1 Ecology Chapters 3-6

2 Chapter 3 The Biosphere

3 Section 3.1 What is Ecology?

4 Ecology Ecology is the scientific study of interactions among organisms and their physical environment. It is the study of connections in nature.

5 Biosphere The Biosphere consists of all life on Earth and all parts of the Earth in which life exists, including land, water, and the atmosphere. It extends from high in the atmosphere to the bottom of the oceans. All things in the biosphere fall into one of two categories: abiotic or biotic.

6 Biotic Factors The biological influences on organisms are called biotic factors. A biotic factor is any living part of the environment with which an organism might interact. Ex. Animals, plants, bacteria, etc.

7 Abiotic Factors Physical components of an ecosystem are called abiotic factors. An abiotic factor is any nonliving part of the environment. Ex. Sun, heat, precipitation,wind, soil, etc.

8 Ecological Methods Regardless of their tools, modern ecologists use three methods in their work: observation, experimentation, and modeling.

9 Other animals 281,000 Known species 1,412,000 Insects 751,000 Fungi69,000 Prokaryotes 4,800 Figure 3.3 Natural capital: breakdown of the earth’s 1.4 million known species. Scientists estimate that there are 4 million to 100 million species. Plants 248,400 Protists 57,700 Fig. 3-3, p. 52

10 Organisms and Species Organisms – Any form of lifeSpecies – Groups of organisms that resemble one another in appearance, behavior, chemistry, and genetic makeup There are 4 million to 100 million species on Earth. Most known species are microorganisms that are too small to be seen with the naked eye. 10 million to 15 million other species 1.4 million species have been named (most are insects)

11 Populations, Communities, & EcosystemsPopulation – all the individuals of a species that live and reproduce in a given area. Community – group of populations living and interacting in geographic area. Ecosystem - a community interacting with its physical environment of matter and energy.

12 Ecosystem An ecosystem is a self sustaining group of living things and their environment. It consists of all the biotic and abiotic factors in a given area. Together, biotic and abiotic factors determine the survival and growth of an organism and the productivity of the ecosystem in which the organism lives.

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14 Biosphere Ecosystems Realm of ecology Communities PopulationsUniverse Galaxies Biosphere Solar systems Planets Earth Biosphere Ecosystems Ecosystems Communities Populations Realm of ecology Organisms Communities Organ systems Organs Figure 3.2 Natural capital: levels of organization of matter in nature. Ecology focuses on five of these levels. Tissues Cells Populations Protoplasm Molecules Atoms Organisms Subatomic Particles Fig. 3-2, p. 51

15 Falling leaves and twigs Soluble mineral nutrientsOxygen (O2) Sun Producer Carbon dioxide (CO2) Secondary consumer (fox) Primary consumer (rabbit) Precipitation Producers Falling leaves and twigs Figure 3.10 Natural capital: major components of an ecosystem in a field. Soil decomposers Water Soluble mineral nutrients Fig. 3-10, p. 57

16 Section 3.2 Energy, Producers, and Consumers

17 Primary Producers Primary producers are the first producers of energy-rich compounds that are later used by other organisms. These organisms are called autotrophs because they use solar or chemical energy to produce “food” by assembling inorganic compounds into complex organic molecules.

18 Two Types of Primary ProducersPhotosynthetic organisms harness solar energy through the process of photosynthesis. They capture light energy and use it to power chemical reactions that convert carbon dioxide and water into oxygen and energy-rich carbohydrates such as sugars and starches. Ex. Plants, algae, cyanobacteria Chemosynthetic organisms use chemical energy in the absence of light to produce carbohydrates. Ex. bacteria

19 Producers (Autotrophs)An organism that can make its own food. The base of the food chain.

20 Consumers Organisms that rely on other organisms for energy and nutrients are called consumers. These organisms are called heterotrophs because they must acquire energy from other organisms – by ingesting them.

21 Types of Consumers Herbivores/Primary Consumers – eat producers ex. rabbits and deer Carnivores/Secondary Consumers – eat herbivores ex. Tertiary Consumers – eat other carnivores Scavengers – eat dead animals Omnivores – eat both plants and animals

22 Consumers (Heterotrophs)An organism that cannot make its own food. Gains energy by eating producers or other consumers.

23 Decomposers and DetritrivoresBacteria or fungi. Feed on and break down dead organic material. Specialized organisms that recycle nutrients in ecosystems. Digest or degrade living or dead organisms into simpler inorganic compounds that producers can take up from soil and water to use as nutrients. Detritrivores Insects and other scavengers that feed on the wastes or dead bodies of other organisms.

24 Termite and carpenter ant work Bark beetle engraving Scavengers Decomposers Termite and carpenter ant work Bark beetle engraving Carpenter ant galleries Long-horned beetle holes Dry rot fungus Wood reduced to powder Figure 3.13 Natural capital: various scavengers (detritivores) and decomposers (mostly fungi and bacteria) can “feed on” or digest parts of a log and eventually convert its complex organic chemicals into simpler inorganic nutrients that can be taken up by producers. Mushroom Time progression Powder broken down by decomposers into plant nutrients in soil Fig. 3-13, p. 61

25 Section 3.3 Energy Flow in Ecosystems

26 Food Chains A food chain is a series of steps in which organisms transfer energy by eating and being eaten.

27 Food Chains

28 Food Webs A food web illustrates a network of feeding interactions.Food webs show how eaters, the eaten, and the decomposed are connected to one another in an ecosystem. All organisms, whether dead or alive, are potential sources of food for other organisms. There is little matter wasted in natural ecosystems. In a food web arrows always point from an organism to the organism that eats it.

29 Humans Blue whale Sperm whale Crabeater seal Elephant sealKiller whale Leopard seal Adelie penguins Emperor penguin Squid Figure 3.18 Natural capital: a greatly simplified food web in the Antarctic. Many more participants in the web, including an array of decomposer organisms, are not depicted here. Petrel Fish Carnivorous plankton Krill Herbivorous plankton Phytoplankton

30 Trophic Levels Each organism in a food chain represents a feeding step or Trophic Level in the passage of energy and materials. 1st Trophic level – producers, the basis of any ecosystem (plants) 2nd Trophic level – primary consumers which eat only producers (insects, rabbits, deer) 3rd Trophic level – secondary consumers which eat primary consumers (birds, foxes, snakes) 4th Trophic level – tertiary consumers which eat primary and secondary consumers (bears)

31 Trophic Pyramid A graphic representation of available energy and organisms in a hierarchy of trophic levels.

32 Pyramids of Biomass and NumbersA pyramid of biomass illustrates the relative amount of living organic matter available at each trophic level in an ecosystem. A pyramid of numbers shows the relative number of individual organisms at each trophic level in an ecosystem.

33 Where Does That Energy Go?

34 (decomposers and detritus feeders)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 Solar energy Heat Heat Figure 3.17 Natural capital: a food chain. The arrows show how chemical energy in food flows through various trophic levels in energy transfers; most of the energy is degraded to heat, in accordance with the second law of thermodynamics. Heat Heat Detritivores (decomposers and detritus feeders) Heat Fig. 3-17, p. 64

35 Ultimate Source of all EnergyPhotograph © 2001 dan klein photophraphy for ATPM

36 Movement of Energy in an EcosystemEnergy enters an ecosystem from the abiotic realm, starting with the sun and chemical compounds. That energy then enters and moves up the trophic levels from plants to herbivores, from herbivores to carnivores, and so on. (the path of energy is one way, it is not cycled like matter) Energy is lost as heat as it moves from one trophic level to the next. (Each organism uses some of the energy it possesses to complete life functions. Therefore, the initial amount of energy is not passed on to the next trophic level.) Only about 10% of the energy that enters a trophic level is available to the next trophic level above it.

37 Energy Flow

38 Section 3.4 Cycles of Matter

39 Nutrient Cycles: Global RecyclingUnlike the one way flow of energy, matter is recycled within and between ecosystems. Global cycles recycle nutrients through the earth’s air, land, water, and living organisms. They connect past, present, and future forms of life. Nutrients –the elements and compounds that organisms need to live, grow, and reproduce. Biogeochemical Cycles Water Carbon Nitrogen Phosphorus Sulfur

40 The Water Cycle A vast global cycle collects, purifies, distributes, and recycles the Earth’s fixed supply of water. Also called the hydrological cycle. It is driven by solar energy and gravity. The worldwide differences in temperature that result from differences in solar energy intensity, absorption, and reflection drive the water cycle. The temperature differences create gradients in the geosphere, atmosphere, and hydrosphere. The hydrological cycle has six main components which are all driven by temperature: 1. precipitation, 2. infiltration, 3. runoff, 4. evaporation, 5. transpiration, and 6. condensation.

41 The Water Cycle Evaporation – Solar energy heats water in oceans, lakes, rivers, and land to evaporate into gas form and return to the atmosphere. Condensation – Change of water from gas to a liquid state as it is cooled in the atmosphere. High condensation leads to precipitation Precipitation – water that reaches the earth’s surface as rain, sleet, or snow. Infiltration – water that seeps into the ground, results in ground water. Runoff - precipitation occurs to fast for the earth to absorb the water which runs over the earth as runoff. Transpiration – water returns to the atmosphere as a gas, escape of water from the leaves of plants.

42 Condensation Transpiration Evaporation Precipitation PrecipitationRain clouds Transpiration Evaporation Precipitation to land Transpiration from plants Precipitation Precipitation Evaporation from land Evaporation from ocean Surface runoff (rapid) Runoff Precipitation to ocean Infiltration and Percolation Surface runoff (rapid) Figure 3.26 Natural capital: simplified model of the hydrologic cycle. Groundwater movement (slow) Ocean storage

43 Effects of Human Activities on the Water CycleWe alter the water cycle by… Withdrawing large amounts of fresh water. Clearing vegetation and eroding soils. Polluting surface and underground water. Contributing to climate change.

44 The Carbon Cycle Carbon cycles through the earth’s air, water, soil, and living organisms and depends on photosynthesis and respiration. Due to carbon’s ability to form long molecular chains carbon forms the backbone of many of life’s molecules. Carbon is the basic building block of carbohydrates, fats, proteins, DNA, and other organic compounds necessary for life. The carbon cycle is based on carbon dioxide (CO2)

45 Figure 3.27 Natural capital: simplified model of the global carbon cycle. Carbon moves through both marine ecosystems (left side) and terrestrial ecosystems (right side). Carbon reservoirs are shown as boxes; processes that change one form of carbon to another are shown in unboxed print. QUESTION: What are three ways in which your lifestyle directly or indirectly affects the carbon cycle? (From Cecie Starr, Biology: Concepts and Applications, 4th ed., Pacific Grove, Calif.: Brooks/Cole, © 2000)

46 The Carbon Cycle: How it WorksTerrestrial producers remove CO2 from the atmosphere. Aquatic producers remove CO2 from the water. All producers use photosynthesis to convert CO2 into complex carbohydrates (like glucose). The cells in consumers carry out aerobic respiration. They break down glucose and convert the glucose back to CO2 for reuse by consumers. The link between photosynthesis and aerobic respiration circulates carbon in the biosphere.

47 The Carbon Cycle: How it WorksSome carbon atoms take a long time to recycle. Over millions of years, buried deposits of dead plant matter and bacteria are compressed between layers of sediment, where they form carbon-containing fossil fuels. This carbon is not released to the atmosphere as CO2 for recycling until these fuels are extracted and burned. In the past 50 years, we have extracted and burned fossil fuels that took millions of years to form.

48 Effects of Human Activities on the Carbon CycleWe alter the carbon cycle by… Clearing trees and plants that absorb CO2 through photosynthesis faster than they can grow back. Adding large amounts of CO2 into the atmosphere by burning fossil fuels and wood. Increased concentrations of CO2 can enhance the planet’s natural greenhouse effect. Global warming disrupts global food production and wildlife habitats, alters temperature and precipitation patterns, and raises the average sea level in various parts of the world.

49 Photosynthesis and Cellular RespirationIn photosynthesis, a plant or other photosynthetic organism absorbs the Sun’s light energy and uses it to combine Carbon dioxide with water to produce sugars and oxygen. A plant needs one type of energy an two compounds to produce sugars. Identify them. Photosynthesis captures the sun’s energy in a sugar molecule. Cellular respiration is the reverse of photosynthesis. In respiration, a cell breaks apart a sugar molecule to release energy. The organism then converts that energy to produce molecules of ATP, which the cell uses to carry on life processes. Write an accurate chemical and word equation to describe the process of photosynthesis and cellular respiration.

50 The Nitrogen Cycle Different types of bacteria help recycle nitrogen through the Earth’s air, water, soil and living organisms. Nitrogen is… The most abundant gas in the atmosphere Crucial component of proteins and nucleic acids (DNA, RNA) About 78% of the earth’s atmosphere is gaseous nitrogen, but most organisms can not use N in this form. The N2 gaseous form must be “fixed” or converted to compounds that organisms can use.

51 Nitrogen Fixation Two natural processes fix N2 into useful compoundsLightning Nitrogen Cycle Nitrogen-fixing bacteria in soil and aquatic environments convert (fix) gaseous nitrogen (N2 ) into ammonia (NH3) which is later converted into ammonium ions (NH4+) that can be used by plants. Ammonia not taken up by plants undergoes nitrification. Specialized soil bacteria convert the NH3 and NH4+ into nitrite ions (NO2-) which are toxic to plants, and then to nitrate (NO3-) ions which are taken up by the roots of plants. Animals get their nitrogen by eating plants or plant-eating animals.

52 The Nitrogen Cycle Plants and animals return nitrogen-rich organic compounds to the environment as wastes, cast-off particles, and through their bodies when they die. In ammonification, large numbers of specialized decomposer bacteria convert organic material into simple nitrogen-containing inorganic compounds such as ammonia (NH3) and water-soluble salts containing ammonium ions (NH4+). In denitrification, nitrogen leaves the soil as specialized bacteria in waterlogged soil and in the bottom sediments of lakes, oceans, swamps, and bogs to convert NH3 and NH4+ back into nitrite and nitrate ions, then into nitrogen gas (N2) and nitrous oxide gas (N2O). These gases are released to the atmosphere to begin the nitrogen cycle again.

53 Excretion, death, decompositionGaseous nitrogen (N2) in atmosphere Food webs on land Nitrogen fixation Fertilizers Uptake by autotrophs Figure 3.29 Natural capital: simplified model of the nitrogen cycle in a terrestrial ecosystem. Nitrogen reservoirs are shown as boxes; processes changing one form of nitrogen to another are shown in unboxed print. QUESTION: What are three ways in which your lifestyle directly or indirectly affects the nitrogen cycle? (Adapted from Cecie Starr, Biology: Today and Tomorrow, Brooks/Cole © 2005) Loss by denitrification Excretion, death, decomposition Uptake by autotrophs Ammonia, ammonium in soil Nitrogen-rich wastes, remains in soil Nitrate in soil Nitrification Ammonification Loss by leaching Loss by leaching Nitrite in soil Nitrification Fig. 3-29, p. 75

54 Effects of Human Activities on the Nitrogen CycleWe add large amounts of nitric oxide (NO) into the atmosphere when N2 and O2 combine as we burn any fuel at high temperatures. This gas can be converted to nitrogen dioxide gas (NO2) and nitric acid (HNO3) which can return to the Earth’s surface as acid rain. We add nitrous oxide (N2O) to the atmosphere through the action of anaerobic bacteria on livestock wastes and commercial inorganic fertilizers applied to soil. This gas can warm the atmosphere and deplete ozone in the stratosphere.

55 Effects of Human Activities on the Nitrogen CycleNitrate ions in inorganic fertilizers can leach through the soil and contaminate groundwater. This is harmful to drink, especially for infants and small children. We release large quantities of nitrogen stored in soils and plants as gaseous compounds into the troposphere through destruction of forests, grasslands, and wetlands. We upset aquatic ecosystems by adding excess nitrates to bodies of water through agricultural runoff and discharges from municipal waste systems.

56 The Phosphorous Cycle Phosphorous is essential to living organisms because it forms a part of vital molecules such as DNA and RNA. Mostly in the form of inorganic rocks, soil minerals, and dissolved sediment in the oceans. Cycled through ecosystem by plants and animals.

57 Nutrient Limitation If ample sunlight and water are available, the primary productivity of an ecosystem may be limited by the availability of nutrients. The nutrient whose supply limits productivity is called the limiting nutrient.

58 We’ve reviewed important matter that cycles through ecosystemsWe’ve reviewed important matter that cycles through ecosystems. But, what about energy? Where does the energy in most of Earth’s ecosystems come from? How does it move through ecosystems, and how does its movement differ from that of matter? Explain why the sun is the ultimate source of an opossum’s energy.

59 Chapter 4 Ecosystems and Communities

60 Section Climate

61 Weather and Climate Weather is the day to day conditions of Earth’s atmosphere. Climate is defined by year after year patterns of temperature and precipitation. Global climate is shaped by many factors, including solar energy trapped in the biosphere, latitude, and the transport of heat by winds and ocean currents.

62 Solar Energy and the Greenhouse EffectThe main force that shapes our climate is solar energy that arrives as sunlight and strikes Earth’s surface. Some is reflected back into space and some is converted into heat. The balance between heat in the biosphere and heat lost to space is largely controlled by carbon dioxide, methane gas, and water vapor. These gases, known as greenhouse gases, allow visible light to enter and trap heat. This phenomena is called the greenhouse effect. When greenhouse gas concentrations rise, more heat is trapped and Earth warms. When they fall, Earth cools.

63 Latitude and Solar EnergyEquatorial regions are warm because solar energy is intense with the sun almost directly overhead at noon all year. Earth’s polar areas receive less solar energy and heat. This difference in heat distribution creates three different climate zones: tropical, temperate, and polar.

64 Heat Transport in the BiosphereThe unequal distribution of heat across the globe creates wind and ocean currents, which transport heat and moisture. Earth has winds because warm air is less dense and rises, and cool air is more dense and sinks.

65 3 Interconnected ForcesSolar Energy The Cycling of Matter Gravity

66 Carbon cycle Phosphorus cycle Nitrogen cycle Water cycle Oxygen cycleBiosphere Carbon cycle Phosphorus cycle Nitrogen cycle Water cycle Oxygen cycle Figure 3.7 Natural capital: life on the earth depends on the flow of energy (wavy arrows) from the sun through the biosphere and back into space, the cycling of crucial elements (solid arrows around ovals), and gravity, which keeps atmospheric gases from escaping into space and helps recycle nutrients through air, water, soil, and organisms. This simplified model depicts only a few of the many cycling elements. Heat in the environment Heat Heat Heat

67 Solar Energy The flow of high-quality energy from the sun through materials and living things in their feeding interactions, into the environment as low-quality energy, and eventually back into space as heat. Solar energy flows through the biosphere, warms the atmosphere, evaporates and recycles water, generates winds, and supports plant growth.

68 Solar Energy About one-billionth of the sun’s output of energy reaches the earth where it is absorbed and converted into heat energy by land, water, and organisms. Much of the energy is reflected away or absorbed by the chemicals, dust, and clouds in the atmosphere.

69 Solar radiation Lower Stratosphere (ozone layer) Greenhouse effectEnergy in = Energy out Reflected by atmosphere (34% ) Radiated by atmosphere as heat (66%) UV radiation Lower Stratosphere (ozone layer) Absorbed by ozone Greenhouse effect Visible Light Troposphere Heat Figure 3.8 Solar capital: flow of energy to and from the earth. Absorbed by the earth Heat radiated by the earth Fig. 3-8, p. 55

70 Section 4.2 Niches and Community Interactions

71 Tolerance Every species has its own range of tolerance, the ability to survive and reproduce under a range of environmental circumstances. A species tolerance for environmental conditions helps determine its habitat, the general place where and organism lives.

72 Niche A niche is the range of physical and biological conditions in which a species lives and the way the species obtains what it needs to survive and reproduce. The competitive exclusion principle states that no two species can share the same niche in the same habitat.

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74 Competition Competition occurs when organisms of the same or different species attempt to use an ecological resource in the same place at the same time. By causing species to divide resources, competition helps determine the number and kinds of species in a community and the niche each species occupies.

75 Predation When one organism captures and feeds on another organism.The organism that does the killing and eating is called the Predator, and the hunted is the Prey. If the predator species is too effective at hunting its prey, it will destroy its own food supply.

76 Herbivory Herbivores can affect both the size and distribution of plant populations in a community and determine the places that certain plants can survive and grow.

77 Keystone species Sometimes changes in the population of a single species, often called a keyston species, can cause dramatic changes in the structure of the entire community.

78 Symbioses Symbiosis – when two organisms live in close proximity and one or both derives a benefit from the relationship. There are 3 kinds of symbiosis: Mutualism - both species benefit Commensalism - one species benefits and the other species is neither harmed nor helped. Parasitism - a member of one species benefits and the other member is harmed.

79 Mutualism

80 Mutualism Ant – Acacia Tree

81 Commensalism Clownfish – Sea Anemone

82 Commensalism

83 Parasitism Humans - Tapeworms

84 Section Succession

85 Primary and Secondary SuccessionEcological succession is a process that occurs when ecosystems change over time, especially after disturbances, as some species die out and new species move in. Primary succession occurs in an area that has been completely destroyed leaving no remnants of an older community. The first species to colonize a barren area is called pioneer species. Secondary succession occurs in an area that has not been completely destroyed.

86 Section Biomes

87 Biomes Biomes are described in terms of abiotic factors like climate and soil type, and biotic factors like plant and animal life. Types of Biomes include tropical rain forest, tropical dry forest, tropical grassland/savanna/shrubland, desert, temperate grassland, temperate woodland and shrubland, temperate forest, northwestern coniferous forest, boreal forest, and tundra.

88 Section 4.5 Aquatic Ecosystems

89 Conditions UnderwaterPhotic zones include areas near the surface in sunlit regions where photosynthesis can occur. Aphotic zones include dark areas with no sunlight, where photosynthesis can not occur.

90 Aquatic Ecosystems Freshwater ecosystems can be divided into three main categories: rivers and streams, lakes and ponds, and freshwater wetlands. Estuaries are special wetlands, formed where a river meets the sea. Estuaries serve as spawning and nursery grounds for many ecologically and commercially important fish and shellfish species including bluefish, striped bass, shrimp, and crabs.

91 Chapter 5 Populations

92 Population Density The concentration of individuals living within a given geographical area. Calculated by dividing the number of individuals in an area by the total area. Ex. A garden that is 50 m2 is plagued by a population of roughly 2500 caterpillars. Calculate the population density of the caterpillars in number of individuals per square meter. 2500 ÷ 50 = 50 caterpillars per square meter. Explain how the size of a population in a habitat differs from the density of the population in a habitat.

93 Climax Community A stable, mature community that undergoes little or no change in species.

94 How Populations Grow

95 Three Things That Affect Population GrowthNumber of Births Number of Deaths Migration Movement of animals from one place to another

96 Types of Migration Emigration ImmigrationMovement of individuals out of an area Immigration Movement of individuals into an area occupied by an existing population

97 Exponential Growth Under ideal conditions with unlimited resources, a population will grow exponentially. Population size Time

98 Exponential Growth

99 Logistic Growth When a populations growth rate stops or slows after a period of exponential growth. Example: When a population reaches carrying capacity. Logistic Growth Curve = r N dN K + N dT K K K = carrying capacity of environment Optimal yield (= 1/2 K) Time (t)

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101 Carrying Capacity Largest number of individuals in a population that a given environment can support.

102 Comparing Exponential and Logistic Growth

103 Population Diversity When a new species enters a habitat, three main phases of development transpire: Lag phase – the new population gets a foothold in the habitat Exponential phase – the population grows dramatically as its natality exceeds its mortality, the species is very successful. Logistic growth – the population reaches its Carrying capacity – the average number of individuals the habitat can support over a long period. Population stops growing exponentially and starts leveling off. Invasive species - A new species that enters into a community and is a little too successful, reduces the biodiversity.

104 Graphing Population Line graph: x axis shows the time that passes, y axis shows the size of the population. Human population growth when graphed makes a J curve. Carrying capacity Population size Lag phase

105 Population Limits A population can grow infinitely large if allowed to breed without limit, a quality that ecologists call a population’s biotic potential. However, populations can not grow without limit because the resources upon which they depend are finite.

106 Limiting Factors Any biotic or abiotic factor that restricts the existence, numbers, reproduction, or distribution of organisms. Density-dependent limiting factors include competition, predation, herbivory, parasitism, disease, and stress from overcrowding. Density-independent limiting factors affect all populations in similar ways regardless of population size. Ex. Unusual weather such as hurricanes, droughts, floods, wildfires, etc.

107 Competition

108 Predation http://www.safaritracks.com/images/lion-zebra.jpg

109 Weather

110 Natural Disasters

112 HUMAN POPULATION

113 Historical Overview Like the populations of many other living organisms, the size of the human population tends to increase with time. In the U.S. and other developed countries, the current growth is low. In some developing countries, the human population is growing at a rate of 3 people per. Second. The human population is well on its way to reaching 9 billion in your lifetime.

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115 Exponential Human GrowthThe following factors have caused a rapid increase in population growth:

116 Agriculture

117 Industry

118 Reliable food source

119 Shipping

120 Improved sanitation

121 Medicine

122 Technology

123 Patterns of Population GrowthQ: Why can’t the human population keep growing exponentially forever? A: The resources on earth are limited

124 Demography The scientific study of human population.Birthrates, death rates, and age structure of a population help to protect why some countries have a high growth rate while others grow more slowly.

125 The Demographic TransitionA dramatic change from high birthrates and deat rates to low birthrates and death rates.

126 Average Annual Growth Rate (%)World Population: Year Average Annual Growth Rate (%) Population 1950 1.47 2,555,360,972 1960 1.33 3,039,669,330 1962 2.19 3,136,556,092 1963 3,206,072,286 1970 2.07 3,708,067,105 1980 1.69 4,454,607,332 1990 1.58 5,275,407,789 2000 1.23 6,078,684,329 2010 1.06 6,812,009,338 2020 .87 7,515,218,898 2030 .68 8,127,227,506 2040 .54 8,646,671,023 2050 .43 9,078,850,714

127 Humans in the BiosphereChapter 6 Humans in the Biosphere

128 Sustainable DevelopmentRenewable resources can be produced or replaced by a healthy ecosystem. Nonrenewable resources can not be replenished within a reasonable amount of time. Sustainable development provides for human needs while preserving the ecosystems that produce natural resources.

129 Biodiversity Variety of species in a specific area.Richest environments for biodiversity are warm and moist biomes such as tropical rain forests, coral reefs, and tropical lakes.

130 Biodiversity Loss and Species ExtinctionExtinction – disappearance of a species when the last of its members dies Endangered species – a species numbers become so low that extinction is possible Threatened species – when a population of species is likely to become endangered

131 Biodiversity Loss and Species ExtinctionHabitat loss – habitats that are destroyed due to human actions or extreme weather Ex. Cutting down the rain forest leads to loss of fertile land Ex. Coral reefs being destroyed by disease, temperature, pollution Habitat fragmentation – separation of wilderness areas from other wilderness areas Contributes to extinction, change in biodiversity, invasion of exotic species, increases risk of fire Habitat degradation – damage to a habitat by pollution; such as air, water, and land Acid precipitation – rain, sleet, snow, and fog with low pH Pesticides use such as DDT poisoning animals through the food chain

132 Biodiversity Loss and Species ExtinctionHuman activities are destroying and degrading the habitats for many wild species and driving some of them to premature extinction. Sooner or later all species become extinct because they cannot respond successfully to changing environmental conditions. Current extinction rates are 100 to 10,000 times higher than natural extinction rates because of human activities.

133 Protecting BiodiversityConservation Biology – study and implementation of methods to protect biodiversity U. S. Endangered Species Act of 1973 made it illegal to harm any species on the endangered or threatened species list.

134 Why Should We Care About Biodiversity?Biodiversity provides us with: Natural Resources (food water, wood, energy, and medicines) Natural Services (air and water purification, soil fertility, waste disposal, pest control) Aesthetic pleasure

135 Meeting Ecological ChallengesThe ecological footprint describes the total area of functioning land and water ecosystems needed both to provide the resources an individual or population uses and to absorb and make harmless the wastes that individual or population generates. According to one data set, the average American has a ecological footprint over four times larger than the global average.

136 Meeting Ecological ChallengesBy recognizing a problem in the environment, researching that problem to determine its cause, and then using scientific understanding to change our behavior, we can have a positive impact on the global environment.

137 Human Impact on Louisiana’s EcosystemsGulf of Mexico Large anoxic zone (an area without oxygen) created by nitrogen-bearing runoff from all states lining the Mississippi River. The nitrogen that human activities put into the Gulf encouraged plant matter to grow rapidly, which depleted the dissolved oxygen for other life-forms. When aquatic life in the area died out, this area, which is still growing, came to be called a dead zone. Wetlands Developers have cut nearly 13,000 km of canals through the wetlands allowing salt water from the Gulf to flow into the wetlands causing freshwater plants to die leading to erosion. Nutria An invasive species decimating plant life increasing erosion and increasing the flow of marine waters into the wetlands.