Environmental Systems

1. Environmental Systems Connections, Cycles, Flows and Feedback Loops

2. Systems Describe Interactions • A system is a network of interdependent components and processes, with materials and energy flowing from one component of the system to another. • Ecosystem • Represents complex collection of animals, plants, and their environment through which materials and energy move.

3. Systems Describe Interactions • We can use general terms to describe the components of a system. • Variables store resources such as energy, matter and water and flows from one variable to another. Plants and animals represent variables.(sun, plants, bunny, coyote, death)

4. Systems are Described in Terms of their Characteristics Open systems are systems that receive input (energy, water, etc.) from their surroundings and produce outputs that leave the system. Throughout is a term we can use to describe the energy and matter that flow into, through, and out of a system. (think about income!)

5. A wetland is an open system! • Nutrients and water are received from upstream. Plants and algae transform the nutrients into vegetation, which then becomes part of the fish. Then a heron catches the fish, eats it, then flies off to another water source.

6. Positive feedbacks refer to factors that result from a process and, in turn, increase that same process. (ex. Over abundance of nutrients in a wetland, increases plant growth and can lead to a biological collapse) Negative feedback refer to factors that result from a process and, in turn, decrease that same process (ex. Too many fish in a pond)

7. Negative feedback loops tend to maintain stability in a system. We often think of systems exhibiting homeostasis, or a tendency to remain more or less stable and unchanging.

8. Elements of Life • Matter is recycled and doesn’t disappear • matter is neither created nor destroyed but rather is recycled over and over again. It can be tranformed or recombined, but it doesn’t disappear; everything goes somewhere (think of the what we through away!) • Just four elements— oxygen, carbon, hydrogen, and nitrogen (symbolized as O, C, H, and N)— make up more than 96 percent of the mass of most living organisms.

9. Organisms use some elements in abundance, others in trace amounts, and others not at all. Carbon is a particularly important element because chains and rings of carbon atoms form the skeletons of organic compounds.