Chapter 3

1. Chapter 3 Ecosystems: What Are They & How Do They Work?

2. Ecology • def. Ecology is the study of how organisms interact with one another and with their nonliving environment. • Ecology is the study of the inter-connections of nature.

3. Organisms • def. Organisms are any form of life, with the cell being the basic unit of an organism and are classified into species. • Approximately 1,412,000 KNOWN species • Insects ~ 751,000 • Prokaryotes ~ 4,800 • Protists ~ 57,700 • Fungi ~ 69,000 • Plants ~ 248,400 • Other Animals ~ 281,000

4. Species • Groups of organisms with like characteristics • Asexual reproduction – one cell that replicates from the original cell • Sexual reproduction – combining sex cells (gametes) from 2 parent cells and have characteristic traits of both parents

5. Eukaryotic vs Prokaryotic • Eukaryotic cells • Surrounded by a membrane • Distinct nucleus – DNA is contained • Several other internal parts called organelles • Prokaryotic cells • No distinct nucleus – DNA is not localized

6. Eukaryotic Cell • Eukaryotic cell has 5 basic structures: • Nucleus • Organelle’s that lie outside the nucleus • Cytosol, a protein-rich, jelly-like fluid in which the organelles are immersed in • Cytoskeleton, an internal scaffolding consisting of 3 types of protein fibers • Plasma membrane, the outer lining of the cell

7. Diagram Of Eukaryotic by Daniel Chiras

8. Animal vs Plant Cells • Go to the following website for diagrams: http://sun.menloschool.org/~cweaver/cells/ • http://sun.menloschool.org/~cweaver/cells/

9. Prokaryotic Cell • Prokaryotic cells are bacteria and have no nucleus.

10. Population • A group of interacting organisms of the same species that occupy a specific space at the same time. • Genetic diversity – same species with different genetic differences • Habitat – the place where the population lives • Community – population of different species that occupy the same place

11. Ecosystems • def. Ecosystem is a community of different species interacting with each other and their non-living environment. • ex. Lake Champlain • Chazy River • The Adirondack Mountains • New York City

12. First of Four Spheres of Earth • Biosphere refers to: • All of the living parts of the separate ecosystems of the Earth acting as one unit • The parts that are organic and self-replicating • Includes all of the plants and animals of the Earth • Includes both living and dead organisms

13. Other Spheres of Earth • Lithosphere – Above the core and mantle and contains the top of the upper mantle and the crust (which includes all of the soil & rocks) • Hydrosphere – All of the liquid water on the Earth and in the ground (groundwater), solid water in the polar ice, permafrost, & sea ice, and water vapor in the atmosphere • Atmosphere – Gaseous envelope that surrounds the Earth as is comprised of multiple layers

14. Atmosphere • Troposphere (layer closest to the Earth and referred to as the boundary layer) contains most of the Earth’s air (78% N2 & 21% O2) and is where all weather is generated. • Stratosphere contains the ozone layer which absorbs ultraviolet radiation from the sun. • Mesosphere is the coldest layer in the atmosphere. • Thermosphere which includes the: • Ionosphere contains ions and is responsible for the absorption of high energy photons from the sun. • Exosphere is the outermost layer and merges with outer space.

15. Our Goal • The goal of ecology is to develop an understanding of interactions between the four spheres and the role that water, air, soil and organisms plays in our planets life support. • The goal of environmental science is to use ecology, chemistry, and all of the sciences to properly understand the affects on the 4 spheres of our Earth that we have and to use the sciences to sustain our planet.

16. What Sustains Life on Earth? • One-way flow of high-quality energy (see fig 3-6 on page 39) – the sun’s energy lights and heats the Earth through various cycles, and allows plants to undergo photosynthesis • Cycling of matter – all chemicals, ions, compounds, nutrients are needed for the survival of organisms on Earth and must be recycled through ecosystems • Gravity – holds the atmosphere close to Earth and allows downward movement of the matter cycle.

17. Solar Energy • See Fig. 3-7 on page 40 and the graphics from An Inconvenient Truth • Most of the energy that reaches the Earth from the sun (1-billionth) is infrared radiation, visible light, and some ultraviolet with much of the solar energy reflected back out or absorbed by chemicals in the atmosphere • It functions to warm the Earth’s crust and troposphere, evaporate and cycle water, and generate winds. • Green plants uptake solar energy to make food through the process of photosynthesis.

18. Photosynthesis • For the simple version, go to: http://earthguide.ucsd.edu/earthguide/diagrams/photosynthesis/photosynthesis.html • For the detailed version, go to: http://www.cix.co.uk/~argus/Dreambio/photosynthesis/photosynthesis%201.htm • For this course we will use the simple version: • 6CO2 + 6H2O + solar energy  C6H12O6 + 6O2

19. Solar Energy (continued) • 34% of solar radiation is reflected back to space by the atmosphere. • Most of the UV is absorbed by the stratosphere in the ozone layer. • Unreflected solar radiation is generally degraded into infrared radiation as heat (about 66%) • Greenhouse gases retain the heat and prevents the heat from escaping back into space and causes the Earth to warm (global warming).

20. Major Biomes • Sub-classifications of the biosphere into separate land units (terrestrial portions) characterized by specific climate and life-forms (vegetation) that has adapted to it • Forests • Grasslands • Deserts

21. Aquatic Life Zones • Marine and freshwater portions of the biosphere • Freshwater life zones – examples: • Lakes • Streams • Ocean & marine life zones – examples: • Estuaries • Coastlines • Coral reefs • Deep ocean

22. Abiotic vs Biotic • Abiotic – chemical & physical factors present in an ecosystem, examples: • Water • Air • Chemicals • Biotic – biological component– contains all living organisms, examples: • Plants • Animals • Microbes

23. Law of Tolerance The existence, abundance, and distribution of a species in an ecosystem are determined by whether the levels of one or more physical or chemical factors fall within the range tolerated by that species. Example: Acid deposition from the mid-west has caused many lakes in the Adirondacks to become too acidic to support many different fresh water species because the acidity fell outside the range of tolerance for those species.

24. Classification of Organisms • Producers (autotrophs) – make their own food & are the source of all food in the ecosystem, ex. green plants & phytoplankton • Consumers (heterotrophs) – obtain their energy by feeding off of other organisms • Decomposers (fungi & bacteria) – organisms that recycle dead organic material (detritus) back into the ecosystem

25. Types of Feeders • Omnivores – Eat both plants and animals, • example: humans • Herbivores – Eat only plants, • example cows • Detritivores – Eat dead organic matter called detritus (debris), • example: carpenter ant

26. Aerobic vs Anaerobic Respiration • Aerobic respiration– uses oxygen to convert organic nutrients back to carbon dioxide & water (reverse of photosynthesis) • C6H12O6 + 6O2  6CO2 + 6H2O + energy • Anaerobic respiration – occurs in the absence of oxygen

27. Biodiversity • def – Biodiversity is the different forms of life that can survive the variety of conditions on Earth • Species Diversity – variety of species that inhabit our planet • Genetic Diversity – variety of genes within a species • Ecological Diversity – variety of biomes and aquatic zones on Earth • Functional Diversity – biological and chemical processes that are needed for the survival of species • See fig 3-14 on page 45

28. Biodiversity www.bhutanabbot.com/aboutbhutan.php

29. Food Web vs Food Chain • Food chain – each organism within the chain is a food source for the next (see fig 3-16 on page 47) • Trophic – feeding level • Food web – a series of interconnected for • chains (see fig 3-17 on page 48)

30. Productivity in an Ecosystem • Gross Primary Productivity (GPP) = Rate at which an ecosystem’s producer converts solar energy to chemical energy as biomass • Net Primary Productivity (NPP) = Rate at which producers use photosynthesis to store energy minus the rate at which they use it for aerobic respiration • NPP = GPP - Eused

31. Importance of Soil • See figs 3-22 & 3-23 on pages 52 & 53 • Provides most of the nutrients needed for plant growth and helps purify water via infiltration • Develops over a long time containing several layers (horizons) of a variety of materials • 0 horizon – top layer (mostly undecomposed or partially decomposed organic matter) • A horizon – top soil (partially decomposed organic matter (humus) & inorganic mineral particles • B horizon – subsoil (combination of soil and rocks) • C horizon – parent material (mostly rock)

32. 0 & A Horizons • Most well-developed soils • The darker the color, the richer the soil is in nutrients • Supports most of the life in an ecosystem (bacteria, fungus, worms, and other decomposers as well as the roots of most plants) • Holds water well but does lose water through percolation to lower horizons • Leaching is the process where nutrients and pollutants are picked up by the water as it percolates through the horizons and is deposited in the groundwater

33. Cycling of Crucial Elements • Water Cycle • Carbon Cycle • Phosphorous Cycle • Nitrogen Cycle • Oxygen Cycle

34. Water (Hydrologic) Cycle • Collects, purifies and distributes the Earth’s fixed water supply (See fig. 3-24 on page 54) • Evaporation – converts liquid water into vapor • Transpiration – evaporation from leaves on plants • Condensation- converts water vapor back to liquid • Precipitation – rain, sleet, hail & snow are released from clouds • Infiltration and percolation – water moves into & through the soil • Runoff – water moves over the surface and back to the streams, lakes & oceans

35. Carbon Cycle • See fig. 3-25 on page 56-57 • Based on CO2 (carbon dioxide) in the troposphere and is the key component of heat regulation and carbonates (CO3-2) in the ocean • Terrestrial producers remove CO2 from the atmosphere and aquatic producers remove it from the water and convert it into simple carbohydrates. • Decomposition of byproducts (aerobic respiration) releases CO2 back into the environment for reuse. • Combustion of fossil fuels such as coal & oil

36. Human Affect on Carbon Cycle • Two ways that humans increase CO2 to the atmosphere are: • Clear cutting trees and plants that absorb CO2 • Burning fossil fuels and wood produces large amounts of CO2 • Increased amounts of CO2 could enhance the greenhouse effect and cause global warming • Global warming could disrupt and alter the way our environmental processes take place

37. Nitrogen Cycle • See fig. 3-27 on page 58 • Nitrogen fixation – bacteria convert nitrogen (N2) to ammonia (NH3) which can be used by plants for growth • Nitrification – special aerobic bacteria convert nitrogen (N2) to nitrogen monoxide (NO) • Both processes add nutrients to plants, that are eaten by animals, and then either excreted or discarded

38. Human Affect on Nitrogen Cycle • Five ways that humans have had effect on the nitrogen cycle • Burning of fossil fuels create NOx which leads to acid rain • Anaerobic bacterial action on livestock waste and commercial fertilizers • Harvesting of nitrogen rich crops, irrigation of crop land & burning/clearing grasslands • Agricultural runoff and discharge of sewage • Destruction of wetland and forests in large quantities

39. Phosphorus Cycle • See fig. 3-29 on page 59 • Phosphates (PO4-3) are the limiting factor for plant growth • Much of the phosphorus flows from land to sea • Addition of phosphates in aquatic systems greatly increases their biological activity

40. Human Affect on Phosphorus Cycle • Three ways that humans increase phosphorus to the environment are: • Commercial production of fertilizers & detergents • Burning & cutting of forests allow phosphates to be washed away by runoff • Runoff and discharge of animal waste, fertilizers from cropland & municipal sewage • Human activities have increased the amounts of phosphates about 3.7 fold

41. Sulfur Cycle • See fig. 3-30 on page 60 • Released from the Earth by volcanoes and from organic material in wetlands as hydrogen sulfide (H2S) • Marine algae produce large amounts of dimethyl sulfide (DMS) which can effect cloud cover and climate • Sulfur dioxide (SO2) which comes from volcanoes and the burning of coal enters the atmosphere and converts to SOx which leads to acid rain

42. Human Affect on Sulfur Cycle • Three ways which humans have altered the environment with sulfur • Sulfur containing coal & oil is burned, it produces about 2/3 the SO2 in the atmosphere • Refining of sulfur containing petroleum to make gasoline and heating oil • Smelting of metals produces large amounts of SO2 into the environment

43. System Analysis • System measurement • Define objectives • Identify & inventory variables • Obtain baseline data • Data analysis • Make statistical analysis • Determine significant interactions • System modeling • construct mathematical models • System simulation • Run the model with different variables • System optimization • Evaluate ways to achieve objectives

44. Sustainability • Ecosystems have sustained themselves for billions of years on Earth by using solar energy and recycling nutrients. If we take our lessons from Earth we ca be come more sustainable by: • Use renewable energy as our energy source • Recycle the chemical nutrients needed for survival, growth & reproduction