The Cycling of Matter

Why Learn About This? Most minerals essential for life cycle between living things and the atmosphere or the ground Atmosphere—gases surrounding Earth Biosphere—living ‘layer’ of Earth Lithosphere—soil/rock layer of Earth Hydrosphere—water parts of Earth Earth is a “closed” ecosystem The only thing in is sun (energy), the only thing out is some heat(energy) Energy ‘flows through’, but matter ‘cycles within’

The Water Cycle The Sun provides energy to drive this cycle Water cycles between lithosphere, atmosphere and biosphere Approximately 4.2 trillion gallons of rain/snow falls per day in the United States

The Carbon Cycle All living things are composed primarily of Carbon Plants take in CO2 from the atmosphere and convert it into sugars, which are then used by animals Animals respire and release CO2 back into the atmosphere CO2 is also produced by burning fossil fuels CO2 traps heat in the atmosphere, so the more CO2 in the atmosphere, the warmer the atmosphere, but we’ll talk more about this later…..

Phosphorous Cycle Phosphorous makes up part of the structure of our DNA Phosphorous cycles between living things and the lithosphere/hydrosphere Does not enter the atmosphere

The Nitrogen Cycle Nitrogen is an important part of our DNA and amino acids Nitrogen makes up the majority of the atmosphere (97%), but most organisms can’t use it directly Nitrogen gas has to be ‘fixed’ (converted into a useable form) Nitrogen can be fixed two ways: By certain types of bacteria in the soil By lightning striking and carrying the NH3 to the ground via precipitation

Too much of a good thing? Too much phosphorous and nitrogen can actually be detrimental to aquatic ecosystems Runoff from farms (fertilizer) can cause algal blooms in neighboring lakes/ponds Algae can block out light, alter food web of the lake

Flow of Energy in Ecosystems The path of energy flow through an ecosystem can be shown using a food chain or web Food webs are more accurate, since most organisms don’t eat only one thing Food web/chain: A diagram of energy flow in an ecosystem

Trophic (feeding) Levels (or steps in the food chain) Producer – makes it’s own energy Producers are autotrophs (self-food) Consumer – has to eat to get energy Consumers are heterotrophs (other-food) Primary consumer - eats producers Herbivores are primary consumers Ex: grasshoppers, mice, rabbits, deer, beavers, moose, cows, sheep, goats and groundhogs.

Trophic levels, cont’ Secondary consumer - eats primary consumers or other secondary consumers Carnivores eat other animals, so they are secondary consumers Ex: snakes, hawks, spiders Omnivores take food from more than one trophic level, in other words, they eat animals and plants Ex:Bears --They eat insects, fish, moose, elk, deer, sheep as well as berries, roots and grass

Trophic levels, cont’ Tertiary consumers - top consumers -- fed on by decomposers or detrivores Ex: Hawks, bears, wolfs, sharks, humans

Trophic levels, cont’ Decomposers -- feed only on organic compounds in dead material Ex. Worms, insects, bacteria, fungi, Detritivores: Eat things that have already died (ravens, magpies, foxes, other scavengers)

Food (Energy) webs Since the sun is an important source of most of the energy in an ecosystem, it is important to include when talking about energy flow in ecosystems The sun energy enters the biosphere through the process of photosynthesis (producers), and then is transferred up the food chain Arrows show the direction of energy flow, so they point towards the organism that is getting the energy

Energy Flow/Food Chain

Food Web Arrows show the Direction of energy flow!

Biomass Biomass: the mass of the living things in an ecosystem, or of a certain group (e.g. biomass of the producers in an ecosystem) Total biomass is found by summing the dry mass biomass of all individuals in a given land area and then reported by naming the area of concern, e.g. biomass per plot, ecosystem, biome, classroom.

Trophic Pyramid or Energy Pyramid Energy passing up the food chain isn’t a very efficient process It has been calculated that only 10% of the energy contained in an organism is actually transferred to the organism that eats it That means that 90% of the energy is lost as heat, etc. via life processes

This explains why there is usually more herbivores than carnivores in an ecosystem, and why there is rarely more than 4 links in a food chain It also explains why the total mass of plants (producers) exceeds the total mass of other trophic levels That original energy input from the SUN gets ‘whittled down’ as you move up the food chain.

A few more vocabulary words… Biodiversity: the number of different types of organisms in an area Organism: an individual life form Population: all the organisms of a certain species Community: all the organisms (of different species) in an ecosystem