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‘Classics’ is a category of posts highlighting research that has made a real difference to biodiversity conservation. All posts in this category will be permanently displayed on the Classics page of ConservationBytes.com

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Ehrlich, P.R., H. A. Mooney. (1983). Extinction, substitution, and ecosystem services. BioScience 33, 248-254

I may be mistaken, but I think this is one of the earliest appearances of the term ‘ecosystem services‘, which is essentially the concept that intact biological communities and functioning species interactions provide humanity with a host of ‘services’ that support or improve our quality of life. The ongoing assault on species and habitats around the globe are, to use Ehrlich & Mooney’s words “accompanied by severe degradation of the public service functions of the systems”.

What are ecosystem services? The list is long and varied, and much of them remain largely unquantified, but I’ll attempt to list the more important ones here:

• Reduce desertification (e.g., intact vegetation producing microclimates resistant to drying out)
• Maintain soils (e.g., root structure of intact vegetation preventing soil erosion)
• Crop pollination (e.g., insect diversity and biomass supported by surrounding intact vegetation)
• Seed dispersal (e.g., animal seed dispersers)
• Food provision (e.g., non-timber forest products)
• Water purification (functioning microbial communities and vegetation ‘filter’ water)
• Fuel provision (e.g., firewood)
• Fibre provision (e.g., flax)
• Climate regulation (e.g., growing vegetation sequestring carbon; evapotranspiration changing microclimates)
• Flood regulation (e.g., intact forests reducing likelihood and frequency of intense floods)
• Disease regulation (see also more recent post on this subject)
• Waste decomposition/detoxification (e.g., dung beetles)
• Nutrient cycling
• Soil formation
• Primary production
• Pharmaceutical sources
• Cultural appreciation (e.g., aesthetic, spiritual, educational, recreational…)

Add your favourite to the list – there are plenty of sources that expand on these. For starters try the Millennium Ecosystem Assessment, the Wikipedia entry, the Ecological Society of America and Gretchen Daily’s lab at Standford University.

What is the value of ecosystem services to humanity?

This is a fairly controversial area because of the difficulty of measuring the link between ecosystem function and the services they provide, but also by the decision to include direct and direct costs of providing the services artificially. However, many people have attempted to put them into financial terms – Robert Costanza and colleagues put together some figures (see here, here, and here for examples) that attracted some criticism. Nonetheless, ecosystems are estimated to provide us with trillions of dollars worth of goods and services. Some examples from the Ecological Society of America:

• Much of the Mississippi River Valley’s natural flood protection services were destroyed when adjacent wetlands were drained and channels altered. As a result, the 1993 floods resulted in property damages estimated at twelve billion dollars partially from the inability of the Valley to lesson the impacts of the high volumes of water.
• Over 100,000 different animal species – including bats, bees, flies, moths, beetles, birds, and butterflies – provide free pollination services. One third of human food comes from plants pollinated by wild pollinators. The value of pollination services from wild pollinators in the U.S. alone is estimated at four to six billion dollars per year.
• Eighty percent of the world’s population relies upon natural medicinal products. Of the top 150 prescription drugs used in the U.S., 118 originate from natural sources: 74 percent from plants, 18 percent from fungi, 5 percent from bacteria, and 3 percent from one vertebrate (snake species). Nine of the top 10 drugs originate from natural plant products.

What does this mean for conservation of biodiversity? Well, since scientists and policy makers alike have embraced the concept, we now have a much more convincing argument for maintaining the intactness of natural ecosystems. In the past we found it hard to convince those struggling to make ends meet (or even to obtain their next meal) about the importance of preventing species extinctions. Why should someone worried about whether or not his or her family will survive another day give a rat’s arse about species conservation? Well, the degradation of ecosystem services ensuing from species extinctions means that everyone’s – including the poorest – lives are reduced in quality and duration as we destroy these systems. See a previous post on Conservation for the People for more information.

CJA Bradshaw