Biodiversity and conservation case studies

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Catatan pelajaran

Big idea: living variety under pressure

Big idea (key concept): Relationships. Every species in an ecosystem is linked to others by feeding, competition and shelter. Remove or add one species and many other species feel it.
Related concept: Consequences. Human choices about farming, fishing, forestry and trade have consequences for living things far away from where the choice was made.
Global context: Globalization and sustainability. Products such as palm oil, fish and timber are traded around the world, so a choice made in a shop can change an ecosystem on another continent. Sustainable use means meeting today's needs without wrecking the supply for the future.
Biodiversity is the variety of living things. It has three levels: genetic diversity (differences between individuals of one species), species diversity (the number and abundance of different species) and ecosystem diversity (the range of habitats).
A varied ecosystem is usually more stable. If one species declines, others can often take over its role, and a disease or a drought is less likely to wipe everything out.
People gain from biodiversity through ecosystem services: pollination of crops, clean water, fertile soil, carbon storage, raw materials, medicines and tourism. There is also an ethical argument that species have a right to exist.
Threats include habitat destruction, invasive species, overexploitation (taking too many), pollution and climate change. They rarely act alone: the riverine rabbit of South Africa faces predators, hunting, farming, fire, floods and road traffic all at once.

Many pressures on one species: the riverine rabbit

Measuring biodiversity

Species richness is the number of different species in an area. It is easy to count but ignores how many individuals there are of each.
A quadrat is a square frame (often 1 m by 1 m) placed on the ground. To avoid bias the positions must be random, for example by using random numbers as coordinates on a measuring grid. Count the organisms in each quadrat, repeat many times and calculate the mean.
Estimated population = mean number per m² × total area in m². This only works if the sample is large enough and the organisms are spread fairly evenly across the area.
A transect is a line laid across a habitat. Quadrats placed at regular intervals along it show how the community changes across a gradient, such as from the sea shore up the beach.
Moving animals cannot be counted in quadrats. In capture-recapture, a first sample is caught, marked and released. A second sample is caught later. Population = (number marked in first sample × size of second sample) ÷ number of marked animals recaptured. It assumes the marked animals mix back in and that marking does not harm them.
An index of diversity uses both richness and evenness. In this course we use Simpson's index: D = N(N − 1) ÷ Σ n(n − 1), where N is the total number of individuals and n is the number of one species. A higher D means more diversity.
Worked example: a meadow has 8, 6, 5, 4 and 2 individuals of five beetle species. N = 25. Σ n(n − 1) = 56 + 30 + 20 + 12 + 2 = 120. D = 25 × 24 ÷ 120 = 5.0. A field with 20, 3 and 2 individuals also has N = 25, but Σ n(n − 1) = 388 and D is only about 1.5, because one species dominates.

Estimating a population with random quadrats

Case study 1: Yellowstone Lake

Yellowstone Lake in the USA was home to the native Yellowstone cutthroat trout. Cutthroat trout are food for many predators, including bears, otters and fish-eating birds such as ospreys.
A non-native predator, the lake trout, was later found in the lake. An invasive species is a non-native species that spreads and harms the native community. Lake trout eat young cutthroat trout. Lake trout live mostly in deep water.
As the lake trout became established, cutthroat trout numbers fell. The small shrimp-like animal×Gammarus×, which the cutthroat trout feed on, rose because it was eaten less. This is a cascade: a change at one level of the food web passes to the levels above and below.
Animals that depend on cutthroat trout lose a food source. Because lake trout live in deep water they are much harder for bears and birds to catch, so they do not replace the food that was lost.
Response: park scientists use gillnets to remove lake trout. This does not need the lake to be drained or poisoned and it protects other species, although some other fish are caught by accident (bycatch). The work must continue every year, which is expensive.
Lesson: it is much cheaper and more effective to prevent invasive species arriving than to remove them once they are established.

Yellowstone Lake food web before and after lake trout

Case study 2: palm oil and tropical forest

Palm oil is in food, soap, cosmetics and fuel. The oil palm gives far more oil from each hectare than other oil crops, so it feeds a large global demand. Most is grown in Indonesia and Malaysia, and production rose steeply between 1991 and 2018.
Much of this land was once tropical rainforest. Clearing it is deforestation. It removes habitat, so species such as the orangutan of Borneo and Sumatra lose their homes and some become endangered.
Rainforest has thousands of species. An oil palm plantation is a monoculture: one crop species in rows. It offers few food sources and few places to nest, so far fewer species live there and the index of diversity is much lower.
Other consequences of clearing forest: soil is washed away without roots to hold it, rivers flood more, and carbon dioxide that was stored in the trees is released. Draining and burning peat forest releases very large amounts of carbon.
Trade-offs. If people stopped using palm oil, other oil crops would be needed, and they give less oil per hectare, so they might need more land in total. Many scientists therefore argue for sustainable palm oil: grow it on land that is already cleared, protect the remaining forest and check the supply chain.
Different groups have different views: farmers want income, companies want low costs, shoppers want cheap products and conservationists want habitat protected. A fair evaluation weighs all of them.

Consequences of clearing a forest

Think like a scientist: evaluating evidence and planning a survey

To evaluate a conservation scheme, ask: did the target population or the index of diversity increase? Compared with what? Over how long? At what cost? Who gains and who loses?
Ex situ conservation protects species outside their habitat: zoos and captive-breeding programmes, botanical gardens and seed banks such as the Millennium Seed Bank in the UK. Animals can be released later (reintroduction), as happened with the Arabian oryx, which had become extinct in the wild.
Ex situ work keeps genetic diversity safe and can rescue a species with very few individuals left, for example by careful breeding to avoid inbreeding. But it is expensive, cannot save the habitat and released animals need a safe place to go.
Local people must benefit or schemes fail. Ecotourism, jobs as park rangers and payments for protecting forest give communities a reason to look after wildlife.
A rise in numbers is not proof that a scheme worked. You need a comparison, such as a similar unprotected area, because numbers might have risen anyway after a good year for food or weather.
Counts must be made the same way each time (same quadrat size, same number of quadrats, same season, random positions) or the results cannot be compared fairly.
Short-term success may not last. A species saved by a feeding programme may collapse when it stops. Long-term monitoring gives stronger evidence.
Different strategies suit different situations. A species with only a handful left may need ex situ breeding as a safety net, while a widespread species with a shrinking habitat is better served by protecting that habitat.
Use command words properly. Describe means say what happens. Explain means give the reason. Evaluate means weigh strengths and weaknesses and reach a judgement. Suggest means apply your knowledge to a new situation.

Think like a scientist: planning a biodiversity survey

A school wants to know whether a mown lawn or an uncut meadow strip has more plant species. Here is how to plan it as a fair test.
The independent variable is the habitat (lawn or meadow strip). The dependent variable is the number of plant species (or the Simpson index) per quadrat. Control variables include quadrat size, the number of quadrats, the time of year and how positions are chosen.
Choose positions with random numbers so the surveyor does not just pick the interesting spots. Use the same number of quadrats in each habitat, and enough of them (at least 10) so that one odd quadrat does not distort the mean.
Record the data in a table with units, then calculate the mean number of species per quadrat and the Simpson index for each habitat. Look for anomalies such as a count that is far from the rest.
Evaluate the method: both areas are in one school, so the result may not apply elsewhere; the survey was done in a single week; it is hard to identify every species accurately. How could each limit be reduced?
Inquiry task: design a survey of insect diversity on two sides of a hedge. State your variables, how you will sample, how many samples you will take and how you will decide which side has more diversity.

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1.What is biodiversity?
Easy
- AThe total mass of all the living things in a habitat
- BThe number of animals that live in a zoo or reserve
- CThe variety of living things in a habitat or ecosystem
- DThe range of different climates found on Earth
2.Which of these is one of the three levels of biodiversity?
Easy
- AGenetic diversity within a species
- BThe diversity of weather in a region
- CThe diversity of rock types in a hill
- DThe diversity of buildings in a city
3.A habitat that contains thousands of individuals of just one species has high biodiversity.
Easy
True or false?
4.Match each term to its meaning.
Easy
- Habitat
- Endangered
- Extinct
- Invasive species
- A non-native species that spreads and harms native species
- A species with no living members left
- The place where an organism lives
- A species at high risk of dying out
5.What is an invasive species?
Easy
- AAny native species that is found in a very large number of habitats
- BA species that has been moved into a zoo for breeding programmes
- CAny species that lives together in one very large group
- DA non-native species that spreads and harms the native community
6.Why should quadrats be placed at random positions?
Easy
- ATo make the survey finish more quickly
- BTo avoid bias in the results
- CTo make sure every quadrat contains plants
- DTo make the mean count as high as possible
7.Complete the sentence about sampling biodiversity.
Easy
A ____ is a square frame used to sample the organisms in a small area.
8.Which of these are ecosystem services provided by biodiversity? (select all that apply)
Easy
- APollination of crops by insects
- BStorage of carbon in forests
- CPurification of water by wetlands
- DProduction of plastic in factories
- EMaking rocks from sediment

Soal lainnya

9.A zoo breeding programme is an example of in situ conservation.
Easy
True or false?
10.Which of these is an example of ex situ conservation?
Easy
- AA national park that protects a forest
- BA marine reserve where fishing is banned
- CA wildlife corridor between two forests
- DA seed bank that stores seeds of rare plants
11.Put the steps of a random quadrat survey in a sensible order.
Easy
- Choose random coordinates on a measuring grid
- Place the quadrat at each position
- Count the organisms inside the quadrat
- Repeat for many positions
- Calculate the mean number per quadrat
12.Clearing a rainforest for farmland threatens biodiversity mainly because it
Easy
- Adestroys the habitat that many species need
- Bmakes the air warmer for every organism
- Cadds too much light for the plants to use
- Dgives predators more places to hide
13.What is a monoculture?
Easy
- AGrowing many different crops on one farm
- BKeeping one type of animal in a field
- CGrowing a single crop species over a large area
- DA forest with only one kind of tree growing wild
14.A national park that protects a natural habitat is an example of in situ conservation.
Easy
True or false?
15.What is the main purpose of the international agreement CITES?
Easy
- ATo pay farmers a fair price for crops grown in protected areas
- BTo control the trade in endangered species and their products
- CTo set the global price of timber and farmed fish each year
- DTo move rare animals between zoos in different countries
16.Complete the sentence about conservation methods.
Easy
Protecting a species in its natural habitat is called ____ conservation.
17.Why does the orangutan decline when rainforest is cleared for palm oil plantations?
Easy
- AIt cannot digest the oil from the palm fruit
- BIt is unable to breathe in open spaces
- CIt moves into water to find food
- DIt loses the trees it uses for food and shelter
18.Match each conservation method to what it does.
Easy
- Seed bank
- Captive breeding
- Fishing quota
- Protected area
- Stores seeds so a plant species can be regrown later
- Breeds rare animals under human care
- Limits how many fish can be caught
- Keeps a habitat safe from development
19.Which statement best describes sustainable use of a resource?
Easy
- AUsing as much as possible as fast as possible
- BNever using the resource at all
- CUsing it so that it stays available later
- DUsing it only in the richest countries
20.
Two fields were surveyed, as shown.
Field Species found Total plants counted
Field X 9 60
Field Y 4 300
Which field has the greater species richness?
Medium
- AField Y, because it has more individual plants
- BField X, because it has more species
- CBoth are the same, because the totals are similar
- DField Y, because its plants are more evenly spread
21.A class counted daisies in six random 1 m² quadrats on a lawn and found 12, 16, 9, 14, 11, 10 daisies. Calculate the mean number of daisies per quadrat.
Medium
22.A school field has an area of 400 m². A random quadrat survey finds a mean of 4.5 clover plants per m². Estimate the number of clover plants in the whole field.
Medium
23.Simpson's index is D = N(N − 1) ÷ Σ n(n − 1). A meadow has beetle species with 8, 6, 5, 4, 2 individuals. Calculate D for the meadow.
Medium
24.Using Simpson's index as D = N(N − 1) ÷ Σ n(n − 1), site P has D = 1.5 and site Q has D = 5.0. What does this show?
Medium
- ASite Q is more diverse than site P
- BSite P is more diverse than site Q
- CSite P has more individual organisms than site Q
- DSite Q has fewer species than site P
25.In a capture-recapture study, 30 beetles are marked and released. Later a second sample of 40 beetles contains 6 marked beetles. Use population = (marked in first sample × size of second sample) ÷ marked recaptured to estimate the population.
Medium
26.In Yellowstone Lake, lake trout eat young cutthroat trout. What is the most likely effect on animals such as ospreys that feed on cutthroat trout?
Medium
- AThey have more food, because there are more fish overall
- BThey are unaffected, because predators do not depend on one fish
- CThey have less food available to catch
- DThey begin to feed on Gammarus instead
27.Which of these are consequences of clearing a forest? (select all that apply)
Medium
- ALoss of habitat for many species
- BMore soil washed away by rain
- CLess carbon stored in vegetation
- DA rise in the number of tree-living species
- EA larger variety of plant species in the cleared area
28.Why do fishing quotas help to conserve fish stocks?
Medium
- AThey keep the number caught below the number of new fish being born
- BThey make fish grow larger before they hatch
- CThey stop other animals in the sea from eating the fish
- DThey raise the price of fish so fewer people buy it
29.Why does a minimum mesh size help a fishery to be sustainable?
Medium
- ALarger fish are easier to see in the net
- BIt makes the nets cheaper to buy
- CIt stops bycatch of every other species
- DYoung fish can escape and grow up to breed
30.Ex situ conservation can protect the genetic diversity of a species, but it does not protect the species' natural habitat.
Medium
True or false?
31.Complete the sentence about diversity index.
Medium
An index of diversity takes into account both the number of ____ and how evenly the individuals are spread between them.
32.Captive-bred animals are released into a habitat that is still being cleared for farmland. What is the most likely outcome?
Medium
- AThey will breed faster, because the cleared land is open and sunny
- BMany will die or fail to breed, because their habitat is not secure
- CThey will quickly build a new habitat for themselves to live in
- DThey will have no predators there, so numbers will rise rapidly
33.A simplified table (rounded values) of palm oil production in Indonesia gives 8 million tonnes in 2000 and 40 million tonnes in 2018. Calculate the percentage increase in production.
Medium
34.Someone says that everyone should stop buying palm oil to save rainforest. Which statement is the best evaluation of this idea?
Medium
- AIt will certainly help, because oil palms are the only crop that harms forests
- BIt will have no effect, because palm oil is not grown in forests
- CIt will help, because no other crop can be grown on cleared forest land
- DIt may not help: other crops give less oil per hectare and may need more land
35.Which method is most suitable for estimating the number of woodlice, which move around, in a garden?
Medium
- ACapture-recapture with marked individuals
- BA single quadrat placed at one spot
- CA transect with no counting
- DCounting only the woodlice that are not moving
36.A transect is laid from the sea wall to the water's edge and quadrats are placed every 5 m. What is this method best used to show?
Medium
- AThe total number of species on the whole planet
- BThe age of the oldest plant on the shore
- CHow the community changes with distance across a gradient
- DHow many animals are marked and released
37.Using D = N(N − 1) ÷ Σ n(n − 1), a community in which one species is very common and the others are rare will have a low D.
Medium
True or false?
38.A food web changes after a non-native predator arrives. Put these events in the most likely order.
Medium
- A non-native predator enters the lake
- The numbers of the native prey fish fall
- The animals that eat the native fish have less food
- The numbers of the prey's own food organisms rise
39.Describe how you would estimate the number of dandelions in a field that measures 50 m by 20 m. (3 marks)
Hard
40.Explain how the arrival of lake trout could affect the animals that feed on cutthroat trout. (3 marks)
Hard
41.A species has fewer than 30 individuals left in the wild. Evaluate the use of ex situ conservation for this species. (3 marks)
Hard
42.A survey of a 200 m² meadow counted snails in seven random 1 m² quadrats: 6, 7, 5, 8, 31, 6, 7. The count of 31 is an anomaly caused by a pile of rotting leaves. Ignore the anomaly, calculate the mean per m², then estimate the population in the meadow.
Hard
43.
Beetle samples from two sites are shown.
Site Beetle species Number of individuals of each species
A (wildflower meadow) 5 8, 6, 5, 4, 2
B (field after intensive farming) 3 20, 3, 2
Using D = N(N − 1) ÷ Σ n(n − 1), which statement is correct?
Hard
- ASite B is more diverse: D is about 1.5 for B and 5.0 for A
- BSite A is more diverse: D is 5.0 for A and about 1.5 for B
- CThe sites are equally diverse because both have 25 beetles
- DSite B is more diverse because one species is very abundant
44.Explain why an oil palm plantation supports far fewer species than the rainforest it replaced. (3 marks)
Hard
45.Suggest two reasons why local communities must be involved in a conservation scheme. (2 marks)
Hard
46.A reserve manager says: "Our tiger count rose from 40 to 52 in five years, so the reserve works." Which extra pieces of evidence would make this claim stronger? (select all that apply)
Hard
- ATiger counts in a similar unprotected area over the same five years
- BEvidence that counts used the same method in every year
- CCounts for the numbers of their prey species
- DThe colour of the reserve's entrance sign
- EThe number of visitors who took photographs
47.In a pond survey, the number of species fell from 25 before pollution to 18 after. Calculate the percentage decrease in species richness.
Hard
48.Explain why captive-breeding programmes try to keep the genetic diversity of the animals as high as possible. (3 marks)
Hard
49.A student compares the number of plant species on a trampled path with a nearby uncut area by placing quadrats at different distances from the path. What is the independent variable?
Medium
- ANumber of plant species in each quadrat
- BSize of the quadrat
- CTime of year the survey was done
- DDistance from the path
50.Pond A has 12 fish species and Pond B, which has a factory nearby, has 6. A student concludes that the factory pollution killed the other species. Which is the best evaluation?
Medium
- AThe conclusion is secure, because 12 is exactly twice 6 species
- BThe conclusion is secure, because factories always kill fish nearby
- CThe conclusion is not secure: the ponds may have differed in other ways
- DThe conclusion is wrong, because a pond can never lose species
51.Which plan gives the fairest comparison of tree density in two woods?
Medium
- ACount trees in a large area of wood A and a small area of wood B
- BUse the same quadrat size and number of random positions in each wood
- CChoose the thickest and most crowded parts of each wood to count
- DCount in wood A during summer and in wood B during winter
52.Park scientists remove lake trout from Yellowstone Lake with gillnets rather than draining or poisoning the lake. What is the main advantage of this method?
Medium
- AIt targets lake trout and leaves the rest of the lake intact
- BIt removes every single fish from the lake in just one day
- CIt is certain to cost nothing to carry out each year
- DIt guarantees no other fish are ever caught by accident
53.A rise in a population after a conservation scheme starts proves that the scheme caused the rise.
Medium
True or false?
54.A fishing fleet catches more fish each year than are born into the population. What is likely to happen to the fish stock?
Medium
- AIt will stay the same because fish breed quickly
- BIt will increase because there is less competition
- CIt will decline and may collapse
- DIt will move to the deep sea and be safe

Catatan ulasan

## Biodiversity and conservation case studies - **Biodiversity** is variety at three levels: genes, species and ecosystems. It gives people **ecosystem services**. - Threats include habitat loss, invasive species, overexploitation, pollution and climate change, and they often act together. - **Measure** with random quadrats (mean per m² × area), transects, capture-recapture and **Simpson's index** (higher D = more diverse). - **Yellowstone Lake:** non-native lake trout eat cutthroat trout, so cutthroat fall, *Gammarus* rise and animals that eat cutthroat lose food. Prevention beats removal. - **Palm oil:** high-yield crop, but plantations replace rainforest with a monoculture that supports few species. Sustainable palm oil and trade-offs matter. - **Conservation:** in situ (parks, reserves) and ex situ (zoos, seed banks), laws such as CITES, sustainable use (quotas, mesh sizes) and community involvement. - **Evaluate** with comparison areas, consistent methods, long-term data and costs.

Biodiversity: The variety of living things, at the level of genes, species or ecosystems.
Species richness: The number of different species in an area.
Index of diversity: A measure that uses both the number of species and how evenly individuals are spread; here Simpson's D = N(N - 1) / sum of n(n - 1).
Quadrat: A square frame placed on the ground to sample the organisms in a small area.
Transect: A line across a habitat along which samples are taken to show change across a gradient.
Capture-recapture: A method of estimating the size of a population of moving animals by marking and re-sampling them.
Ecosystem services: Benefits that people get from natural systems, such as pollination, clean water and carbon storage.
Invasive species: A non-native species that spreads and harms native species.
Monoculture: Growing one crop species over a large area.
Deforestation: The clearing of forest, which removes habitat, soil and stored carbon.
In situ conservation: Protecting species in their natural habitat.
Ex situ conservation: Protecting species outside their natural habitat, for example in zoos and seed banks.
Quota: A limit on the amount of a resource, such as fish, that may be taken.
Sustainable use: Using a resource so that it remains available for the future.
CITES: An international agreement that controls trade in endangered species.

Kartu flash

What is biodiversity?

The variety of living things, at the level of genes, species and ecosystems.

Name the three levels of biodiversity.

Genetic diversity, species diversity and ecosystem diversity.

Why must quadrats be placed at random?

To avoid bias in the results.

How do you estimate a population from quadrat data?

Mean number per m² multiplied by the total area in m².

State the capture-recapture formula.

Population = (number marked in first sample × size of second sample) ÷ number of marked animals recaptured.

State Simpson's index as used in this course.

D = N(N - 1) ÷ Σ n(n - 1). A higher D means more diversity.

What is a transect used for?

To show how a community changes across a gradient, using samples along a line.

What is an invasive species?

A non-native species that spreads and harms native species.

What happened to Yellowstone Lake after lake trout became established?

Cutthroat trout fell, Gammarus rose, and animals that eat cutthroat trout lost a food source.

Why do oil palm plantations have low biodiversity?

They are monocultures that give few food sources and few nesting places.

Why might stopping palm oil use not help forests?

Other oil crops give less oil per hectare and may need more land.

What is in situ conservation?

Protecting species in their natural habitat, for example in national parks.

What is ex situ conservation?

Protecting species outside their habitat, for example zoos, captive breeding and seed banks.

What are the limits of ex situ conservation?

It is expensive, it does not save the habitat and animals can only be released if a safe habitat exists.

Why do fishing quotas work?

They keep the catch below the number of new fish born, so the stock can recover.

Why does a larger mesh size help?

Young fish escape and can grow up to breed.

What does CITES do?

It controls international trade in endangered species and their products.

How do you evaluate a conservation scheme?

Compare with an unprotected area, use the same method each time, look at long-term data and consider cost and who benefits.

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Site	Beetle species	Number of individuals of each species
A (wildflower meadow)	5	8, 6, 5, 4, 2
B (field after intensive farming)	3	20, 3, 2

Field	Species found	Total plants counted
Field X	9	60
Field Y	4	300