Ecology-Matter & Energy Cycling

Ecology What is ecology? The study of organisms and how they interact with each other and their environment A relatively new field of science

Ecology Nutrients cycle through living and nonliving components in the ecosystem The sun and gravity drive the cycling of all nutrients on earth Life on earth depends on the flow of energy (sun) through the environment

Ecology Three important cycles are The carbon-oxygen cycle The water cycle The nitrogen cycle

The Carbon-Oxygen Cycle Why is the C-O cycle needed? Carbon and oxygen are required to make glucose, the energy source for all cells Energy from the sun is stored in carbohydrates

The Carbon-Oxygen Cycle Carbon dioxide cycles through autotrophs It is converted into sugar (photosynthesis) Oxygen is given off in the process CO2 is released as the sugar is broken down by heterotrophs and autotrophs cellular respiration Oxygen is consumed to enable the electron transport chain Energy +6CO2 + 6H2O C6H12O6 +602

The Carbon-Oxygen Cycle How do humans intervene with the cycle? Burning fossil fuels also adds to the CO2 in the atmosphere, as well as other pollutants Removing large numbers of trees and forested areas

The Water Cycle Why do we need the H2O cycle? Water is needed for all cell processes Every cell consists of about 80% water You can live for a few weeks without food, but only a few days without water!

The Water Cycle Water evaporates from the surface or from plant leaves (transpiration) As the vapor cools and condenses, clouds form When the droplets get heavy, they fall (precipitation)

The Water Cycle Water can then: Runoff on the surface of the land Infiltrate into the top layers of soil Percolate into deep underground reservoirs Water eventually runs back to the ocean to cycle again

The Water Cycle How do humans intervene? Drawing huge amounts of groundwater Paving streets and walkways Cutting forests

The Nitrogen Cycle Why do we need the N cycle? Nitrogen is needed in amino acids-the building block of proteins All cell structures contain protein

The Nitrogen Cycle Nitrogen in the gas form is not useable by green plants Bacteria (N-fixers) put the nitrogen into water-soluble molecules in the soil Other bacteria break down dead organisms and animal waste to release nitrogen compounds

The Nitrogen Cycle Plants take up the nitrogen compounds with their roots They make amino acids and eventually plant proteins Animals eat plants and use the amino acids to make animal proteins

The Nitrogen Cycle How do humans intervene in the N Cycle? Nitrogen is mined for fertilizers Fossil fuels release nitrous oxides into the atmosphere

Food Chains and Webs Food chains are simple diagrams of the feeding sequence of an ecosystem

Food Chains and Webs Food chains are simple diagrams of the feeding sequence of an ecosystem They show organisms feeding on one thing at one trophic level

Food Webs Most animals feed on different things and at different trophic levels, forming a web. Food webs represent several interconnected chains

Energy Pyramids Energy pyramids illustrate that as energy moves up through the trophic levels, energy is “lost” The energy does not disappear, but changes into unusable forms (heat, metabolism, indigestible fiber, etc) About 90% of the food energy is not passed to the next level.

Energy Pyramids There are fewer consumers at the upper levels due to the amount of energy available Aquatic ecosystems have more trophic levels than terrestrial ecosystems There are many microscopic levels in the food web