AP® Environmental Science review sheet from Aim for Five (aimforfive.com/enviro/units/2/2-2)
Unit 2 · Topic 2.2
2.2 Ecosystem Services
Ecosystem services are the benefits people get from nature: goods like food and wood, regulation of climate and floods, cultural value like recreation, and supporting processes like soil formation. When ecosystems are damaged, those services are lost, which costs money and harms people.
Key terms
- provisioning services
- regulating services
- cultural services
- supporting services
- economic value
Four categories of services
Some benefits could fit more than one category, so explain your reasoning. Timber you harvest is provisioning; the same forest storing carbon is regulating; hiking in it is cultural; and the soil it builds is supporting. Pollination and water purification are usually counted as regulating services, because nature is regulating a process that people would otherwise have to do themselves.
| Category | What it means | Examples |
|---|---|---|
| Provisioning | Goods people take directly from nature | Food, fresh water, timber, fuel wood, fiber, medicines |
| Regulating | Nature keeping conditions stable | Forests storing carbon and moderating climate, wetlands absorbing floodwater, mangroves blocking storm surge, pollination, water purification |
| Cultural | Nonmaterial benefits | Recreation, tourism, hunting and fishing for sport, education, spiritual and artistic value |
| Supporting | Background processes the other services depend on | Nutrient cycling, soil formation, primary productivity, habitat |
Ecosystem services have economic value
Many services are free, so people often don't notice them until they're gone. But they have real economic value. If a wetland that soaked up floodwater is drained, towns downstream may face expensive flood damage. If bees decline, farmers may have to rent hives or pollinate by hand. One widely cited study estimated that all of Earth's ecosystem services are worth more than 100 trillion dollars a year, more than the world's total economic output.
Protecting an ecosystem can be cheaper than replacing its services with technology. New York City, for example, found that protecting forests and farmland in the upstate watershed that supplies its drinking water cost far less than building a filtration plant to clean the water.
Putting a price on services helps decision makers compare choices fairly. If a developer only counts the value of the houses that could be built on a wetland, draining it looks like a gain. If the cost of lost flood protection, fisheries and water filtering is counted too, the same project may be a net loss for the community.
How human activities disrupt services
The pattern to remember: people often trade a long-lasting service for a short-term provisioning gain. The lost services are an economic cost even if no one pays it directly at first.
- Clearcutting a forest provides lumber (provisioning) but loses carbon storage, erosion control and habitat, and may hurt tourism.
- Overfishing provides food now but can collapse fisheries, ending the provisioning service and the jobs that rely on it.
- Draining wetlands for building land removes flood control and water filtering.
- Clearing mangroves for shrimp farms removes the storm protection they gave coastal towns.
- Pesticide overuse can kill pollinators and the natural predators that control crop pests.
Worked examples
Try each one yourself first, then open the solution.
- Example 1
Classifying services
Classify each benefit as provisioning, regulating, cultural or supporting: (a) a coral reef attracts scuba-diving tourists; (b) a forest's roots hold soil on a hillside and reduce landslides; (c) fishers catch grouper on the reef; (d) decomposers in the forest recycle nitrogen.
Show the solutionHide the solution
- Step 1: (a) Tourism and recreation are nonmaterial benefits: cultural.
- Step 2: (b) Preventing erosion and landslides keeps conditions stable: regulating.
- Step 3: (c) Fish are a good taken directly from nature: provisioning.
- Step 4: (d) Nutrient cycling is a background process that supports everything else: supporting.
Answer: (a) Cultural, (b) regulating, (c) provisioning, (d) supporting.
- Example 2
Protect or build? A cost comparison
A town can build a water treatment plant that costs 40 million dollars to build plus 2 million dollars a year to run, or spend 15 million dollars once to protect the forested watershed that already cleans its water. Compare the total costs over 20 years and identify the ecosystem service involved.
Show the solutionHide the solution
- Step 1: Plant: 40 million dollars + (20 years × 2 million dollars per year) = 40 million dollars + 40 million dollars = 80 million dollars.
- Step 2: Protection: 15 million dollars, paid once.
- Step 3: Difference: 80 million dollars − 15 million dollars = 65 million dollars saved by protecting the watershed.
- Step 4: The forest and soil filter and purify water, which is a regulating service.
Answer: The plant costs 80 million dollars over 20 years versus 15 million dollars for protection, a savings of 65 million dollars; the service is water purification (regulating).
Common mistakes
- Calling all ecosystem services provisioning. Only goods you take directly (food, wood, water, medicine) are provisioning.
- Mixing up regulating and supporting. Regulating services directly moderate conditions for people (floods, climate); supporting services are underlying processes like nutrient cycling and soil formation.
- Saying a damaged ecosystem has ‘no economic impact’ because nothing was sold. Lost services cost money, like flood damage or water treatment.
On the exam
- A common question describes a human activity and asks for an ecosystem service that's disrupted and the economic result. Name the specific service and its category, then the cost.
- When comparing costs, set up the calculation clearly over the stated time period, including yearly costs.
Connected topics
Videos
Check yourself
4 questions on 2.2 Ecosystem Services. Pick an answer to see if you got it, and why.
Mangrove forests along a tropical coast reduce the height of storm surges and protect coastal towns from flooding. This benefit is best classified as which type of ecosystem service?
Which of the following is an example of a provisioning ecosystem service?
A city gets its drinking water from a river that flows out of a large forested watershed. As farms and housing begin spreading into the watershed, the water quality starts to decline.
Engineers estimate that a new water filtration plant would cost about $6 billion to build plus $250 million per year to run. Instead, the city spends about $1.5 billion buying land and paying farmers to protect forests and streamside vegetation in the watershed.
Described scenario
Which reasoning best supports the city's decision?
Which of the following would most likely reduce the benefit of the city's plan?
0 of 4 answered