Ecosystems and Nutrient Cycles Chapters 3

Transcription

1 Ecosystems and Nutrient Cycles Chapters 3

2 Prokaryotic and Eukaryotic cells Figure 3-2 Prokaryotic cells: Have organelles. Bacteria and Archaea are composed of prokaryotic cells. Eukaryotic cells: cells, containing membrane-bound organelles that each perform a specific function.

3 Biosphere Parts of the earth's air, water, and soil where life is found Ecosystem Community Population A community of different species interacting with one another and with their nonliving environment of matter and energy Populations of different species living in a particular place, and potentially interacting with each other A group of individuals of the same species living in a particular place Organism An individual living being Cell The fundamental structural and functional unit of life Figure 3-3 Molecule Atom Chemical combination of two or more atoms of the same or different elements Smallest unit of a chemical element that exhibits its chemical properties

4 Ecosystems Have Living and Nonliving Components Abiotic: Nonliving components Water Air Nutrients Rocks Heat Solar energy Biotic: Abiotic Factors (Ex: Leaf litter is biotic)

5 Several Abiotic Factors Can Limit Population Growth Principle: Too much or too little of any abiotic factor can limit or prevent growth of a population, even if all other factors are at or near the optimal range of tolerance

6 Range of Tolerance for a Population of Organisms Figure 3-10 INSERT FIGURE 3-10 HERE

7 Living Components of Ecosystems Producers, Photosynthesis Chemosynthesis Consumers, Primary Secondary Tertiary and higher levels Generally not more than 3 or 4 levels due to the energy pyramid

8 Photosynthesis vs. Chemosynthesis Photosynthesis o Uses to provide the energy required to produce carbohydrates from carbon dioxide and water. 6 CO H 2 O C 6 H 12 O O 2 Chemosynthesis o Uses the energy from certain compounds such as hydrogen sulfide from to provide the energy to produce carbohydrates. o Performed by Bacteria and Archaea ( ). o Occurs at

9 Discuss with your table partner: What do photosynthesis and chemosynthesis have in common? How do the two processes differ? Fill in your answers on the next slide.

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11 Releasing Stored Energy All organisms store energy in sugars and other organic molecules. This energy is released as needed through either: -aerobic respiration (with oxygen) C 6 H 12 O O 2 6 CO H 2 O - anaerobic respiration (without oxygen) also known as Plants perform both photosynthesis and aerobic respiration.

12 Detritivores and Decomposers Detritivores: dead organisms. Decomposers: to break down dead organisms. Recycle nutrients into the surrounding area. Beetle larvae Fig 3-11 in an Ecosystem

13 Energy Flow Through the Ecosystem file:///d:/media/lite/powerpoint_lectures/chapter3/videos_animations/matter_energy.html

14 Nutrient and Energy Flows Through the Ecosystem

15 Living Components of Ecosystems First Trophic Level Second Trophic Level Third Trophic Level Fourth Trophic Level Producers (plants) Primary consumers (herbivores) Secondary consumers (carnivores) Tertiary consumers (top carnivores) Heat Heat Heat Heat Solar energy Heat Heat Heat Decomposers and detritus feeders Level: A step in a food chain flow of energy in an ecosystem.

16 Gross Primary Productivity (GPP) Gross Primary Productivity is the rate at which producers (for almost all producers) into. Usually measured in a unit of energy per unit of area over a given time span. Example : kcal/m 2 /year Some of the gross primary productivity is needed to support the producer and is not passed along the food chain.

17 Net Primary Productivity Net Primary Productivity (NPP) is the amount of chemical energy available after the requirements of the have been.

18 Discuss with your table partner: What could you measure to determine the NPP of an ecosystem? (Hint: Productivity = rate of photosynthesis) By measuring the increase in or the decrease in the Estuaries and swamps generally have a high net primary productivity. Why? Why is the NPP compared for different ecosystems rather than the GPP? NPP can be measured. GPP cannot.

19 Estimated Annual Average NPP in Major Life Zones and Ecosystems Figure 3-16

20 Nutrient Cycles Nutrient cycles (= biogeochemical cycles): natural processes that involve the flow of nutrients from the nonliving environment (air, water, soil, rock) to living organisms (biota) & back again. Nutrient cycles involve one way flow of high quality energy from the sun through the environment & recycling of crucial elements. Fig. 4 6

21 Major Locations (Reservoirs) of Nutrients hydrologic involving flows through the hydrosphere, in the form of liquid water, compounds dissolved in water, & sediments carried by water. atmospheric involving flows through the atmosphere, as gases or airborne particles (particulates). sedimentary involving flows through the lithosphere (Earth's crust = soil & rock), as solid minerals. (lithospheric)

22 Water Cycle Main Processes: evaporation: conversion from liquid to vapor form (surface to atmosphere). : evaporation from leaves of water extracted from soil by roots & transported through the plant (surface to atmosphere). transportation in atmosphere: transport as vapor. condensation: conversion of vapor to liquid droplets (clouds). precipitation: movement as rain, sleet, hail, & snow (atmosphere to surface). infiltration: movement soil. percolation: downward flow soil to aquifers. flow in aquifers: below ground flow of water. : surface flow downslope to ocean.

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24 Review with your table partner: What are the similarities and differences between evaporation and transpiration? Put the following terms in the correct order that they would occur: Percolation, Precipitation, Infiltration.

25 Discuss with your table partner: How might deforestation of a tropical rainforest affect the rainfall in a region? (What process would be changed and how could this affect rainfall)

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27 Role of Water: Water Cycle terrestrial ecosystems major factor determining aquatic ecosystems literally that surrounds & serves as environment of aquatic organisms flows of water are major means material & transport water is critical for human activities agriculture, industry, & municipal use Human Influences: large quantities of fresh water water diversion, groundwater depletion, wetland drainage clear increase runoff, decrease infiltration & groundwater recharge, increase flooding & soil erosion modify water add nutrients (P, N ) and/or pollutants

28 Role of Carbon: building block of (carbohydrates, fats, proteins, & nucleic acid) essential to life Carbon Cycle currency of chemical energy for life stored as bonds in organic compounds carbon dioxide (CO 2 ) is a traps heat near Earth's surface & plays a key role as "nature's thermostat

29 Carbon Cycle Processes photosynthesis ( = carbon ) moves C from to (C,H,O compounds) in organisms; movement through food web: C movement in organic form from organism to ; movement between oceans and atmosphere: uptake and release from oceans aerobic respiration: organic molecules broken down to release back to atmosphere;

30 Carbon Cycle Processes Cont. movement to sediments and rock: C forms CaCO 3 through biological processes ( in plankton and larger marine organisms); enters sediments after organisms die; and eventually becomes rock ( ). Fossil fuel formation: organic molecules are buried, compressed, and heated to form (oil, natural gas), and elemental carbon (coal) combustion: organic molecules broken down by to release CO 2 back to atmosphere; Limestone

31 Carbon Cycle Photosynthesis, Respiration, and decay happen in both land and ocean ecosystems Plants perform both photosynthesis and Combustion inputs to the atmosphere include burning of fossil fuels, (not shown), and (not shown). (Combustion) (Photosynthesis) Fossil fuel formation Rock formation

32 Review with your table partner: What are two ways that humans are shifting the carbon cycle to increase the amount of carbon found in the atmosphere (CO 2 ) rather than stored in organic (carboncontaining) molecules? Human Influences to Carbon Cycle:

33 Nitrogen Cycle Nitrogen (N 2 ) is the most common gas in the atmosphere (78%). However, most organisms cannot utilize N 2 (don t have the enzymes to break the triple bond) Nitrogen is needed by all living things. N is part of and protein. Nutrient in many ecosystems: typically addition of N in fertilizers leads to increased productivity

34 Nitrogen Cycle Processes nitrogen : conversion of N 2 (nitrogen gas) to NH 4+ (ammonium), Performed by bacteria & blue-green algae (anaerobic), e.g., Rhizobium in nodules on roots of legumes; N 2 is also fixed by lightning nitrification: conversion of NH 4+ to NO 2 - (nitrite) and to NO 3- (nitrate) by ; (Oxidation process) of NO 3 by plants, forms proteins and other N containing organic compounds, enters ;

35 Nitrogen Cycle Processes Cont. ammonification: decomposers return nitrate to Ammonium (NH +) 4 by saprophytes and denitrification: conversion of NH 4+ to N 2 by combustion or microbes. Conversion of NOx to N 2 by bacteria (reduction process)

36 Fig. 5 6 Nitrogen Cycle

37 Review with your table partner: Name a form of nitrogen that can t be used by most organisms. Name a form of nitrogen that can be used by most organisms. Why do legume plants (bean family) have an advantage in getting enough of the usable nitrogen compounds they need? Continue to next slide

38 What three types of bacteria are involved in the nitrogen cycle? Which are involved in producing usable nitrogen compounds and which are involved in cycling nitrogen compounds back to the atmosphere? - produce usable ammonium compounds (in soil or legume nodules) -produce usable nitrate compounds -cycle nitrogen back to the atmosphere (N 2 )

39 Inorganic Fertilizers During WWII, Fritz Haber developed process to convert atmospheric nitrogen into ammonia to make inorganic nitrate. (Process happens at high temperatures, which consumes a lot of.) Revolutionized farming: increasing yields. Part of the

40 Human Influences on the Nitrogen Cycle emit nitric oxide (NO), which leads to and acid rain; Beijing emit nitrous oxide into the atmosphere nitrous oxide (N 2 O) is a potent greenhouse gas & also depletes in stratosphere Use of nitrogen fertilizers which leads to of water bodies

41 Phosphorous Cycle Occurs in the form PO 4 ) Released from rocks by (slow process) Needed by all living things for:,, Phospholipids Can be limiting factor for growth No component of cycle

42 Human Influences of Phosphorous Cycle: large quantities for fertilizers and detergents Cutting down reduces available phosphate Add excess phosphate to aquatic systems from feedlots, runoff from farmland, and sewage discharges

43 Eutrophication Definition: Process: End Result: Addition of excess (usually phosphorous or nitrogen to a water body due to - Nutrients cause an overgrowth of. - Algae block light and start to die. - use up oxygen as they break down dead algae. (Note it is the decomposition that uses up oxygen- algae themselves are photosynthetic.) Low oxygen levels can kill fish = low oxygen = no oxygen

44 Sulfur Cycle Sulfur compounds are found in rocks, soil and fossil fuels (esp. ) Sulfur is required by all living things (2 amino acids contain sulfur) Sulfur is found in the as sulfur dioxide (SO 2 ) and sulfuric acid (H 2 SO 4 )

45 Sulfur Cycle Coal Plant Human Influences: Fossil fuel burning (especially coal) (refining of metal ores) releases SO x to atmosphere Sulfur compounds in the atmosphere cause Acid Rain Damage Smelting