Chapter 5: Introduction to Ecology and Ecosystems

Vocabulary flashcards covering key ecology and ecosystem concepts from Chapter 5.

Ecology

The study of the interactions of living organisms with each other and their environment, aimed at understanding the distribution and abundance of life in the physical world.

Ecosystem

All the living organisms in an area and their interactions with the abiotic (non-living) environment.

Abiotic

Non-living components of an environment, such as air, water, minerals, and climate.

Biome

A large group of ecosystems classified by climate and dominant vegetation (e.g., tropical rainforest, deserts, tundra).

Ocean ecosystem

Marine ecosystems covering ~75% of Earth's surface, including shallow (coral reefs) and deep ocean regions.

Freshwater ecosystem

Aquatic ecosystems in lakes, rivers, streams, and springs; cover about 1.8% of Earth's surface.

Terrestrial ecosystem

Ecosystems on land, including forests, deserts, grasslands, and tundra.

Food chain

A linear sequence of organisms showing energy transfer from one to the next with a single path.

Food web

A holistic, non-linear network of feeding relationships that describes energy and matter flow in an ecosystem.

Trophic level

A position in a food chain or web, defined by the organism's role and energy source.

Primary producer

Organisms at the base of the food chain that synthesize energy, often through photosynthesis (photoautotrophs).

Primary consumer

Herbivores that eat primary producers.

Secondary consumer

Carnivores that eat primary consumers.

Apex consumer

Top predator at the end of a food chain with no natural predators.

Detritivore

Multicellular organisms that feed on dead organic matter and often fragment it to aid decomposition.

Decomposer

Fungi and bacteria that break down dead organic matter, recycling nutrients.

Autotroph

Organism that produces its own energy, either via photosynthesis or chemosynthesis.

Photoautotroph

Autotrophs that use sunlight to drive photosynthesis (e.g., plants, algae, photosynthetic bacteria).

Chemoautotroph

Autotrophs that obtain energy from inorganic molecules (e.g., hydrogen sulfide) rather than sunlight.

Heterotroph

Organisms that rely on consuming other organisms for energy.

Gross Primary Productivity (GPP)

Total amount of energy captured by photosynthesis in an ecosystem.

Net Primary Productivity (NPP)

GPP minus the energy used by producers for maintenance; energy available to heterotrophs. ~1% of solar energy.

Productivity

Rate at which energy or biomass is produced in an ecosystem (often measured as GPP or NPP).

Biomass pyramid

A pyramid showing the amount of living organic matter (biomass) at each trophic level; can be upright or inverted.

Energy pyramid

A pyramid illustrating the flow of energy through trophic levels; always upright.

Pyramid of numbers

A pyramid showing the count of individuals at each trophic level; can be upright or inverted.

Grazing food web

A food web base with producers and herbivores, feeding up to carnivores; often linked to a detrital web.

Detrital food web

A food web base with decomposers/detritivores feeding on dead material; linked to grazing web.

Ecological pyramids

Models (numbers, biomass, energy) used to visualize ecosystem structure and energy flow.

Autotrophs vs. heterotrophs

Autotrophs produce their own energy; heterotrophs obtain energy by consuming others.

Photoautotrophs

Autotrophs that use light energy to convert CO2 into organic matter.

Chemoautotrophs

Autotrophs that use inorganic chemical energy (not light) to synthesize organic compounds.

NPP vs. GPP relationship

NPP is the portion of GPP available to heterotrophs after plant maintenance needs.

Hydrologic (water) cycle

Movement of water through evaporation, condensation, precipitation, runoff, and storage; drives climate and ecosystem dynamics.

Biogeochemical cycle

Recycling of inorganic nutrients through living organisms and the environment, driven by energy flow.

Carbon cycle

Movement of carbon among atmosphere, oceans, organisms, and geologic reservoirs; includes fossil fuel emissions and biological processes.

Nitrogen cycle

Pathway of nitrogen through fixation, ammonification, nitrification, and denitrification; nitrogen fixation makes N usable for living systems.

Phosphorus cycle

Movement of phosphate (PO4 3−) through weathering, runoff, ocean sediments, and biological uptake; has long atmospheric residence time.

Nitrogen fixation

Process by which N2 gas is converted to ammonium or other usable forms by bacteria (e.g., Rhizobium, cyanobacteria).

Ammonification

Conversion of organic nitrogenous waste to ammonium (NH4+).

Nitrification

Conversion of ammonium to nitrites (NO2−) and then to nitrates (NO3−) by bacteria.

Denitrification

Conversion of nitrates back to nitrogen gas (N2), returning nitrogen to the atmosphere.

Eutrophication

Nutrient enrichment (often from fertilizers) causing excessive plant/algal growth and oxygen depletion.