Wednesday, January 8, 2020
Ecology Notes
What is ecology? !
- Study of interactions between organisms and their environments!
- Think about:!
• Organism !
• Environment (abiotic and biotic)!
What is environmental science?!
- Study of ALL aspects of environment!
• Includes human interaction!
• Is interdisciplinary and broad!
- Can assign value to ecological problems!
• Can judge situations as good or bad!
Population!
- Exponential population growth- population grows exponentially!
• dN (population size) / dt (time) = rate of change in population change = rN !
- r= intrinsic rate of increase !
- N =population size!
• Assumes unlimited resources and constant environment!
- Logistic growth- something causes growth rate to slow/stop and population plateaus!
• dN / dt = rN(1-N/K)!
- K= carrying capacity!
- The bigger population gets, the smaller the growth rate gets!
- Density-independent- factors the affect population growth regardless of size!
• Temperature, precipitation, catastrophic events!
- Density-dependent- factors that affect growth in accordance with size!
• Resource availability, disease, competition !
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, Wednesday, January 8, 2020
- Population regulation- when population raises and falls below carrying capacity in
repetitive manner!
- Life table- summarizes age-specific schedules of survival and fecundity (typically for
females) in convenient format!
• Age | Number Alive | Mortality rate for age | Fecundity!
• Cohort- group of individuals of same age-class (single birth year/age)!
Ecosystem Services!
- Ecosystem services: many and varied benefits that humans freely gain from the
natural environment and from properly-functioning ecosystems!
• Idea has existed for centuries!
- Modern notions began brewing in 1950s!
• Term was coined and promoted to explain environmental issues beginning in
1970s!
• Examples:!
- Supporting services: nutrient cycling, photosynthesis, soil formation, pollination!
• Pollination: abiotic (wind, water, rain), biotic (>100k species)!
- Honeybees pollinate crops worth >$200B annually!
- Provisioning services: food, potable water, medicine, raw materials, energy!
• Pharmaceutical discovery: aspirin (willows), opiates (poppies), penicillin (fungi)!
- Regulating services: waste decomposition, resource purification, pest control!
- Cultural services: cultural, recreational, educational, aesthetic, scientific!
- Natural capital: world’s stock of natural resources, which includes geology, soils, air,
water, and all living organisms!
- Ecological footprint: ecological assets that a given population requires to produce its
natural resources it consumes and absorb its waste. T!
• Tracks use of six categories of surface areas:!
- Cropland!
- Grazing land!
- Fishing grounds!
- Built-up land !
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- Forest area!
- Carbon demand on land!
Water!
- Hydrological cycle: how water moves around planet!
• There’s generally no creation of water, same water recirculates!
• Transpiration/evaporation is going from liquid—>gas!
• Condensation+precipitation is going from gas—>liquid!
• Biotic use—>runoff—>infiltration—>biotic use is movement of liquid water!
- What moves with water?!
• Sediment, pollution, etc.!
- Watershed: any area of land where precipitation collect and trains off into a common
outlet, such as into a river bay, or other body of water !
• Connects the landscape!
• Human communities in same watershed use snd compete for water resources!
- Aquifer: underground layer of water-bearing permeable rock, rock fractures or
unconsolidated materials!
- Water table: upper-surface aquifer where water is accessible!
- Saltwater intrusion: movement of saline water into freshwater aquifers, which can
lead to groundwater quality degradation!
• Canals being built can increase this condition!
• Global warming is another cause of this!
- Tri-state water wars: battle for limited water between GA, FL, AL!
• Competing interests: upstream consumption and recreation in Atlanta;
downstream use for agriculture, power generation, consumption; fisheries in
Apalachicola Bay!
- Legislation!
• Clean Water Act (1972)!
- Landmark legislation to: restore and maintain chemical, physical, and biological
integrity of nation’s water”!
• Clean Water Rule (2015)!
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