Environmental Systems and Societies · Topic 2: Ecology

ES2.1 — Individuals, populations, communities, and ecosystems

Environmental Systems and Societies · SL / HL · syllabus-mapped notes

1. The biosphere, species and classification

   The nested hierarchy of life, the biological species concept, binomial naming, and the tools taxonomists use to identify organisms.

2. Populations, niches and interactions

   What a population is, the abiotic and biotic factors that shape distribution, the niche concept, and the six ways populations interact.

3. Population dynamics and human populations

   Carrying capacity, density-dependent regulation and negative feedback, J- and S-curves, and why human carrying capacity is hard to assess.

4. Estimating abundance: sampling methods

   Random, systematic and transect sampling; quadrats for non-mobile organisms; and capture-mark-release-recapture with the Lincoln index.

5. Communities, ecosystems and sustainability

   Defining community, habitat and ecosystem, then sustainability, tipping points, keystone species and the biosphere-integrity boundary.

6. HL: Clades, realized niches and life cycles

   Clades versus the traditional hierarchy, fundamental versus realized niche, r- and K-strategists, and reading human impact from life cycles.