Ecosystem Energetics Vocabulary

Flashcards on Ecosystem Energetics.

Potential Energy

Stored energy (e.g., chemical energy).

Kinetic energy

Energy of motion (e.g., chasing prey, heart beats).

1st Law of Thermodynamics

Energy cannot be created or destroyed – but can be converted from one form to another.

2nd Law of Thermodynamics (Entropy)

Order turns to disorder. For example, heat loss when energy is converted from one form to another.

Exothermic Reactions

Energy is given off.

Endothermic Reactions

Energy is absorbed.

Primary Productivity

Rate autotrophs convert carbon dioxide into organic compounds.

Gross Primary Productivity (GPP)

The total rate of photosynthesis (energy assimilated) by autotrophs.

Net Primary Productivity (NPP)

Rate of energy storage as organic molecules after energy is expended for cellular respiration (R). Growth!

Standing Crop Biomass (SCB)

Amount of organic matter per area.

Photosynthetically Active Radiation (PAR)

A measure of biologically relevant incoming light energy (400 to 700 nanometers).

Compensation Depth

GPP = R, NPP = 0

Autochthonous Organic Carbon

Organic carbon produced within an ecosystem, comes from photosynthesis by aquatic photoautotrophs (plants, algae, phytoplankton).

Allochthonous Organic Carbon

Organic carbon produced outside of an ecosystem, comes from dead organic matter input from adjacent terrestrial ecosystems, can be dissolved (DOM) or particulate (POM) organic matter.

River Continuum Concept (RCC)

Describes the continuum of the relative importance of allochthonous and autochthonous sources of carbon in flowing water ecosystems.

Secondary Production

Net energy allocated to production in heterotrophs.

Trophic Cascade

Changes in top consumers ripple down through different trophic levels with alternating + and - impacts

Assimilation Efficiency

Measures the efficiency of extracting energy from food (A/I).

Production Efficiency

Measures how efficiently assimilated energy is incorporated into secondary production (P/A).

Grazing Food Chain

Source of energy for the herbivores is living plant biomass (NPP).

Detrital Food Chain

Source of energy for the decomposers is dead organic matter or detritus.

Trophic Efficiency (TE)

Measures the transfer of energy between trophic levels.