Ecosystems What Are They and How Do They

Ecosystems: What Are They and How Do They Work? Chapter 3 Dr. Wesam Al Madhoun

Core Case Study: Tropical Rain Forests Are Disappearing § Cover about 2% of the earth’s land surface § Contain about 50% of the world’s known plant and animal species § Disruption will have three major harmful effects • Reduce biodiversity • Accelerate global warming • Change regional weather patterns

Natural Capital Degradation: Satellite Image of the Loss of Tropical Rain Forest

3 -1 What Is Ecology? § Concept 3 -1 Ecology is the study of how organisms interact with one another and with their physical environment of matter and energy.

Cells Are the Basic Units of Life § Cell Theory: all living things composed of cells. § Eukaryotic cell: surrounded by membrane and has a distinct nucleus (a membrane bounded structure contain DNA) § Prokaryotic cell: surrounded by membrane but no distinct nucleus.

Structure of a Eukaryotic Call and a Prokaryotic Cell

Species Make Up the Encyclopedia of Life § Species: a set of individuals that can mate and introduce fertile offspring. § 1. 75 Million species identified § Insects make up most of the known species § Perhaps 10– 14 million species not yet identified

Ecologists Study Connections in Nature § Ecology : study of how organism interact with their living environment of other organism and with their non living (a biotic) environment of soil, water and energy. § Levels of organization • Population: a group of individual of the same species living in the same place, same time. • Genetic diversity: genetic variation in a population. • Community: all the population of different species that live in a particular place. • Ecosystem: a community of different species interacting with each other and with nonliving environment. • Biosphere: consist of the parts of the earths, air water and soil where life is found.

Biosphere Parts of the earth's air, water, and soil where life is found Ecosystem A community of different species interacting with one another and with their nonliving environment of matter and energy Community Populations of different species living in a particular place, and potentially interacting with each other Population A group of individuals of the same species living in a particular place Organism Cell Molecule Atom An individual living being The fundamental structural and functional unit of life Chemical combination of two or more atoms of the same or different elements Smallest unit of a chemical element that exhibits chemical properties Stepped Art Fig. 3 -3, p. 52

Population of Glassfish in the Red Sea

Genetic Diversity in a Caribbean Snail Population

Science Focus: Have You Thanked the Insects Today? § Pollinators § Eat other insects § Loosen and renew soil § Reproduce rapidly § Very resistant to extinction

Importance of Insects

3 -2 What Keeps Us and Other Organisms Alive? § Concept 3 -2 Life is sustained by the flow of energy from the sun through the biosphere, the cycling of nutrients within the biosphere, and gravity.

The Earth’s Life-Support System Has Four Major Components § Atmosphere • Troposphere: 17 km above sea level at tropic, and 7 km at north and south poles “contain majority of the air that we breath”. • Stratosphere: 17 -50 km above earth surface. § Hydrosphere: consist of all the water on and near the earth surface. § Geosphere: consist of the earth’s intensely hot core, a thick mantle of rock, thin outer crust. § Biosphere: occupies atmosphere, hydrosphere and geosphere where life exist.

Vegetation and animals Atmosphere Biosphere Soil Rock Crust Lithosphere Mantle Biosphere (living organisms) Atmosphere (air) Core Mantle Geosphere (crust, mantle, core) Crust (soil and rock) Hydrosphere (water) Fig. 3 -6, p. 55

Life Exists on Land in Water § Biomes : large regions (forest, desert, grasslands) with distinct climate and certain species. § Aquatic life zones • Freshwater life zones • Lakes and streams • Marine life zones • Coral reefs • Estuaries • Deep ocean

Major Biomes along the 39 th Parallel Average annual precipitation 100– 125 cm (40– 50 in. ) 75– 100 cm (30– 40 in. ) 50– 75 cm (20– 30 in. ) 25– 50 cm (10– 20 in. ) below 25 cm (0– 10 in. ) Denver Baltimore San Francisco St. Louis Coastal mountain ranges Sierra Nevada Great American Desert Coastal chaparral Coniferous forest and scrub Rocky Mountains Desert Great Plains Coniferous forest Mississippi River Valley Prairie grassland Appalachian Mountains Deciduous forest Fig. 3 -7, p. 55

What Happens to Solar Energy Reaching the Earth? § UV, visible, and IR energy § Radiation • • Absorbed by ozone Absorbed by the earth Reflected by the earth Radiated by the atmosphere as heat § Natural greenhouse effect

Solar radiation Reflected by atmosphere UV radiation Most absorbed by ozone Radiated by atmosphere as heat Lower Stratosphere (ozone layer) Visible light Troposphere Heat Absorbed by the earth Heat radiated by the earth Greenhouse effect Fig. 3 -8, p. 56

3 -3 What Are the Major Components of an Ecosystem? § Concept 3 -3 A Ecosystems contain living (biotic) and nonliving (abiotic) components. § Concept 3 -3 B Autotrophs (self feeding, Heterotrophs (other feeders), Detritovores (feed on waste or dead bodies).

Ecosystems Have Living and Nonliving Components § Abiotic • • • Water Air Nutrients Rocks Heat Solar energy § Biotic • Living and once living

Major Biotic and Abiotic Components of an Ecosystem

Oxygen (O 2) Precipitation Carbon dioxide (CO 2) Producer Secondary consumer (fox) Primary consumer (rabbit) Producers Water Decomposers Soluble mineral nutrients Fig. 3 -9, p. 57

Several Abiotic Factors Can Limit Population Growth § Limiting factor principle • Too much or too little of any a biotic factor can limit or prevent growth of a population, even if all other factors are at or near the optimal range of tolerance.

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

Producers and Consumers Are the Living Components of Ecosystems (1) § Producers, autotrophs • Photosynthesis: the way, energy enter most ecosystem • Chemosynthesis: producers (bacteria) convert inorganic compound to more complex nutrient without sun light. § Consumers, heterotrophs • Primary (plant eaters such as rabbits) • Secondary (meat eater, birds , frogs) • Third and higher level (tigers , wolves)

Producers and Consumers Are the Living Components of Ecosystems (2) § Detritivores : feed on waste and dead bodies such as some insects and earth worms. § Aerobic respiration: use of oxygen to convert glucose (C 6 H 12 O 6) back into carbon dioxide and water § Anaerobic respiration, fermentation: some decomposers get the energy they need by breaking down glucose in the absence of oxygen.

Science Focus: Many of the World’s Most Important Species Are Invisible to Us § Microorganisms • Bacteria • Protozoa • Fungi

3 -4 What Happens to Energy in an Ecosystem? § Concept 3 -4 A Energy flows through ecosystems in food chains and webs. § Concept 3 -4 B As energy flows through ecosystems in food chains and webs, the amount of chemical energy available to organisms at each succeeding feeding level decreases.

Energy Flows Through Ecosystems in Food Chains and Food Webs § Food chain: a sequence of organism, each of which serves as a source of food or energy for the next. § Food web: a complex network of interconnected food chains.

First Trophic Level Second Trophic Level Producers (plants) Heat Primary consumers (herbivores) Heat Third Trophic Level Fourth Trophic Level Secondary consumers (carnivores) Tertiary consumers (top carnivores) Heat Solar energy Heat Decomposers and detritus feeders Fig. 3 -13, p. 62

Usable Energy Decreases with Each Link in a Food Chain or Web § Biomass: the dry weight of all organic matter contained in its organisms. § Ecological efficiency: the % of useable chemical energy transferred as biomass from one trophic level to the next § Pyramid of energy flow: cumulative energy loss.

Usable energy available at each trophic level (in kilocalories) Tertiary consumers (human) 10 Secondary consumers (perch) 100 Primary consumers (zooplankton) Heat Decomposers Heat 1, 000 Heat 10, 000 Producers (phytoplankton) Fig. 3 -15, p. 63

Some Ecosystems Produce Plant Matter Faster Than Others Do § Gross primary productivity (GPP): is the rate at which ecosystem producers (plants) convert solar energy into chemical energy as biomass found in their tissues. § Net primary productivity (NPP): NPP = GPP – R. where R is energy used in respiration. • Ecosystems and life zones differ in their NPP

Terrestrial Ecosystems Swamps and marshes Tropical rain forest Temperate forest Northern coniferous forest Savanna Agricultural land Woodland shrubland Temperate grassland Tundra (arctic and alpine) Desert scrub Extreme desert Aquatic Ecosystems Estuaries Lakes and streams Continental shelf Open ocean 800 1, 600 2, 400 3, 200 4, 000 4, 800 5, 600 6, 400 7, 200 8, 000 8, 800 9, 600 Average net primary productivity (kcal/m 2/yr) Fig. 3 -16, p. 64

3 -5 What Happens to Matter in an Ecosystem? § Concept 3 -5 Matter, in the form of nutrients, cycles within and among ecosystems and the biosphere, and human activities are altering these chemical cycles.

Nutrients Cycle in the Biosphere § Biogeochemical cycles, nutrient cycles • • • Hydrologic Carbon Nitrogen Phosphorus Sulfur § Connect past, present , and future forms of life

Condensation Global warming Precipitation to land Ice and snow Transpiration from plants Condensation Evaporation from land Surface runoff Runoff Lakes and reservoirs Infiltration and percolation into aquifer Groundwater movement (slow) Processes Evaporation from ocean Reduced recharge of aquifers and flooding from covering land with crops and buildings Precipitation to ocean Point source pollution Surface runoff Aquifer depletion from overpumping Increased flooding from wetland destruction Ocean Processes affected by humans Reservoir Pathway affected by humans Natural pathway Fig. 3 -17, p. 66

Science Focus: Water’s Unique Properties § Properties of water due to hydrogen bonds between water molecules: • Exists as a liquid over a large range of temperature • Changes temperature slowly • High boiling point: 100˚C • Expands as it freezes • Filters out harmful UV

Carbon Cycle Depends on Photosynthesis and Respiration § Link between photosynthesis in producers and respiration in producers, consumers, and decomposers § Additional CO 2 added to the atmosphere • Tree clearing • Burning of fossil fuels

Carbon dioxide in atmosphere Respiration Photosynthesis Forest fires Animals (consumers) Diffusion Burning fossil fuels Deforestation Transportation Respiration Carbon dioxide dissolved in ocean Marine food webs Producers, consumers, decomposers Carbon in limestone or dolomite sediments Plants (producers) Carbon in plants (producers) Carbon in animals (consumers) Decomposition Carbon in fossil fuels Compaction Processes Reservoir Pathway affected by humans Natural pathway Fig. 3 -18, p. 68

Nitrogen Cycles through the Biosphere: Bacteria in Action (1) § Nitrogen fixed – N 2 converted to nutrient by: • Lightning : electrical discharge in the atmosphere. • Nitrogen-fixing bacteria: in soil or plan roots. § Nitrification : is the biological oxidation of ammonia with oxygen into nitrite followed by the oxidation of these nitrites into nitrates § Denitrification: is a microbially facilitated process of nitrate reduction that may ultimately produce molecular nitrogen (N 2) through a series of intermediate gaseous nitrogen oxide products.

Nitrogen Cycles through the Biosphere: Bacteria in Action (2) § Human intervention in the nitrogen cycle • • Additional NO and N 2 O Destruction of forest, grasslands, and wetlands Add excess nitrates to bodies of water Remove nitrogen from topsoil

Processes Nitrogen in atmosphere Reservoir Pathway affected by humans Natural pathway Nitrogen oxides from burning fuel and using inorganic fertilizers Nitrates from fertilizer runoff and decomposition Denitrification by bacteria Electrical storms Volcanic activity Nitrogen in animals (consumers) Nitrification by bacteria Nitrogen in plants (producers) Decomposition Uptake by plants Nitrate in soil Nitrogen loss to deep ocean sediments Nitrogen in ocean sediments Bacteria Ammonia in soil Fig. 3 -19, p. 69

300 Projected human input Nitrogen input (teragrams per year) 250 200 Total human input 150 Fertilizer and industrial use 100 50 Nitrogen fixation in agroecosystems Fossil fuels 0 1900 1920 1940 1960 1980 2000 Year 2050 Fig. 3 -20, p. 70

3 -6 How Do Scientists Study Ecosystems? § Concept 3 -6 Scientists use field research, laboratory research, and mathematical and other models to learn about ecosystems.

Some Scientists Study Nature Directly § Field research: “muddy-boots biology” § New technologies available • Remote sensors • Geographic information system (GIS) software • Digital satellite imaging § 2005, Global Earth Observation System of Systems (GEOSS) – integrate sensors, gauges and satellite that monitor earth, atmosphere and oceans

Some Scientists Study Ecosystems in the Laboratory § Simplified systems carried out in • • Culture tubes and bottles Aquaria tanks Greenhouses Indoor and outdoor chambers § Supported by field research

Some Scientists Use Models to Simulate Ecosystems § Computer simulations and projections § Field and laboratory research needed for baseline data