Wolf Island Mystery

Moose Primary Consumer

Consumes 30–40 lbs of vegetation per day. Overpopulates without wolves.

Balsam Fir Primary Producer

Saplings can only grow into mature trees when moose browsing is suppressed!

Wolves protect the forest by eating the plant-eaters! Slide 5 of 8

Energy & Matter Flow

The 10% Ecological Energy Rule

Wolves: 1,000 kcal

Moose: 10,000 kcal

Balsam Fir Trees: 100,000 kcal

Where Does 90% of the Energy Go?

At each trophic level, roughly 90% of energy is lost as metabolic heat and waste through cellular respiration.

Why are apex predators rare? Because it takes an enormous base of producers to support even a small pack of wolves!

Biomass Pyramids: Energy limits the number of trophic levels Slide 6 of 8

Environmental Disruption

Vanishing Ice Bridges & Genetic Isolation

Climate Warming

In the 1960s, ice bridges formed across Lake Superior in 8 out of 10 winters, letting new wolves walk to the island.

Today, ice bridges form in less than 2 out of 10 winters.

Genetic Rescue (2018)

Isolated wolves suffered severe spinal deformities from inbreeding. In 2018, National Park biologists made a decision: relocate 19 new mainland wolves to the island.

Result: New packs formed, pups were born, and trophic balance resumed!

Abiotic factors directly alter biotic community resilience Slide 7 of 8

Student Mission

Your Field Investigation Protocol

1

Plot Field Data

Map 40 years of wolf and moose population records on your dual-axis chart.

2

Model Energy

Calculate energy loss through the boreal food chain using the 10% rule.

3

Defend Your CER

Argue whether Isle Royale’s forest canopy can survive without apex wolves.

Open your student packet to Part 1: Field Census Data Slide 8 of 8

Producers (Balsam Fir)

3,600,000 kcal

100% available energy

Primary Consumers (Moose)

Energy:

kcal

10% of producer level

Apex Predators (Wolves)

Energy:

kcal

10% of herbivore level

Why does the 10% rule explain why there are hundreds of moose on Isle Royale, but rarely more than 20 to 50 wolves?

3 Predicting Trophic Cascades: Cause-and-Effect Flow

Fill in each box with an INCREASE (▲) or DECREASE (▼) to map the chain reaction when wolf numbers drop:

Event 1 Wolves Die Off (▼) Due to parvovirus/isolation

Event 2: Moose

Predation pressure changes

Event 3: Fir Saplings

Browsing pressure impact

Event 4: Forest Health

Canopy diversity & songbirds

4 Scientific Argumentation: Claim, Evidence & Reasoning (CER)

Question: "Can Isle Royale’s balsam fir forest remain stable and biodiverse without an active apex wolf population?"

Claim: (State your direct scientific answer to the question)

Evidence: (Cite at least TWO specific data points with years/numbers from Part 1)

Reasoning: (Connect evidence using trophic cascade, 10% energy law, or carrying capacity)

ISLE ROYALE INVESTIGATION PACKET • STUDENT WORKBOOK PAGE 2 OF 2

4. CER Argument: ___ / 4

Total Score: ___ / 16

Evaluator Feedback & Instructional Next Steps

Teacher Signature: _________________

Student Investigation Self-Audit Checklist

My graph includes labeled dual axes with correct units. I calculated producer-to-predator calories with units (kcal). My CER cites at least TWO specific historical census years. My reasoning explains why wolves indirectly protect tree growth.

ISLE ROYALE ECOLOGICAL STUDY • ASSESSMENT RUBRIC PAGE 1 OF 1