Content Objective: Demonstrate an understanding of ecosystem sustainability, including the requirements for sustainability, the impact of human activities on ecosystem stability, the role of keystone species, the effects of pollution and resource harvesting, the concept of ecological succession, and the restoration of natural processes in ecosystems.
Language Objective: Create a one-page set of notes on one of the topics discussed above.
Syllabus Details:
D4.2.1—Sustainability as a property of natural ecosystems - "Illustrate ecosystem sustainability with evidence of forest, desert or other ecosystems that have shown continuity over long periods. There is evidence for some ecosystems persisting for millions of years."
D4.2.2—Requirements for sustainability in ecosystems - "Include supply of energy, recycling of nutrients, genetic diversity and climatic variables remaining within tolerance levels."
D4.2.12 (HL) —Ecological succession and its causes - Succession can be triggered by changes in both an abiotic environment and in biotic factors.
D4.2.13 (HL) —Changes occurring during primary succession - "Use any suitable terrestrial example to illustrate these general principles: increases in size of plants,amount of primary production, species diversity, complexity of food webs and amount of nutrient cycling."
D4.2.14 (HL) —Cyclical succession in ecosystems - "Students should appreciate that in some ecosystems there is a cycle of communities rather than a single unchanging climax community. Include the example of wood pasture, which cycles from pasture to scrub to woodland and back to pasture."
D4.2.15 (HL) —Climax communities and arrested succession - Given any specific environmental conditions, ecological succession tends to lead to a particular type of climax community, but human influences can prevent this from developing. Use grazing by farm livestock and drainage of wetlands as examples.
D4.2.6—Assessing sustainability of resource harvesting from natural ecosystems - "Sustainability depends on the rate of harvesting being lower than the rate of replacement. Include one terrestrial plant species and one species of marine fish as examples of renewable resources and how sustainability of harvesting can be assessed."
D4.2.7—Factors affecting the sustainability of agriculture - "Include the need to consider soil erosion, leaching of nutrients, supply of fertilizers and other inputs, pollution due to agrochemicals, and carbon footprint."
D4.2.8—Eutrophication of aquatic and marine ecosystems due to leaching - "Students should understand the effects of eutrophication resulting from leaching of nitrogen and phosphate fertilizers, including increased biochemical oxygen demand (BOD)."
D4.2.9—Biomagnification of pollutants in natural ecosystems - "Students should understand how increased levels of toxins accumulate in the tissues of consumers in higher trophic levels. Include DDT and mercury as examples."
D4.2.10—Effects of microplastic and macroplastic pollution of the oceans - "Students should understand that plastics are persistent in the natural environment due to nonbiodegradability. Include examples of the effects of plastic pollution on marine life."
D4.2.3—Deforestation of Amazon rainforest as an example of a possible tipping point in ecosystem sustainability -"Include the need for a large area of rainforest for the generation of atmospheric water vapour by transpiration, with consequent cooling, air flows and rainfall. Include uncertainty over the minimum area of rainforest that is sufficient to maintain these processes."
D4.2.11—Restoration of natural processes in ecosystems by rewilding - "Methods should include reintroduction of apex predators and other keystone species, re-establishment of connectivity of habitats over large areas, cessation of agriculture and resource harvesting and minimization of human influences including by ecological management. Include the example of Hinewai Reserve in New Zealand."
D4.2.4—Use of a model to investigate the effect of variables on ecosystem sustainability
Activity 1 - Sustainability of Ecosystems
1. Watch this TED talk about Biosphere 2
2. Ecosystem have the potential to be sustainable over long periods of time. In IB talk, we say that ecosystems are interrelated and interdependent. How does this video show that?
Activity 2 - Human Impacts
Activity 3 - Succession (HL Only)