Conservation, Systems & Environmental Design — Problem set, Grade 12

Join conservation evidence, feedback, risk, and a complete design-and-monitoring proposal.

Review the key ideas

Biodiversity Loss

Distinguish abundance decline, local loss and global extinction. Compare standardized evidence, causal pressures and actual conservation outcomes without an undated universal extinction multiplier.

Sustainability & Solutions

Sustainability proposals require explicit service, resource boundaries, evidence, trade-offs, and monitoring. Footprint values depend on model assumptions and dates.

Environmental Systems, Feedback & Risk

Conservation, feedback, and explicit risk assumptions make environmental decisions traceable.

Environmental Design & Evidence-Based Capstone

A strong design connects mechanism, numbers, trade-offs, uncertainty, and a testable monitoring plan.

Problem 1

For each scenario, name the driver of biodiversity loss: (a) a mangrove forest is cleared for a shrimp farm, (b) a non-native vine spreads through a forest and smothers the native trees, (c) elephants are killed faster than they can reproduce for their ivory.
Answer and explanation

(a) habitat loss, (b) invasive species, (c) overexploitation.

(a) Clearing the mangrove removes the natural habitat, so this is habitat loss/destruction — the largest driver overall. (b) A non-native vine spreading and harming native trees is an invasive species. (c) Killing elephants faster than the population can replace itself is overexploitation. All three appear in the HIPPO list of biodiversity threats.

Problem 2

A tropical forest reserve originally covered 8,000 hectares. Logging and farming have reduced the intact forest to 2,000 hectares. What percentage of the original forest habitat has been lost?
Answer and explanation

75%.

Area lost = 8,000 - 2,000 = 6,000 hectares. Dividing by the original area: 6,000 ÷ 8,000 = 0.75, or 75% of the forest habitat lost. Only a quarter of the original forest remains.

Problem 3

A conservation plan preserves the same total forest area as before, but chops it into several small, isolated patches separated by farmland. Explain why this may still harm biodiversity even though no net area was lost.
Answer and explanation

Fragmentation isolates populations, shrinks patches below what some species need, and increases harmful edge effects, so the divided habitat supports less biodiversity than the same area kept intact.

Even with the same total area, breaking a habitat into isolated patches causes several problems. Populations in different patches are cut off from one another, reducing gene flow and making local extinctions more likely. Wide-ranging or large species may need more continuous space than any single small patch provides. And more edge means more of the habitat is exposed to drying winds, sunlight, predators, and invasive species that penetrate from the surrounding farmland. So fragmentation can reduce biodiversity even when the raw acreage is unchanged — which is why connecting habitat with corridors is a key conservation strategy.

Problem 4

The average ecological footprint in a high-consumption country is about 8.0 global hectares (gha) per person, while Earth's biocapacity is about 1.6 gha per person. If everyone on Earth lived this way, how many Earths would be required?
Answer and explanation

About 5 Earths.

Earths needed = footprint ÷ biocapacity per person = 8.0 gha ÷ 1.6 gha = 5.0. If every person on the planet consumed at this level, humanity would need five Earths' worth of resources and waste absorption — a stark illustration that the highest-consumption lifestyles cannot scale to the whole global population.

Problem 5

The Montreal Protocol phased out ozone-destroying CFCs and the ozone layer is now recovering. Explain what this success story suggests about how humanity can address global problems like climate change, and why systemic policy can matter more than individual action alone.
Answer and explanation

It shows that when science identifies a global pollutant and nations coordinate policy to phase it out, an Earth system can recover — evidence that climate change is also solvable through international, system-level action rather than individual effort alone.

The Montreal Protocol worked because nearly every country agreed to the same binding phase-out of CFCs, replacing them with safer chemicals across entire industries at once. Because the change was made at the level of laws and whole industries — not left to individual consumers — it reached the true source of the problem, and the ozone layer began healing within decades. This is encouraging for climate change: the largest emissions come from how societies produce energy, move goods, and grow food, which are shaped by policy and infrastructure. Individual choices help and build momentum, but coordinated, system-level policy has the leverage to cut emissions at their source — just as it did for ozone.

Problem 6

Why can habitat corridors help but need case-specific evaluation?
Answer and explanation

They can improve movement and gene flow but also transport disease or invasives; compare evidence and target species.

Response criteria

  • State a scientifically accurate conclusion.
  • Show the calculation or mechanism that supports it.
  • Include units, conditions, or limits where relevant.

Problem 7

Chapter review: A population estimate falls from500 to350 under comparable methods. Find percent decline. Explain why this does not prove global extinction or identify a unique cause.
Answer and explanation

Decline=(500−350)/500=30%. Living individuals remain in the defined population, and the record alone cannot distinguish survival, reproduction, movement or the pressures affecting them.

Decline=(500−350)/500=30%.

Living individuals remain in the defined population, and the record alone cannot distinguish survival, reproduction, movement or the pressures affecting them.

Response criteria

  • Use the stated measurements or conditions, with correct units.
  • Connect the result to the physical or environmental mechanism or evidence relationship.
  • Identify the assumption, model limit or further evidence requested.

Problem 8

What makes a sustainability proposal measurable?
Answer and explanation

A baseline, defined service and boundary, predicted outcomes, resource/impact accounting, trade-offs, and monitoring.

Response criteria

  • State a scientifically accurate conclusion.
  • Show the calculation or mechanism that supports it.
  • Include units, conditions, or limits where relevant.

Problem 9

Chapter review: Energy per use falls from10 to6 units while annual uses rise from100 to140. Find old/new total and percent saving; state a separate service criterion.
Answer and explanation

Old=1000 units; new=840; saving=160 units=16%, smaller than the40% per-use reduction. Adequate service quality, access or reliability needs a separate measure.

Old=1000 units; new=840; saving=160 units=16%, smaller than the40% per-use reduction.

Adequate service quality, access or reliability needs a separate measure.

Response criteria

  • Use the stated measurements or conditions, with correct units.
  • Connect the result to the physical or environmental mechanism or evidence relationship.
  • Identify the assumption, model limit or further evidence requested.

Problem 10

Inputs 120,outputs 95. Find storage change.
Hints

Write the relationship first; substitute with consistent units.

Answer and explanation

25 units

120−95=25.

Problem 11

Why might equal expected-loss options have different consequences?
Answer and explanation

They may differ in extreme outcomes, who is exposed, reversibility, and uncertainty.

Response criteria

  • State a scientifically accurate conclusion.
  • Show the calculation or mechanism that supports it.
  • Include units, conditions, or limits where relevant.

Problem 12

Chapter review: Event A has probability0.05 and consequence200 units; B has probability0.20 and consequence40. Find expected losses and explain why the smaller expected value need not settle the choice.
Answer and explanation

A=10 units; B=8 units. B has lower expected loss, but worst-case severity, uncertainty, distribution, constraints and priorities still need transparent consideration.

A=10 units; B=8 units.

B has lower expected loss, but worst-case severity, uncertainty, distribution, constraints and priorities still need transparent consideration.

Response criteria

  • Use the stated measurements or conditions, with correct units.
  • Connect the result to the physical or environmental mechanism or evidence relationship.
  • Identify the assumption, model limit or further evidence requested.

Problem 13

What belongs in a monitoring plan?
Answer and explanation

Measured outcomes, method, comparison period, controls for confounders, schedule, and revision criteria.

Response criteria

  • State a scientifically accurate conclusion.
  • Show the calculation or mechanism that supports it.
  • Include units, conditions, or limits where relevant.

Problem 14

Cost 900 units,annual savings 300. Find simple payback.
Hints

Write the relationship first; substitute with consistent units.

Answer and explanation

3 years

900/300=3.

Problem 15

Chapter review: A proposed change saves12 W for1500 h/year while providing the same service. Its extra production energy is24 kWh. Find annual saving and energy break-even; name one pilot measure beyond energy.
Answer and explanation

Annual saving=0.012×1500=18 kWh. Energy break-even=24/18≈1.33 years under fixed use/lifespan assumptions. Measure service adequacy, reliability, actual hours, access or maintenance as a separate pilot outcome.

Annual saving=0.012×1500=18 kWh.

Energy break-even=24/18≈1.33 years under fixed use/lifespan assumptions.

Measure service adequacy, reliability, actual hours, access or maintenance as a separate pilot outcome.

Response criteria

  • Use the stated measurements or conditions, with correct units.
  • Connect the result to the physical or environmental mechanism or evidence relationship.
  • Identify the assumption, model limit or further evidence requested.
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