System – A complex assemblage of functional components, with the relationships between them, that together constitute an entity or whole. Examples: PPS – a SCHOOL system City of Portland – an URBAN system Old Growth Forest – an ECO system Drainage basin – a HYDROLOGIC system Human Body – a BIOLOGIC system Sun, planets, etc. – a SOLAR system

2. What is the function of these components? Select one of the mentioned systems: 1. List three of the functional components (there will likely be more than three) 2. What is the function of these components? 3. Describe how these componenets relate to each other? 4. Now imagine removing one of the components – what would happen?

All systems have: (and using a forest as an example…..) INPUTS - Sunlight, water, CO2, migration, more OUTPUTS - O2, habitat, food, emigration, more FLOWS (into, through, out of the system) – water, oxygen, nitrogen STORAGES - standing biomass, diverse gene pool BOUNDARIES – (who/what characterizes these?) PROCESSES (Precipitation, Respiration, Diffusion, Erosion)

The ‘Systems’ approach The environment is seen as a set of complex parts. The study of plants, geology, atmosphere, soils, populations, and many other components and how they interact to make up a functional whole. This approach considers an integrated view. For example, how do soil components affect a tree population, which in turn affects a local microclimate that in turn determines the local hydrology as well as suitable habitat for birds and fish, which provide the basis for a food chain for larger predators, which if disturbed will affect biodiversity, which will elicit a response from wildlife biologists, which are employed by a large federal government, etc., etc., etc…..

Characteristics of a system All systems have structure or organization. All systems function in some way. Function implies the flow and transfer of material (mass) or energy. Function requires the presence of some driving force, or source of energy. All systems show some degree of integration (components act together to form a whole) Changes in the value of one variable or reservoir is "sensed" throughout the system, resulting in regulation of variables.

Equilibrium What does this word mean to you? A state of balance among the components of a system.

Definition of ECO-system…… “a community of interdependent organisms and the physical environment they inhabit”

Open System - exchanges matter AND energy with the surroundings There are three types of systems, based on very specific criteria: Open System - exchanges matter AND energy with the surroundings Closed System - exchanges energy but NOT matter with the surroundings. Closed systems do not occur naturally. Isolated System - does not exchange matter or energy with the surroundings. Does not exist on Earth…..

For the system you characterized previously, list some inputs and outputs.

Assignment Consider 2 systems: 1. Cleveland High School 2. An ecosystem of your choice that you know For each, characterize the following: Open or closed? Explain. Describe 3 (or more) inputs of the system. Describe 3 (or more) outputs of the system. Have they been in equilibrium over the past year? Characterize the nature of the inputs/outputs that verify your thinking on this. Have they changed over the past decade? Explain your evidence. If your answer to #5 was yes, then does this mean that they have been out of equilibrium? Explain.