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Ecosystems. How they work. 1) Matter, energy and life. All chemical reactions, involve rearrangements of atoms to form different kinds of matter. Molecules and compounds: Molecule : consists of two or more atoms bonded together in a specific way
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Ecosystems How they work
1) Matter, energy and life • All chemical reactions, involve rearrangements of atoms to form different kinds of matter. • Molecules and compounds: • Molecule: consists of two or more atoms bonded together in a specific way • Compound: consists of two or more different kinds of atoms bonded together
On the chemical level, the cycle of growth, reproduction, death, and decay of organisms is a continuous process of taking atoms from the environment, assembling them into living organisms (growth), disassembling them (decay) and repeating the process.
Back to the four spheres… • Matter is constantly being exchanged within and between the four spheres • Key elements include: C, H, O, N, P, and S. • These key elements will form part of organic molecules as proteins, carbohydrates, lipids, and nucleic acids.
Organic, inorganic, natural or synthetic • Organic are the carbon based molecules that make up the tissues of living organisms • Inorganic are molecules or compounds with neither carbon – carbon nor carbon – hydrogen bonds. • Natural compounds are those making up living organisms • Synthetic are human made organic compounds.
In conclusion, • Elements essential to live are present in the atmosphere, hydrosphere or lithosphere as simple molecules. • In living organisms, they are organized in highly complex organic compounds.
ENERGY • Does not have mass, nor occupies space • Light, heat, movement, and electricity • Affects matter causing changes in its position or its state • It is the ability to move matter.
Laws of thermodinamics • First Law of Thermodynamics: "Energy is neither created nor destroyed; it only changes form." It can be related to: "You can't get something for nothing“ or "There is no such thing as a free lunch".
Laws of thermodinamics B. Second Law of Thermodynamics: "Systems will go spontaneously in one direction only toward increasing entropy." Entropy: measure of the degree of disorder in a system. It can be described as:" It takes energy to get energy" or "In any energy conversion, you will end up with less usable energy than you started with" or "If you think things are confused now, just wait" or "Everything moves in the direction of increasing disorder".
Energy changes in organisms • The same principle of storage and release of energy applies to ecosystems
2) Energy flow in ecosystems Energy Source • The ultimate source of energy on our planet: the sun. • The first basic principle of ecosystem sustainability: "For sustainability, ecosystems use sunlight as their source of energy.” • Our planet is sustainable as long as the sun exists. Ecosystems do not use energy at a faster rate than that available from the sun. (The same cannot be said for humans because of our rate of fossil fuel consumption.)
This figure shows energy flow through Trophic Levels in a Grazing Food Web. Each trophic level is represented as biomass boxes and the pathways taken by the energy flow are indicated with arrows.
3) The cycling of matter in ecosystems • Energy flows but nutrients cycle. The molecules in an organism will eventually be found in another organism. • Recycling is fundamental for sustainability • Prevents accumulation of wastes • Guarantees that the ecosystem will not run out of essential elements.
Carbon cycle • Changing the location of this element is the primary issue in global warming. We are moving carbon from where it has been stored (fossil fuels) to the atmosphere, where it acts to reduce the amount of heat re-radiated to space.
Phosphorus cycle • Changing the location of this element is one of the primary reasons for the increased nutrient load in aquatic ecosystems. We move phosphorus from where it has been concentrated, e.g., in guano, and deposit it on soil (or in consumer products), where it is released to water.
Nitrogen cycle • Changing the location of this element is the other reason for the increased nutrient load in aquatic ecosystems. (Nitrogen and phosphorus are limiting factors in aquatic ecosystems.)
4) Implications for human societies • One of the reasons for studying natural ecosystems is that they are models of sustainability. • As a result we might benefit from understanding what it is that makes them sustainable and, where possible, how to emulate them
The value of Ecosystem Capital • Ecosystem capital is defined as the goods and services we derive from natural systems. • “The value of the world’s ecosystem services and natural capital” • 17 major ecosystem goods and services (pg 80)
The value of Ecosystem Capital • The total value to human welfare of a year’s services amounts to $38 trillion • The gross world production of the world economy is calculated in $25 trillion. • “ecosystem services provide an important portion of the total contribution to human welfare on this planet”
The value of Ecosystem Capital • If the true value of goods and services provided by ecosystems is considered, then efforts to conserve natural ecosystems should be intensified. • Local decisions about the use of ecosystems might have global undesirable consequences • Governmental decisions should concentrate on maintaining the ecosystem as a public good.
http://www.uwsp.edu/geo/faculty/ritter/geog101/textbook/earth_system/natural_systems.htmlhttp://www.uwsp.edu/geo/faculty/ritter/geog101/textbook/earth_system/natural_systems.html • http://apesnature.homestead.com/chapter3.html
