Chapter 3 Principles of Ecology

Ecosystems Nature in Balance

A. Organisms and their Environments I. Ecology 3.1 A. Organisms and their Environments Ecology-scientific study of interactions between organisms and their environment Biosphere- Portion of earth that supports life Biotic factors- All living things Abiotic factors - Non-living parts of the ecosystem (air, temp, light, soil, water, etc.)

Non living Materials in an Ecosystem

Population- group of organisms belonging to the same species Organism- a living thing (from one cell to multicellular) Population- group of organisms belonging to the same species Communities-collection of interacting populations Ecosystem- interactions among populations in a community and the community’s physical surroundings (abiotic factors)

Communities and Interdependence

Niche- role a species plays (includes the space, food and, other conditions needed to survive and reproduce) Habitat- place where an organism lives out its life

Ecology Movie 12 min.

B. Species Relationships 1. Feeding Relationships Autotrophs- produce own food (plants, some bacteria) Heterotrophs- depend on autotrophs to make their food for them

Herbivore – feed on grass and other plants Carnivores- kill and eat live animals Omnivores- feed on both plants and animals Detritivores-feed on dead organisms (buzzard, vultures, Scavengers ) Decomposers-break down dead or decaying organisms into basic compounds

2. Symbiotic Relationships Predator-Prey - benefits the predator harmful to prey Commensalism - one benefits the other is neither helped nor harmed Mutualism - both benefit Parasitism- (parasite-host) the parasite benefits the host is harmed but, not quickly killed

Energy flow What’s a food web? What’s a Food Chain?

Trophic levels

C. Matter and Energy Flow 1. Food Chain - Simple model that scientists use to show how matter and energy move through an ecosystem Trophic level - a feeding step in a food chain or web (producer, primary consumer, secondary consumer…)

Think of organisms that would be in a food chain and web

2. Food web – expresses all the possible feeding relationships at each trophic level

3. Pyramid of energy – the amount of energy available decreases at each trophic level. Only about 10% is available for the next level to use, the other 90% is used by the organism for heat, movement, and reproduction… 4. Pyramid of numbers – Population size normally decreases at each higher trophic level.

Water Cycle

D. Geochemical Cycles 1. Water Cycle Evaporation – water rises as vapor Condensation – formation of clouds Precipitation – Water (rain, snow, or hail) falling from the sky Infiltration – (Seepage) water soaking into the ground Runoff – water flowing above the ground to lakes or the ocean

2. Carbon Cycle The Carbon dioxide that is found in the air is taken into plants by the process of photosynthesis and stored as glucose for the plant to use for energy when it needs it. Animals consume (eat) the plants and use the glucose for energy and breaths out CO2 during respiration. Decomposers release carbon stored in dead organisms Humans release carbon when we burn (combustion) organic materials (wood and paper) or fossil fuels (Coal, oil, and gas)

Carbon occurs in all living things and forms nearly 10 million known compounds. Carbon is the major chemical constituent of most organic matter, from fossil fuels to the complex molecules (DNA and RNA) that control genetic reproduction in living organisms. Carbon is stored on Earth in a number of major reservoirs: Carbon dioxide (CO2) in the atmosphere Carbon dioxide dissolved in water Carbonate (CaCO3) rocks (limestones and corals) Fossil fuels - deposits of coal, petroleum, and natural gas derived from once-living things Living plants Dead organic matter - e.g. harvested wood and wood products, plant litter, humus in the soil Carbon is continuously cycled between these reservoirs in the ocean, on the land, and in the atmosphere. This carbon cycle has been continuing naturally since plant life took hold on land about 400 million years ago. Quantities are expressed in billion tonnes of carbon.

3. Nitrogen Cycle Nitrogen makes up 78% of the atmosphere Nitrogen-fixing Bacteria can make nitrogen into usable form for other organisms Legumes contain nitrogen-fixing bacteria in their roots nitrogen is added to the soil (ex. clover, soybeans, peas) Consumption of plants high in nitrogen enables us to make proteins for our bodies. Excretion of excess nitrogen in the urine or animal waste returns nitrogen to the soil for plant use. Decomposers release nitrogen stored by plants and animals