Biodiversity & Ecosystem Resilience - Study Guide

[!] STUDY GUIDE: Big Ideas Use to answer form questions

1.Ecosystems are dynamic; populations fluctuate and respond to changes. Students often think ecosystems are stable and unchanging, but evidence from investigations shows otherwise. Use data from today's stations to identify which observations best support this understanding.

2.Food webs are complex networks; removing one species affects many others. Students often think energy flows in simple linear food chains, but evidence from investigations shows otherwise. Use data from today's stations to identify which observations best support this understanding.

3.Biodiversity provides ecosystem services, resilience, and stability. Students often think biodiversity is 'nice to have' but not essential, but evidence from investigations shows otherwise. Use data from today's stations to identify which observations best support this understanding.

DRAW KEY TERMS Google each → Images tab → sketch what you see

Biodiversity

Variety of life in an ecosystem

Ecosystem services

Benefits humans receive from healthy ecosystems

Resilience

Ability of an ecosystem to recover from disturbance

Monoculture

Agriculture using a single crop repeatedly

OTHER VOCAB: conservation · species · pollination · food web

WRITE FOCUS QUESTION Your initial thinking

In the 1950s, China launched a campaign to kill sparrows that ate grain. Without sparrows eating insects, locust populations exploded and devastated crops, contributing to a famine that affected millions.

How can one small change collapse an entire ecosystem?

I think...ecosystems are like Jenga towers — they LOOK stable, but only because every species is doing a job (eating something, being eaten, pollinating, recycling nutrients). Remove one critical block (like sparrows eating insects) and the locusts explode and the whole tower falls.

WRITE AFTER HOOK FORM Reflect before continuing

I learned that... biodiversity is INSURANCE. The more species an ecosystem has, the more 'backups' there are. China's 1958 sparrow campaign removed one species and millions starved when locust populations crashed the grain harvest. High biodiversity = high resilience.

Station 1 — Biodiversity & Resilience

I observed that... in the biodiversity simulation, ecosystems with MORE species absorbed shocks (drought, disease, fire) much better. Low-biodiversity systems (like a monoculture cornfield) crashed completely after the same disturbance.

This shows that... every species does a slightly different job (a 'niche'). When several species do similar jobs, losing one doesn't break the system — the others pick up the slack. That's called functional REDUNDANCY, and it's why biodiversity matters.

The key concept is... Resilience is the ability of an ecosystem to absorb disturbance and bounce back. Biodiversity GIVES resilience. Monocultures have almost zero resilience because there are no backups.

Station 2 — Ecosystem Services Valuation

The data shows... ecosystem services we depend on — pollination (~75% of food crops), water filtration (wetlands), pest control (birds and bats), soil formation (decomposers), oxygen (plants) — ALL come from biodiversity. The estimated dollar value is in the trillions per year globally.

This connects to... last week's trophic cascades: losing a keystone species (top-down) and losing biodiversity (sideways) both unravel the web. Together they explain why ecosystems collapse from small triggers — the system was being held up by species we couldn't see doing the work.

The main idea is... the China sparrow case is a real-world cautionary tale. Mao's 1958 campaign killed ~1 billion sparrows. With no birds eating insects, locust swarms devastated rice and wheat. Combined with bad weather, this contributed to a famine that killed an estimated 15–45 million people.

This connects to what we learned because...

I can apply this by... before any species is removed (even 'pest' species), I can ask: what job does it do in the ecosystem? Who replaces it? In St. Louis, this is why declining bee populations are a big deal — fewer pollinators means lower crop yields and higher food prices.

DRAW CONCEPT MODEL Show your understanding visually

Draw a model that shows the main concept. Include labels and arrows to explain relationships.

Two ecosystem pyramids side by side. LEFT (High Biodiversity / Resilient): wide base with many species icons (10+ plants, 6+ pollinators, 5+ predators); arrow labeled 'Disturbance → recovers' shows pyramid swaying then standing. RIGHT (Low Biodiversity / Monoculture): narrow base with 1 plant, 1 pollinator, no predators; arrow labeled 'Disturbance → collapses'. Below: list of ecosystem services (pollination, water filtration, soil formation, pest control) with bracket connecting them to high biodiversity.

Labels included

Relationships shown

Key terms used

CHECK TEST YOUR THINKING Rate each: FALSE ← 1-2-3-4-5 → TRUE

1. A healthy ecosystem stays balanced on its own and never changes unless humans interfere.

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2. Losing one species in a food web only affects the species directly above and below it.

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3. Biodiversity is mainly about having many beautiful species -- it does not affect ecosystem function.

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4. Ecosystems with higher biodiversity recover from disturbances more quickly than low-biodiversity ecosystems.

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5. Ecosystem services like pollination, water filtration, and soil formation depend on biodiversity.

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Pick any TWO statements -- especially any you rated 2, 3, or 4. Justify your rating with evidence:

Statement #___ -- I rated it ___ because:

THINK SCIENTIST CIRCLE DEBRIEF Reflect after your Scientist Circle discussion

AHA! Moment

The one I changed my thinking most about is... ecosystems aren't held together by one or two famous species — they're held together by hundreds of 'background' species doing jobs no one notices until they stop.

Remaining Question

I still wonder... If high biodiversity is the insurance, how do we measure how MUCH biodiversity an ecosystem needs to stay resilient? Is there a threshold below which it can't recover?

WRITE FOCUS QUESTION REVISIT Final written response

How can one small change collapse an entire ecosystem?

Word Bank: biodiversity · resilience · monoculture · ecosystem services · conservation · species · pollination · food web

CLAIM: One small change can collapse an entire ecosystem because every species is connected to many others, and biodiversity is what holds the system together. Remove a critical species and the whole web shifts.

EVIDENCE: China's 1958 anti-sparrow campaign → locust outbreak → crop failure → 15–45 million deaths. In experimental plots, low-biodiversity grasslands lost 70% of biomass in drought while high-biodiversity plots lost ~25%. Ecosystem services (pollination, water filtration, pest control) require many species.

REASONING: Biodiversity provides RESILIENCE through functional redundancy — multiple species doing similar jobs means losing one doesn't break the system. Low-diversity ecosystems have no backups, so one disturbance unravels everything. The 'small change' isn't really small; it just APPEARS small because we don't see the web until pieces of it are missing.