Energy Flow and Matter Cycles!

Trophic Structure 37.9 – 37.14

What you need to know! How energy flows through the ecosystem by understanding the vocabulary that relate to food chains and food webs. Explain primary productivity graphs.

Trophic Levels Structural levels that help organize ecosystems Food chains are the simplest trophic system Producers (autotrophs) always form the bottom level Primary consumers (herbivores) always form the second level Secondary consumers, tertiary consumers, and quaternary consumers (omnivores and carnivores) make up all the top most levels Decomposers (Detritivores) are a trophic level that consume waste and dead organisms They are traditionally excluded from graphic representations A food web is a more accurate, dynamic representation of the feeding relationships within a community

Primary Productivity The amount of sun energy converted into chemical energy for use by life in an ecosystem This can be measured in mass or energy The mass of all the life in an ecosystem is the biomass The primary productivity is the energy available to the rest of the organisms in an ecosystem The more energy available, the more life the ecosystem can support

Energy Budget Only 10% of the energy from one trophic level makes it to the next level Most of the energy is used by the organism and lost as heat (entropy) Energy flows up trophic levels and is ultimately lost (it does not cycle like nutrients)

Biogeochemical Cycles Chapter 37.15 – 37.20

What you need to know! The water, carbon, nitrogen, and phosphorus chemical cycles The various abiotic reservoirs for each cycle

Nutrients Recycle Biogeochemical cycles are the interactions between biotic and abiotic factors that account for the recycling of nutrients in an ecosystem All four major cycles share a pattern: Nutrients are stored in an abiotic reservoir Nutrients move through the food web Detritivores decompose everything back to the reservoir

The Water Cycle

Water Cycle Evaporation & transpiration (from plants) accounts for all the water in the atmosphere. Water forms clouds (condensation), and then rains (precipitation) back down to the Earth. Water runs into streams and rivers (runoff) or is absorbed into the ground (seepage) to become ground water. Water is taken up by the roots of plants or it makes its way to the oceans, flowing above ground or below ground. Abiotic Reservoir = Oceans, Lakes, & atmosphere

The Carbon Cycle

Carbon Cycle Photosynthesis, cellular respiration, and decomposition take up and release Carbon and Oxygen. Volcanic eruptions and erosion release Carbon Dioxide into the atmosphere and oceans Burial and decomposition of dead organisms store Carbon underground (coal & oil). Human activities, such as cutting and burning forests, and burning fossil fuels, release Carbon Dioxide into the atmosphere. Climate change (global warming) Abiotic Reservoir = atmosphere & fossil fuels

The Nitrogen Cycle

Nitrogen Cycle Nitrogen Fixation changes the nitrogen in the air into nitrogen that plants can use in the soil (nitrate ions & ammonium ions). Lightning, bacteria, fertilizer Once Nitrogen has been fixed in the soil it is then taken up by the roots of plants (producers). Abiotic Reservoir = atmosphere

The Phosphorus Cycle

Phosphorus Cycle It is not abundant in the atmosphere, so it follows a simple cycle. soil  producer  herbivore  carnivore  decomposer  back to soil Abiotic reservoir = rocks

Human Disturbance Human alteration of habitats can impact multiple ecosystems Example: When forests are cut down there are fewer plants to absorb essential nutrients in the soil Water washes the nutrients away to other ecosystems These other ecosystems are also altered