KHAEMENES ACADEMY · BIOLOGY 10 · WEEK 33 · DAY 04

Disturbance, Succession & Community Change

Analyze recovery after disturbance as contingent change rather than a guaranteed march toward one climax state.

Safety and evidence boundary

Use supplied long-term ecological datasets and low-risk simulations. Do not manipulate wild populations, introduce species, enter unsafe field sites, or infer a single cause from correlation alone. Population models are approximations with explicit scale and boundary assumptions.

Explicit science instruction

Disturbances alter resources, organisms and physical conditions. Primary succession begins where developed soil/biological legacies are minimal; secondary succession follows disturbance where legacies remain. Recovery depends on severity, frequency, dispersal, climate and surviving organisms.

Communities can follow multiple trajectories and may cross thresholds into alternative states.

Worked example with reasoning

After a fictional fire, Site A retains soil and seed bank and regains vegetation quickly; Site B loses soil and recovers slowly. Calling both simply “succession” hides different starting conditions and mechanisms.

Guided question

Why does disturbance history matter for predicting recovery?

Independent work

  1. Compare two before/after datasets.
  2. Classify primary/secondary contexts.
  3. Identify biological legacies.
  4. State one alternative stable-state possibility.

Investigation / Data Lab

Population-model comparison

Question: Which model better describes the supplied population series, and where does each fail?

  1. Plot a supplied long-term dataset with units and sampling notes.
  2. Create an exponential projection from an early growth interval.
  3. Create or interpret a logistic projection with a stated K value.
  4. Compare residual/pattern mismatches qualitatively and identify a disturbance, interaction, or survey-effort change that neither model captures.
  5. Revise one parameter or model assumption and explain whether fit improves.

Evidence standard: keep the raw data, both model curves, assumptions, and a reasoned model choice.

Misconception check

Succession is not always a linear, predetermined sequence ending in one permanent climax community.

Formative understanding check

What is a biological legacy?

Worked response

Surviving organisms, seeds, roots, soil structure, microbes or other remnants that influence recovery.

Open-book formative practice only; not an official mastery attempt or grade.

Mentor evidence conference

Ask Archaemenes to challenge your systems model, quantitative interpretation, alternative explanations, and boundary conditions.

Open Archaemenes

Teacher guidance

Foundation: use recovery timelines. Core: compare trajectories. Extended: analyze resilience, thresholds and intervention tradeoffs.

Preserve learning evidence

Keep models, calculations, graphs, corrections and uncertainty notes in the matching Week 33 evidence field.