Core Ecology Concepts: Ecosystems, Cycles, and Biodiversity

Core Ecology Concepts

Biodiversity

• Definition: Variety of all living things in one area.
• Importance: Increases stability and health of ecosystems.
• Threats: Pollution, deforestation, climate change, invasive species.

Ecosystems

• Definition: A system of living (biotic) and nonliving (abiotic) things interacting.
• Biotic Components: Plants, animals, fungi.
• Abiotic Components: Water, sunlight, soil, air, temperature.
• Producers' Role: Make food from sunlight (photosynthesis).
• Balance: All parts depend on each other.

Energy Pyramid

• Purpose: Shows how energy moves through trophic levels.
• Trophic Levels: Producer → Primary → Secondary → Tertiary.
• Energy Transfer: Only 10% passed to the next level; 90% is lost as heat.
• Fewer Top Predators: Less energy is available at the top.

Food Chains and Webs

Food Chains

• Definition: A straight line showing who eats whom.
• Start: Always begin with a producer (like a plant).
• Flow: Shows how energy passes from one organism to another.

Food Webs

• Definition: A network of connected food chains.
• More Realistic: Shows how organisms eat and are eaten by multiple others.
• Key Species Loss: Can disrupt the whole web.
• Decomposers: Break down dead matter and recycle nutrients (e.g., fungi, bacteria).

Biogeochemical Cycles

Water Cycle

• Steps: Evaporation → Condensation → Precipitation → Collection.
• Evaporation: Water turns to vapor due to heat.
• Precipitation: Rain, snow, sleet, or hail falls from clouds.
• Oceans: Major source of evaporation and water storage.

Carbon Cycle

• Definition: Movement of carbon among air, living things, and Earth.
• Photosynthesis: Plants take in CO₂ to make food.
• Human Impact: Burning fossil fuels adds CO₂; deforestation reduces carbon removal.
• Fossil Fuels: Store ancient carbon; release CO₂ when burned.

Nitrogen Cycle

• Definition: Movement of nitrogen through air, soil, plants, and animals.
• Importance: Needed to build proteins and DNA.
• Bacteria Role: Convert nitrogen into usable forms (nitrogen fixation).
• Fertilizers: Too much nitrogen runoff harms ecosystems (e.g., causes algae blooms).

Species Interactions and Change

Symbiosis

• Definition: Close relationship between two species.
• Mutualism: Both benefit (e.g., bee & flower).
• Parasitism: One benefits, one is harmed (e.g., tick on a dog).
• Commensalism: One benefits, other unaffected (e.g., barnacle on whale).

Ecological Succession

• Definition: Natural change in ecosystems over time.
• Primary Succession: Starts from bare rock (no soil).
• Secondary Succession: Happens after a disturbance (soil present).
• Pioneer Species: First to colonize (e.g., moss, lichen).
• Climax Community: Stable, mature ecosystem.
• Disturbances (e.g., fire): Reset the process and allow regrowth.