Key Ecological Concepts and Processes

Key Ecological Concepts

• Ecosystem: A complex system where living and non-living things interact in an area.
• Biotic: Living or once-living things.
• Abiotic: Non-living things.
• Producer: Organisms that use sunlight to produce food, initiating food webs/chains.
• Consumer: An organism that depends on producers to feed on.
• Trophic Level: An organism's position in a food chain or web, showing a hierarchy of feeding relationships.
• Population: A group of the same species living in the same area.
• Biodiversity: The variety of life within an ecosystem.
• Herbivore: An organism that only consumes plants.
• Carnivore: An organism that feeds on other organisms.
• Omnivore: An organism that feeds on other organisms and plants.
• Detritus: Remains of organisms and plants that have been decomposed.
• Decomposer: An organism that breaks down dead organisms.

Photosynthesis and Cellular Respiration

• Photosynthesis: Plants convert light energy into chemical energy, producing sugars from carbon dioxide and water, releasing oxygen. (Carbon Dioxide + Water → Sugar + Oxygen)
• Cellular Respiration: Animals consume food and convert it into energy, releasing carbon dioxide and water.

Energy Flow in Ecosystems

• Energy flows through an ecosystem linearly: Sun → Producer → Primary Consumer → Secondary Consumer → Tertiary Consumer.
• Approximately 10% of energy is transferred from one trophic level to the next.

Matter Cycling in Ecosystems

• Nitrogen Cycle: Nitrogen enters the cycle through nitrogen fixation by bacteria. These bacteria then provide nitrogen to plants. When we eat plants and animals, we consume nitrogen. Denitrifying bacteria return nitrogen to the atmosphere.
• Water Cycle: The sun heats water sources (lakes, oceans), causing evaporation. Water vapor cools and condenses into clouds. Excess water in clouds falls as precipitation.
• Carbon Cycle: Carbon initially cycles through our atmosphere. Plants consume atmospheric carbon, and animals consume plants and animals. When we breathe or animals use carbon in other ways, or through combustion, carbon is released back into the air, continuing the cycle.

Human Impact on Ecosystems

• Pollution: Human activities introduce harmful substances into air, water, and soil.
• Deforestation: Cutting down trees destroys habitats and reduces oxygen production.
• Climate Change: Burning fossil fuels increases greenhouse gases, resulting in global warming and extreme weather patterns.

Ecological Relationships (Symbiosis)

• Mutualism: (+/+) Both organisms benefit. (e.g., fungi help trees absorb water/minerals; trees provide fungi with sugars)
• Commensalism: (+/0) One organism benefits, the other is unaffected. (e.g., barnacles on a whale)
• Parasitism: (+/-) One organism benefits (parasite), the other is harmed (host). (e.g., ticks on mammals)