Intro to Ecology
- Abiotic + biotic+processes (*sustainability particularly concerned about human role)
- Look at flows of energy and nutrients
- Why do we care?
- Example of Easter Island and idea of carrying capacity (how many organisms a given ecosystem can support)Heterotrophs and autotrophs
WHY study this? Life needs energy.
- Electromagnetic Radiation
- Shortwave, Longwave, thermal radiation
- Visible light (photosynthetically active range PAR)
- All of these are involved in overall energy budget for organisms, ecosystems, even global
- Latent energy: phase changes (solid->liquid->gas) takes energy! This is energy that doesn’t affect temperature
- Kinetic energy: temperature (molecular motion), transferred by molecules bumping into each other and transferring energy (conduction)
#1st Law of Thermodynamics: Energy is neither created nor destroyed (EVER!)
- 2nd Law: Entropy increases!
- Entropy is “disorder”—heat energy is more disordered than chemical bonds (like that stored in fossil fuels or food), so we can’t reuse energy!
- Sunlight is low entropy (ordered), life is intermediate, heat HIGH entropy
- WHO CARES?? Informs how much E can pass between trophic levels (like plants to herbivores)
- Net radiation equation, depends on albedo (how much radiation is reflected)
- Flow of electrons, when something is oxidized it loses an electron (and often we see an oxygen in there GETTING that electron), when something is reduced it gains an electron (LEO GER)
- Chemicals of life are reduced (that is, they gain electrons, for example carbon is in a reduced form in sugars)
- Take home? Reduced molecules have energy in them that organisms can use (remember that sugar?)
- Aerobic and Anaerobic Respiration
- Respiration here DOESN’T mean breathing, it means breaking down sugars for energy—both autotrophs and hetertrophs do it; oxygen is often electron acceptor
- Anaerboic Resp’n happens where there ISN’T oxygen
- Recent (last 400000 yrs) correlation with temperature
- CO2 concentration has gone up in the last 100 yrs, rise caused by human outputs
- Concentration may have effects on sea level
- 4 in the last 120,000 years (usually happen every 100,000 years)
- We are in an interglacial period
- Scientists can reconstruct temperature data from ice cores and sediment cores (from oxygen isotopes), AND glacial scrapings
- Most recent ice age (with 4 glaciations) 15,000-120,000 years ago
- How do we know where glaciers were before? Edges push sediment like with Cape Cod, striations from scraping
- What are causes of glaciation?? Plate tectonics? CO2? *Milankovitch cycles (could be a trigger)
- Milankovitch cycles: refers to changes in incoming solar radiation (insolation) from tilt, elliptical rotation, precession (twirling like a top)
- Equilibrium! (ball well diagrams)
- Positive feedbacks (responses in a system that perpetuate given processes) EX, ice albedo
- Sea level
- “Eustatic” means global average; “Isostatic” means regional
- Scientists can reconstruct over long history with looking at oxygen isotopes and ancient coral reefs
- Global sea level dropped during glaciations: WHY?
- What happens to eustatic sea level when sea ice melts? When ice sheets melt?
- What factors affect isostatic change?
Deposition, Weathering, and Acid-Base Chemistry
- Biogeochemistry—what is it??
- A really big word for the biological processes that affect nutrient flows, and studying them on a longer (geologic) time scale
- Which elements are most important to life? (CHONPS, cations, minerals)
- The wonderful-ness of water
- Universal solvent (TONS of things dissolve in it!), POLAR!
- At equilibrium, you have water, OH-, ***H+
- Pure water has a pH of 7 (water in contact with air: 5.7, surface ocean 8.1)
- Salts (cation plus anion) dissociate completely
- Organic molecules can be big, and have different parts that like water (hydrophyllic)
- Acids and bases
- pH scale: measures acidity (amount of H+) of solution, lower number means greater acidity, higher number means more basic (alkaline)
- when acids and bases mix with water, pH changes
- ACID: anything that donates a proton (H+)
- Strong acids give it ALL away! Ex H2SO4
- Weak acids are a little more modest—Ex COOH
- BASE: anything that donates OH- or takes up H+
- Conjugate base is the base left when an acid gives away its H+
- Dissociation constants tell us how strong an acid or base a substance is, and pKa tells us the pH of the solution at equilibrium
- pH of a solution can affect how much an acid or base dissolves
- EX when in acidic solution, COOH doesn’t dissolve!
- CO2 in water (carbonate complex)
- CO2 is an ACID in water (because it forms H2CO3)
- Ocean pH from 8.2 to 8.1
- In water, corrosive to shells of marine life (calcium carbonate); HOW WILL THEY ADAPT??
- 65 mya extinction event linked to ocean acidification
- NOx, S
- NOx formed during combustion
- Can make smog (with VOC and sun) and acid rain (with water)
- H2SO4, HNO3
- More S, NOx in industrial revolution, but concentrations decreasing in US after Clean Air Act (and so has acid rain)
- Weathering, nutrients come in and move around soil
- Acidity has effects on what can grow, charge in soil surface
- Acid Neutralizing Capacity (ANC)—how much acid soils can take
WHY?? Who cares??
Water quality, nutrient cycling, ecosystem health, soils, watersheds, **acidification!
A quick exam review reference for the first 15 lectures:
• Hierarchy of life : Org, Pop, Community, Ecosys, Biosphere, niche=functional role, habitat=place in nature
• Origen of life: Eukaryotes=nucleated/mitochondria, Prokaryotes=archaea and bacteria
• Energy flow through an ecosystem, trophic efficiency, heat exchange, sensible heat
• Plant physiology, photosynthesis ATP, ADTP, rubisco
• Carbon cycle, GPP, NPP, NEP, understand the relationships in these.
• Climate Glaciation, ball well diagrams, Eustatic vs. Isostatic, Milankovich cycles, positive Feedbacks
• Vegetation biomes: soil types, fertility, water holding capacity, Whitaker biome diagram, Walter diagrams
• Acids and bases: Acid is a proton donor, Carbonate complex, carbonic acid, depends on pH
• Nutrient flows: Nitrogen cascade, NOx=oxidized, NH3=reduced, NO3 is more mobile
• Evolution: Stabilizing, directional, disruptive, genetic drift, artificial selections, kin selection
• Nt+1=lambdaNt, dN/dT=rN, r-selected vs K-selected, management harvest at k/2
• Population dynamics, survivorship, maternity function, metapopulations vs. source-sink
• Species interactions: mutualism, realized niche, Gauss hypothesis (one species per niche), overlap, Interspecific and intra specific competition, character displacement
• Predatory Herbivory Parasitism: Parasitoids consume host, Lotka voltera equation, exploitive comp, interference comp, alleopathy. S-shaped curves.