CH 3: What is Ecology?

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. Energy Pyramid Biomass 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 increase in concentration of a pollutant from one link in a food chain to another • Build up of pollutant in an individual. Concentrates in the fatty tissues. • Classic example: DDT (dichlorodiphenyltrichloroethane)

16. Nutrient Cycles • nutrient: any atom, ion, or molecule an organism needs to live, grow, or reproduce. • macronutrients needed in relatively large amountse.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 amountse.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. 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.