1. CH 3: What is Ecology?
* Study of relationships between organisms & their
environment.
Levels of organization:
biosphere- biotic (living) & abiotic (non-living) factors
ecosystem: community + non–living environment
community: populations of different species in given area
population: a group of interacting individuals of same species
Individuals/Species

2. Vocabulary for Ecosystems
1. Abiotic: non–living components. Ex: water, air,sun
2. Biotic: living components Ex: plants, animals, bacteria
3. Trophic level- feeding level for an organism
4. Biome: large regions characterized by a climate & plants
major biomes: temperate grassland, temperate deciduous forest, desert, tropical rain forest, tropical deciduous forest, tropical savannah, coniferous forest, tundra.
5. Aquatic Life Zones: major marine or freshwater portion of the biosphere
major aquatic life zones:
lakes, streams, estuaries, coastlines, coral reefs, & ocean

3. Factors Limiting Populations
Tolerance: the ability of species to tolerate changes in their environment (physical or chemical factors).
Ex: Pollution, global warming, habitat loss
2. Limiting factor: any environmental factor that reduces survival, reproduction, or growth of organisms.
Ex: pH, excess fertilizers, temperature

4. Key Players in Ecosystems
Autotrophs/ producers: make their own food via
photosynthesis (plants) or chemosynthesis (bacteria in thermal vents use hydrogen sulfide (H2S) & carbon dioxide)
2) Heterotrophs/ consumers: can’t make their own food, feed on other organisms or their remains.
Ex: herbivores, carnivores, decomposers, etc.

5. Categories of Consumers
primary consumers: (=herbivores) feed directly on producers;
secondary consumers: (=carnivores) feed on primary consumers;
tertiary consumers: feed only on carnivores;
scavengers: feed on dead organisms;
decomposers (saprobes): consumers that complete the breakdown & recycling of organic materials from the remains & wastes of other organisms; fungi and bacteria
detritivores: feed on detritus (partially decomposed organic matter, such as leaf litter & animal dung). DUNG BEETLES

6. The Importance of Decomposers

7. Food Chains Food chains are a simple food path; one way
Food webs are multiple food chains that are interconnected. More complex than food chains.

8. Ecological Pyramids Represent the flow of energy through an ecosystem.
Ecological efficiency- ~10% transfer from one trophic level to the next. Organisms use energy for basic processes.
Food chains and webs only have 4-5 trophic levels, because too little energy left to support top consumers.

9. Biomass Pyramid
Energy Pyramid

10. Primary Productivity of Ecosystems
1.Gross primary productivity (GPP) -rate producers convert solar energy into chemical energy.
2. Net primary productivity (NPP) NPP = GPP – Respiration by producers

11. Ecosystem Disturbances
Watersheds (land area that drains into a stream, river, lake or wetland) greatly impacted by ecological disturbances.

12. Leaching
Carrying of chemicals or nutrients through the soil by water.

13. The Intermediate Disturbance Hypothesis
ecosystems experiencing intermediate levels of disturbance have higher biodiversity than those with high or low disturbance levels.
Resistance- measure of how much a disturbance can affect the ecosystem’s energy flow
Resilience- The rate at which an ecosystem returns to its original state after a disturbance.

14. Restoration Ecology
Restoration ecology- Focuses on restoring damaged ecosystems.
Ex: Florida Everglades & Chesapeake Bay- restore water levels and nutrients

15. BIO….. Bioaccumulation Biomagnification
Build up of pollutant in an individual. Concentrates in the fatty tissues.
Classic example: DDT
(dichlorodiphenyltrichloroethane)
increase in concentration of a pollutant from one
link in a food chain to
another

16. Nutrient Cycles
nutrient: any atom, ion, or molecule an organism needs to live, grow, or reproduce.
macronutrients needed in relatively large amounts e.g., N, P, S, K, Ca, Mg
Ca+2 and Mg+2 : abundant in soils and are attracted to the negative charge of soil particles.
K+ : weakly attracted to soil and tends to be leached from soils by water. Plants growth can be stunted with low levels.
micronutrients needed in relatively small amounts e.g., Na, Zn, Cu, Cl,

17. BIOGEOCHEMICAL CYCLES
Flow of matter through an ecosystem
Involves Carbon, Hydrogen, Phosphorus, Nitrogen, and Sulfur

18. Hydrologic Cycle
Transpiration- plants release water from their leaves into the air.
Evapotranspiration- evaporation + transpiration.
Runoff- water moves across the land surface into streams and rivers, eventually to the ocean.

19. The Carbon Cycle Involves: * Respiration * Photosynthesis
* Decomposition
* Combustion of
Fossil Fuels

20. The Phosphorus Cycle 1. Only SEDIMENTARY & Non-gaseous cycle
2. Weathering of rocks (major role), decomposition, and excretion
3. P important in DNA,RNA, ATP
4. Humans impact this cycle by use of FERTILIZERS- problem in freshwater ecosystems

21. The Nitrogen Cycle Key terms:
Nitrogen fixation- Nitrogen fixing bacteria convert N2 gas into ammonia (NH3)
Nitrification- bacteria convert ammonium into nitrites (NO2-) and then into nitrates (NO3-)
Denitrification- bacteria convert nitrates (NO3-) back into N2 gas
Ammonification- NH4+ created by decomposers.
Assimilation- Producers
take up NH4+ or NO3-
The Nitrogen Cycle

22. Cultural Eutrophication
Excess nutrients (P and N)enter a water system.
Causes algal blooms and eventually Oxygen is depleted in the water (hypoxic to anoxic) = Death of other organisms.
#1 CAUSE- Runoff from fertilizers and animal wastes!

23. * Combustion of coal- releases excess SO2-
Leads to ACID RAIN/DEPOSITION- H2SO4
*Natural source - Volcanic eruptions, weathering of rocks, decomposition.