Ecology is a branch of biology that focuses on the relationships between living organisms and their environment. It encompasses the study of interactions among organisms and their physical surroundings, including both biotic (living) and abiotic (non-living) components. This study note will cover key concepts in ecology as outlined in the International Baccalaureate (IB) syllabus, including ecological economics, ecosystems, energy flow, nutrient cycling, and the biosphere.
Ecological economics is an interdisciplinary field that examines the relationship between economic systems and the Earth's biosphere. Unlike traditional environmental economics, which primarily focuses on how economic activities impact the environment, ecological economics views the economy as a subsystem of the larger ecological system.
When industries or human activities produce goods and services, by-products or waste materials are often created. Examples include:
Tip:
Understanding the flow of energy and matter in the biosphere helps in designing sustainable economic systems that minimize waste and environmental impact.
An ecosystem is a community of living organisms interacting with their physical environment within a specific area. Key components include:
The interactions between biotic and abiotic components shape the structure and dynamics of ecosystems, influencing factors such as biodiversity, nutrient cycling, and ecosystem services.
Example:
In a forest ecosystem, trees (biotic) use sunlight (abiotic) for photosynthesis. The leaves that fall decompose, returning nutrients to the soil (abiotic), which are then used by other plants.
The biosphere is the narrow, life-supporting zone around the Earth where the atmosphere, hydrosphere, and lithosphere meet. It contains all living organisms, including:
The biosphere can be thought of as a large, complex system of living communities interacting with each other and with the non-living components of the Earth's systems.
Note:
The biosphere is essential for the survival of life on Earth, providing the necessary conditions for various ecosystems to function.
Organisms obtain nutrients through different methods:
A community consists of different species living in the same area, interacting with each other. These interactions can be:
Nutrient cycling involves the movement of nutrients through the biotic and abiotic components of an ecosystem. Key cycles include:
Energy flows through ecosystems in a unidirectional manner, from primary producers to various consumers. The main steps include:
$$ \text{Energy Flow in an Ecosystem:} \quad \text{Sun} \rightarrow \text{Producers} \rightarrow \text{Consumers} \rightarrow \text{Decomposers} $$
Energy is lost at each trophic level, primarily as heat during metabolic processes. This limits the number of trophic levels in an ecosystem.
Common Mistake:
A common misconception is that energy is recycled in ecosystems. In reality, energy flows in a one-way direction and is eventually lost as heat.
The carbon cycle is crucial for maintaining the Earth's climate. Human activities, such as burning fossil fuels and deforestation, have disrupted this cycle, leading to increased atmospheric carbon dioxide levels and climate change.
Tip:
Understanding the carbon cycle can help in developing strategies to mitigate climate change by reducing carbon emissions and enhancing carbon sequestration.
Ecology is a complex but fascinating field that integrates various aspects of biology and environmental science. By understanding the interactions between organisms and their environment, we can develop sustainable practices to preserve biodiversity and maintain ecosystem health.