances in biotechnology and genetic modification ensue, further opportunities to harness genetic resources will arise.

Fossil fuels are also generated through primary productivity but relate to geological eras many millions of years in the past, when the carbon cycle involved the storage or sequestration of huge volumes of plant-based carbon in reservoirs that eventually became rocks. For example, coal formed in wetlands, and limestone formed in the oceans. These processes continue to operate but at such slow rates that fossil fuels cannot be considered renewable.

Freshwater, a vital resource for human well-being, is renewable. It is a component of the hydrological cycle, a fundamental facilitating factor in ecosystem and society functioning. Water from precipitation reaches the Earth’s surface and its subsequent passage depends largely on how evaporation, recharge of groundwater reservoirs, and runoff are affected by the ecosystems through which it passes. Forest and mountain ecosystems are especially important in this context, accounting for the vast majority of total runoff. Cultivated land accounts for most of the remainder. Wetlands are also important as water stores and hydrological regulators.

Regulating Services

Climate, flood, and disease regulation, water purification, and pollination are major regulating services. Climate and the Earth’s ecosystems have been interdependent throughout geologic time; the major link between the two is the global carbon cycle, though other biogeochemical cycles are also involved. This mutual development has manifested in various ways but is especially significant in terms of global temperature regimes and atmospheric composition.

The Earth and its atmosphere form a closed system, or nearly so, in terms of chemical constitution. The redistribution of atoms and molecules between the Earth’s core, lithosphere, biosphere, and atmosphere has been, and continues to be, mediated by life-forms on land and in the oceans. Overall, this relationship has maintained life in the biosphere and helped to spur evolution. It also has caused major shifts in the carbon cycle as carbon is removed from the atmosphere into the biosphere and, eventually, the lithosphere. The evolution of photosynthesis, for example, was particularly important because it not only fixed carbon from the atmosphere but also released oxygen, paving the way for the evolution of mammals, including humans.

Beginning with the Industrial Revolution, humans began to alter the carbon cycle profoundly through fossil-fuel and deforestation. Evidence indicates that these may contribute to global warming. The speed of the alteration in the carbon cycle is more rapid than the gradual processes that characterize the geological past; thus, concerns about serious consequences for human well-being seem to be justified.

Flood regulation is a function of all ecosystems but is most important in forests, grasslands, and wetlands. Following receipt of high rainfall or snowfall such ecosystems store water in the vegetation and soils and temper its release to groundwater, streams, and rivers. This reduces the impact of floodwaters on ecosystems and society in built-up areas like river valleys, estuaries, and deltas. Degradation of upstream ecosystems can impair this capacity and imperils millions of people. Erosion control is also linked with the preservation of an adequate vegetation cover in river catchments and safeguards downstream land use and settlements. The passage of water through ecosystems—in which vegetation, microorganisms, and soils act as filters—contributes to water purification. Pollutants such as metals, excess nutrients such as nitrogen, and sediments are removed, which improves conditions for downstream ecosystems and land use.

Many diseases experienced by crops and animals (including humans) are influenced by ecosystem diversity; pest and disease outbreaks are not likely in biodiverse regions because the passage of viruses is made difficult by the buffering capacity of non-host species. The natural control of vectors is also enhanced with high biodiversity.

Pollination is another vital ecosystem service. It facilitates the sexual reproduction of many plants, including crops, with genetically diverse offspring as a result. Without such fertilization, fruiting would not occur. Many animal species—bats, birds, and insects such as bees, butterflies, flies, moths, and beetles—are involved in pollination. A large percentage of human food production depends on these wild pollinators; thus, the service is of economic importance.

Cultural Services

Cultural services—aesthetic, spiritual, educational, and recreational—do not immediately provide tangible resources akin to food, for example, but they contribute to human well-being in many ways. Furthermore, in the context of education, they may improve their understanding of ecosystem form and function and contribute to sustainable management strategies. Distinct types of ecosystems provide a sense of place, influence culture, inspire art forms, and are important in many religions. Wealth generation—through the value of landscape, wildlife, and recreation—is another cultural ecosystem service. Other forms of employment, such as forestry, conservation, and management, also contribute to wealth generation.

Future Context

According to the United Nations, the global human population surpassed 8 billion people in November 2022. This has compounded pressure on already stretched ecosystem services. According to the MEA, humans have altered global ecosystems more substantially since the mid-twentieth century than at any other time in history. This happened because of a threefold growth in population, rapid conversion of forests and grasslands to agricultural land, technologies such as automobiles requiring fossil fuels, and rising standards of living that encompass increased resource use. More than half of the services provided are being degraded mostly at the expense of the poorest people. One aspect of this degradation is the high rate of plant and animal extinction such as the loss of genetic resources, a process that, unlike many other environmental problems, is irreversible. Unsustainable practices and resulting inequity require immediate attention from local, national, and international political and environmental institutions. Each requires the inventory and valuation of ecosystem services, monitoring, investment in management, education programs, and cooperation at all scales.

The Need for Standardization

As global efforts accelerate to offset human-created environmental damage, there is a need for ways to measure, classify, and quantify ecosystem services in enterprises such as the land used in food or renewable energy production. Beginning in the mid-2010s and continuing into the next decade, academic efforts materialized to achieve these types of protocols. This reflects an awareness that standardized approaches are needed for long-term policy decisions that can impact whole societies.

An example of this need for standardization is in the area of freshwater ecosystems. New approaches have been suggested for the development of environmental quality benchmarks for freshwater and river systems. This can entail efforts such as a standardized way of measuring harmful chemicals such as pesticides present in freshwater. This allows more accurate ways to monitor changes, both improvements, and deteriorations, which can inform regulatory decision-making.

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