Ecosystems: Components and Classification

• An ecosystem comprises a community of living organisms interacting with their non-living environment within a defined space.
• Example: A grassland ecosystem includes zebras and abiotic factors.

Ecosystem Components

• An ecosystem includes producers (plants, algae), consumers (herbivores, carnivores), and decomposers (fungi, bacteria).
• The abiotic environment includes climate factors (temperature, light), inorganic substances (water, O₂, CO₂, nitrogen, phosphorus), and organic matter (carbohydrates, proteins, lipids from dead organisms, waste).
• Organisms interact with each other and with the abiotic factors.
• Ecosystems vary in size. They can be as small as a tree hole or as vast as a forest.

Classifying Ecosystems

• Ecosystems are classified based on their origin into natural and artificial ecosystems.
• Natural ecosystems develop naturally with minimal human intervention, like forests, grasslands, and aquatic ecosystems (rivers, streams, oceans).
• Artificial ecosystems are human-created, such as rice paddies, shrimp ponds, urban areas, and industrial parks, providing food, shelter, and recreation.
• Without human maintenance, artificial ecosystems will transform into natural ones.

Energy and Nutrient Flow in Ecosystems

• Organisms in an ecosystem are linked through feeding relationships, utilizing others for energy.
• Dead organisms, fallen leaves, and waste become detritus, serving as food for other organisms to recycle matter and energy through the ecosystem.

Food Chains, Food Webs, and Trophic Levels

• Food chains and webs illustrate feeding and energy relationships among organisms in an ecosystem.

• A food chain shows the sequence of energy or nutrient transfer which starts with producers or detritus and ends with consumers. Each organism or component is a link.

• Organisms are organized into trophic levels from bottom to top. They start at level 1, then level 2, 3, 4 and so on from lowest to highest. Detritus is level 1 in detritus-based food chains.

• Common food chains start with producers, but can also begin with detritus.

• In ecosystems, organisms often consume multiple species and are consumed by various others, creating food webs.

• Food webs are interconnected food chains, sharing links.

Energy Transformation Between Trophic Levels

• Most energy for Earth's ecosystems comes from sunlight. The angle of sunlight affects this.
• Solar energy converts into chemical energy by producers, then transfers through the food web and releases as heat.

Ecological Efficiency and Ecological Pyramids

• Each trophic level transforms energy at a certain rate called productivity.

• Productivity at a trophic level refers to the rate of organic matter or energy production per unit area over time.

• Only a fraction of energy transfers from lower to higher trophic levels.The percentage of the energy transformed between trophic levels is ecological efficiency.

• On average, ecological efficiency is approximately 10%. High inefficiency results in consumers at higher trophic levels having lower productivity.

• To show biomass or population sizes at each trophic level, ecological pyramids are constructed.