2.1I Ecosystems Notes

1. An ecosystem is a dynamic system formed by a community of living organisms (biotic components) interacting with their physical environment (abiotic components) in a specific area.
2. Ecosystems function as open systems, meaning that both energy and matter can enter and exit continuously.
3. The balance of these flows maintains ecosystem productivity and stability.

Components of an Ecosystem

1. Biotic Components: Producers (plants, algae), consumers (herbivores, carnivores, omnivores), and decomposers (bacteria, fungi).
2. Abiotic Components: Sunlight, temperature, soil composition, water, oxygen, minerals, and atmospheric gases.
3. These two sets of components are linked through energy flow and nutrient cycling.

Ecosystem as an Open System

Energy Flow in an Ecosystem

1. Energy enters ecosystems primarily from the Sun.
2. Producers (autotrophs), such as plants and algae, convert solar energy into chemical energy through photosynthesis.
3. This energy is then passed through trophic levels via feeding relationships: Producers → Primary Consumers → Secondary Consumers → Tertiary Consumers → Decomposers.
4. With each transfer, energy is lost as heat, following the Second Law of Thermodynamics.

Matter Cycling in an Ecosystem

1. Unlike energy, matter cycles through ecosystems.
2. Essential elements like carbon, nitrogen, phosphorus, and water move through biotic and abiotic components in interconnected cycles.
3. Decomposers are vital, breaking down dead material and recycling nutrients into soil and atmosphere.

Examples of Ecosystems and Their Interactions

1. Tropical Rainforest

1. Energy Flow: High levels of sunlight support dense plant growth, which in turn sustains a diverse array of herbivores and predators.
2. Matter Cycling: Rapid decomposition due to warm, moist conditions ensures nutrients are quickly recycled, supporting continuous plant growth.

2. Coral Reef

1. Energy Flow: Algae living within coral polyps photosynthesize, providing energy to the coral and forming the base of the food web.
2. Matter Cycling: Nutrients like nitrogen and phosphorus are recycled through the interactions between coral, algae, and fish.

3. Arctic Tundra

1. Energy Flow: Limited sunlight and a short growing season restrict energy input, resulting in fewer trophic levels.
2. Matter Cycling: Decomposition is slow due to cold temperatures, causing nutrients to remain locked in the soil for long periods.

Sustainability in Ecosystems

1. A sustainable ecosystem maintains a balance between inputs and outputs, allowing it to persist over long periods.
2. In a steady-state ecosystem, energy and matter cycle efficiently, preventing depletion of resources.
3. Some ecosystems, such as tropical rainforests, have existed for millions of years due to their ability to self-regulate and adapt to environmental changes.

Characteristics of Sustainable Ecosystems

1. Energy balance: Input of solar energy ≈ Output of heat through respiration.
2. Matter balance: Nutrient uptake by plants ≈ Return of nutrients via decomposition.
3. Dynamic equilibrium: Continuous but balanced change through feedback loops.

Flow Diagrams and Energy Balance

1. Flow diagrams show the movement of energy and matter through an ecosystem’s components.
2. Arrows represent inputs, storages, transfers, and outputs.
3. A steady-state ecosystem shows equal input and output rates, maintaining long-term stability.

Human Activity and Ecosystem Tipping Points

1. Tipping points occur when an ecosystem experiences a sudden shift to a new state due to accumulated stress or disturbance.
2. These changes can be triggered by natural events or human activities, such as deforestation, pollution, or climate change.

Characteristics of Tipping Points

1. Threshold Effect: A critical point is reached where the system shifts rapidly.
2. Irreversibility: Once crossed, returning to the original state is difficult or impossible.
3. Feedback Loops: Positive feedback mechanisms amplify changes, accelerating the shift.

How Human Activities Cause Tipping Points

1. Human activities can disrupt ecosystems by altering climate, resource availability, and species interactions.
2. These changes can push ecosystems past their resilience threshold, leading to permanent ecological shifts.
3. Key Factors Leading to Tipping Points:
   1. Deforestation and Habitat Loss: Reduces biodiversity and disrupts climate regulation.
   2. Climate Change: Increases temperatures, alters precipitation, and causes extreme weather.
   3. Pollution: Eutrophication, ocean acidification, and toxic waste lead to ecosystem collapse.
   4. Overexploitation of Resources: Unsustainable hunting, fishing, and water extraction disrupt ecological balance.

Consequences of Tipping Points

1. Loss of Biodiversity: Species that depended on the old ecosystem may go extinct.
2. Disrupted Climate Regulation: Loss of carbon sinks (like rainforests) accelerates climate change.
3. Decline in Ecosystem Services: Loss of freshwater, fertile soil, and natural disaster buffering.
4. Irreversible Changes: Once a tipping point is crossed, recovery may take centuries or may not happen at all.

Detecting and Preventing Tipping Points

1. Monitoring: Use GIS and satellite imagery to track land-use and vegetation change.
2. Field studies: Compare disturbed vs. undisturbed sites (species diversity, soil quality).
3. Indicators: Decline in key species, soil moisture loss, reduced canopy cover.
4. Management: Promote reforestation, sustainable agriculture, and ecosystem restoration.