APES - Systems of Change

System

A a set of components or parts that work together as a whole to carryout a specific function

open system

a system in which exchanges of matter or energy occur across system boundaries

closed system

A system in which energy enters and leaves but matter does not

isolated system

A system in which no matter or energy enters or leaves

Feedback

An output-A systems response to an input. This occurs when the output of the system also serves as an input and leads to further changes in the system.

negative feedback loop

An increase in output leads to a later decrease. Stabilizing. Self-regulating.It usually keeps a system in a relatively constant condition

positive feedback loop

feedback loop that causes a system to change further in the same direction. An increase in output leads to a further increase in the output

exponential growth

Growth pattern in which the individuals in a population reproduce at a constant rate

doubling time

the time required for a population to double in size

environmental unity

A principle of environmental studies that states that everything is connected to everything else

Uniformitarianism

A principle that geologic processes that occurred in the past can be explained by current geologic processes

reservoir

the amount of whatever is being measured

steady state

a state in which inputs equal outputs, so that the system is not changing over time. A state of dynamic equilibrium

average residence time

average time it takes for the total reservoir of a particular material to be cycled through the system. (ART=S/F where S is the size of the reservoir and F is the rate of transfer)

biota

All living things within a given area (Biotic factor)

Biosphere

part of Earth in which life exists including land, water, and air or atmosphere

ecosystems

a community of organisms and its local nonliving environment in which matter (chemical elements) cycles and energy flows.

Gaia Hypothesis (James Lovelock)

States that life on Earth, through a complex of negative and positive feedback, regulates the planetary environment to help sustain life

Lag time

time between a stimulus and the response of a system

overshoot and collapse

The result of long lag times or delay between stimulus and response causing the resulting changes to be recognized.