Introduction
Succession is a key ecological process in IB Environmental Systems and Societies (ESS). It explains how ecosystems develop and change over time, moving from bare ground or disturbed land to more complex, stable communities.
In the 2026 syllabus, succession is directly tied to systems thinking, as it shows how ecosystems respond to change, recover, and stabilize. Examiners often test it through diagrams, data-response questions, and essays, making it essential knowledge for Paper 1 and Paper 2.
Quick Start Checklist: Succession in ESS
- Succession = Natural change in ecosystems over time.
- Primary succession: Starts from bare surfaces (lava flows, sand dunes).
- Secondary succession: Follows disturbance (fire, deforestation, farming).
- Leads to climax communities or new stable states.
- Tested through diagrams, case studies, and application questions.
Primary vs Secondary Succession
Primary Succession
- Begins on bare, lifeless surfaces with no soil (e.g., volcanic rock, glacial retreat).
- Pioneer species (lichens, mosses) colonize first.
- Soil forms as organisms break down rock and accumulate organic matter.
- Over time, more complex species establish, leading to a climax community.
Secondary Succession
- Occurs after a disturbance (wildfire, agriculture, storm damage).
- Soil already exists, so succession is faster than primary succession.
- Grasses → shrubs → trees → mature ecosystem.
Succession and Systems Thinking
Succession is a great example of feedback loops in ecosystems:
- Positive feedback: Fire can encourage grassland dominance.
- Negative feedback: Shade from growing trees limits pioneer species.
It also connects to human impacts: deforestation, farming, and urbanization often interrupt succession, preventing ecosystems from reaching a climax state.
How Succession is Tested in ESS
- Paper 1 (Data-response)
- Interpreting diagrams of succession stages.
- Explaining changes in biomass, biodiversity, or energy flows.
- Paper 2 (Extended response)
- Discussing human impacts on succession.
- Comparing primary and secondary succession.
- Evaluating conservation strategies that influence succession.
- Internal Assessment (IA)
- Fieldwork often involves studying succession in local habitats, such as sand dunes, abandoned farmland, or forest regeneration.
Case Study Examples
- Sand dune succession: Pioneer grasses stabilize dunes, followed by shrubs and trees.
- Forest regeneration: Abandoned farmland slowly transitions back to woodland.
- Volcanic succession: New land from eruptions colonized by lichens, mosses, then larger plants.
Including such case studies in your answers makes your essays more specific and exam-ready.
Frequently Asked Questions (FAQs)
1. Do I need to memorize every stage of succession?
Not word-for-word. Instead, understand the general sequence (pioneers → intermediate species → climax community) and be able to apply it to different ecosystems.
2. What’s the difference between climax community and equilibrium?
A climax community is the stable end-point of succession, while equilibrium refers to balance within an ecosystem. ESS often uses both terms to highlight system stability.
3. How do I revise succession effectively?
Draw succession diagrams, practice labeling them, and connect the process to energy flows, biodiversity, and human impacts. RevisionDojo provides step-by-step visuals tailored for ESS exams.
Conclusion
Succession in ESS shows how ecosystems change and stabilize over time, making it central to systems thinking and sustainability. By understanding primary vs secondary succession, feedback loops, and human impacts, you’ll be prepared for both exam questions and IA investigations in the 2026 syllabus.
Call to Action
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