ecosystems chapter 48 all most all regions on the earth function as systems running on energy from...
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
Primary producers are autotrophs (self-feeders) that can
capture sunlight energy and incorporate it into organic
compounds
Consumers are heterotrophs (not self-feeders) that feed on
tissues of other organisms Herbivores eat plants
Carnivores eat animals
Omnivores eat a variety of organisms
Parasites reside in or on living host & extract energy from them
The Nature of Ecosystems
Primary producers are autotrophs (self-feeders) that can capture
sunlight energy and incorporate it into organic compounds
Consumers are heterotrophs (not self-feeders) that feed on tissues
of other organisms
Decomposers 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
Detritivores - 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 WEASEL BADGER COYOTE
GROUND SQUIRRELPOCKET GOPHER
PRAIRIE VOLE
CLAY-COLORED SPARROWEARTHWORMS, 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 gullOsprey Green heronSummer flounderSheepshead minnowHard clamFlying insectsMud snailShrimpsGreen algaPlankton 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 cycleMain 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 CO2) and
nitrogen.
3. In sedimentary cycles, the element does not have a
gaseous phase; an example is phosphorus.
ATMOSPERE
OCEAN LAND
evaporation from ocean
425,000
precipitation into ocean 385,000
evaporation from land plants 71,000
precipitation onto land 111,000
wind driven water vapor40,000
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 timeleaching 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!
Greenhouse effect
CO2, 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!
Global warming - long-term higher temperatures at the Earth's surface
If 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 burningDeforestation
CO2
NO3-
IN SOIL
NITROGEN FIXATION
by industry for agriculture
FERTILIZERS
FOOD WEBS ON LAND
NH3-, NH4
+
IN SOIL
NITRIFICATION
bacteria convert NH4+ to
nitrate (NO2-)
loss by leaching
uptake by autotrophs
excretion, death, decomposition
uptake by autotrophs
NITROGEN FIXATIONbacteria convert to ammonia
(NH3+) ; this dissolves to
form ammonium (NH4+)
loss by leaching
AMMONIFICATIONbacteria, fungi convert the
residues to NH3 ; this
dissolves to form NH4+
NITRIFICATION
bacteria convert NO2- to
nitrate (NO3-)
DENTRIFICATIONby bacteria
NITROGENOUS WASTES, REMAINS IN SOIL
GASEOUS NITROGEN (N2) IN ATMOSPHERE
NO2-
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
sedimentation setting 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 (PO4
-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.