Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Ecosystems CHEMICAL CYCLING IN ECOSYSTEMS –Depend on a recycling of chemical elements –What gets recycled in our ecosystem? Energy?? NOOO Water Carbon Phosphorus

And the answer is….  CARBON  Why!!!??  It is used as the building block in every organic molecule and therefore is the backbone of life. So…What does this mean in ecology? …let’s look at how carbon flows through an ecological system.  CARBON  Why!!!??  It is used as the building block in every organic molecule and therefore is the backbone of life. So…What does this mean in ecology? …let’s look at how carbon flows through an ecological system.

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings What Is Carbon? An element The basis of life on earth Found in rocks, oceans, atmosphere

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The Carbon Cycle The same carbon atoms are used repeatedly on earth. They cycle between the earth and the atmosphere.

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 19.29a CO 2 in atmosphere Burning Wood and fossil fuels Cellular respiration Higher-level consumers Decomposition Detritivores Photosynthesis Producers Primary consumers Detritus (a) The carbon cycle The carbon cycle What do we eat that has carbon?

The Carbon Cycle (Terrestrial) Fig p

The Carbon Cycle (Aquatic) Fig p

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Carbon Cycle Producers: Plants take in CO2 and make sugar by photosynthesis. Consumers: Animals eat plants to get energy (respiration) from sugar and make proteins from the carbon. –Breath out CO2 as a waste product of respiration. Animals die and dentritus (decomposers) break down the carbon and other elements back into the soil and air for plants to use again.

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Plants Use Carbon Dioxide Plants pull carbon dioxide from the atmosphere and use it to make food –— photosynthesis. The carbon becomes part of the plant (stored food).

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Animals Eat Plants When organisms eat plants, they take in the carbon and some of it becomes part of their own bodies.

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Plants and Animal Die When plants and animals die, most of their bodies are decomposed and carbon atoms are returned to the atmosphere. Some are not decomposed fully and end up in deposits underground (oil, coal, etc.).

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Carbon Slowly Returns to Atmosphere Carbon in rocks and underground deposits is released very slowly into the atmosphere. This process takes many years.

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Carbon Cycle Diagram Carbon in Atmosphere Plants use carbon to make food Animals eat plants and take in carbon Plants and animals die Decomposers break down dead things, releasing carbon to atmosphere and soil Bodies not decomposed — after many years, become part of oil or coal deposits Fossil fuels are burned; carbon is returned to atmosphere Carbon slowly released from these substances returns to atmosphere

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The carbon cycle Carbon is found in carbohydrates, fats, proteins, bones, cartilage and shells Carbon cycle = describes the route of carbon atoms through the environment Photosynthesis by plants, algae and cyanobacteria –Removes carbon dioxide from air and water –Produces oxygen and carbohydrates –Plants are a major reservoir of carbon Respiration returns carbon to the air and oceans –Plants, consumers and decomposers

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Sediment storage of carbon Decomposition returns carbon to the sediment –The largest reservoir of carbon –May be trapped for hundreds of millions of years Aquatic organisms die and settle in the sediment –Older layers are buried deeply and undergo high pressure –Ultimately, it may be converted into fossil fuels Oceans are the second largest reservoir of carbon

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Humans affect the carbon cycle Burning fossil fuels moves carbon from the ground to the air Cutting forests and burning fields moves carbon from vegetation to the air Today’s atmospheric carbon dioxide reservoir is the largest in the past 800,000 years –It is the driving force behind climate change The missing carbon sink: 1-2 billion metric tons of carbon are unaccounted for –It may be taken up by plants or soils of northern temperate and boreal forests

Importance of Nitrogen (N)  Nitrogen is a part of all living cells and is a necessary part of all proteins, enzymes and metabolic processes involved in the synthesis and transfer of energy.  Nitrogen is a part of chlorophyll, the green pigment of the plant that is responsible for photosynthesis.  Nitrogen is a part of all living cells and is a necessary part of all proteins, enzymes and metabolic processes involved in the synthesis and transfer of energy.  Nitrogen is a part of chlorophyll, the green pigment of the plant that is responsible for photosynthesis.

Importance of Nitrogen (N)  Helps plants with rapid growth, increasing seed and fruit production and improving the quality of leaf and forage crops.  Nitrogen often comes from the air (legumes get their N from the atmosphere, water or rainfall contributes very little nitrogen)  Helps plants with rapid growth, increasing seed and fruit production and improving the quality of leaf and forage crops.  Nitrogen often comes from the air (legumes get their N from the atmosphere, water or rainfall contributes very little nitrogen)

Nitrogen Cycle (N)

The nitrogen cycle  Nitrogen comprises 78% of our atmosphere  It is contained in proteins, DNA and RNA  Nitrogen cycle = describes the routes that nitrogen atoms take through the environment  Nitrogen gas in the atmosphere (N 2 ) cannot be used by organisms  Has to be in the form of ammonia (NH 3 ) or nitrates (NO 3 - )

Steps  1. Nitrogen fixation = lightning or nitrogen-fixing bacteria combine (fix) nitrogen with hydrogen  Change N 2 to ammonium ions NH 4 +  These are then used by plants  2. Nitrification = soil bacteria converts ammonium NH 4 + to nitrites (NO 2 - ) and then nitrates (NO 3 - )  3. Assimilation = Plants absorb ammonium (NH 3 ), ammonia ions (NH 4 + ), and nitrate ions (NO 3 - )through their roots. Other organisms gain this energy when they consume the plants  1. Nitrogen fixation = lightning or nitrogen-fixing bacteria combine (fix) nitrogen with hydrogen  Change N 2 to ammonium ions NH 4 +  These are then used by plants  2. Nitrification = soil bacteria converts ammonium NH 4 + to nitrites (NO 2 - ) and then nitrates (NO 3 - )  3. Assimilation = Plants absorb ammonium (NH 3 ), ammonia ions (NH 4 + ), and nitrate ions (NO 3 - )through their roots. Other organisms gain this energy when they consume the plants

Nitrogen Cycle Continued  4. Ammonification = decomposing bacteria convert dead organism and other waste to ammonia (NH 3 ) or ammonium (NH 4 + ) which can be reused by plants  5. Denitrification = Specialized bacteria convert ammonia (NH 3 ) back into nitrites (NO 2 - ) and nitrates (NO 3 - ) and then back into nitrogen gas (N 2 )and nitrous oxide gas (N 2 O), releasing them back into the air  4. Ammonification = decomposing bacteria convert dead organism and other waste to ammonia (NH 3 ) or ammonium (NH 4 + ) which can be reused by plants  5. Denitrification = Specialized bacteria convert ammonia (NH 3 ) back into nitrites (NO 2 - ) and nitrates (NO 3 - ) and then back into nitrogen gas (N 2 )and nitrous oxide gas (N 2 O), releasing them back into the air

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 19.29b Denitrifying bacteria Assimilation by plants Nitrogen (N 2 ) in atmosphere Amino acids and proteins in plants and animals Detritus Detritivores Nitrogen- fixing bacteria in root nodules of legumes Decomposition Nitrogen fixation Nitrogen- fixing bacteria in soil Ammonium (NH 4 + ) Nitrifying bacteria Nitrates (NO 3 – ) The nitrogen cycle (b) The nitrogen cycle

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Nitrogen Fixation by bacteria Plants need nitrogen but cannot take it in from the air. Bacteria in the soil on the roots of plants take in nitrogen (N 2 ) and make ammonia (NH 4 ) which plants can then use to get nitrogen.

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Humans affect the nitrogen cycle Haber-Bosch process = production of fertilizers by combining nitrogen and hydrogen to synthesize ammonia –Humans overcame the limits on crop productivity Fixing atmospheric nitrogen with fertilizers –Increases emissions of greenhouse gases and smog –Washes calcium and potassium out of soil –Acidifies water and soils –Moves nitrogen into terrestrial systems and oceans –Reduces diversity of plants adapted to low-nitrogen soils –Changed estuaries and coastal ecosystems and fisheries

Importance of Phosphorus (P)  Like nitrogen, phosphorus (P) is an essential part of the process of photosynthesis.  Involved in the formation of all oils, sugars, starches, etc.  Helps with the transformation of solar energy into chemical energy; proper plant maturation; withstanding stress.  Like nitrogen, phosphorus (P) is an essential part of the process of photosynthesis.  Involved in the formation of all oils, sugars, starches, etc.  Helps with the transformation of solar energy into chemical energy; proper plant maturation; withstanding stress.

Importance of Phosphorus (P)  Effects rapid growth.  Encourages blooming and root growth.  Phosphorus originates from rocks  Effects rapid growth.  Encourages blooming and root growth.  Phosphorus originates from rocks

Phosphorus Cycle (P)

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 19.29c The phosphorous cycle Uplifting of rock Phosphates in rock Weathering of rock Phosphates in organic compounds Consumers Producers Rock Precipitated (solid) phosphates Phosphates in solution Phosphates in soil (inorganic) Detritus Detritivores in soil (c) The phosphorus cycle What part of you has phosphate?

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Humans affect the phosphorus cycle Mining rocks for fertilizer moves phosphorus from the soil to water systems Wastewater discharge also releases phosphorus Runoff containing phosphorus causes eutrophication of aquatic systems –Produces murkier waters –Alters the structure and function of aquatic systems –Do not buy detergents that contain phosphate

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The water cycle Figure 19.29d Precipitation over the sea (283) Solar heat Water vapor over the sea Oceans Net movement of water vapor by wind (36) Evaporation from the sea (319) Evaporation and transpiration (59) Water vapor over the land Precipitation over the land (95) Surface water and groundwater Flow of water from land to sea (36) (d) The water cycle

Hydrologic (Water) Cycle Fig p. 83

Human impacts on the hydrologic cycle Removing forests and vegetation increases runoff and erosion, reduces transpiration and lowers water tables Irrigating agricultural fields depletes rivers, lakes and streams and increases evaporation Damming rivers increases evaporation and infiltration Emitting pollutants changes the nature of precipitation The most threatening impact: overdrawing groundwater for drinking, irrigation, and industrial use –Water shortages create worldwide conflicts

Implications  We observe the dynamic balance of matter cycles at all levels of scale from the ecological system to the individual organism.  For Ecologists..Aldo Leopold’s dictum that an action is right when it maintains the stability and integrity of the biotic community holds true.  We observe the dynamic balance of matter cycles at all levels of scale from the ecological system to the individual organism.  For Ecologists..Aldo Leopold’s dictum that an action is right when it maintains the stability and integrity of the biotic community holds true.