• materials (C,H,N,O,P,S)

• energy to build ATP

• autotrophs, a.k.a self feeders

• evolved over 2 billions years ago (cyanobacteria

• no super efficient but hasn’t really changed since its evolution

• drastically change O2 atmosphere concentration

• autotrophs & heterotrophs

• oxidation process → releases CO2

• 1 glucose = 38 ATP 4 metabolic processes

(gycolosis-cytosol)

(krebs-mitochondria)

• amount of plant produced over time

(mass/area/time : gm-2d-1)

• total amount of plant material at a point in time (gm^2)

• all CO2 fixed into organic matter of plant (over a period of time)

• rate of organic matter available for other uses beyond supporting energy cost (respiration) of primary producers

• Ra - autotrophic respiration

• Re - ecosystem respiration

• Rh - heterotrophic respiration (microbes)

NEP=GPP-Re

• can be positive or negative

• only CO2

• overall ecosystem C balance from all sources and sinks (physical biological)

• anthropogenic

• other forms of C

• exchange of CO2 b/w ecosystem and atmosphere

• ≈ NEE

• NEP=GPP-Ra-Rh or NEP=NPP-Rh

• NPP : C that is stored in plants and what they “provide” to the ecosystem

  • litter inputs

  • herbivory

  • very little NPP escapes decomposition and is stored in ecosystem

• Rh is closely correlated w/ NPP because NPP is the input(quantity quality)

• Rh : what is transpired by heterotrophs in the ecosystem

  • heterotrophic respiration

  • largest avenues of C loss from an ecosystem

  • decomposer microbes and their predator account for most Rh

• physical and chemical breakdown of detritus

  • detritus : dead plant, animal, and microbial material

• dead plant material leaf root system litter

• animal bodies & residues

phase 1: leaching

phase 2: fragmentation

phase 3: chemical alteration

• physical process by which mineral ions and small water soluble compound dissolve in water (forms dissolved organic matter (DOM))

  • absorbed by organisms

  • react w minerals in soil

  • exported from system

• RAPID (if h2o present..CLEOOOOO NOORRR ;( )

• (mostly) labile : compounds easily broken down

  • le suga

  • la animo acids

• larger pieces of organic matter broken into smaller pieces by soil/animals they eat and create surfaces for microbe colonization

  • INCREASE SURFACE AND MASS

• mix into soil and return OM to soil as fecal pellets and respire CO2 (Rh)

• INCREASE portion of litter that is accessible to microbial attack

• pierce protective barriers (cuticle, bark, skin, exoskeleton o_O)

• INCREASE FRAG/ INCREASE DECOMP

• feeding activity of animals

• chemical changes that occur to OM

  • primarily by heterotrophic microbes

• OM → (mineralization) → CO2

  • (inorganic) mineral

  • nutrients

  • water

• OM → (transformation) → complex organic compounds OM soil mineral complexes

  • recalcitrant : resist further microbe breakdown

• those that maximize growth, survival, and reproduction of soil organisms

• feeding activity of soil animals

• heterotrophic microbes

• OCCURS TO MEET THE ENERGETIC AND NUTRITIONAL DEMANDS OF DECOMPOSER ORGANISMS

• important in c-cycle bc of carbon balance

  • heterotrophic respiration → Re = Rh + Ra

• the release of nutrients that are tied up in OM is essential for maintaining productivity and nutrient cycle

  • rate of decay is a control over productivity

• climate mitigation

• plant nutrition

• can persist for a long time

  • controls biological activity

  • physical and chemical ____???

• senescence : deteriorate w time

• bacteria and fungi already colonized while on plant

rate that mass is lost over time

• d/dt : change in quantity over time

• K : decomposition rate constant

• units: time ^-1

• (negative exponential model)

• of intrinsic (litter quality) factors

• of extrinsic (environmental and biological) factors

• time required to decompose under steady state conditions

• 2 ways to measure

  • measure mass loss over time and fit curve to estimate K, then MRT = 1/K

  • MRT = litter pool/ litter fall so K = litter fall/ litter pool

g litter m^-2 / g C m^-2

litter traps to catch leaves stems and root ingrowth cores

microbes

• relatively larger standing stalk

• turnover time: weeks

• filamentous hyphae

• reproduce sexually/asexually by sporulation

• breakdown of all classes of plant molecules

• small standing stock

• 1-10 days

• single cell

• large surface : volume (rapidly absorb substrate)

• reproduce by cell division

• can grow and divide quickly

• both can secrete extracellular enzymes to break down OM

• partially degraded OM + enzymes + microbial biomass on and within the OM makes it more palatable for other decomposers

slay

• substrate quality

• microbial community

  • players, biomass, activity, nutrients

• environment

  • moisture, temp

• litter quality

  • size of molecules

    • large molecules cannot pass through membranes

  • types of chemical bonds

    • ester bonds vs aromatic rings

  • regularity of structures

    • lignin has highly irregular structure

    • no specific enzyme.. so broken down slowly by nonspecific enzymes

  • toxicity

    • phenolics kill or reduce activity of microbe

  • nutrient concentrations

    • nutrients (N,P) are required by microbes to produce new microbial biomass

• support biomass and activity of decomposers

• some OM persists storage

• plant biomass dies

  • litter then goes through

    • mineralization

    • transformation

    • leaching

• nutrients enter

• climate/environment (aid w decomp??)

  • temp

  • moisture

  • oxygen

• INCREASE TEMP = INCREASE RATE OF REACTION

• decomposer organisms have a thermal tolerance range and optimum

  • acclimate and adapt overtime

• in general

  • INCREASE TEMP = INCREASE DECOMP

  • highest in warm moist condition if oxygen is available

• water facilitates the diffusion of substrate nutrients to microbe and waste products away from microbes

• INCREASE MOISTURE = INCREASE DECOMP

  • until soil becomes so waterlogged that aerobic conditions inhibit decomposition

• terminal electron acceptors in oxic respiration

• anerobic metabolism e- acceptors (NO3^- & SO4^2-)

• less energetically favorable than oxic respiration

• LOW O2 → results in lower microbial biomass; DECREASES DECOMP

• LOW O2 → limits macroinvertebrate; DECREASES FRAGMENTATION AVAILABLITY in the ecosystem will part determine the quality of litter and microbial biomass/activity

• the effects of nutrients on decomp are largely indirect and mediated by C quality of the substrate

• living things need a certain ratio of carbon to build their bodys and offspring

  • nutrients (C:N ; C:P)

• high C:N (low N) - decay slower (general pattern)

• low C:N (high N) - generally decay quickly

look at the powerpoint stuff. check lecture 13

• the one with green boxes

• substrate N limited

• not enough N to meet/sustain microbe population and activity growth

• ABSORBS (NH4+) from ecosystem

  • N IMMOBILIZATION

GAGA OOOO EEH

• microbial growth is often C limited

• need to decompose the OM to meet energy demands of decomposer if substrate has SURPLUS N for microbial needs

• RELEASE N to the ecosystem

  • N MINERALIZATION

• C → structural

• N,P → physiology

  • photosynthesis

• ecological traits are functionally coordinated and adapt along environmental gradients

• a way to conceptually organize trade-offs between resource acquisition and conservation

• LES : leaf economic spectrum

• WES : wood economic spectrum

• RES : root economic spectrum

• resource acquisition

• traits that promote fast C acquisition

  • photosynthesis

• large leaves

• high nutrient content

  • N&P

• fast growing (not structurally complex)

• low tissue longevity (low density)

decomposition (tissue quality)

• low C:N (high N)

• not structurally complex

• faster rate of decay

• resource conservation

• traits that promote conservation of tissues

  • lower productivity

• smaller, denser

• structurally complex (cellulose lignin gurl)

• well protected tissues

• lower nutrient concentration

• long tissue longevity

decomposition (tissue quality)

• high C:N (low N)

• complex and defended (jealous tbh..)

• slower rate of decay

• inputs → nutrients

• climate/environment

  • temp, moisture, O2

• decomposer → community activity and pop size and composition determines decomp rate and extent

• INTERCONNECTED

  • each component must be thought of within the entire context

1. what kind of litter is being produced

2. does the environment support high or low microbial biomass and activity

part of lecture 13 notes :)

• atmosphere N(triple bond)N

• N2 nonreactive

• inorganic reduced

  • NH3 : ammonia

  • NH4+ : ammonium

• inorganic oxidized

  • NO3- : nitrate

  • N2O : nitrous oxide

• organic

  • DON

    • urea

    • amines

    • amino acids

• N fixation

• N deposition (not focused in class)

• denitrification

• leaching

• fire → volatilization N

• biomass removal

• mineralization

• immobilization

• nitrification

• plant uptake

• inputs (N-fixation) and losses (denit, leaching) are relatively small in comparison to the internal cycling

  • mineralization

  • immobilization

  • nitrification

  • plant uptake

• vast majority of nutrients that support GPP are recycled in the ecosystem

  • recycled N supports approx. 90% annual plant demand

• balance is a critical regulator of N availability for GPP

• (1) N absorbed by plants used by plant to build plant body and for its physiology eventually plant tissues die → litter

  • DOM contains C, N, P

• (2) microbes break down organic matter during this process dissolved organic matter is released through action of exoenzymes

  • also called dissolved organic nitrogen DON

• microbes absorb it and use the C to meet their energy needs and also use the C and N to build new microbial biomass

• if DON is N poor (high C:N) the microbe must take NH4+ from the environment to meet its needs

• N IMMOBILIZATION

  • N is taken into the microbes body and others cannot use it until the microbe secretes it → enzyme or dies and decomposes

• ex. N poor → sawdust

• is DON is N rich (low C:N) and the microbe has a surplus of N after its needs are met then it releases NH4+ to the environment

• N MINERALIZATION

  • keeps eating (yum) to get C and releases N

• ex. N rich → manure

general rules

• C:N 25:1 or lower : mineralization

• C:N > 25:1 : immobilization

within the soil profile usually both are happening simultaneously and the balance between them regulates the size of the soluble N pool

• must also consider if the environment supports high microbial activity and pop growth bc the carbon status of the microbes is what is driving the decomposition

  • → magnifies the effects if substrate quality (C:N) on the rates of immobilization vs mineralization

• C:N → determines mineralization vs immobilization

• climate → effect rate

• NO3^-

  • nitrate can be taken up by the plants and microbes but must then be reduced to NH4+ so more energetically expensive

  • negative charge so less likely to stick to soil particles (generally have a neg. charge) than NH4+ cation

  • nitrification rate is key for controlling magnitude leaching loss

• find nitrification in places that support HIGH N MINERALIZATION (tropic) or places w added NH4+ fertilizer

  • agriculture

• bc nitrification substrates (NH4+, NO2-) are not rich in energy

• nitrifiers grow slow and compete poorly for NH4+ against plants and microbes immobilizing N competition regulates nitrification rates

• nitrogen fixation : N2 → NH3

  • N-FIX LIMITED TO WARM, HIGH LIGHT ENVIRONMENTS W/ ENOUGH P

• enzyme : nitrogenase

  • denatured by oxygen so nitrogen fixation requires a low or no oxygen environment (anaerobic)

• N-fixing microbes : bacteria

  • free-living or form symbiotic relationship w/ plants

• very energetically demanding to fix N can use up to 25% of GPP

• only competitively advantageous in low N systems bc if reactive N is available it is energetically cheap to take it up and other microbes would outcompete the comparatively slow growing N-fixers or plants would not feed N-fixers to get N they would simply take it up from the environment

• enzymatic reaction so INCREASE in WARMER TEMPERATURE

• energy availability

  • need HIGH productivity to fuel it

  • HIGH light

  • WARM temps (tropics)

  • not shade but sunny

    • overstory or disturbed open canopy

• other nutrients available = P

  • require a lot of ATP

• N-FIX LIMITED TO WARM, HIGH LIGHT ENVIRONMENTS W/ ENOUGH P

• denitrification : NO3- → NO2- → NO → N2O →N2

  • form of anerobic respiration - heterotrophic bacteria

    • bacteria facultative anaerobes <- normally respire O2 but in absence use N-oxides

• ONLY OCCURS IF OXYGEN IS ABSENT

  • 3 conditions required

    • low oxygen

    • high nitrate concentrations

    • supply organic carbon

• NO3- <- product of nitrification

  • bc anaerobic process conditions that favor denit often limit supply NO3- nitrification aerobic

• HIGH DENIT - wetlands w/ aerobic zone or lateral supply of NO3- rice paddies, periodic flooding/draining

• need organic matter to fuel anerobic respiration

  • DECREASE OM = DECREASE DENIT

• leaching of dissolved organic nitrogen (DON) or NO3- nitrate

• often large fluxes after disturbance when there is reduced uptake NO3, NH4 → NO3

• occurs when fertilizer application exceeds plants and microbial demands

• fire volatilizes N

  • the amount lost and forms (NO-, N2, NH3) depends on the temperature of the fire

• essential for all organism

  • DNA, RNA, ATP & phospholipids that form cell membranes

• limits or colimits primary production in many ecosystem both terrestrial and aquatic (lakes, streams, oceans)

  • especially tropical forest and freshwater ecosystems

• P - rarely found in elemental form

  • orthophosphates (basic→acidic)

    • PO4^-3 (pH 14)

    • HPO4^-2 (pH 10)

    • H2PO4- (pH 5)

      • pH 5, 10 → primary forms taken up by the plants

    • H3PO4 (pH 0)

    • PH3 - phosphines

      • gas form extremelly rare

        • negligible atmospheric component

  • Porg - organic P <- living or dead plant/animal/microbe biomass

    • dissolved forms and particulates (porg & orthophosphates)

  • Procks

• break down of primary (rocks) minerals over time

  • jESUS CHrIST mARIE! THeyRE miNERalS! (bb moment lol)

• one of the slowest biogeochemical cycles on earth

  • boooo

• atmosphere does not PLAY.. a significant role since P-compounds are solid (not gas)

• they can dissolve in water or be in particulate form

• main P source to the oceans is runoff from river

  • 15 (looks like 1.5 on her notes tho.. idk hard to see lmk) Mt dissolved P

  • 20 Mt suspended particulate P

• Prock weathering non-reversable

• background levels in an ecosystem depends on the parent material

  • parent material: what rocks are made of

    • controls the amount of P in the rock to begin with

• weathering rates INCREASE WITH

  • INCREASE TEMPERATURE

  • INCREASE PRECIPITATION

  • INCREASE SLOPE

  • INCREASE VEGETATION

• P can cycle 100,000 + years before reaching the bottom of the ocean

• only a small component enters the “fast” cycle

  • most remain bound up in rocks

    • aww :c

• inputs: OM

• output: H2PO4-

• soil microbes

• rate and amount immobilized or released depends on

  • environment (moisture, temp)

  • C:P of substrate (litter)

    • 300:1 immobilization

    • <200:1 mineralization

• fast and reversible

• P from soil solution is attached/bound to the surface of soil particles adsorption

• the reverse desorption

• clay surfaces or Fe and Al oxide (+ charges) depends on soil type

  • INCREASE CLAY or INCREASE Fe & Al oxides then

  • INCREASE P will be unavailable bc bounded/absorbed

• oxisols → soil order → highly weathered tropics dominant colloid are Fe, Al oxides

• precipitation: process by which metal ions (Al3+, Fe3+) (Ca 2+ - calcarous soil) react w phosphate ions in the soil solution to form minerals such as Al-, Fe-, Ca-, phosphate

• slow involves a permanent change into metal phosphate but metal phosphate can release phosphate back upon dissolution

  • dissolution : release rate slow - form of weathering of a secondary mineral

• assimilation

• available P moves through soil by diffusion

• take up mostly HPO4^2- and H2PO4- <- pH dependent

• long filamentous hyphae

• INCREASE ROOT SURFACE which INCREASES the PROBABLILITY of encountering P

• appox. 80% terrestrial plants form mycorrhizal symbiosis

  • critical step in the evolution of land plants

• 3 pools exist in equilibrium w each other

• fixed P pool → primary mineral

• active P pool → absorbed, secondary mineral, organic matter-P

• clay content (absorption)

• soil minerology [Fe, Al] (absorption)

• soil pH

  • high pH Ca+

  • low pH Al- , Fe-

• organic matter

  • mineralized → release P

  • competes for absorption sites

• prevent Ca and Mg ions from binding w soap

• banned in 17 states

• NOT TEXAS (who wouldve though tho)

• EPA sets voluntary limits

• P often limits primary production

• if you add P → stimulate rapid growth of phytoplankton and algae

• FW & estates coast w carbonate sediments or co-limited N and P

• shades out benthic primary producers leading to sediment resuspension switching system to an alternate stable state

  • phytoplankton dominated

• can be toxic depending on community composition of algae

  • harmful algae blooms

  • red tide

• can create dead zones

  • INCREASE ALGAL GROWTH which sink and decompose but aerobic respiration of decomposers takes O2 out of water column

  • hypoxic zones

    • cannot sustain many organisms

• humans → mine P approx. 23 Tg (10^12g)/ year

  • spread it all around

    • fertilizers, livestock feed, trade livestock move food crops

  • INCREASE CONSUMPTION of P → approx. 3% annually

    • INCREASE POPULATION

    • meat

• we release lot of P from rocks (concentrated) @ a rate that exceeds new P rock formation

• morocco (#1)

• china (#2)

• south africa

• algeria

• syria

• no known substitues

• estimated peak of production

  • 2030

• BUT recent discovery “new” reserves pushes this date back a few decades

_> i needa see the source for that bc w ohio i be trippin

protect aquatic environments, promote food security