Syllabus concepts to know

• 1.2.1 Systems are sets of interacting or interdependent components.
• 1.2.2 A systems approach is a holistic way of visualizing a complex set of interactions, and it can be applied to ecological or societal situations.
• 1.2.3 In system diagrams, storages are usually represented as rectangular boxes and flows as arrows, with the direction of each arrow indicating the direction of each flow.
• 1.2.4 Flows are processes that may be either transfers or transformations.
• 1.2.5 Systems can be open or closed.
• 1.2.6 The Earth is a single integrated system encompassing the biosphere, the hydrosphere, the cryosphere, the geosphere, the atmosphere and the anthroposphere.
• 1.2.7 The concept of a system can be applied at a range of scales.
• 1.2.8 Negative feedback loops occur when the output of a process inhibits or reverses the operation of the same process in such a way as to reduce change.
• 1.2.9 As an open system, an ecosystem will normally exist in a stable equilibrium, either in a steady- state equilibrium or in one developing over time (for example, succession), and will be maintained by stabilizing negative feedback loops.
• 1.2.10 Positive feedback loops occur when a disturbance leads to an amplification of that disturbance, destabilizing the system and driving it away from its equilibrium.
• 1.2.11 Positive feedback loops will tend to drive the system towards a tipping point.
• 1.2.12 Tipping points can exist within a system where a small alteration in one component can produce large overall changes, resulting in a shift in equilibrium.
• 1.2.13 A model is a simplified representation of reality; it can be used to understand how a system works and to predict how it will respond to change.
• 1.2.14 Simplification of a model involves approximation and, therefore, loss of accuracy.
• 1.2.15 Interactions between components in systems can generate emergent properties.
• 1.2.16 The resilience of a system, ecological or social, refers to its tendency to avoid tipping points and maintain stability.
• 1.2.17 Diversity and the size of storages within systems can contribute to their resilience and affect their speed of response to change (time lags).
• 1.2.18 Humans can affect the resilience of systems through reducing these storages and diversity.