global environment week four

ecosystem

system of a.biotic organisms and their physical environment

including energy flow, nutrient cycling, habitat structure, systems within systems

have to have physical component interacting with biologial component

population

organisms of same species living in same habitat (abundance, biomass)

community

coexisting populations of different species, diversity and food web structure (energy flow)

carbon exchange

plants take co2 from air and use sunlight to turn into sugar (org c) and oxygen (photosynthesis)

carbon passes through food chain, then respiration and decomposition release back to air as co2 (inorganic c)

chemosynthesis

chemical reactions to turn co2 into energy instead of sunlight for extreme environments

redfield ratio

relative number of atoms in phytoplankton to grow

carbon:nitrogen:phosphorus = 106:16:1

liebigs law of minimum

only one nutrient limits growth at any one time, in least supply relative to what is needed

1st law of thermodynamics

conservation of matter and energy, only transformed

ecosystems are essentially just transformation systems for energy and matter - nutrient cycling through food chain

2nd law of thermodynamics

energy degradation (entropy) energy moves from organized to disorganized (less usefull), energy cannot be recycled to original organized state

residence time of c in atmosphere

size/flow = 870/120 gt/yr = 7.25 years

marine biological pump

atmospheric co2 dissolves in ocean, phytoplakton turn into organic carbon, dead plankton and waste sink as marine snow, storing carbon for centuries, allows for more co2 absorption

solubility pump

co2 dissolves in water turning into carbonate, cold water sinks carrying carbon down - used for making shells in long torm storage

protozoa produce biillion tons of caaco3 per year (live in plankton)

algae produce 1,5 billion per year

trophic levels

usually only 4 because longer is unstable and energy dissapates as it goes up, some is exreted, some respired, feed inefficiencies (not all food consumed)

energy balance equation

in (eaten) = excreted (e) + respired ® + death (d) + passed on to next trophic (o)

energy transfer efficiency

energy at trophic n / n-1, usually 10%

amount of energy reaching each level depends on NPP

biomass pyramid

decreases up the food chain becasue of how much is required to make just one top predator

only inverted when biomass producers is consumed and replaced rapidly (lake), prey can reproduce and have different biomasses throughout the year

energy pyramid

production is creation of organic matter, change in biomass per time, change in energy per area per time

never inverted, always bigger at bottom

GPP

gross primary production = amount of CO2 fixed by plant in photosynthesis

NPP + Rp, or NEP + Rhet + Rp

water limited in nature because photosynthesis stops when scarce

R

respiration = amount of CO2 lost through metabolic activity

NPP

net primary production = net amount of PP after cost of Rp

NPP = NEP + Rhet

rate of accumulation of plant biomass

rate of accumulation of plant biomass

(GPP - R) + NPP

NEP

net ecosystem production = GPP - Rp - Rhet

GPP - Rp = NPP → NEP = NPP - Rhet

essentially, C gained by photosynthesis - C lost from ecosystem through community respiration = net c storage in ecosystem

c cycling

if NEP (net c storage in ecosystem) > 0, sink for c —> biomass accumulates

if<0, source for c → forest fire, newly tilled field

if=0, c is transferred to ecosystem and atmosphere at equal rates

effects of deforestation on c cycling

removes co2 sink, stored c is released as co2, increaed rate of decomposition releasing more co2, land use change replaces sink with c source

lithosphere

topmost layer of rock surface of planet

rock cold enough to be solid (away from core), with water gasses and life

varying chemistry and structure of minerals make up parent rock -influences life

volcanoes

make new rock, and elemental composition as it forms determines crystalline structure and chemical properties (ability to react with acid) and physical properties (hardness)

soil

made by breakdown of rock, acquire different physical/chemical properties based on type of rock broken down (parent rock)

form slow, changing on weathering and decomposition, can be removed rapidly by natural/anthropogenic activities

organic matter

influences plant growth, more content with top layers

wetlands accumulate more because flooded water have slower decomposition rates

minerals in soil

sand silt clay

bigger has more space, water drains fast, not many nutrients held, small has more surface area, charged surface holds water and nutrients (electrochemical binding)

high rainfall areas have nutrient poor soil because rain washes them away and plants uptake quickly

electrochemical soil

weakly negatively charged, water is polar, most plant nutrients are positively charged → forming weak chemical attractions/repulsions

negative charge of particle attracts water particle 1, positive end of water pointed towards soil, negative towards other water

negative charge attracts particle 2, water 1 is in the way, 2 must bind to 1, 2 is further from soil with less neg charge, less for holding, easier to be lost

all water lines up, less pull each one, ones closer can’t be used by plants because of strenght of bond

can have so much water no new water is attracted (hydrophobic bc of lipid from dying microbial

ground water collects

soil water zone - closest to surface where plant roots and animal activity happens, excess doesnt stay

unsaturated zone - water goes deeper with no biological activity other than soil microbes (middle ground) - speed of water passing based on soil size

saturated zone - after water table ends up stored long term (groundwater) all space between soil is full of water

water table

between unsaturated and saturated zones, can be above ground in differences of elevation

phosphorus

negative charge, repelled by soil

major plant nutrient, required in high quantities but most is locked in rock

when we add to soils, excess not taken up enters water ways and causes algae

dead zones and eutrophication

levels of phosphorus enter water creating overgrowth of algae

nutrients decline, algae dies

bacteria in water decompose algae

cell resp in decomposition requires oxygen, o gets removed from water to support

so much removed oxygenic species like fish cnat breathe and drown

this can happen naturally, but usually from agriculture