BIOEE 1610 Final

Why does N fixation occur in low-productivity oceanic waters, but not in productive estuaries and coastal waters?

All cyanobacteria grow slowly in seawater (molybdenum constraint), but slow growth per se OK, as long as little grazing. In productive coastal waters, upwelling ecosystems, etc., generalist zooplankton grazers consume cyanobacteria (mistaking them for large chains of algae, which are abundant) In low-production oceanic waters, generalist zooplankton are very small, since most phytoplankton are small; they are too small to consume the cyanobacteria (which are much larger)

Rauto

Autotrophic Respiration: the proportion of GPP that's consumed and respired away by primary producers (autotrophs) and is lost by the ecosystem as respiratory heat for their own maintenance

Trophic transfer efficiency

CE x AE x PE represents the % of energy (or organic matter) that's transferred from one trophic level to the next Lindeman 10% "law" trophic transfer efficiencies in aq ecos are generally greater Trophic energy transfer efficiencies vary from far less than 1% to 20% or so. In aquatic ecosystems, the average is indeed approximately 10%, on average. Generally far lower in terrestrial ecosystems. ->because primary producers in aquatic systems have better food quality (more protein, less hard to digest structural material) ... warm blooded animals are inefficient and invertebrates are the most efficient

iClicker: Which of the following best characterizes the consumption efficiencies in terrestrial ecosystems?

Consumption efficiencies are 50% for aquatic ecosystems, only half of this amount in grasslands, and lower yet in forests

Why is NEP negative in the deep oceans and streams/rivers?

Deep oceans: no GPP in deep ocean, just RH Streams/rivers: respiration exceeds GPP...GPP often low in streams (due to shading) & Respiration (RH) can be high, driven by microbes and animals consumer dead leaves.

N cycle inputs/outputs

External inputs: deposition of N2 from the atmosphere ("acid rain," plus gases**), inputs from upstream waters, mixing from deep ocean waters, plus N fixation Exports: in waters flowing downstream (largely as nitrate dissolved in water bc nitrate much less adsorbed in soils than is inorganic phosphate and can flow in groundwater), sinking out of surface ocean, etc., plus loss of N2O gases Internal recycling of nitrogen always greater than the rate of N fixation (and usually greater than other external inputs)

P cycle inputs/outputs

External inputs: deposition of dust from the atmosphere, inputs from upstream waters, mixing from deep ocean waters Exports: in waters flowing downstream, sinking out of surface ocean, etc... largely by erosion of particle-bound P In most ecosystems, the rate of recycling through mineralization far exceeds weathering and rates of external inputs the rate of P flow globally 3x greater now than before the industrial and ag revolutions -> fertilizers, P components in detergents, desertification (↑ P dust in atm)

Factors limiting terrestrial primary productivity

Land: - solar radxn, CO2 (only significant at a global level, not comm level), water, soil nutrients, and temperature water(precip) and temperature(light) are critical factors -> why trop rainforests are LIT for NPP -> spring/summer usually ideal - Top-down grazing by animals ("Why is the world green").... may lead to rates 25% higher or lower than the mean rates set by light and water ideal conditions only reach 3-10% efficiency (terr ecos use radxn inefficiently), natural conditions even less, particularly in desserts NPP approx 1/2 of GPP IN TERR ECOS (half of total photosynthesis is being used by the plants to meet their metabolic needs) (not true for aq ecos where relationship of NPP to GPP depends upon light and mixing depths)

Where is NPP the highest?

Land: the tropics Aq: low at tropical latitudes, greater at higher latitudes

iClicker: Aquatic ecosystems with high nutrients select for

Large phytoplankton with low surface to volume ratio (less need for enzymes to take up nutrients) -> smaller food chains & less biodiversity Short food chains are efficient, so high production of fish per unit of primary production/more efficient food chain w less trophic levels

How do humans influence NPP?

More than 1/3 of ice-free land is used for agriculture NPP↑ with the length of the growing season NPP can be influenced by [limiting] nutrient resources (N or P fertilizer) (without humans) slightly more than 1/2 NPP on land, slightly less than 1/2 in aquatic ecosystems -> the average rate of NPP/area is higher on land, but the oceans cover 70% of Earth's surface

What is the biggest pollution problem in coastal marine ecosystems?

N P is a bigger problem in freshwater lakes

Nutrient limitation in estuaries and coastal marine systems

N usually limiting - bc of the relative lack of N-fixing cyanobacteria & mixing with coastal marine waters, which are much more N limited eutrophication worsened in these systems w ↑N input

iClicker: Which of the following best describes the relationship of NPP to GPP in aquatic ecosystems (planktonic)?

NPP can be as high as 95% of GPP, is quite variable across ecosystems, and can even be negative

Net primary productivity (NPP)

Net rate of organic matter production by autotrophs / the actual productivity available for consumption by heterotrophic organisms or higher trophic levels (bacteria, fungi, animals, human harvesting) GPP-Rauto (the respiration of plants or algae carrying out photosynthesis) approx 1/2 of GPP IN TERR ECOS (half of total photosynthesis is being used by the plants to meet their metabolic needs ) importance: - communities and ecosystems are dependent on the energy of NPP organisms - global carbon cycle (stored carbon in trees) the rate varies: - highest NPP in tropical rainforests, wetlands, estuaries, and giant kelp beds (largest in subtropical gyres)

iClicker question: The year-to-year variation in CO2 uptake by oceans and land is

Not well understood at all, but seems real, and probably due to climatic influences on both the oceans and terrestrial ecosystems. ocean: Change in ocean conveyor belt, due to changes in precipitation, ice melting, and river runoff from year-to year. Also, changes in NPP and NEP in high latitude waters, as wind-driven mixing of surface ocean waters varies? terr: Change in NEP, as NPP and respiration respond to differences in temperature and precipitation

iClicker: Which of the following best describes how your textbook discusses the relative importance of nutrients as a factor controlling NPP in aquatic ecosystems compared to terrestrial ecosystems?

Nutrients far more important in aquatic ecosystems

Mineralization

Organic matter -> inorganic matter Inverse of immobilization how do they balance each other? As organic matter is decomposed, carbon is respired and released to atmosphere as CO2...The nitrogen and phosphorus (and potassium, calcium, iron, etc.) in the organic matter is released to the environment. essential in supplying nutrients for net primary production

Major causes of extinction

Over-exploitation

no-take zone

area where there's no fishing aloud must be sufficiently larger than home region of fish in order to be effective, but most are inadequate size focused on local areas, little protection against global and regional threats to many ecosystems should be around 12.5 times the area of the species' home range, in order to keep fishing pressure on the population within the MPA at 2% or less of the pressure outside

Ocean acidification

as ocean waters take up more CO2, they become more acidic now 30% more acidic than pre Ind Rev ecological disruption: pH drops makes it impossible for for sea creatures with shells and structures composed of carbonate minerals (corals, clams, oysters, etc.) to excrete carbonate

When are global CO2 concentrations the highest? Why?

at the end of winter in the N hemisphere, uptake highest in N hem summer bc of dominance of respiration over GPP in the winter N hem oscillates more than the S hem

The use of fossil fuels fixes N inadvertently

atm N2 and O are not stable together chemically, heat causes minimal nitrification reaction...so burning ffs catalyzes this reaction e.g. auto exhaust

Live consumer system

autotrophs->herbivores-carnivores

Decomposers

bacteria and fungi

Terr CO2 sinks

balance bxn NPP and NEP/heterotrophic respiration partly results from net accumulation of organic matter in biomass and soils during forest succession -> as forests grow, GPP > eco resp -> NEP ↑ approximated by the known amounts of C emitted and how much remains in the atm

Connection between CO2 and global warming was first proposed

by Svante Arrhenius 100 years ago

Methane

byproduct of using natural gas as a source of energy...more than 1/2. Nat gas makes up 20% of ff use. absorbs infrared radiation at greater wavelengths than other greenhouse gasses, so it's a far more potent, yet it has a much atmospheric concentration catalytic role in producing ground level ozone human alteration of the methane cycle is far greater than for CO2 (human activity since the Ind Rev has more than doubled the methane atm concentration, CO2 only a 40% increase) lasts less time (abt 12 yrs) in the atm than CO2 (abt a century) natural sources: - produced biologically and seeps into ancient geological formations - most of its flux comes from Oxygen-free decomposition-->methanogenesis

Pesticides

chemicals used to control pests developed simultaneously w synthetic N fertilizer control target pests in particular times + places most polluting when they're unselective, persistent, and and biomagnify in food chains

Secondary productivity

rate of production of biomass by heterotrophs there is a general positive relationship bxn primary and secondary productivity (as PP increases, there's more plant life to be created by heterotrophs so they can create their own biomass) by herbivores, always less and often far less bc of low efficiency - much dies and supports decomposers - not all biomass that isn't eaten by herbivores is available for incorporation into consumer biomass - some lost in feces - not all the assimilated energy was actually converted into biomass, some lost in R heat

Molybdenum

required for nitrogen fixation Low molybdenum availability in seawater does not completely stop growth..... Slows growth, making cyanobacteria more vulnerable to grazing mortality...essentially blooms are prevented in seawater the high availability of Molybdenum in freshwaters allows cyanobacteria blooms

Closed ecosystem

reutilization of available material colimitation by N and P more common e.g. subtropical gyres (no input/output of matter or energy w surrounding ecosystems)

iClicker question: The major sinks of carbon that are slowing the accumulation of CO2 in the atmosphere are

roughly 50% by forests and 50% by oceans

Future of terr CO2 sinks

significant year to year variability in uptake

The Carbon cycle

split by CO2 and methane

Complementary selection

starting off with the single best site, then adding sites complementary to the ones already selected

Liquid biofuel

substances like ethanol or hydrocarbons that can substitute for gasoline or diesel oil make superficial sense/work politically, but ecological consequences can be v high and actually aggravate global warming ethanol comes from crops that could be used for food (e.g. corn and sugar) super inefficient, esp for corn (energy loss during fermentation) causes more air pollution than gas and leads to ↑ levels of water pollution as ethanol use ↑ -> N pollution ↑by 30+% in the Mississippi River indirect land use consequences that can ↑ gg emissions bigger footprint than other renewable energy sources What is the greenhouse gas impact, relative to using fossil fuels? Carbon neutral, since when burned just releasing back the CO2 captured by the crop during photosynthesis?

Future of oceanic CO2 sinks

surface waters warming -> CO2 solubility ↓ ↑ earth temperature -> warmer waters -> glacial melting -> less salty waters -> slow N Atl sink -> slower rate of uptake -> ↑ earth temps

What types of nutrient limitation are most common where

temperate grasslands and forests - limitation by N or colimitxn tropical forests and savanna's - limitation by P polar regions (e.g. boreal forests and tundra) and deserts - limitation by N alone younger soils - N most limiting (Plenty of available P in the very young soils on volcanic rock, less N fixation) older soils - P most limiting (Plants that have nitrogen-fixing symbionts are favored, and over geological time, they increase the amount of nitrogen to all plants)

Standing crop

the bodies of the living organisms within a unit area constitute a standing crop of biomass

Methane "sink"

the chemical alteration of it to other compounds largest" photooxidation in the atm, which oxidizes methane to CO2 and H2) methane's rate of input into the atm is roughly equal to its sink

Nitrogen cycle

the continual transformation of N including assimilation into biomass and mineralization back into ammonium humans have disturbed the balance of the cycle whereas the P cycle is more geologically controlled, the N cycle is more so controlled by bacterially mediated processes Internal recycling of nitrogen always greater than the rate of N fixation (and usually greater than other external inputs)

Assimilation efficiency (AE)

the efficiency by which animals convert the food they ingest into energy for growth + reproduction the remainder is lost as feces -> decomp system hard to find the AE of microorganisms (no food or feces)

Decomposition

the gradual disintegration of dead organic matter brought about by physical and biological agencies includes release of energy and mineralization of chemical nutrients

Radiative forcing

the imbalance between incoming solar radiation and outgoing infrared radiation that results in global warming

Oceanic CO2 sinks

the net uptake of CO2 in oceans is known w relatively high precision bc the mixing of waters makes the oceans easier than terr fir taking samples in a representative way ... but the future of these sinks is know w less precision CO2 soluble in water, but warm waters release CO2 back into the atm whereas cold waters absorb it net uptake about 2.3 pg/year high uptake during NPP, low during het resp Great Oceanic Conveyor Belt (esp. N Atlantic sink) v important... only sinks C for about 11 years and then it rises again to the surface

Methanogenesis

the production of methane by bacteria in the absence of oxygen e.g. in animal guts and termites & wetlands (as the salinity of wetlands↑, the atm methane flux dramatically ↓ these bacteria can't outcompete oxygen-respiring bacteria when they're present

Primary productivity

the rate at which biomass is produced per unit area or volume through photosynthesis/the total amount of plant (or algal) material produced or energy captured per surface area per time like biomass, can be expressed as many different units on different time scales a succession of factors may limit primary productivity through year and season Importance: - all organisms need energy -> PP is a source of that energy, which is needed to maintain order in the eco (2nd law of thermodynamics)

Stoichiometry

the relationship between the abundances of elements in organisms

Biogeochemistry

the science that addresses the "biotic controls on chemistry of the environment and the geochemical control of the function of ecosystems" AKA the biotic control of the chemistry in an environment

Carbon compounds

the second most substantial thing that living things are made of energy accumulated and stored enters the food web/community as CO2 -> photosynthesis -> (NPP) -> sugar/fat/protein compounds/cellulose molecule -> (consumed)

Gross primary productivity (GPP)

the total fixation of energy by photosynthesis / total amount of photosynthesis per surface area per time / Total rate of CO2 fixed into organic matter per unit time represents total ecosystem photosynthesis a proportion of this, however, is respired away by primary producers(autotrophs) themselves and is lost by the ecosystem as respiratory heat (Rauto) -> total photosynthesis is about 1/2 respired by plants on terr ecos Carbon only accumulates in an ecosystem when GPP > the rate of whole ecosystem respiration

Problems with pesticides

toxic to non-target species drift out of targeted areas persistence in the environment beyond their target time (env pollutants)

Nitrogen

unique nutrient bc limiting in most ecosystems yet super abundant in the inaccessible N2 form this N2 must be fixed into ammonium

Sources of nutrients/inputs to terrestrial ecosystems

weathering of parent bedrock and soil (particularly in young soils) (Dominant input route for: P, Mg, Ca - more important for P) atmospheric deposition: net flux of materials from the atm to the ecosystem (dryfall and wetfall) uptake by vegetation and some cyanobacteria, e.g. nitrification Rate of nutrient input depends on: - Composition of initial parent material (Limestone? Shale? Granite?) - Extent of past weathering (intensity, duration)

Planktonic cyanobacteria

• Commonly fix nitrogen in lakes and ponds • Are very important components of low productivity sub-tropical gyres (cyanobacteria can thrive there bc primary herbivores are too small to eat the cyanobacteria in subtropical gyres, which are much larger than other phytoplankton there) • Are absent from virtually all estuaries and coastal marine ecosystems globally (unless very low salinity) • Are absent from upwelling ecosystems, high-latitude waters, and other ocean systems with moderate to high rates of net primary production.

Why study ecosystems?

• in general, need to study next lowest scale of organization to gain understanding of underlaying mechanisms at the scale of interest. • ecosystems are the appropriate scale for understanding functioning for many purposes of environmental management, including effects of pollutants and response to global change.

Nutrient limitation in subtropical gyres

↓↓NPP NPP colimited by N and P, tho P has a lower concentration and is thus more limiting -> Redfield Ratio - N:P 15:1

Production efficiency (PE)

% of assimilated energy incorporated into new biomass remainder lost as R heat varies depending on the taxonomic class of the org

Consumption efficiency (CE)

% of total productivity available at one trophic level that's consumed by the trophic level above For primary consumers, CE is the % of Joules produced per unit time and area as NPP that finds its way to the guts of herbivores For secondary consumers, % of herbivore productivity eaten by carnivores The remainder dies without being eaten and enters the decomposer system

Decomposers efficiency

(bacteria & fungi) often have efficiencies of 40 to 50% Not investing any energy in temperature control, or searching for food.... Although may produce a lot of enzymes released to the environment to help get food

iClicker: Why should ecologists be interested in NEP?

- Negative rates of NEP in agricultural systems reflect a loss of organic matter that can lead to degrades soils - High rates of NEP in natural ecosystems can store carbon, helping to mitigate global climate change -> Organic carbon can be accumulating from positive rates of NEP in tree trunks, soils, or both (forests are important) - Global climate change may change NEP in natural ecosystems, leading to feedbacks that may slow or accelerate global change

Why are ecologists be interested in NEP AQUATIC ECOSYSTEMS?

- Water quality concerns (low dissolved oxygen) - Transfer of organic matter across ecosystem boundaries, with this organic matter fueling "detritus"-based food webs - Storage of carbon in oceans, mitigating climate change (as with terrestrial ecosystems, except storage is largely inorganic, with organic matter transfer to deep sea serving as one vector for carbon dioxide in deep sea)

Current rate of extinction

10% of species per decade

iClicker: How much of the energy of GPP do you think plants respire for their own metabolic needs?

50% or so on average

Liebig's Law of the Minimum

A plant's growth is limited by the one essential mineral nutrient that is in the relatively shortest supply Barrel analogy Realized N was limiting

iClicker: Which of the following best characterizes the production efficiency for fish?

Fish spend more energy than zooplankton in searching for their food, which gives them a far lower production efficiency (10% rather than 40% for zooplankton)

Net ecosystem productivity (NEP)

GPP - Rtotal (Rauto - Rhet).... NEP = NPP - Rhet measures the net rate if accumulation or loss of organic material, energy, or carbon from the ecosystem High soil carbon and high plant biomass both suggest positive rates of NEP NEP can be negative in some terrestrial ecosystems, at least for a while...Respiration (RH) usually higher than GPP in agricultural ecosystems newly converted from natural ecosystems. This reflects a loss of soil organic carbon. & immediately after disturbances

GPP in aquatic systems

GPP is a function of light, and so decreases with depth as light decreases

iClicker: Which of the following is the greatest threat to biodiversity?

Habitat loss Much of this is direct disturbance (agriculture, urban/suburban sprawl), but remember nitrogen pollution One approach to addressing threat of habitat loss: Protected Areas to conserve important habitat. ...Not surprisingly, biodiversity globally has continued to go down despite more area covered by protected areas

How do disturbances affect nutrient cycling?

Hubbard brook Export of materials increased dramatically in clear cut watershed Uptake by plants stops, but mineralization continues, so inorganic N builds up and is exported downstream

Constraints on primary productivity in aquatic biomes

Interaction of nutrients and light Nutrient limitxn more significant in aq systems than terr systems because recs are more scarce in aq systems & land plants have more structural carbon NPP high in upwelling systems, low in subtropical gyres (bc nutrient availability differences!)

iClicker question: The annual oscillation in the "Keeling" curve is best explained by

a seasonal effect on carbon dioxide uptake and release by terrestrial ecosystems, with greater uptake during the northern hemisphere summer.

Nutrient limitation in freshwater lakes

P limited when there's↑ P input -> ↑P concentration -> ↑NPP excess inputs lead to damage via eutrophication used to think it was C-limited when did the experiment in the Erlenmeyer flask, but after doing a full lake experiment found out it was actually P

Heterotrophic Respiration (RH)

Rate of respiration (organic matter consumption) by all heterotrophs (microbes, herbivores, detritivores, carnivores)

Aquatic ecosystems with low nutrients select for

Small phytoplankton with high surface to volume ratio (lot of sites for enzymes to take up nutrients relative to mass of chlorophyll) -> longer food chains & more biodiversity Long food chains are inefficient, so less production of top predator fish per unit of primary production

Temperatures effect on NPP (terr)

Temperature has a major influence on both water and nutrients...NPP increases as temp increases - physiological process of photosynthesis - relationship between temperature and evaporation (evap↑ as temp↑ -> higher temperatures mean lower H2O availability -> ↓NPP) - decomposition↑ as temp↑ -> higher rate of released nutrients -> NPP↑

What are biomes structured on?

Terr: water and temperature Aq: light and nutrients

Paris Accord target

aims to keep temperature change "well below 2º C " Clear recognition that warming beyond 1.5o C is dangerous

Nitrification

ammonium -> nitrate used by autotrophs, resulting energy of the N conversion is used to fix CO2 into biomass N2O (greenhouse gas) is a byproduct of nitrification and denitrification

Detrivores

animals that consumer dead matter

iClicker: Considering all of the potential feedbacks to a changing climate, which of the following best describes how the terrestrial carbon sink may change in the future?

The net effect is hard to predict, and climate scientists do not agree

Nitrogen fixation

The reduction of molecular N2 to biologically available forms of nitrogen Carried out by a variety of bacteria Essential to all life on Earth About half of N fixation is in oceans, half on land... highest in tropical regions and savannas -> P more limiting in tropical regions (reason the Amazon is so productive is that is gets a ton of P dust being blown from the Sehel Desert) very low in boreal/polar regions -> N more limiting in polar regions Internal recycling of nitrogen always greater than the rate of N fixation

iClicker: In 2016, ethanol from corn makes up approximately 0.8% of energy use in the US. What percentage of the US corn harvest went to produce this ethanol?

approximately 40% This ethanol contributed 0.8% of the nation's total energy Several models indicate national ethanol policy will make the national goal to reduce nitrogen pollution down Mississippi River by 45% to limit size of dead zone difficult or impossible, and instead nitrogen pollution likely to increase.... 30% to 40% or more

Target pest resurgence

When pesticide treatment kills large #s of the pest AND its natural enemies -> secondary pests released from natural control and more pests rise

Does low Fe limit ocean NPP?

Yes, particularly in "high nutrient, low chlorophyll" (HNLC) regions During 1980s, improved sampling techniques showed that dissolved iron (Fe) concentrations in oceans are thousands of times lower than previously thought. John Martin

Does the Redfield ratio apply to aq ecos too?

Yes, phytoplankton in the world's oceans (and lakes) have a relatively constant ratio of carbon, nitrogen, and phosphorus (C:N:P = 105:15:1) Slight N deficit, but this is made up by nitrogen fixation in surface waters

iClicker: Which of the following best characterizes the production efficiency for zebras?

Zebras and other warm-blooded animals use a lot of energy for thermoregulation, giving them a very low production efficiency (~ 3%)

Microbivores

a group of animals that operate alongside the detrivores and can be difficult to distinguish from them specialist microbivores feed on bacteria and fungi, but most detrivores consume detritus too terr: classified according to size freshwater: classified less by size and more by the ways they obtain food...(shredders shred tree leaves to finer particles; collector-filterers eat on the finer particulate matter that would otherwise be carried downstream)

CO2 sinks

a reservoir that takes up a chemical element or compound from another part of its natural cycle critically important for reducing the impact of fossil fuel combustion... without them CO2 concentration ↑ much faster less than 1/2 of emitted CO2 stays in the atm because if them future of global warming is tied to the sinks, the trajectory of global warming will change if the sinks change

Integrated pest management

combines physical control (simply keeping pests away from crops), cultural control (rotating crops in field so pests can't ↑), biological and chemical control, and the use of resistant crop varieties pesticides are used sparingly each case is different, no 2 pest situations are the same

Ecosystems

community of organisms interacting with the physical-chemical environment E.g. entire lakes or ponds, entire bogs or marshes, entire forests or defined parts of forest, entire pieces of oceans... Considered as a functioning unit. Boundaries are defined.

Phytoplankton respiration (RA)

constant over depth Note that turbulence and flows of water move phytoplankton throughout the mixed layer - important for photosynthesis

Nutrient limitation

constraint on rate of NPP by one or more nutrients Caused by a low availability of the limiting nutrient relative to the needs of the plant to produce its biomass Generally, nitrogen (N) and phosphorus (P) are the nutrients most likely to be limiting Optimal ratio of nitrogen to phosphorus (N:P) in plants is 15:1 (by moles, +/- 5) NPP is N-limited, if environmental availability is <10:1, and P-limited if environmental availability is >20:1

Transfer efficiencies

consumption efficiency (CE), assimilation efficiency (AE), and production efficiency (PE)

Decomposer system

fraction of the NPP that's not eaten by herbivores passes through it faster at higher temperatures High soil carbon often reflects low decomposition due to low temperatures

Phosphorous cycle

geologically controlled as trace amounts of P in rocks are weathered down to soil as a "geologic" cycle; no gas phase transfers; phosphorus stays in same oxidation-reduction state

Biogeochemistry cycles

global P cycle, climate change (tied to the global C cycle), and ocean acidification (tied to the global C cycle).

Mauna Loa

has measured global CO2 atm concentration since 1958 location minimizes variation in concentrations associated with metabolism within a forest canopy, thus is more likely to reflect global data and long term trends The Keeling Curve

Sulfur

important in the decomposition of sediments in marine coastal ecosystems component of many essential amino acids (essential for life) rarely limits prim prod bc of relatively high abundance human activity has doubled the amount of S in atm -> increased deposition in terr ecos comes from burning fossil fuels -> acid rain (diluted sulfuric acid) is a growing problem, especially in China -> loss of fish, forest diebacks, loss of plant species

Open ecosystems

input/output of matter and energy with surrounding systems external outputs less likely to meet balanced needs of primary producers -> usually limitation by a single element depending on the relative inputs of N and P e.g. coastal salt water marshes (↑ rates of exchange of water with adjacent estuaries through tidal action)

Aquatic system inputs and outputs

largely depend on how open or closed the system is atmospheric inputs become more important in larger lakes because it's a closed system estuaries receive nutrients from upstream and downstream (reverse estuary flow) deep-ocean nutrients and atm deposition dominate nutrient sources in the ocean biomes away from shore

Nutrient outputs for terrestrial ecosystems

rate of loss greater in open ecosystems can take years to minutes streamflow of C, P, and Fe particles, N in dissolved form release into the atm affected by vegetation...clearcutting forests

Biological control

manipulate the natural enemies of a pest to control it

Biomass

mass of organisms per unit area of ground (or water) usually expressed in units of energy (e.g. Joules/sq. m.), dry organic matter (e.g. grams per sq. m.), or mass of carbon (g of C/sq. m.)

Hot spots/regional variation in N pollution

mostly in India, Eastern China, Eastern US, and Brazil corresponds with major ag areas bc they have the greatest use of fertilizer DOES NOT correspond to regions w the highest rate of N fixation

Atmospheric deposition (terr)

net flux of materials from the atm to the ecosystem 2 main components: - Dryfall: settling of particles during periods without rain - Wetfall: flux of materials dissolved into rain and snow

Denitrification

nitrate -> molecular nitrogen (N2) happens constantly from bacteria aerobic respiration ... only occurs largely in environments devoid of Oxygen as a form of respiration when bacteria switch to use nitrate instead of Oxygen in their respiration Globally important bc it removes biologically available nitrogen N2O (greenhouse gas) is a byproduct of nitrification and denitrification the oceans dominate denitrification (happens in the sediments of the continental shelf)

Nutrient recycling

nutrient elements are available to primary producers as simple, inorganic molecules and ions in the atm, soil, and water -> assimilated/incorporated into complex organic compounds in biomass during primary production -> metabolized + released back into the environment for reuse important bc nutrient resources on Earth are finite

Immobilization

occurs when an inorganic element is incorporated into organic form, often during primary production e.g. CO2 -> plant carbohydrates energy required from the sun inverse of mineralization

Economic injury level (EIL)

pest control usually doesn't try to eliminate pests, but rather reduce the pest population to a level where further pest reduction would cost more than would be gained by the increased yield

Colimitation

phenomenon in some ecosystems in which both N and P are limiting to production

Consumption efficiencies for herbivores

plankton systems = 50% grasslands = 25% forests = 5%