Ecological Succession and Disturbances

Active learning helps students grasp ecological succession because the topic involves dynamic, staged changes that are best visualized through hands-on models and real-world examples. Watching a tray of soil develop over weeks or mapping disturbances on aerial photos makes abstract concepts concrete and memorable for students who learn by doing and seeing.

• Grade 12
• Biology
• 4 activities
• 35 min–50 min

Learning Objectives

1. Compare and contrast the initial conditions and processes of primary and secondary ecological succession.
2. Analyze the impact of specific natural disturbances (e.g., wildfire, flood) on the species composition and structure of an ecosystem.
3. Evaluate the long-term consequences of anthropogenic disturbances (e.g., deforestation, urbanization) on ecosystem resilience and biodiversity.
4. Predict the trajectory of ecological change over time following a significant environmental disturbance, citing supporting evidence.

Case Study Analysis

⏱ 45 min·Small Groups

Tray Simulation: Primary Succession

Provide trays with bare rocks, lichens (moss substitute), soil builders, and seeds. Small groups add layers weekly, watering and recording species establishment over 4-6 weeks. Compare growth rates and discuss pioneer roles. Accelerate with heat lamps if time is short.

Prepare & details

Differentiate between primary and secondary succession.

Facilitation Tip: During the Tray Simulation, remind students to record observations daily to track changes in soil depth and pioneer species establishment, reinforcing the slow pace of primary succession.

Setup: Groups at tables with case materials

Materials: Case study packet (3-5 pages), Analysis framework worksheet, Presentation template

• Analyze
• Evaluate
• Create
• Decision-Making
• Self-Management

Jigsaw

⏱ 50 min·Small Groups

Jigsaw: Disturbance Analysis

Assign groups one disturbance type (fire, flood, logging) with Ontario examples and data sets. Each group analyzes impacts on succession stages, then rotates to teach peers. Synthesize findings in a class chart on community changes.

Prepare & details

Analyze how disturbances, such as fires or floods, can influence community structure.

Facilitation Tip: For the Jigsaw Case Studies, assign each group a unique disturbance type to ensure diverse examples are shared, preventing overlap and deepening understanding of varied recovery pathways.

Setup: Flexible seating for regrouping

Materials: Expert group reading packets, Note-taking template, Summary graphic organizer

• Understand
• Analyze
• Evaluate
• Relationship Skills
• Self-Management

Case Study Analysis

⏱ 35 min·Pairs

Prediction Cards: Post-Disturbance Timeline

Distribute species cards with traits (pioneer, intermediate, climax). Pairs sequence them after a simulated disturbance, justifying choices based on tolerances. Class votes and revises timelines using real recovery data from Parks Canada reports.

Prepare & details

Predict the long-term ecological changes following a major environmental disturbance.

Facilitation Tip: When using Prediction Cards, have students justify their timelines in pairs before revealing the correct sequence, fostering discussion and correcting misconceptions in the moment.

Setup: Groups at tables with case materials

Materials: Case study packet (3-5 pages), Analysis framework worksheet, Presentation template

• Analyze
• Evaluate
• Create
• Decision-Making
• Self-Management

Case Study Analysis

⏱ 40 min·Whole Class

Patch Dynamics Map: Whole Class Model

On a large poster, map an ecosystem grid. Students add disturbance events and track succession patches over simulated years. Discuss how spatial variation creates mosaics, using markers for species shifts.

Prepare & details

Differentiate between primary and secondary succession.

Setup: Groups at tables with case materials

Materials: Case study packet (3-5 pages), Analysis framework worksheet, Presentation template

• Analyze
• Evaluate
• Create
• Decision-Making
• Self-Management

Teaching This Topic

Teach this topic by starting with local examples students recognize, like forest fires or farmland abandonment, to build relevance. Avoid presenting succession as a linear progression toward a single climax, as research shows ecosystems are dynamic and disturbance-dependent. Use peer comparisons and real data to challenge oversimplified ideas about stability and recovery.

What to Expect

Successful learning looks like students accurately distinguishing between primary and secondary succession, explaining how disturbances shape ecosystems, and using evidence from simulations or case studies to support their claims. They should also recognize that climax communities are not static but shift with ongoing disturbances.

Watch Out for These Misconceptions

Common Misconception

During the Patch Dynamics Map activity, watch for students who assume ecological succession always ends in a single, unchanging climax community.

What to Teach Instead

Use the Patch Dynamics Map to overlay aerial photos of Ontario landscapes, asking students to identify patches at different seral stages and explain why these mosaics persist due to frequent disturbances.

Common Misconception

During the Tray Simulation activity, watch for students who believe primary and secondary succession follow identical processes and timelines.

What to Teach Instead

Have students time the colonization of bare rock versus disturbed soil trays, then compare pioneer species and soil depth differences to highlight the slower, harsher conditions of primary succession.

Common Misconception

During the Jigsaw Case Studies activity, watch for students who assume anthropogenic disturbances always harm ecosystems more than natural ones.

What to Teach Instead

Use the case studies to guide students in comparing human actions like clear-cutting to natural events like wildfires, then facilitate a debate using evidence from their research to weigh context-dependent effects.

Assessment Ideas

Exit Ticket

After the Tray Simulation, provide two scenarios: Scenario A describes a lava flow, and Scenario B describes a clear-cut forest. Ask students to write one sentence identifying the type of succession each will undergo and one key difference in the initial colonizing species.

Discussion Prompt

During the Jigsaw Case Studies activity, pose the question: 'How can a large wildfire, while destructive, actually benefit a forest ecosystem in the long term?' Guide students to discuss concepts like seed germination, nutrient cycling, and habitat diversity using their case study evidence.

Quick Check

After the Prediction Cards activity, present students with images of different stages of succession. Ask them to label each image with the correct stage and explain their reasoning by referencing the timelines they predicted during the activity.

Extensions & Scaffolding

• After completing the Patch Dynamics Map, challenge students to research a human activity that mimics natural disturbances (e.g., prescribed burns) and present a 2-minute case for its ecological benefits.
• During the Tray Simulation, provide students who struggle with pre-mixed soil samples to jumpstart the activity, then ask them to compare their results to the control group's slower process.
• For deeper exploration, have students design a controlled experiment to test how different pioneer species affect soil formation in a secondary succession tray model.

Key Vocabulary

Ecological Succession	The gradual process by which ecosystems change and develop over time, involving the replacement of one community of organisms by another.
Primary Succession	Ecological succession that begins in an environment devoid of life and soil, such as on newly formed volcanic rock or glacial till.
Secondary Succession	Ecological succession that occurs in an area where a previous community existed but was disturbed, leaving soil intact, such as after a forest fire or abandoned farmland.
Disturbance	An event, natural or human-caused, that disrupts an ecosystem, altering its structure, composition, or function.
Pioneer Species	The first species, typically hardy and fast-growing, to colonize a barren or disturbed environment during primary succession.