Chapters 21 & 22

Humans modify cycles: •Fossil fuel burning -___ ppm in 1960, ___ ppm CO2 now -Taking carbon from ___ ___ and moving it to ___ -increases ___ ___ (blocks ___ of ___ ___ ___ from surface) -annual fluctuations due to ___ -could be ___-___ rise in average temp in next 50 years

310 350 fossil sink atmosphere greenhouse effect reflection long wavelength heat seasonality 2-3C

Term applied to a body of water with high nutrient content & high productivity

Eutrophic

Nutrient enrichment of a body of water; called cultural when accelerated by introduction of massive amounts of nutrients from human activity

Eutrophication

barrier created by differences in salinity

Halocline

Conversion of an element from inorganic to organic form in microbial or plant tissue, rendering the nutrient unavailable to other organisms

Immobilization

is the uptake and assimilation of mineral nutrients by microbial decomposers

Immobilization

Microbial breakdown of humus & other organic matter in soil to inorganic substances

Mineralization

is the process through which microbial decomposers convert nitrogen and other elements from organic compounds into inorganic (mineral) forms

Mineralization

Disturbance & nutrient loss from the Hubbard Brook Forest: •Disturbance radically increases ___ ___ at ___ ___. •___ ___ ___ and ___ ___ ___ increases nitrate in soil water up to ___ •Nitrate losses greatest at sites with ___ ___

N loss ecosystem scale small scale trenching & removal of plants 1000x rapid decomposition

Term applied to a body of water low in nutrients & productivity

Oligotrophic

barrier based on density

Pycnocline

Where will decomposition rates be highest?

Tropics

-Lignin: has ___ ___ ___ in it -Look @ % carbon remain in leaves over time, ___ ___ ___ ___ & then ___ ___ ___ over time -Proteins break down ___ ___ -Cellulose & hemicellulose: break down ___ ___ -Takes ___ ___ ___ for lignin to break down

a lot of carbon drops off very quickly comes back up pretty quickly relatively quickly a long time

Decomposition very important: •bacteria - may be ___ or ___ -dominant decomposers of ___ ___ ___ •fungi -dominant decomposers of ___ ___ -Decomposition involves a ___ of ___ ___ until the organic material is ___

aerobic anaerobic dead animal matter plant material succession microbial decomposers mineralized

Decomposition slower in ___ ___

anaerobic environments

The nitrogen cycle: •Pool is ___ •___ important:*** -N2 fixing bacteria convert ___ to ___ -Nitrifying bacteria convert ___ to ___ or ___

atmosphere nitrification N2 to NH3 NH3 to NO2 or NO3

The carbon cycle: -Carbon in ___ is pool → taken up by ___ → ___ or ___ -___ → releases carbon back into ___ -Respiration: releases ___ ___ & ___ -Sink: ___ -Carbon will ___ ___ unless some type of ___ ___ happens

atmosphere plants eaten or decomposed Methane atmosphere carbon dioxide & methane fossilization stay fossilized geologic uplift

The oxygen cycle is largely under ___ ___

biological control

Nutrients in organic matter are mineralized during decomposition: •As plant material is consumed ___ is lost as ___, nitrogen is ___ to meet the demands of the ___ •The C/N ratio ___ -lower C/N ratios are ___ ___ to decompose

carbon CO2 immobilized decomposers declines even easier

Nutrients in a lake: -In the fall, temperate climate, surface waters ___→ surface waters & hypolimnion temperatures are ___ ___ → ___ ___ in density → water column ___ ___ -Still pretty well mixed in ___ -More oxygen in ___ ___ b/c more ___

cool pretty similar no difference can mix spring upper layers phytoplankton

-Nutrients in stratified water column: nutrients @ bottom can't get to surface waters; important b/c ___ occurring in bottom & has a lot of ___ but ___ ___ ___ ___ -Increase in ___ ___ in line with time period (right around ___ ___, ___ ___r); can get lots of ___ -Late summer, ___ are limiting -In winter, ___ is limiting

decomposition nutrients can't get to top primary production late spring, early summer phytoplankton nutrients light

•The combined ___ in carbon and ___ in nitrogen concentration of the residual organic matter results in a ___ ___ in the ratio of carbon to nitrogen as the process of decomposition proceeds toward the development of ___ and ___ ___ ___.

decrease increase continuous decline humus & soil organic matter

Plant species richness ___ with ___ soil acidity

decreases increasing

Other factors that influence nutrients: •___ •___ •___ ___

disturbance waste land use

Nutrient cycling in streams: •Nutrients in streams subject to ___ ___: nutrient spiraling •Spiraling length is due to rate of ___ ___ and ___ ___ •Nutrient export ___ ___ ___ due to processing •Increased nutrient input leads to ___

downstream transport nutrient cycling & water velocity less than input eutrophication

Disturbance & nutrient loss from the Hubbard Brook Forest: •Uptake by vegetation most important in ___ ___ and ___, ___ ___. •Human populations increase nutrient ___ ___ •And so does the ___ ___ ___ ___

fertile soils warm, moist conditions nutrient transport type of land use

The phosphorus cycle: -Limiting nutrient in ___ ___ -Rocks get ___ → phosphorus gets released into ___ or into ___ -In water can end up settling out ___ ___ & over time can ___ and ___ ___ → is the ___ → will stay there unless there is some kind of ___ ___ -In soil: can be taken up by ___; when plants eventually ___ it can be put back into soil; some can be ___ ___ into water

freshwater systems weathered soil water into sediment compact & form rock sink geologic uplift plants decompose leached out

CO2 & Global warming: -CO2 levels in Northern Hemisphere winter are ___ -Once seasons flip & get into spring/summer, then increase in ___ ___ → ___ ___ → carbon dioxide levels ___ ___

higher primary production more photosynthesis go down

Nutrient spiral through streams: -How fast the spiral is going depends on ___ ___ ___ ___ ___ -Nutrients get washed from ___ ___ to a ___ ___

how big the stream is small stream bigger stream

Hubbard Brook Experimental Forest: •___ ___ increase nutrient transport and so does ___ ___ ___ ___ -Part was forested & part was deforested -Affected ___ ___ -Streams flowing out of deforested area ___ in ___ ___ ___ -Affected ___ ___ -Looking at concentration of nitrate ___ ___ ___

human populations type of land use stream flow increased rate of flow nitrate concentrations in those streams

-Winter: some ___ maybe -Spring: ice thaws, later in spring start to get ___ ___ -Summer: ___ ___ -Fall: thermocline ___ ___ -Light peaks in ___ ___, ___ ___

ice slight thermocline biggest thermocline goes away late spring, early summer

Hubbard Brook Experimental Forest: -In deforested basin, nitrate levels ___ more than ___ control basin -Main point: ___ ___ of nutrients into stream after ___ the forest b/c plants were ___ ___ ___ ___ & ___ ___ ___ into the streams -___ ___ ___ in deforested areas b/c plants ___ ___ ___ ___ -More populated rivers increases ___ (___)

increased 10x big flush cutting taking up less nutrients & getting washed out higher erosion rates hold soil in place nitrate (nitrogen)

CO2 & Global warming: -Has to do with amount of ___ ___ that's on the earth -More land in the ___ ___ → more ___ ___ here -When it's winter time in ___ ___, there are less plants ___, ___ ___ plants are lower in ___ so they ___ ___ ___

land mass Northern hemisphere terrestrial plants Northern hemisphere photosynthesizing Southern Hemisphere abundance can't keep up

•Decomposition rates have a negative relationship with ___ •Positive relationship with ___ -The more lignin you have in the plant, the ___ it decays -As N content increases, decomposition rate ___ -As lignin content increases, decomposition rate ___

lignin %N slower increases decreases

Factors that influence decomposition rates: •Leaves with higher ___:___ ratios lost ___ ___. •___ availability •___ ___ ___ & ___ may also play a role. •___ ___ ___ •___ ___ may increase decomposition rates. •___ ___ also matters -Peaks in decomposition rates throughout the day; has to do with ___

lignin:nitrogen less mass oxygen higher environmental temps & precipitation time of day N availability soil acidity temperature

Decomposition is a complex process involving a variety of organisms: •Nutrients ___ ___ ___ ___. •Need to be released ___ ___ ___ for use by other taxa.

locked up in tissue back to environment

Several factors influence the rate of decomposition: •Because lignin is a ___-___ energy source, the proportion of ___ within lignin-based compounds is used as an ___ of ___ ___ ___

low-quality carbon index plant litter quality

Decomposition rates vary throughout the day, follow temperature: -if its hotter, fungi breaking stuff down ___ ___ b/c ___ ___ ___ → ___ decomposition rate

more rapidly higher metabolic rate higher

Nutrients in organic matter are mineralized during decomposition: •Mineralization is the process through which microbial decomposers convert ___ and other elements from ___ ___ into ___ (___) ___ •These decomposers also need ___ for their own ___ & ___ •Immobilization is the ___ & ___ of mineral nutrients by microbial decomposers

nitrogen organic compounds inorganic (mineral) forms nitrogen growth & reproduction uptake & assimilation

The nitrogen cycle: -Nitrogen in form of ___ ___ in the pool → plants ___ ___ ___ → converted by ___ ___ ___ into ammonium → ___ ___ convert ammonium to nitrite or nitrate → taken up by ___ & passed to ___ ___ ___ ___ -Plants like to use ___ -When plants die, nitrate can be released ___ ___ ___ & converted back to ___ -A lot of recycling of nitrogen in the ___

nitrogen gas can't use it nitrogen fixing bacteria nitrifying bacteria plants animals that eat it nitrate back into soil ammonium ocean

The phosphorus cycle: •Sink is ___ ___ (P lost in ___ ___ ___) •Pool in ___ ___ •Incorporated by plants as ___, then ___ •PO4 causes ___ ___ in lakes, accelerates ___ •Why phosphates banned in ___

ocean sediment runoff to oceans sedimentary rocks PO4 animals algal blooms eutrophication detergents

Which of the following influence decomposition rates?

pH, temperature, lignin, moisture, nutrients

The carbon cycle: •___ fixes carbon (___ CO2 in atmospheric pool) •C passed ___ ___ ___, or through ___ •___ of decomposers and ___ ___ ___ releases CO2 to ___

photosynthesis lowers up food chain decomposers respiration higher trophic levels atmosphere

The nitrogen cycle: •NO3 taken up by ___, passed to ___ •or NO3 ___ and passed back to ___ •or Fungi and bacteria convert ___ into ___ and it is ___ through the ___ ___

plants animals denitrified atmosphere NO3 NH3 recycled food web

Nutrient cycling: •Nutrient cycles have ___, ___ and can be ___ or ___ •Nitrogen cycle linked to ___ ___ •Different nutrients vary in sinks and pools, and effects of ___ ___

pools, sinks open or closed bacterial groups human disturbance

Plant species richness decreases with increasing soil acidity: •Acid soils have ___ ___ ___ and ___ -More acidic soils have ___ decomposition rates & so they have ___ nutrient levels in the soil → ___ plant species there

poorer nutrient levels & cycling slower lower fewer

Rates of decomposition: •Rate at which nutrients available to ___ ___ determined by rate of decomposition. •How do you measure decomposition rates? •Use ___ ___ to study decomposition in ___ ___. -Weigh bags @ start, let them sit for awhile, then weigh them again to see decomposition rate over time

primary producers litter bags temperate forests

Eventually nutrients travel to estuaries: -Estuary: where ___ meets the ___ -Freshwater is ___ ___ than salt water -Mississippi river has a lot of nutrients in it -Hypoxia: less than ___/___ of dissolved oxygen -Dead zone: bottom is ___ in oxygen & decomposers ___ ___ the oxygen leaving ___ ___oxygen for other organisms -Hypoxia occurs along ___ ___; hazardous for any ___ ___, ___, ___ that can't escape it

river ocean less dense 2mg/L low use up very little sediment surface benthic inverts, worms, clams

The sulfur cycle is both ___ & ___

sedimentary & gaseous

Relationship between %N & decomposition: -More nitrogen loaded tissues → ___, ___ ___ ___, ___ to digest, ___ to decompose -___ leaves with low nitrogen content lose ___ ___ → decompose ___ ___

softer, not as tough easier easier tough less mass more slowly

Decomposition slower in anaerobic environments: -can come into play in ___ -___ in lakes -Decomposers → ___ -In anaerobic environment, don't have ___ they need to break down plants as easily so decomposition rate is ___

soil hypoxia fungi oxygen slower

The oxygen cycle is largely under biological control: •The major source of oxygen (O2) that supports life is ___ ___, generated by two processes -___ ___ ___ ___ = 2 H2O → O2 + 4 H+ -___ ___ •The expectation is that oxygen lost to ___ ___ and gained from ___ would balance out, but this is ___ ___ ___ •The ___ of oxygen must have exceeded its ___ at some point in the past, giving an ___ ___ of oxygen in the atmosphere

the atmosphere breakup of water vapor photosynthetic production aerobic respiration photosynthesis not the case input loss overall abundance

Temperature and moisture also important: -Temperature: decomposition rate is faster in warmer climates (longer season, higher metabolic rates)

warmer climates (longer season, higher metabolic rates)

Nutrients in a lake: -layers -sun beats down on surface waters & ___ surface water up -So there is a ___ in the summer -B/c upper layer is ___, it is ___ ___, so it is ___ on top of hypolimnion → ___ ___

warms thermocline warmer less dense floating not mixing

Higher rate of decomposition in ___ ___

wetter climate

The carbon cycle: •No longer a closed cycle, because -Harvesting the ___ ___ -Generation of CO2 by ___ ___ ___

world's forests CO2 burning fossil fuels