Ecosystem Ecology
Ecology
• “study of the interactions between the
organisms and their environment”
Biotic
Living
organisms
Abiotic
Nonliving
organisms
Wildflower,
animals,
bacteria
Sunlight,
precipitation,
temperature,
soil, rock
Flow of Energy
• Photosynthesis
a. Sun + 6 H2O + 6 CO2  C6H12O6 + 6 O2
b. performed by plants, algae, and some bacteria
http://www.phschool.com/science/biology_place/biocoach/photosynth/overview.html
• Cellular Respiration
a. C6H12O6 + 6 O2 Energy + 6 H20 + 6 CO2
b. fuels own metabolism and growth
c. aerobic v. anaerobic
http://bcs.whfreeman.com/friedlandapes/#t_668210____
Trophic Levels/Feeding Levels
Food Chain v. Food Web
http://bcs.whfreeman.com/friedlandapes/#t_66
8210____ (modified
http://bcs.whfreeman.com/friedlandapes/#t_668210____ (modified)
• Scavengers
a. consume dead animals (vulture)
• Detritivores
a. break down dead tissues and waste products
into smaller particles (dung beetles)
• Decomposers
a. complete the breakdown process by
recycling the nutrients from dead tissues
back into the ecosystem (fungi, bacteria)
• Gross Primary Productivity
ex) total paycheck
• Net Primary Productivity
ex) paycheck after taxes
Energy Flow
• Biomass: total mass of all living matter in
an ecosystem
• Energy is lost at each level (heat)
a. 10% gained;
90% lost
b. ecological
efficiency
Matter Cycles Through the
Biosphere
• Biosphere: combination of all ecosystems on
Earth
• Biogeochemical Cycles: movements of matter
within and between ecosystems that involved
biological, geological, and chemical processes
The Hydrologic Cycle
1.
2.
3.
4.
5.
6.
7.
Evaporation
Transpiration
Infiltration
Precipitation
Condensation
evapotranspiration
Runoff
http://bcs.whfreeman.com/friedlandapes/#t_668210____
• Human Activities
a. harvesting trees
- decreased evapotranspiration, increased
runoff
b. construction
1.
2.
3.
4.
5.
6.
The Carbon Cycle
Photosynthesis
Respiration
Exchange
Sedimentation and burial
Extraction
Combustion
http://bcs.whfreeman.com/friedlandapes/#t_668210____
• Humans and the carbon cycle
a. combustion of fossil fuels
b. deforestation
The Nitrogen Cycle
• Nitrogen
a. proteins and nucleic acids
b. useable form  nitrates and nitrites
c. earth’s atmosphere  78% nitrogen gas
d. most abundant element in the atmosphere
• Steps
a. nitrogen fixation (nitrogen gas-N2) into
ammonia-NH3)
b. nitrification (ammonia to nitrites and nitrates)
c. ammonification (decomposers)
d. denitrification
e. leaching
http://bcs.whfreeman.com/friedlandapes/#668210__690858__
Human affect
• Deforestation
• Fertilizers
• runoff
Phosphorous Cycle
• Major component of DNA, RNA and ATP
• Doesn’t exist in atmosphere
a. limited to soil and H2O
• Steps
a. weathering of phosphate rocks
b. plants take up phosphate from soil and
animals eat the plants
c. decomposers release phosphate back in to
soil
d. animal excretion
Human Influence
• Fertilizers
• Runoff into aquatic ecosystem
a. excess growth of algae (algal bloom)
resulting in hypoxia
• Found in detergents
Calcium, Magnesium, Potassium
and Sulfur
• Important in transmitting signal between cells
• Derived mostly from rocks and decomposed
vegetation
• Calcium and Magnesium – limestone and marble
The Sulfur Cycle
• Similar to phosphorous cycle
• Important for proteins
• Found mainly in rocks and soil (coal, oil) as
minerals
• Steps
a. Weathering
b. plants and animals relationship
c. decomposers
- sulfates convert to hydrogen sulfide gas
which escapes into atmosphere, water, soil,
marine sediments
* result in acid rain
Human Influence
• Emissions from coal-burning power plants
Ecosystem Disturbances
• Disturbance: event caused by physical,
chemical, or biological agents that results in
changes in population size
a. natural and anthropogenic
• Understanding Biogeochemical Cycles
a. helps in determining change by disturbance
b. watershed studies
- watershed: all of the land in a given
landscape that drains into a stream, river,
lake, or wetland
• Resistance v. Resilience
a. resistance: measure of how much a
disturbance can affect the flows of energy and
matter
b. resilience: rate at which an ecosystem can
bounce back
• Intermediate Disturbance Hypothesis
a. rare disturbances  low diversity
b. frequent disturbances  low diversity
c. intermediate disturbances  highest diversity
Ecosystem Services
• Instrumental Value
a. value in terms of how much economic
benefit
b. ecosystem services
c. provisions
• Intrinsic Value
a. moral value of an animal’s life