Ecology and Ecosystem Dynamics: Key Concepts and Processes

Anthropogenic

Caused by humans. Pollution, deforestation.

Natural disruptions

Non-human causes of change. Hurricanes, volcanic eruptions.

Episodic event

Happens irregularly. Drought.

Periodic event

Occurs at regular intervals. Seasonal floods.

Random event

Unpredictable. Meteor impact.

Provisioning services

Products obtained from ecosystems. Food, timber, water.

Regulating services

Natural processes that regulate the environment. Pollination, climate regulation.

Supporting services

Processes necessary for all other services. Soil formation, nutrient cycling.

Cultural services

Non-material benefits. Recreation, tourism, spiritual value.

Succession Natural change in species composition over time. After a volcanic eruption.

Primary succession Starts with bare rock, no soil. Lava → lichen → moss → forest.

Secondary succession

Occurs after a disturbance, but the soil remains. Forest regrows after fire.

Pioneer species

First species to colonize disturbed areas. Lichens, mosses.

Climax community

Stable, mature ecosystem. Old-growth forest.

Resistance

Ability of an ecosystem to remain unchanged after disturbance. Coral reefs resisting bleaching.

Resilience

Ability of an ecosystem to recover after disturbance. Forest regrowing after wildfire.

Symbiosis

Close relationship between two species. Mutualism, commensalism, parasitism.

Mutualism

Both species benefit. Bees and flowers.

Commensalism

One benefits, the other unaffected. Barnacles on whales.

Parasitism

One benefits, other harmed. Flea on a dog.

Competition

Species fight for same resources. Trees competing for sunlight.

Predation

One organism hunts another. Lion and zebra.

Keystone species

A species critical to ecosystem stability. Sea otters control urchin populations.

Evaporation

Water changes from liquid to vapor. From oceans/lakes.

Transpiration

Water released from plant leaves. Tree leaves release vapor.

Condensation Water vapor forms clouds. Cloud formation.

Precipitation

Rain, snow, or hail falls to Earth. Rainstorm.

Infiltration

Water soaks into soil. Groundwater recharge.

Runoff

Water flows over land into rivers. Rainwater flowing into a stream.

Photosynthesis

Process by which producers use sunlight, CO₂, and water to make glucose (C₆H₁₂O₆). Plants turning sunlight into chemical energy.

Cellular respiration

Process by which organisms convert glucose and oxygen into energy (ATP). Humans and animals use this for energy.

Producer (autotroph)

Organism that makes its own food via photosynthesis or chemosynthesis. Plants, algae.

Consumer (heterotroph)

Organism that obtains energy by eating other organisms. Animals, humans.

Primary consumer

Eats producers (herbivore). Rabbit eats grass.

Secondary consumer

Eats primary consumers. Snake eats rabbit.

Tertiary consumer

Eats secondary consumers. Hawk eats snake.

Decomposer

Breaks down dead material into nutrients. Fungi, bacteria.

Gross Primary Productivity (GPP)

Total energy captured by producers via photosynthesis. Measured in kcal/m²/year.

Net Primary Productivity (NPP)

Energy left over after producers use some for respiration. (NPP = GPP - Respiration) NPP represents energy available to consumers.

Trophic level

Each step in a food chain or web. Producers → Primary consumers → Secondary consumers.

10% Rule

Only ~10% of energy is passed to the next trophic level. If producers capture 10,000 kcal, primary consumers get ~1,000 kcal.

Tundra

Cold, treeless biome with permafrost and low biodiversity.

Taiga (Boreal Forest)

Cold forest biome dominated by coniferous trees. Northern Canada and Russia.

Temperate Deciduous Forest

Moderate climate, trees lose leaves in winter, fertile soil. Eastern U.S.

Tropical Rainforest

Warm, wet, high biodiversity, poor soil due to leaching. Amazon Rainforest.

Grassland/Savanna

Moderate rainfall, frequent fires, grasses dominate.

Desert

Low precipitation, temperature extremes, drought-adapted plants.

Chaparral (Shrubland)

Hot, dry summers, mild winters, fire-adapted shrubs.

Ecosystem

A community of living (biotic) and nonliving (abiotic) components interacting in a specific area. A pond ecosystem includes fish, algae, water, and sunlight.

Biotic factors

Living components of an ecosystem. Plants, animals, bacteria, fungi.

Abiotic factors

Nonliving environmental factors. Temperature, water, sunlight, pH, and soil nutrients.

Biome

A large geographic region with similar climate, vegetation, and animal life. Tropical rainforest, tundra, desert, taiga.

Habitat

The natural environment where a species lives. A coral reef for clownfish.

Niche

The role a species plays in its environment — how it gets food, reproduces, and interacts. Bees pollinate flowers and make honey.