Everything about Ecosystem Services totally explained
Humankind benefits from a multitude of resources and processes that are supplied by natural
ecosystems. Collectively, these benefits are known as
ecosystem services and include products like clean drinking water and processes such as the
decomposition of wastes. Ecosystem services are distinct from other ecosystem products and functions because there's human demand for these natural assets. Services can be subdivided into five categories:
provisioning such as the production of food and water;
regulating, such as the control of climate and disease;
supporting, such as nutrient cycles and crop pollination;
cultural, such as spiritual and recreational benefits; and
preserving, which includes guarding against uncertainty through the maintenance of diversity.
As human populations grow, so do the resource demand imposed on ecosystems and the impacts of our global footprint. Many people have been plagued with the misconception that these ecosystem services are free, invulnerable and infinitely available. However, the impacts of
anthropogenic use and abuse are becoming evermore apparent – air and water quality are increasingly compromised, oceans are being over-fished, pests and diseases are extending beyond their historical boundaries,
deforestation is eliminating flood control around human settlements. It has been reported that approximately 40-50% of Earth’s ice-free land surface has been heavily transformed or degraded by anthropogenic activities, 66% of marine
fisheries are either overexploited or at their limit, atmospheric CO
2 has increased more than 30% since the advent of
industrialization, and nearly 25% of Earth’s bird species have gone extinct in the last two thousand years . Consequently, society is coming to realize that ecosystem services are not only threatened and limited, but that the pressure to evaluate trade-offs between immediate and long-term human needs is urgent. To help inform decision-makers, economic value is increasingly associated with many ecosystem services and often based on the cost of replacement with anthropogenically-driven alternatives. The on-going challenge of prescribing economic value to nature is prompting transdisciplinary shifts in how we recognize and manage the environment, social responsibility, business opportunities, and our future as a species.
A brief history
The simple notion of human dependence on Earth’s ecosystems probably reaches to the start of our species’ existence, when as hunter-gatherers we benefited from the products of nature to nourish our bodies and the habitats that provided shelter from harsh climates. Recognition of how ecosystems could provide even more complex services to humankind date back to at least
Plato (c. 400 BC) who understood that
deforestation could lead to soil
erosion and the drying of springs . However, modern conceptualization of ecosystem services likely began with Marsh in 1864 when he challenged the idea that Earth’s natural resources are not infinite by pointing out changes in
soil fertility along the Mediterranean. Unfortunately, his observations and cautioning passed largely unnoticed at the time and it wasn’t until the late 1940’s that society’s attention was again brought to the matter. During this era, three key authors – Osborn, Vogt, and Leopold – awakened and promoted the recognition of human dependence on the environment with the idea of ‘natural capital’. In 1956, Sears brought attention to the critical role of the ecosystem in processing wastes and recycling nutrients. An environmental science textbook called attention to “the most subtle and dangerous threat to man’s existence… is the potential destruction, by man’s own activities, of those ecological systems upon which the very existence of the human species depends”. The term ‘environmental services’ was finally introduced in a report of the
Study of Critical Environmental Problems, which listed services including insect
pollination,
fisheries,
climate regulation and
flood control. In following years, variations of the term were applied but eventually ‘ecosystem services’ became the standard among scientific literature.
Modern expansions of the ecosystem services concept have come to encompass
socio-economic and
conservation objectives, which are discussed below. For a more complete history of the concepts and terminology surrounding ecosystem services, see Daily (1997) The following lists represent samples of each:
» Provisioning services
:• foods (including
seafood and
game) and spices
» :• precursors to
pharmaceutical and industrial products
:•
energy (
hydropower,
biomass fuels)
» Regulating services
:•
carbon sequestration and
climate regulation
» :• waste
decomposition and detoxification
:•
nutrient dispersal and cycling
» Supporting services
:• purification of
water and
air » :• crop
pollination and seed
dispersal
:•
pest and
disease control
» Cultural services
:• cultural, intellectual and spiritual inspiration
» :•
recreational experiences (including
ecotourism)
:• scientific discovery
» Preserving services
:•
genetic and
species diversity for future use
» :• accounting for uncertainty
:• protection of options
To understand the relationships between humans and natural ecosystems through the services derived from them, consider the following cases:
» • In
New York City, where the quality of drinking water had fallen below standards required by the
U.S. Environmental Protection Agency (EPA), authorities opted to restore the polluted
Catskill Watershed that had previously provided the city with the ecosystem service of
water purification. Once the input of sewage and pesticides to the
watershed area was reduced, natural
abiotic processes such as soil
adsorption and
filtration of chemicals, together with biotic recycling via
root systems and
soil microorganisms,
water quality improved to levels that met government standards. The cost of this investment in
natural capital was estimated between $1-1.5 billion, which contrasted dramatically with the estimated $6-8 billion cost of constructing a
water filtration plant plus the $300 million annual running costs.
•
Pollination of
crops by
bees is required for 15-30% of U.S.
food production; most large-scale farmers import non-native honey
bees to provide this service. One study reports that in
California’s agricultural region, it was found that
wild bees alone could provide partial or complete
pollination services or enhance the services provided by
honey bees through behavioral interactions. However,
intensified agricultural practices can quickly erode
pollination services through the loss of species and those remaining are unable to compensate for the difference. The results of this study also indicate that the proportion of
chaparral and
oak-woodland habitat available for
wild bees within 1-2 km of a
farm can strongly stabilize and enhance the provision of pollination services, thereby providing a potential insurance policy for farmers of this region.
» • In watersheds of the
Yangtze River (
China),
spatial models for water flow through different forest habitats were created to determine potential contributions for
hydroelectric power in the region. By quantifying the relative value of ecological parameters (vegetation-soil-slope complexes), researchers were able to estimate the annual economic benefit of maintaining forests in the
watershed for power services to be 2.2 times that if it were harvested once for
timber.
Ecology
Understanding of ecosystem services requires a strong foundation in
ecology, which describes the underlying principles and interactions of organisms and the
environment. Since the scales at which these entities interact can vary from
microbes to
landscapes, milliseconds to millions of years, one of the greatest remaining challenges is the descriptive characterization of energy and material flow between them. For example, the area of a forest floor, the
detritus upon it, the microorganisms in the soil and characteristics of the soil itself will all contribute to the abilities of that forest for providing ecosystem services like carbon sequestration, water purification, and
erosion prevention to other areas within the
watershed. Note that it's often possible for multiple services to be bundled together and when benefits of targeted objectives are secured, there may also be ancillary benefits – the same forest may provide
habitat for other organisms as well as human recreation, which are also ecosystem services.
The complexity of Earth’s ecosystems poses a challenge for scientists as they try to understand how relationships are interwoven among organisms, processes and their surroundings. As it relates to human ecology, a suggested research agenda Such parameters provide indications of how species respond to changes in the environment (for example predators, resource availability, climate) and are useful for identifying species that are disproportionately important at providing ecosystem services. However, a critical drawback is that the technique doesn't account for the effects of interactions, which are often both complex and fundamental in maintaining an ecosystem and can involve species that are not readily detected as a priority. Even so, estimating the functional structure of an ecosystem and combining it with information about individual species traits can help us understand the
resilience of an ecosystem amidst environmental change.
Many ecologists also believe that the provision of ecosystem services can be stabilized with
biodiversity. Increasing biodiversity also benefits the variety of ecosystem services available to society. Understanding the relationship between biodiversity and an ecosystem's stability is essential to the management of natural resources and their services.
The Redundancy Hypothesis
The concept of ecological redundancy is sometimes referred to as
functional compensation and assumes that more than one species performs a given role within an ecosystem. More specifically, it's characterized by a particular species increasing its efficiency at providing a service when conditions are stressed in order to maintain aggregate stability in the ecosystem. However, such increased dependence on a compensating species places additional stress on the ecosystem and often enhances its susceptibility to subsequent
disturbance. The redundancy hypothesis can be summarized as "species redundancy enhances ecosystem resilience".
The Rivet Hypothesis
Another idea uses the analogy of rivets in an airplane wing to compare the exponential effect the loss of each species will have on the function of an ecosystem; this is sometimes referred to as
rivet popping. If only one species disappears, the efficiency of the ecosystem as a whole is relatively small; however if several species are lost, the system essentially collapses as an airplane wing were it to lose too many rivets. The hypothesis assumes that species are relatively specialized in their roles and that their ability to compensate for one another is less than in the redundancy hypothesis. As a result, the loss of any species is critical to the performance of the ecosystem. The key difference is the rate at which the loss of species affects total ecosystem function.
The Portfolio Effect
A third explanation, known as the
portfolio effect, compares biodiversity to stock holdings, where diversification minimizes the volatility of the investment, or in this case, the risk in stability of ecosystem services. This is related to the idea of
response diversity where a suite of species will exhibit differential responses to a given environmental perturbation and therefore when considered together, they create a stabilizing function that preserves the integrity of a service.
Several experiments have tested these hypotheses in both the field and the lab. In ECOTRON, a laboratory in the UK where many of the
biotic and
abiotic factors of nature can be simulated, studies have focused on the effects of earthworms and symbiotic bacteria on plant roots.
Economics
There is an extensive disparity between the actual and perceived values of ecosystem services. The reasons for such incongruence are probably related to society’s generally tardy and limited acknowledgment of our interrelatedness with the natural environment. Although environmental awareness is rapidly improving in our contemporary world, ecosystem capital and its flow are still poorly understood, threats continue to impose, and we suffer from the so-called ‘
tragedy of the commons’. Many efforts to inform decision-makers of current versus future costs and benefits now involve organizing and translating scientific knowledge to
economics, which articulate the consequences of our choices in comparable units of impact on human well-being. An especially challenging aspect of this process is that interpreting ecological information collected from one spatial-temporal scale doesn't necessarily mean it can be applied at another; understanding the dynamics of ecological processes relative to ecosystem services is essential in aiding economic decisions. Weighting factors such as a service’s irreplaceability or bundled services can also allocate economic value such that goal attainment becomes more efficient.
The economic valuation of ecosystem services also involves social communication and information, areas that remain particularly challenging and are the focus of many researchers. In general, the idea is that although individuals make decisions for any variety of reasons, trends reveal the aggregative preferences of a society, from which the economic value of services can be inferred and assigned. The six major methods for valuing ecosystem services in monetary terms include :
- Avoided Cost – services allow society to avoid costs that would have been incurred in the absence of those services (for example waste treatment by wetland habitats avoids health costs)
- Replacement Cost – services could be replaced with man-made systems (for example restoration of the Catskill Watershed cost less than the construction of a water purification plant)
- Factor Income – services provide for the enhancement of incomes (for example improved water quality increases the commercial take of a fishery and improves the income of fishers)
- Travel Cost – service demand may require travel, whose costs can reflect the implied value of the service (for example value of ecotourism experience is sufficient that a visitor is willing to pay to get there)
- Hedonic Pricing – service demand may be reflected in the prices people will pay for associated goods (for example coastal housing prices exceed that of inland homes)
- Contingent Valuation – service demand may be elicited by posing hypothetical scenarios that involve some valuation of alternatives (for example visitors willing to pay for increased access to national parks)
Management and policy
Although monetary pricing continues with respect to the valuation of ecosystem services, the challenges in policy implementation and management are enormous. The administration of
common pool resources is a subject of extensive academic pursuit. From defining the problems to finding solutions that can be applied in practical and sustainable ways, there's much to overcome. Considering options must balance present and future human needs, and decision-makers must frequently work from valid but incomplete information. Existing legal policies are often considered insufficient since they typically pertain to human health-based standards that are mismatched with necessary means to protect ecosystem health and services. To improve the information available, one suggestion has involved the implementation of an
Ecosystem Services Framework (ESF
Further Information
Get more info on 'Ecosystem Services'.
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