* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Ecology13
Maximum sustainable yield wikipedia , lookup
Ecological fitting wikipedia , lookup
Biogeography wikipedia , lookup
Storage effect wikipedia , lookup
Biodiversity wikipedia , lookup
Reforestation wikipedia , lookup
Molecular ecology wikipedia , lookup
Triclocarban wikipedia , lookup
Habitat destruction wikipedia , lookup
Overexploitation wikipedia , lookup
List of ecoregions in North America (CEC) wikipedia , lookup
Sustainable agriculture wikipedia , lookup
Biodiversity action plan wikipedia , lookup
Biological Dynamics of Forest Fragments Project wikipedia , lookup
Habitat conservation wikipedia , lookup
Reconciliation ecology wikipedia , lookup
Renewable resource wikipedia , lookup
Natural environment wikipedia , lookup
Ecology The Biosphere 1 •Ecology is the scientific study of interactions between organisms & their environment, or surroundings. •An ecosystem is a collection of all the organisms that live in a particular place, together with their nonliving, or physical, environment. 2 •The biosphere contains all the portions of the planet where all life exists, including: •Land, water, air or atmosphere •The biosphere extends from about 8 kilometers above Earth's surface to as far as 11 kilometers below the surface of the ocean. 3 Interactions & Interdependence Biosphere Biome Ecosystem Community Population Individual 4 Interactions & Interdependence •A species is a group of organisms so genetically similar to one another that they can breed and produce fertile offspring. •Populations are groups of individuals that belong to the same species and live in the 5 same area. Interactions & Interdependence •Communities are groups of different populations (species) that live together in a defined area. •Ecosystem is a community together with its environment functioning as a unit. •A biome is a group of ecosystems that have the same climate and similar dominant communities. 6 Energy Flow Where does the energy for life processes come from? •Without a constant input of energy, living systems cannot function. Sunlight is the main energy source for life on Earth. 7 •Autotrophs use energy from sunlight to turn simple inorganic compounds into complex organic molecules. Only plants, some algae (cyanobacteria), and certain bacteria can capture energy from sunlight and use that energy to produce food. Because they make their own food, autotrophs are called producers. 8 •Most autotrophs use sunlight in a process known as photosynthesis. oDuring photosynthesis, these autotrophs use light energy to convert carbon dioxide and water into oxygen and energy-rich carbohydrates. oPhotosynthesis is responsible for adding oxygen to— and removing CO2 from—Earth's atmosphere. 9 Energy Flow 10 11 • Many organisms cannot harness energy directly from the physical environment. • Organisms that rely on other organisms for their energy and food supply are called heterotrophs. oHeterotrophs are also called 12 consumers. •There are different heterotrophs. Herbivores eat plants. Carnivores eat animals. Omnivores eat plants and animals. Detrivores (scavengers) feed on plant and animal remains and dead matter. Decomposers, like bacteria and fungi, break down organic matter. 13 Feeding Relationships • The relationships between producers and consumers connect organisms into feeding networks based on who eats whom. • Energy flows through an ecosystem in one direction, from the sun or inorganic compounds to autotrophs (producers) and then to various 14 heterotrophs (consumers). Feeding Relationships •Food Chains •A food chain is a series of steps in which organisms transfer energy by eating and then being eaten. Small Fish Zooplankton Squid Algae Shark 15 • Food Webs Feeding Relationships –Ecologists describe a feeding relationship in an ecosystem that forms a network of complex interactions as a food web. –A food web links all the food chains in an ecosystem together. 16 •Each step in a food chain or food web is called a trophic level. •Producers always make up the first trophic level. •Consumers make up the second, third, or higher trophic levels. •Each consumer depends on the trophic level below it for energy. 17 •An ecological pyramid is a diagram that shows the relative amounts of energy or matter contained within each trophic level in a food chain or food web. •There are three kinds: Energy pyramids Biomass pyramids Pyramids of numbers 18 •Energy Pyramid: The 10% Rule •Only part of the energy that is stored in one trophic level is passed on to the next level. •About 10% of the energy is passed on to the next (higher) trophic level 0.1% Third-level consumers 1% Second-level consumers 10% First-level consumers 100% Producers 19 • Biomass Pyramid • The total weight of living tissue within a given trophic level is called biomass. • A biomass pyramid represents the mass amount of potential food available for each trophic level in an ecosystem. Feeding Relationships 50 grams of human tissue 500 grams of chicken 5000 grams of grass 20 •Pyramid of Feeding Relationships Numbers 1 •A pyramid of 10 numbers shows 100 the relative count of individual organisms at each 1000 trophic level. *10% Rule is NOT exact. 21 The Living and the Non living: Biotic & Abiotic Factors • The biological influences on organisms within an ecosystem are called biotic factors. • Biotic factors include all the living things with which an organism might interact. 22 • Physical, or nonliving, factors that shape ecosystems are called abiotic factors. These may include: – temperature – precipitation – humidity – wind – nutrient availability – soil type 23 – sunlight Biotic & Abiotic Factors • The area where an organism lives is called its habitat. A habitat includes both biotic and abiotic factors. 24 • A niche is the full range of physical and biological conditions in which an organism lives and the way in which the organism uses those conditions. –EX: The range of temperatures needed and the place in the food web of a specific snake –The total combination of biotic and abiotic factors in an ecosystem often determines the number of different 25 niches in that ecosystem. Community Interactions • Competition occurs • When organisms of the same or different species try to use the same ecological resource (any necessity of life, such as water, nutrients, space), at the same place/time. • The competitive exclusion principle states that two species • cannot occupy the same niche or 26 habitat at the same time. Community Interactions • These warblers avoid direct competition, because each species feeds in a different part of the tree. 27 Community Interactions •An interaction in which one organism captures and feeds on another organism is called predation. •The organism that does the killing and eating is called the predator. •The food organism, often running and screaming is the prey. 28 Community Interactions •Any relationship in which two different species live very closely together is called symbiosis. •Symbiotic relationships include: –mutualism –commensalism –parasitism 29 Community Interactions •Mutualism: both species benefit from the relationship. –Nitrogen fixing bacteria: lives on roots of legumes. The bacteria make nitrogen compounds to be used by the plants. The plants give the bacteria moisture and Bees and Flowering Plants exhibit mutualism nutrients. Humans and E. coli 30 Community Interactions •Commensalism: one member of the association benefits and the other is neither helped nor harmed. –Sharks: the remora attaches to the shark and gets uneaten bits of food. The shark gets nothing but is unharmed.** Nurse shark Shark Remora andReef Sea Turtle 31 Community Interactions •Parasitism: one organism lives on or inside another organism and harms it. –Athlete’s foot: the parasites feed on the host. –Schistosoma Worms –Mosquitoes are parasites! 32 Community Interactions Symbiosis Organism Organism 1 2 Mutualism + gains Commensalism + gains Parasitism + gains + : gain - : loss 0 : no effect + gains 0 no effect - loses 33 Succession • Sometimes, – Ecosystems change; an ecosystem older inhabitants changes in response graduallyto dieanout abrupt and new organisms disturbance. (asteroid move in,impact!) this in the community. – causes At otherchanges times, change occurs as a • more Thesegradual series ofresponse changes to in natural a community over fluctuations in thetime environment. is called ecological (Earth’s rotation/length succession. of day) 34 34 • On land, succession that occurs on surfaces where no soil exists is called primary succession. For example, primary succession occurs on rock surfaces formed after volcanoes erupt. • The first species to populate the area are called pioneer species. 35 Primary Succession Stages 1.A volcano destroys the land leaving only rock 2.Lichens appear. 3.Mosses and grasses appear. 4.Tree seedlings and shrubs move in. 36 • The ecosystem can be changed by natural events, such as fires. • After the disturbance, community interactions can restore the ecosystem to its original condition through secondary succession. • Healthy ecosystems usually recover o Once the populations arebut fairly from natural disturbances, may forfrom a long timehuman we call it notstable recover larger 37 a climax community Biomes • A biome is a complex of terrestrial communities that covers a large area • Characterized by certain soil and climate conditions and specific plants and animals. –Variations in plants and animals help different species survive under different conditions in different 38 biomes. Biomes –Plants and animals exhibit variations in tolerance, or the ability to survive and reproduce under conditions that differ from their optimal conditions. 39 Biomes and Climate •The climate of a region is an important factor in determining which organisms can survive there. •Within a biome, temperature and precipitation can vary over small distances. eg a valley on a mountain. •The climate in a small area that differs from the climate around it is called a 40 microclimate. Average Precipitation (mm) Biomes Average Temperature (°C) • Two components of climate, temperature and precipitation, can be summarized in a graph called a climate diagram. 41 • The world's major biomes include: – tropical rain forest – tropical dry forest – tropical savanna – desert – temperate grassland – temperate woodland and shrubland – temperate forest – northwestern coniferous forest – boreal forest – tundra 42 60°N 30°N 0° Equator 30°S 60°S 43 Ten Major Biomes Biome Tropical Rain Forest Tropical Dry Forest Tropical Savanna Desert Temperate Grassland Temperate woodland and Shrubland Temperate Forest Northwestern Coniferous Forest Boreal Forest Tundra Precipitation Temperature high hot Soil poor Diversity high Trees dense Grasses sparse variable rich moderate medium medium mild Which one is ours? Circle it! variable mild clay moderate sparse dense low moderate variable summer hot poor rich moderate moderate sparse absent sparse dense summer low, summer hot winter moderate moderate summer moderate, winter cold high summer mild, winter cold poor low medium medium rich high dense sparse rocky, acidic low dense sparse moderate poor, acidic moderate dense sparse poor absent medium low summer mild, winter cool summer mild, winter cold low 44 Biomes 45 Biomes Tropical Rain Forests • Tropical rain forests are home to more species than all other biomes combined. • Abiotic factors: hot and wet yearround; thin, nutrient-poor soils • Plants: broad-leaved evergreen trees; ferns; large woody vines and 46 climbing plants. Tropical Rain Forest • Wildlife: sloths, capybaras, jaguars, anteaters, monkeys, toucans, parrots, butterflies, beetles, piranhas, caymans, boa constrictors, and anacondas. • Location: parts of South and Central America, Southeast Asia, parts of Africa, southern India, and 47 Tropical Dry Forest • During the dry season, most trees drop their leaves to conserve water. • Abiotic factors: generally warm year-round; alternating wet and dry seasons; rich soils subject to erosion • Plants: tall, deciduous trees; drought-tolerant plants; aloes and other succulents 48 Tropical Dry Forest • Wildlife: tigers, monkeys, elephants, Indian rhinoceroses, hog deer, great pied hornbills, pied harriers, spotbilled pelicans, termites, snakes and monitor lizards • Location: parts of Africa, South and Central America, Mexico, India, Australia, and tropical islands 49 Tropical Savanna • Compact soils, frequent fires, and the action of large animals prevent them from becoming dry forest. • Abiotic factors: warm temps; seasonal rains; compact soil; frequent fires set by lightning • Plants: tall, perennial grasses; droughttolerant/fire-resistant trees or shrubs50 Tropical Savanna • Wildlife: lions, leopards, cheetahs, hyenas, jackals, aardvarks, elephants, giraffes, antelopes, zebras, baboons, eagles, ostriches, weaver birds, and storks • Location: large parts of eastern Africa, southern Brazil, and northern Australia. 51 Desert • All deserts are dry, defined as having annual precipitation of less than 25 centimeters. • Abiotic factors: low precipitation; variable temperatures; soils rich in minerals but poor in organic material • Plants: cacti and other succulents; plants with short growth cycles 52 Desert Wildlife: mountain lions, gray foxes, bobcats, mule deer, pronghorn antelopes, desert bighorn sheep, kangaroo rats, bats, owls, hawks, roadrunners, ants, beetles, butterflies, flies, wasps, tortoises, rattlesnakes, and lizards Location: Africa, Asia, the Middle East, 53 U.S., Mexico, S. America, and Australia Temperate Grassland Periodic fires and heavy grazing by large herbivores maintain the unique plant community. Abiotic factors: warm-hot summers; cold winters; moderate, seasonal precip.; fertile soils; occasional fires Plants: lush, perennial grasses and herbs; most are resistant to drought, 54 fire, and cold Temperate Grassland Wildlife: coyotes, badgers, pronghorn antelopes, rabbits, prairie dogs, introduced cattle, hawks, owls, bobwhites, prairie chickens, mountain plovers, snakes, ants and grasshoppers Location: central Asia, North America, Australia, central Europe, and upland plateaus of South America 55 Temperate Woodland and Shrubland • This biome is characterized by a semiarid climate and mix of shrub communities and open woodlands. • Abiotic factors: hot, dry summers; cool, moist winters; thin, nutrientpoor soils; periodic fires • Plants: woody evergreen shrubs; herbs that grow during winter and 56 die in summer Temperate Woodland and Shrubland • Wildlife: coyotes, foxes, bobcats, mountain lions, black-tailed deer, rabbits, squirrels, hawks, California quails, warblers, lizards, snakes, and butterflies • Location: western coasts of North and South America, areas around the Mediterranean Sea, South Africa, and 57 Australia Temperate Forest These forests have cold winters that halt plant growth for several months. Abiotic factors: cold to moderate winters; warm summers; year-round precipitation; fertile soils Plants: broadleaf deciduous trees; some conifers; flowering shrubs; herbs; a ground layer of moss & ferns58 Temperate Forest • Wildlife: deer, black bears, bobcats, squirrels, raccoons, skunks, songbirds, turkeys. • Location: eastern United States, southeastern Canada, most of Europe, parts of Japan, China, and Australia. This is your biome! 59 Northwestern Coniferous Forest • Moist air from the Pacific Ocean provides abundant rainfall • Abiotic factors: mild temperatures; abundant precipitation during fall, winter and spring; cool dry summer; rocky, acidic soil. • Plants: Douglas fir, Sitka spruce, western hemlock, redwood. 60 Northwestern Coniferous Forest • Wildlife: bears, elk, deer, beavers, owls, bobcats, and members of the weasel family • Location: Pacific coast of northwestern United States and Canada, from northern California to Alaska. 61 Boreal Forest (Taiga) These forests are called boreal forests, or taiga. Winters are bitterly cold. Abiotic factors: long, cold winters; short, mild summers; moderate precipitation; high humidity; acidic, nutrient-poor soils Plants: needleleaf conifers & broadleaf deciduous trees; small, berry shrubs 62 Boreal Forest (Taiga) • Wildlife: lynxes, timber wolves, members of the weasel family, small herbivorous mammals, moose, beavers, songbirds, and migratory birds • Location: North America, Asia, and northern Europe 63 Tundra • Characterized by permafrost, a layer of permanently frozen subsoil. • Abiotic factors: strong winds; low precip.; short, soggy summers; long, cold, dark winters; poorly developed soils; permafrost • Plants: ground plants such as mosses, lichens, sedges, & short grasses 64 Tundra • Wildlife: birds, mammals that can withstand the harsh conditions, migratory waterfowl, shore birds, musk ox, Arctic foxes, caribou, lemmings and other small rodents • Location: northern North America, Asia, and Europe 65 Other Areas • Mountain ranges and polar icecaps do not fit into any major biomes. • Nearly 75% of the Earth’s surface is covered with water. • Aquatic ecosystems are determined primarily by depth, flow, temperature, and chemistry of the overlying water. NOT ANIMALS 66 Freshwater • Flowing-water ecosystems • Rivers, streams, and brooks are freshwater that flows over land. • Downstream, water may meander slowly, turtles, beavers & otters live. • Standing-water ecosystems • Lakes and ponds are standing-water ecosystems. 67 A Wetland is an ecosystem in which water covers the soil or is present at or near the surface of the soil at least part time. • The water in wetlands may flow or be standing; fresh, salty, or brackish. • The three main types of freshwater wetlands are bogs, marshes, and swamps. 68 Marine Ecosystems •The well-lit upper layer of the ocean is known as the photic zone. (for light) •Algae and other producers can grow only in this thin surface layer. •Below the photic zone is the aphotic zone, which is permanently dark. •Chemosynthetic autotrophs are the only producers that can survive here69 Marine Ecosystems • In addition to the division between photic and aphotic zones, marine biologists divide the ocean into zones based on the depth and distance from shore: – the intertidal zone – the coastal ocean – the open ocean 70 Land 200 m 1,000 m Coastal ocean Open ocean 4,000 m 6,000 m Continental shelf Continental slope and continental rise Ocean trench Abyssal plain Photic zone Apho tic zone 10,000 m 71 Intertidal Zone • Organisms that live in the intertidal zone are exposed to regular and extreme changes in surroundings. • Competition among organisms in the rocky intertidal zone often leads to zonation: an arrangement of organisms in a particular habitat in horizontal bands. 72 Coastal Ocean • The coastal ocean extends from the low-tide mark to the outer edge of the continental shelf. • It falls within the photic zone, and photosynthesis occurs throughout its depth. • The coastal ocean is often rich in plankton and many other organisms. 73 Coral Reefs • Coral reefs, found in tropical coastal waters, are named for the coral animals whose skeletons of calcium carbonate A.K.A. • limestone make up their primary structure. • An extraordinary biodiversity of organisms exists among coral reefs. 74 Open Ocean • The open ocean, the oceanic zone, Who are ARGUABLY THE most important organism on Earth since they produce most of extends from the edge of the Earth’s oxygen!! continental shelf outward. • It is the largest marine zone. • Most of the photosynthetic activity on Earth occurs in the photic zone of the open ocean by the smallest producers, mainly algae 75 Benthic Zone • The ocean floor contains organisms that live attached to or near the bottom. • These organisms are called benthos. The ocean floor is called the benthic zone. 76 Benthic Zone • Benthic ecosystems often depend on food from organisms that grow in the photic zone. • Chemosynthetic primary producers support life without light near deepsea vents using chemicals to create energy not sunlight! 77 Video Review Biomes 78 Ecology Populations 79 Populations • 3 important characteristics of a population are its: –geographic distribution: or where –Population density or How many –growth rate: how fast it increases or decreases. 80 • 3 factors can affect population size: –the number of births –the number of deaths –the #of individuals that enter (immigrate) –or leave (emigrate) the population • A population grows when: • birthrate is greater than death rate. 81 • Under ideal conditions with unlimited resources, a population will grow exponentially. • Exponential growth occurs when the individuals in a population reproduce at a constant rate. • The population becomes larger and larger until it approaches an infinitely large size. 82 Populations Exponential Growth 83 Logistic Growth • In nature, exponential growth can not continue in a population for very long. • As resources run out, the growth slows or stops. • Logistic growth occurs when a population's growth slows or stops following a period of exponential growth. 84 • Called an S curve Populations 85 Carrying Capacity • The largest number of individuals of a population that a given environment can support is called its carrying capacity. • When a population reaches the carrying capacity of its environment, its growth levels off. The average growth rate is zero. 86 Limiting Factors • A limiting factor is one that when it is reduced it results in end of most growth in the ecosystem. • EX A limiting nutrient/food • In the context of populations, a limiting factor is a factor that causes population growth to decrease and stop 87 • A limiting factor that depends on population size is called a density-dependent limiting factor. • Density-dependent limiting factors include: Competition (for food, space, mates…) Predation Parasitism Disease • These factors occur more when a population is large and dense. •Small, scattered populations are not affected as much. 88 Populations Population Growth can be Logistic Exponential growth characterized by No limits on growth Unlimited resources growth represented by Constant growth rate characterized by Limits on growth J-shaped curve represented by S-shaped curve which cause a Falling growth rate Fill in the Missing Circles! 89 Competition •• Competition will also occur between When populations become members of different species. crowded, organisms compete for o This lead toand food,competition water space,can sunlight evolutionary change. other essentials. o time, theamong species may evolve • Over Competition members of the to occupy different niches. (see same species is a densitywarblers, finches, etc.) dependent limitingmammals, factor (depends on population density) are stable o But once the populations it’s reached its climax community 90 Populations Predation • Populations in nature are often controlled by predation. • The regulation of a population by predation takes place within a predator-prey relationship, one of the best-known mechanisms of population control. 91 Populations Wolf and Moose Populations on Isle Royale Moose Wolves 92 Populations Parasitism and Disease • Parasites can limit the growth of a population. • A parasite lives in or on another organism (the host) and consequently harms it. Eyelash mite aka Demodex folliculorum *generally commensal and NOT a true parasite, but scary to think about! 93 • Density-independent limiting factors affect all populations in similar ways, regardless of the population size. • Examples of density-independent limiting factors include: unusual weather natural disasters seasonal cycles human activities—such as damming rivers and clear-cutting forests Kaibab Deer 94 Human Population DO NOW: • If the human population continues to grow at a rate of 1.4 percent per year, the population would double in size (to 12 billion people) in only 51 years! What effect might this increase in population have on the environment and on other people? 95 The size of the human population tends to increase with time. For most of human existence, the population grew slowly. Limiting factors kept population sizes low. (disease, scarce food sources) About 500 years ago, the human population began growing rapidly. Life was made easier and safer by advances in agriculture and industry. Death rates were reduced due to improved sanitation, medicine, and healthcare, while birthrates increased. 96 Human Population Our advances allowed for exponential Human Population Growth growth. 97 Human Population • Yet, over the past century, population growth in the USA, Japan, and much of Europe has slowed dramatically. • This dramatic change in birth and death rates is called a demographic transition. 98 The demographic transition has 4 main stages – In stage 1, there are high death rates and high birthrates called Pre-industrial – In stage 2, the death rate drops, while the birthrate remains high. The population increases rapidly. Called Developing or Urbanizing – In stage 3, the birthrate begins to decrease, causing population growth to slow but still above the death rate. Called Mature Industrial – In stage 4 birthrate drops drastically and *matches the now stable low death rate. Called Post Industrial. 99 The demographic transition is complete when the birthrate falls to meet the death rate, and population growth stops. Human Population 100 • Population growth depends, in part, on how many people of different ages make up a given population. • Demographers can predict future growth using models called agestructure diagrams. • Age-structure diagrams show the population of a country broken down by gender and age group. 101 Human Population U.S. Population In the USA, there are 80+ almost equal numbers of people 60–64 Population predictors assume that those in each age who group. reach child bearing age will have children. While on average 40–44 this is This age structure generally true, it is NOT always true. diagram predicts a 20–24 slow but steady growth rate for the 0–4 8 6 4 2 0 2 near future. Females Age (years) Males 4 6 8 102 Percentage of Population In Rwanda, there are many more young Rwandan Population children than 80+ teenagers, and 60–64 many more teenagers than adults. 40–44 This age structure diagram predicts a 20–24 population that will double in about 30 0–4 Percentage of Population 103 years. Age (years) Males Females 104 Human Population • Ecologists suggest that if growth does not slow down, there could be serious damage to the environment and global economy. • Economists assert that science, technology, and changes in society may control the negative impact of population growth. Human Population Graph 105 Human Impact & Sustainability DO NOW: • What positive effect have humans had on their environment? • What negative effect have humans had on their environment? 106 Ecologists refer to necessities that humans get from the ecosystem as “ecosystem goods and services” because they are needed have value to individuals and societies. To obtain these resources human activities have drastically affected the biosphere: Hunting & gathering resources Agriculture & industry Urban development 107 Human Impact Challenges for the Future • While increasing world food supplies, modern agriculture has created ecological problems. For example: –Monoculture or one crop use (corn) leads to problems with insect pests and diseases only curable by chemicals –water for irrigation is becoming more scarce. 108 Industrial Growth and Urban Impact • The Industrial Revolution added machines and factories. • The energy comes mostly from fossil fuels: coal, oil, and natural gas. • Industrial waste pollutes air, water, and soil. • Dense human communities also produce waste. • Suburban growth consumes farmland and kills native plants and animals. 109 Fill in the blanks! Human Activities that have changed the biosphere include Hunting and gathering may have once caused Industrial growth Agriculture Urban development often relies on the methods of the have resulted in Modern agriculture Extinctions of large animals High standard of living Increased pollution which increased Food supply Pesticide use Monocultured crop use 110 • Human Impact on resources: 2 categories • Renewable resources can regenerate, or can be replenished by biogeochemical cycles in a reasonable amount of time • Examples: wood, carbon, nitrogen. • A nonrenewable resource is one that cannot be replenished by natural processes in a reasonable time. • Examples: coal, oil, gold, iron 111 Human Impact on Resources: Sustainable development is a way of using natural resources without depleting them, and without causing long-term environmental harm. Land provides space for human communities and raw materials for industry. Land also includes the soils in which crops are grown. If managed soil’s a renewable resource 112 Soil erosion is the wearing away of surface soil by water and wind. –Plowing the land removes the roots that hold the soil in place, which increases the rate of soil erosion. • Desertification is the process by which productive areas are turned into deserts. Desertification is caused by a combination of farming, overgrazing, and drought. 113 • A variety of sustainable-development practices can prevent problems such as soil erosion and desertification. • contour plowing: fields are plowed across the slope of the land to reduce erosion • leaving stems and roots after harvest in place to help hold the soil • planting a field with rye rather than leaving it unprotected from erosion114 Earth’s forests are an important resource because they provide wood for products and fuel: remove carbon dioxide and produce oxygen. Forests store nutrients. provide habitats and food for organisms. moderate climate, limit soil erosion. protect water from pollution. 115 Deforestation • Loss of forests, or deforestation, has several effects: –Erosion can wash away nutrients in the topsoil. –Grazing or plowing can permanently destroy soils and microclimates, which kills more vegetation. 116 Sustainable Forest Management • Mature trees can be harvested selectively to promote the growth of younger trees and preserve the forest ecosystem. • replanting • Tree geneticists are breeding new, faster-growing trees that produce high-quality wood. 117 Fish as Resources • Overfishing, or harvesting fish faster than they can be replaced by reproduction, has greatly reduced the amount of fish in parts of the world’s oceans. • Until recently, fisheries seemed to be a renewable resource, but overfishing has changed all that!! Without change by 2048 most oceans are predicted to be unfishable 118 Sustainable Development • The U.S. National Marine Fisheries Service has issued guidelines that specify how many fish, and of what size, can be caught in various parts of the oceans. • They have helped some fish populations recover. • Aquaculture or fish farming: The raising of aquatic animals for human consumption, which is called aquaculture, is also helping to sustain fish resources. 119 Protected Fish Stock 120 Biodiversity Watch the video. Why are other organisms important? 121 Biodiversity Insects 54.4% Protists 4.2% Other Animals 19.7% Plants 18% Fungi Bacteria 0.3% 3.4% Species Biodiversity 122 • Biodiversity, is all of the variety, of all organisms in the biosphere. • Ecosystem diversity includes the variety of habitats, communities, and ecological processes on Earth • Species diversity is the number of different species in the biosphere. • Genetic diversity is the total of all the different forms of genetic information carried by all organisms on Earth. 123 Biodiversity • Biodiversity is one of Earth's greatest natural resources. • Species of many kinds have provided us with foods, industrial products, and medicines— including painkillers, antibiotics, heart drugs, antidepressants, and anticancer drugs. 124 Threats to Biodiversity • Human activity can reduce biodiversity by: –altering habitats –hunting species to extinction –introducing toxic compounds into food webs –introducing invasive species to new environments 125 Biodiversity • Extinction occurs when a species disappears from all or part of its range. • A species whose population size is declining in a way that places it in danger of extinction is called an endangered species. • As the population of an endangered species declines, the species loses genetic diversity. 126 Habitat Alteration • When land is developed, natural habitats may be destroyed. • Development often splits ecosystems into pieces, a process called habitat fragmentation. • The smaller a species’ habitat is, the more vulnerable the species is to further disturbance. 127 Demand for Wildlife Products • Throughout history, humans have pushed animal species to extinction by hunting them for food or products. • Today, in the U.S., endangered species are protected from hunting. • The Convention on International Trade in Endangered Species,bans international trade in products derived from endangered species. 128 Pollution • Many forms of pollution threaten biodiversity. • One of the most serious problems occurs when toxic compounds accumulate in the tissues of organisms. • DDT, one of the first pesticides, is a good example of this. 129 For a long time DDT was considered harmless, and it drained into rivers and streams in low concentrations. DDT has two hazardous properties: –It is nonbiodegradable, which means that it cannot be broken down by organisms. –Once DDT is picked up by organisms, it cannot be eliminated from their bodies. 130 • When DDT enters food webs, it undergoes biological magnification. • In biological magnification, concentrations of a harmful substance increase in organisms at higher trophic levels in a food chain or food web. • In 1962, biologist Rachel Carson wrote Silent Spring, which alerted people to the dangers of biological 131 magnification. Fish-Eating Birds Magnification of DDT Concentration 10,000,000 Large Fish Small Fish 1,000,000 100,000 Biomagnification Zooplankton 10,000 Producers Water 1000 1 132 • The widespread use of DDT threatened populations of many animals—especially fish-eating birds like the bald eagle—with extinction. • By the early 1970s, DDT was banned in the U.S. and in most other industrialized countries; as a result, affected bird populations have recovered. 133 Another threat to biodiversity comes from plants and animals that humans transport around the world (on purpose or not). Invasive species are introduced species that reproduce rapidly because their new habitat has no predators to control their population. Ex. zebra mussels in the Great Lakes Hundreds of invasive species are causing ecological problems in the United States. 134 Biodiversity Conserving Biodiversity • Conservation is the wise management of natural resources, including the preservation of habitats and wildlife. 135 Strategies for Conservation • Many conservation efforts are aimed at managing individual species to keep them from becoming extinct. • Conservation efforts focus on protecting entire ecosystems as well as single species. • Protecting an ecosystem ensures that the natural habitats of many different species are preserved. 136 Conservation Challenges • Protecting resources for the future can require people to change the way they live and earn their living today. • Conservation regulations must be informed by solid research and must try to maximize benefits while minimizing economic costs. 137 Our Future • Human alteration of the atmosphere & Earth means Invasive Species may be able to live in places where they once could not. • Other organisms may become threatened or extinct in areas where they once thrived. 138 Our Future • DO NOW: Write down how much you would be willing to pay for: 1. Fresh, clean drinking water 2. Clean air to breathe 3. An endangered plant containing a substance that can cure cancer 4. Gas for your family car 139 Our Possible Future 140 Our Future 141 Our Future • One sign of global warming is melting polar ice. 142