IB ESS Topic 2 Ecology delves into the scientific foundations of natural systems, specifically how ecosystems function. Ecology helps us understand how energy and matter interact in ESS topics.
You can access resources for each subtopic by following the links below.
Topic 2 Ecology Flashcards
2.1 Individuals, populations, communities, and ecosystems
How can natural systems be modelled, and can these models be used to predict the effects of human disturbance? This part of the course explores the connections between living things and the physical surroundings where they live. It shares common ground with concepts in biology.
2.2 Energy and biomass in ecosystems
How can flows of energy and matter through ecosystems be modelled?
How do human actions affect the flow of energy and matter, and what is the impact on ecosystems? Here, we learn about the movement of energy through ecosystems, from solar input to biomass (chemical energy), and its distribution via food webs.
2.3 Biogeochemical cycles
How do human activities affect nutrient cycling, and what impact does this have on the sustainability of environmental systems? This topic covers the flow and storage of water and nutrients, particularly nitrogen and carbon, within Earth’s atmosphere, geosphere, biosphere, and hydrosphere.
2.4 Climate and biomes
How does climate determine the distribution of natural systems? How are changes in Earth systems affecting the distribution of biomes? In this part of ESS, we study the link between Earth’s climate and its interaction with the Sun. We also explore how climate patterns affect light and precipitation inputs, shaping the characteristics and distribution of biomes worldwide.
2.5 Zonation, succession and change in ecosystems
How do ecological systems change over time and over space? Finally, we examine methods for measuring changes in ecosystems across landscapes and over time. The strategies and tools introduced in section 2.5 are valuable for conducting individual investigations in ESS.
Topic 2 Reading List
The Sixth Extinction – Elizabeth Kolbert (2014) Explores the current mass extinction event through field research on affected species. Kolbert’s work directly connects to biodiversity loss and human impacts on Earth’s biota.
Half-Earth: Our Planet’s Fight for Life – E.O. Wilson (2016) Wilson, who is one of the world’s foremost modern biologists, argues that protecting half of Earth’s land and sea is the only way to prevent mass extinction. This book has clear links to conservation strategies and ecosystem services.
The Hidden Life of Trees – Peter Wohlleben (2016) reveals how trees communicate and support each other through root networks and symbiosis. Trees are pretty much my favorite organism on Earth. Wohllben’s writing shows how forests are systems and connects to nutrient cycling.
Finding the Mother Tree – Suzanne Simard (2021) If you’ve ever wondered how other species communicate, this book is for you. A forest ecologist explains how mycorrhizal networks link trees underground. It’s like a whole tree society exists that people aren’t even aware of, with rich content about biotic interactions and ecosystem dynamics.
Entangled Life – Merlin Sheldrake (2020) Examines the world of fungi and how they shape ecosystems; relevant to decomposition, nutrient cycling, soils, and symbiotic relationships. This book is also great for ESS topic 5.1 Soil systems.
The Song of the Dodo – David Quammen (1996) This book came out while I was at university, and my Forest Ecology professor recommended it. It traces the ideas of island biogeography and species extinction while connecting to habitat fragmentation, biodiversity, and conservation biology.
Wilding – Isabella Tree (2018) Documents the rewilding of a British farm and the return of native species. This book is about the Knepp Estate that’s mentioned by name in the ESS syllabus. It connects directly to restoration ecology and ecosystem resilience.
The Serengeti Rules – Sean Carroll (2016) It’s hard to imagine just how cool the Serengeti is until you’ve been there in person. This book explains keystone species and trophic cascades through vivid field stories. It’s directly relevant to food webs and population dynamics in IB ESS topics 1 and 2.
Feral – George Monbiot (2013) George Monbiot is one of the best science and nature writers of the past 25 years. He makes the case for rewilding ecosystems, with links to trophic levels, ecosystem services, and conservation ethics.
The World Without Us – Alan Weisman (2007) I read this book not long after I saw the Will Smith movie, I Am Legend. Unlike the movie, the book has nothing to do with zombies. But like the movie, The World Without Us imagines what Earth would be like if humans disappeared. It’s an excellent way to think about ecological footprints, and it’s also a story of ecological succession on a global scale.
Connections to other ESS topics
Topic 2 is the scientific underpinning of Environmental Systems and Societies. Use it to approach topics #3 through #8, especially from a systems and sustainability angle.
- Foundations: perspectives, systems, and sustainability
- Ecology: how ecosystems function (this topic)
- Biodiversity and conservation: evolution, threats, conservation measures
- Water: systems, access, aquatic food production, and water pollution
- Land: soil, agriculture, forestry
- Atmosphere and climate change: causes, mitigation, adaptation
- Natural resources: use, choices, impact, waste
- Human populations & urban systems: sustainability, urban environments, air pollution*
- Higher Level ESS:
- HL.a Environmental law: rules for resource use, sustainability and justice
- HL.b Environmental economics: ecological economics, perspectives and sustainability
- HL.c Environmental ethics: moral responsibility toward the environment
Happy learning!
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