Ecosystems Components Energy Flow and Matter Cycling All

Ecosystems: Components, Energy Flow, and Matter Cycling “All things come from earth, and to earth they all return”—Menander

Key Questions: What is ecology? What are the major parts of the earth’s life support systems? What are the major components of an ecosystem? What happens to matter and energy in ecosystems? What are ecosystem services? How do they affect the sustainability of the earth’s life support systems?

Ecology and the levels of organization of matter Ecology—Greek oikos meaning house Study of how organisms interact with one another and their non-living environment (biotic and abiotic components) Studies connections in nature on the thin life supporting membrane of air, water, and soil Levels of Organization of Matter Subatomic to biosphere

Ecosystem Organization Organisms Biosphere Made of cells Eukaryotic vs Prokaryotic Species Groups of organisms that resemble one another in appearance, behavior, and genetic make up Sexual vs Asexual reproduction Production of viable offspring in nature 1. 5 million named; 10 -14 million likely Ecosystems Communities Populations Genetic diversity Communities Ecosystems Biosphere Populations Organisms Fig. 4. 2, p. 66

Earth’s Life Support Systems Troposphere To 11 miles Air is here Atmosphere Biosphere Vegetation and animals Soil Crust Rock Stratosphere 11 to 30 miles Ozone layer Hydrosphere Solid, liquid, and gaseous water Lithosphere Crust and upper mantle Contains nonrenewable res. core Lithosphere Mantle Crust (soil and rock) Biosphere (Living and dead organisms) Hydrosphere (water) Lithosphere (crust, top of upper mantle) Atmosphere (air)

Sustaining Life on Earth… One way flow of high quality energy The cycling of matter (the earth is a closed system) Gravity Biosphere Carbon cycle Phosphorus Nitrogen cycle Causes downward movement of matter Water cycle Heat in the environment Heat Oxygen cycle

Major Ecosystem Components Abiotic Components Water, air, temperature, soil, light levels, precipitation, salinity Sets tolerance limits for populations and communities Some are limiting factors that structure the abundance of populations Biotic Components Producers, consumers, decomposers Plants, animals, bacteria/fungi Biotic interactions with biotic components include predation, competition, symbiosis, parasitism, commensalism etc.

Limiting Factors on Land & in H 2 O Terrestrial Sunlight Temperature Precipitation Soil nutrients Fire frequency Wind Latitude Altitude Aquatic/Marine Light penetration • Water clarity Water currents Dissolved nutrient concentrations • Esp. N, P, Fe Dissolved Oxygen concentration Salinity

The Source of High Quality Energy of sun lights and warms the planet Supports photosyn. Powers the cycling of matter Drives climate and weather that distribute heat and H 2 O Solar radiation Energy in = Energy out Reflected by atmosphere (34%) Radiated by atmosphere as heat (66%) UV radiation Absorbed by ozone Lower Stratosphere Visible (ozone layer) Greenhouse light Troposphere effect Heat Absorbed by the earth Heat radiated by the earth Earth

Fate of Solar Energy… Earth gets 1/billionth of sun’s output of nrg 34% is reflected away by atmosphere 66% is absorbed by chemicals in atm = reradiated into space Visible light, Infrared radiation (heat), and a small amount of UV not absorbed by ozone reaches the atmosphere Energy warms troposphere and land Evaporates water and cycles it along with gravity Generates winds A tiny fraction is captured by photosynthesizing organisms Natural greenhouse effect vs. Global Warming

Primary Productivity The conversion of light energy to chemical energy is called “gross primary production. ” Plants use the energy captured in photosynthesis for maintenance and growth. The energy that is accumulated in plant biomass is called “net primary production. ”

Primary Productivity NPP=GPP-respiration rate GPP= RATE at which producers convert solar energy into chemical energy as biomass Rate at which producers use photosynthesis to fix inorganic carbon into the organic carbon of their tissues These producers must use some of the total biomass they produce for their own respiration NPP= Rate at which energy for use by consumers is stored in new biomass (available to consumers) Units Kcal/m 2/yr or g/m 2/yr How do you measure it? AP Lab Site Most productive vs. least productive

What are the most productive Ecosystems? Estuaries Swamps and marshes Tropical rain forest Temperate forest Northern coniferous forest (taiga) Savanna Agricultural land Woodland shrubland Temperate grassland Lakes and streams Continental shelf Open ocean Tundra (arctic and alpine) Desert scrub Extreme desert 800 1, 600 2, 400 3, 200 4, 000 4, 800 5, 600 6, 400 7, 200 Average net primary productivity (kcal/m 2/yr) 8, 000 8, 800 9, 600

Fate of Primary Productivity and Some important questions… Since producers are ultimate source of all food, why shouldn’t we just harvest the plants of the world’s marshes? Why don’t we clear cut tropical rainforests to grow crops for humans? Why not harvest primary producers of the world’s vast oceans? Vitousek et al: Humans now use, waste, or destroy about 27% of earth’s total potential NPP and 40% of the NPP of the planet’s terrestrial ecosystems

Biotic Components of Ecosystems Producers (autotrophs) Source of all food Photosynthesis Heat Consumers=heterotroph Aerobic respiration Anaerobic respiration Methane, H 2 S Abiotic chemicals (carbon dioxide, oxygen, nitrogen, minerals) Heat Decomposers (bacteria, fungus) Producers (plants) Decomposers Matter recyclers… Release organic compounds Heat into soil and water where they can be used by producers Consumers (herbivores, carnivores) Heat Solar energy

Trophic Levels Each organism in an ecosystem is assigned to a feeding (or Trophic) level Primary Producers Primary Consumers (herbivores) Secondary Consumer (carnivores) Tertiary Consumers Omnivores Detritus feeders and scavengers Directly consume tiny fragments of dead stuff Decomposers Digest complex organic chemicals into inorganic nutrients that are used by producers Complete the cycle of matter

Detritivores vs Decomposers stop Detritus feeders Bark beetle engraving Long-horned beetle holes Carpenter ant galleries Termite and carpenter ant work Decomposers Dry rot fungus Wood reduced to powder Time progression Mushroo m Powder broken down by decomposers into plant nutrients in soil Fig. 4. 15, p. 75

Energy Flow and Matter Cycling in Ecosystems… Food Chains vs. Food Webs KEY: There is little if no matter waste in natural ecosystems! First Trophic Level Producers (plants) Heat Second Trophic Level Third Trophic Level Fourth Trophic Level Primary consumers (herbivores) Secondary consumers (carnivores) Tertiary consumers (top carnivores) Heat Solar energy Heat Detritvores (decomposers and detritus feeders) Heat

Generalized Food Web of the Antarctic Humans Blue whale Sperm whale Killer whale Note: Arrows Go in direction Of energy flow… Elephant seal Crabeater seal Leopard seal Adélie penguins Emperor penguin Petrel Squid Fish Carnivorous plankton Herbivorous zooplankton Krill Phytoplankton Fig. 4. 18, p. 77

Food Webs and the Laws of matter and energy Food chains/webs show matter and energy move from one organism to another through an ecosystem Each trophic level contains a certain amount of biomass (dry weight of all organic matter) Chemical energy stored in biomass is transferred from one trophic level to the next With each trophic transfer, some usable energy is degraded and lost to the environment as low quality heat • Thus, only a small portion of what is eaten and digested is actually converted into an organisms’ bodily material or biomass (WHAT LAW ACCOUNTS FOR THIS? ) Ecological Efficiency: The % of usable nrg transferred as biomass from one trophic level to the next (ranges from 5 -20% in most ecosystems, use 10% as a rule of thumb) Thus, the more trophic levels or steps in a food chain, the greater the cumulative loss of useable energy…

Pyramids of Energy and Matter Pyramid of Energy Flow Pyramid of Biomass Heat Tertiary consumers (human) Heat Decomposers Heat 10 Secondary consumers (perch) 100 1, 000 10, 000 Usable energy Available at Each tropic level (in kilocalories) Heat Primary consumers (zooplankton) Producers (phytoplankton) Heat

Ecological Pyramids of Energy

Ecological Pyramids of Biomass

Implications of Pyramids…. Why could the earth support more people if the eat at lower trophic levels? Why are food chains and webs rarely more than four or five trophic levels? Why do marine food webs have greater ecological efficiency and therefore more trophic levels than terrestrial ones? Why are there so few top level carnivores? Why are these species usually the first to suffer when the ecosystems that support them are disrupted?

Ecosystem Services and Sustainability Solar Capital Lessons From Nature! Water resources and purification Air resources and purification Soil formation and renewal Waste removal and detoxification Natural pest and disease control Climate control Natural Capital Biodiversity and gene pool Recycling vital chemicals Renewable energy resources Nonrenewable mineral Potentially resources renewable matter resources 1. Use Renewable Solar Energy As Energy Source 2. Recycle the chemical nutrients needed for life

Matter Cycles You are responsible for knowing the water, carbon, nitrogen, sulfur, and phosphorus cycles Know major sources and sinks Know major flows Know human activities are disrupting these cycles

Carbon Cycle

Nitrogen Cycle

Zonation in Lakes

Thermal Stratification in Lakes