Energy Flow and Biogeochemical Cycles - Bio 1108

ecosystem

community of living organisms and their interactions with their abiotic (nonliving) environment.

equilibrium

steady state of an ecosystem where all organisms are in balance with their environment and with each other

resistance

the ability of an ecosystem to remain at equilibrium in spite of disturbances

resilience

the speed at which an ecosystem recovers equilibrium after being disturbed

food chain

A linear sequence of organisms through which nutrients and energy pass

trophic level

each of several hierarchical levels in an ecosystem, comprising organisms that share the same function in the food chain and the same nutritional relationship to the primary sources of energy.

primary producer

the bottom of the food chain, usually photosynthetic organisms (plants
and/or phytoplankton)

primary consumer

consumes the primary producer

secondary consumer

usually carnivores that eat the primary consumers

apex consumer

highest-level consumer in the ecosystem

decomposer

feed on dead/decaying organisms

producers

(plants, algae, cyanobacteria) capture light energy and CO2 to produce sugars through photosynthesis

consumers

gain chemical energy and nutrients from producers

decomposers

recycle nutrients by breaking down organic matter (cellulose, etc.) and releasing carbon and other nutrients back to environment

food web

graphic representation of a holistic, nonlinear web of primary producers, primary consumers, and higher-level consumers used to describe ecosystem structure and dynamics

holistic ecosystem model

this model attempts to quantify the composition, interaction, and dynamics of entire ecosystems; it is the most representative of the ecosystem in its natural state.

mesocosm

a simulated outdoor ecosystem used for scientific research, bridging the gap between laboratory experiments and field studies

microcosm

simplified, artificial, or natural ecosystem that is small enough to be studied in a controlled environment like a laboratory, or a miniature replica of a larger, more complex ecosystem

conceptual model

this model consists of flow charts to show interactions of different compartments of the living and nonliving components of the ecosystem

analytical model

this model uses simple mathematical formulas to predict the effects of changes on ecosystem structure and dynamics

simulation model

this model uses complex computer algorithms to model ecosystems and to predict the effects of changes

photoautotrophs

such as plants, algae, and photosynthetic bacteria, serve as the energy source for a majority of the world’s ecosystems

chemoautotrophs

synthesize complex organic molecules, such as glucose, for their own energy; usually they do this without sunlight and rather use other sources of energy

heterotrophs

acquire energy from digesting living or previously living organisms

biomass

the total mass, in a unit area at the time of measurement, of living or previously living organisms within a trophic level

Gross primary productivity

The rate at which photosynthetic primary producers incorporate energy from the sun

net primary productivity

the energy that remains in the primary producers after accounting for the organisms’ respiration and heat loss. The net productivity is then available
to the primary consumers at the next trophic level

Trophic level transfer efficiency (TLTE)

The measurement of energy transfer efficiency between two successive trophic levels

10%

Average TLTE

Net production efficiency (NPE)

allows ecologists to quantify how efficiently organisms of a particular trophic level incorporate the energy they receive into biomass

• Varies with species (large mammals are more efficient at producing biomass than smaller mammals because of their lower surface area:volume; also more efficient in ectotherms)

Ecological pyramid

diagrams that depict the biomass, number of organisms, and energy at each trophic level

biomagnification

the increasing concentration of persistent toxic substances in organisms at each trophic level

biogeochemical cycles

this diagram depicts the recycling of inorganic matter between living organisms and either environment (C, H, N, O, S, P)

2.5%

percent of fresh water on Earth

Water cycle

What cycle is shown here?

Carbon Cycle

What cycle is shown here?

Nitrogen Cycle

What cycle is shown here?