Chapter 4 Ecosystems: What Are They and How Do They Work? © Brooks/Cole Publishing Company / ITP
Key Concepts • Basic ecological principles • Major components of ecosystems • Matter cycles and energy flow • Ecosystem studies • Principles of Sustainability
4-1 THE NATURE OF ECOLOGY • Ecology- study of relationships between organisms and their environment • Ecology examines how organisms interact with their nonliving (abiotic) environment such as sunlight, temperature, moisture, and vital nutrients • Biotic interaction among organisms, populations, communities, ecosystems, and the ecosphere
The Nature of Ecology • Ecosystem organization • Organisms • Populations • Communities • Ecosystems • Biosphere Fig. 4-2 p. 57
Organisms • organism: any form of life. • organisms are classified into species. • species: groups of organisms that resemble each other, and in cases of sexually reproducing organisms, can potentially interbreed. • estimates of 5 to 100 million species, most are insects & microorganisms; so far only about 1.8 million named; each species is the result of long evolutionary history. • wild species: population that exists in its natural habitat (= native species). • domesticated or introduced species: population introduced by humans (= non–native species).
Populations • population: a group of interacting individuals of the same species. • examples: sunfish in a pond, white oak trees in a forest, people in a city; • habitat: the place where a population usually lives. • genetic diversity: in natural populations individuals vary in their genetic makeup. © Brooks/Cole Publishing Company / ITP
Communities • community: populations of all species living together in a given area. • a biological community is a complex interacting network of plants, animals and microorganisms. • example: redwood forest community, consisting of populations of redwoods & other trees, shrubs and herbaceous species, animals and microorganisms. © Brooks/Cole Publishing Company / ITP
Ecosystems & Ecosphere ecosystem: a community of different species interacting with one another & with their non–living environment of matter & energy. examples: a patch of woods, a lake or pond, a farm field, an entire watershed in a tropical rain forest. ecosphere (=biosphere): all of Earth's ecosystems together. © Brooks/Cole Publishing Company / ITP
OBJ 4. 1 What is Life? • All life shares a set of basic characteristics • Made of cells that have highly organized internal structure and functions • Characteristic types of deoxyribonucleic acid (DNA) molecules in each cell
Living Organisms • Capture and transform matter and energy from their environment to supply their needs for survival, growth, and reproduction • Maintain favorable internal conditions, despite changes in their external environment through homeostasis, if not overstressed
Living Organisms • Perpetuate themselves through reproduction • Adapt to changes in environmental conditions through the process of evolution
OBJ 4. 2 4-2 THE EARTH’S LIFE-SUPPORT SYSTEMS Earth's major components Fig. 4–7
OBJ 4. 3 What Sustains Life? Energy From Sun one–way flow of usable energy from sun, through feeding interactions, to low–quality forms (heat) Fig 4-9 © Brooks/Cole Publishing Company / ITP
Cycling of Matter * the continual flow of matter between the nonliving environment & living organisms; Gravity * enables Earth to hold its atmosphere; causes downward movement of matter in nutrient cycles.
4-3 ECOSYSTEMS COMPONENTS • biome: large regions characterized by a distinct climate & specific life–forms, especially vegetation, adapted to the region. • major biomes: • temperate grassland, temperate deciduous forest, desert, tropical rain forest, tropical deciduous forest, tropical savannah, coniferous forest, tundra • aquatic life zone: major marine or freshwater portion of the ecosphere, containing numerous ecosystems. • major aquatic life zones: • lakes, streams, estuaries, coastlines, coral reefs, & the deep ocean © Brooks/Cole Publishing Company / ITP
OBJ 4. 4 Major Components of Ecosystems • abiotic: non–living components • examples: water, air, nutrients, & solar energy • biotic: living components (=biota) • examples: plants, animals, & microorganisms © Brooks/Cole Publishing Company / ITP
Major Components of Ecosystems Major components of aquatic ecosystems. Fig. 4–11 © Brooks/Cole Publishing Company / ITP
Major Components of Ecosystems Major components of terrestrial ecosystems. Fig. 4–12 © Brooks/Cole Publishing Company / ITP
OBJ 4. 5 Range of Tolerance Variations in it’s physical and chemical environment • Differences in genetic makeup, health, and age. • Ex: trout has to live in colder water than bass
Law of Tolerance The survival, growth, & reproduction of organisms is determined, in part, by maximum & minimum tolerance limits for physical conditions such as temperature. Fig. 4–13 © Brooks/Cole Publishing Company / ITP
Limiting Factor • More important than others in regulating population growth • Ex: water light, and soil • Lacking water in the desert can limit the growth of plants
Limiting Factor Principle • too much or too little of any abiotic factor can limit growth of population, even if all the other factors are at optimum (favorable) range of tolerance. • Ex: If a farmer plants corn in phosphorus-poor soil, even if water, nitrogen are in a optimum levels, corn will stop growing, after it uses up available phosphorus.
Dissolved Oxygen Content • Amount of oxygen gas dissolved in a given volume of water at a particular temperature and pressure. • Limiting factor of aquatic ecosystem
OBJ 4. 6 COMPONENTS OF AN ECOSYSTEM: PRODUCERS Producers or autotrophs- makes their own food from compound obtained from environment. • Ex: plant gets energy or food from sun
Consumers or Heterotrophs • Obtain energy and nutrients by feeding on other organisms or their remains
Consumers • Herbivores (plant-eaters) or primary consumers • Feed directly on producers • Deer, goats, rabbits http://www.holidays.net/easter/bunny1.htm
Consumers • Carnivores (meat eater) or secondary consumers • Feed only on primary consumer • Lion, Tiger
Consumers • Tertiary (higher-level) consumer • Feed only on other carnivores • Wolf
Consumers • Omnivores- consumers that eat both plants and animals • Ex: pigs, humans, bears
Consumers • Scavengers- feed on dead organisms • Vultures, flies, crows, shark
Consumers • Detritivores- live off detritus • Detritus parts of dead organisms and wastes of living organisms. • Detritus feeders- extract nutrients from partly decomposed organic matter plant debris, and animal dung.
Consumers • Decomposers - Fungi and bacteria break down and recycle organic materials from organisms’ wastes and from dead organisms • Food sources for worms and insects • Biodegradable - can be broken down by decomposers
Fig. 4–16 © Brooks/Cole Publishing Company / ITP
OBJ 4. 7 Food Web • Complex network of interconnected food chains • Food web and chains • One-way flow of energy • Cycling of nutrients through ecosystem
Grazing Food Webs • Energy and nutrients move from plants to herbivores • Then through an array of carnivores • Eventually to decomposers (100,000 Units of Energy)
Grazing Food Webs • Energy and nutrients move from plants to herbivores • Then through an array of carnivores • Eventually to decomposers (1,000 Units of Energy)
Grazing Food Webs • Energy and nutrients move from plants to herbivores • Then through an array of carnivores • Eventually to decomposers (100 Units of Energy)
Grazing Food Webs • Energy and nutrients move from plants to herbivores • Then through an array of carnivores • Eventually to decomposers (10 Units of Energy)
Grazing Food Webs • Energy and nutrients move from plants to herbivores • Then through an array of carnivores • Eventually to decomposers (1 Units of Energy)
Detrital Food Webs • Organic waste material or detritus is the major food source • Energy flows mainly from producers (plants) to decomposers and detritivores.
OBJ 4. 8 Photosynthesis & Respiration • photosynthesis: complex chemical reaction in plants, in which solar radiation is captured by chlorophyll (& other pigments) & used to combine carbon dioxide & water to produce carbohydrates (e.g., glucose), other organic compounds, & oxygen. • carbon dioxide + water + solar energy glucose + oxygen • 6 CO2 + 6 H2O + solar energy C6H12O6 + O2 • aerobic respiration: complex process that occurs in the cells of organisms, in which organic molecules (e.g., glucose) are combined with oxygen to produce carbon dioxide, water, & energy. • glucose + oxygen carbon dioxide + water + energy • C6H12O6 + O2 6 CO2 + 6 H2O + energy • Anaerobic Respiration or Fermentation: Breakdown of glucose in absence of oxygen © Brooks/Cole Publishing Company / ITP
Producers transmit 1-5% of absorbed energy into chemical energy, which is stored in complex carbohydrates, lipids, proteins and nucleic acid in plant tissue
Chemosynthesis- • Bacteria can convert simple compounds from their environment into more complex nutrient compound without sunlight • Ex: becomes consumed by tubeworms, clams, crabs • Bacteria can survive in great amount of heat
OBJ 4. 9 • Genetic diversity • Species diversity • Ecological diversity • Functional diversity
OBJ 4. 10 Second Law of Energy • Organisms need high quality chemical energy to move, grow and reproduce, and this energy is converted into low-quality heat that flows into environment • Trophic levels or feeding levels- Producer is a first trophic level, primary consumer is second trophic level, secondary consumer is third. • Decomposers process detritus from all trophic levels.