Presentation on theme: "Ecosystems Chapter 48 All most all regions on the earth function as systems running on energy from the sun processed through photosynthesizers."— Presentation transcript:
Ecosystems Chapter 48 All most all regions on the earth function as systems running on energy from the sun processed through photosynthesizers.
The Nature of Ecosystems An ecosystem is an array of organisms interacting with one another and with the physical environment, connect by a one- way flow of energy and a cycling of materials. Ecosystems are open systems through which energy flows and material are cycled. Ecosystems require energy and nutrient input and generate energy (usually as heat) and nutrient output. Energy cannot be recycled.
Availability of nutrients as well as ENERGY profoundly influences the structure of the ecosystem
The Nature of Ecosystems zPrimary producers are autotrophs (self-feeders) that can capture sunlight energy and incorporate it into organic compounds zConsumers are heterotrophs (not self-feeders) that feed on tissues of other organisms yHerbivores eat plants yCarnivores eat animals yOmnivores eat a variety of organisms yParasites reside in or on living host & extract energy from them
The Nature of Ecosystems zPrimary producers are autotrophs (self-feeders) that can capture sunlight energy and incorporate it into organic compounds zConsumers are heterotrophs (not self-feeders) that feed on tissues of other organisms zDecomposers are also heterotrophs and include fungi and bacteria that extract energy from the remains or waste products of organisms; these organisms engage in extracellular digestion zDetritivores - include small invertebrates that ingest decomposing particles of organic matter (detritus)
Structure of Ecosystems Trophic (“feeding”) Levels are a hierarchy of energy transfers (Who Eats Whom?) 1st level (closest to the energy source) - Primary producers (Autotrophs) 2nd level - Primary consumers (Herbivores) 3rd level - Secondary consumers (primary carnivores) 4th level - Tertiary consumers (secondary carnivores & parasites) - decomposers feed on organisms from all levels
Energy Flow through the Ecosystem Ecological Pyramids (two types) - (1) Biomass pyramid - makes provision for differences in size of organisms by using the weight of the members in each trophic level (2) Energy pyramid - reflects trophic structure most accurately b/c it is based on energy losses at each level 5,060 decomposers/detritivores21 383 3,368 20,810 top carnivores carnivores herbivores producers Kcal/ sq. m / yr
Food Chain A simple sequence of who eats whom is called a food chain. Interconnected food chains comprise food webs in which the same food resource is often part of more than one food chain…. Plants
MARSH HAWK CROW UPLAND SANDPIPER GARTER SNAKE FROG SPIDER WEASELBADGERCOYOTE GROUND SQUIRRELPOCKET GOPHER PRAIRIE VOLE CLAY- COLORED SPARROW EARTHWORMS, INSECTS (E.G., GRASSHOPPPERS) FIRST TROPHIC LEVEL Primary producers SECOND TROPHIC LEVEL Primary consumers (e.g., herbivores) HIGHER TROPHIC LEVELS Complex array of carnivores, omnivores and other consumers. Many feed at more than one trophic level continually, seasonally, or when an opportunity presents itself The loss of energy at each transfer in a food chain limits the number of trophic levels in each ecosystem to 4 or 5. Energy flows into ecosystems from the sun and due to heat losses at each energy transfer step, you see a one-way flow of energy.
Biological Magnification in Food Webs DDT is a synthetic organic pesticide. DDT is water insoluble but winds can carry DDT in vapor form. DDT is fat soluble, so it can accumulate in the tissues of organisms. DDT can show biological magnification - it becomes more and more concentrated in tissues of organisms at higher trophic levels of a food web DDT and modified forms, disrupt metabolic activities and are often toxic to many aquatic and terrestrial animals. DDT Residues Ring-billed gull fledgling Herring gull Osprey Green heron Summer flounder Sheepshead minnow Hard clam Flying insects Mud snail Shrimps Green alga Plankton Water 75.5 18.5 13.8 3.57 1.28 0.94 0.42 0.30 0.26 0.16 0.083 0.040 0.00005
Biogeochemical Cycle Overall movement of nutrients (ions & molecules) from the physical environment, through organisms, & then back to the environmental reservoir constitutes a biogeochemical cycle. Environment serves as a reservoir for the nutrients geochemical cycle Main nutrient reservoirs in the environment fraction of nutrient available to ecosystem primary producers herbivores, carnivores, parasites detritivores, decomposers
3 Categories of Biogeochemical Cycles 1. In the hydrologic cycle, oxygen and hydrogen move as water molecules. 2. In the atmospheric cycles, elements can move in the gaseous phase; examples include carbon (mainly CO 2 ) and nitrogen. 3. In sedimentary cycles, the element does not have a gaseous phase; an example is phosphorus.
ATMOSPERE OCEANLAND evaporation from ocean 425,000 precipitation into ocean 385,000 evaporation from land plants 71,000 precipitation onto land 111,000 wind driven water vapor 40,000 surface and groundwater flow 40,000 Hydrologic Cycle water slowly moves on a global scale from the oceans, through the atmosphere, onto land, then back to the ocean
Carbon Cycle diffusion between atmosphere and ocean BICARBONATE & CABONATE DISSOLVED IN OCEAN WATER MARINE FOOD WEBS MARINE SEDIMENTS, INCLUDING FORMATIONS WITH FOSSIL FUELS combustion of fossil fuels incorporation into sediments death, sedimentation uplifting over geologic time sedimentation photosynthesis aerobic respiration photosynthesis aerobic respiration TERRESTRIAL ROCKS SOIL WATER LAND FOOD WEBS ATMOSPHERE (mainly carbon dioxide) PEAT, FOSSIL FUELS combustion of wood deforestation volcanic action death, burial, compaction over geologic time leaching runoff Carbon Cycle is the global movement of carbon through ecosystems. Carbon in the atmosphere is in the form of carbon dioxide and carbon in water is in the form of bicarbonate and carbonate.
Greenhouse Gases and a Warmer Planet (pg 888-889)-READ! zGreenhouse effect zCO 2, Ozone, Methane, Nitrous oxide, CFC’s Rays of sunlight penetrate the lower atm & warm the Earth’s surface The surface radiates heat to the lower atm. Some heat escapes into space. But greenhouse gases & water vapor absorb some infrared energy and radiate a portion of it back towards Earth. Increased concentrations of greenhouse gases trap more heat near Earth’s surface resulting in the Earth’s surface temp. to rise.
Greenhouse Gases and a Warmer Planet (pg 888-889)-READ! zGlobal warming - long-term higher temperatures at the Earth's surface zIf the temperature of the lower atmosphere were to rise by 4˚C (7˚F) then the sea levels may rise by as much as 2 feet.
Greenhouse Gases Fossil Fuel burning Deforestation CO 2
NO 3 - IN SOIL NITROGEN FIXATION by industry for agriculture FERTILIZERS FOOD WEBS ON LAND NH 3 -, NH 4 + IN SOIL NITRIFICATION bacteria convert NH 4 + to nitrate (NO 2 - ) loss by leaching uptake by autotrophs excretion, death, decomposition uptake by autotrophs NITROGEN FIXATION bacteria convert to ammonia (NH 3 + ) ; this dissolves to form ammonium (NH 4 + ) loss by leaching AMMONIFICATION bacteria, fungi convert the residues to NH 3 ; this dissolves to form NH 4 + NITRIFICATION bacteria convert NO 2 - to nitrate (NO 3 - ) DENTRIFICATION by bacteria NITROGENOUS WASTES, REMAINS IN SOIL GASEOUS NITROGEN (N 2 ) IN ATMOSPHERE NO 2 - IN SOIL
Sedimentary Cycle GUANO FERTILIZER ROCKS LAND FOOD WEBS DISSOLVED IN OCEAN WATER MARINE FOOD WEBS MARINE SEDIMENTS excretion weathering mining agriculture uptake by autotrophs death, decomposition sedimentationsetting out leaching, runoff weathering uplifting over geolgic time DISSOLVED IN SOILWATER, LAKES, RIVERS uptake by autotrophs death, decomposition Most phosphate moves in the form of (PO 4 -3 ) phosphate ion
Eutrophication - any activity that adds dissolved nutrients to an ecosystem Runoff from agricultural applications of fertilizers adds large amounts of phosphorous to aquatic ecosystems. Human activities are accelerating the process of eutrophication. We are adding nutrients to aquatic ecosystems that are naturally low in those nutrients & so promote destructive algal blooms.