ESS 311-Ecosystem Ecology Midterm

NPP

Net primary production is the net carbon gain by all the plants in an ecosystem that produce net useful chemical energy; it is equal to the difference between the rate at which the plants in an ecosystem produce useful chemical energy (GPP) and the rate at which they use some of that energy during respiration.

NEP

net ecosystem production

-on a short time scale, it is the balance between GPP and respiration that dominate the carbon balance of terrestrial ecosystems

DOC

dissolved organic carbon

DOM

dissolved organic matter

Heterotroph

organism that obtains food by consuming other living things; also called a consumer

-organic carbon source

Autotroph

an organism that is able to form nutritional organic substances from simple inorganic substances such as carbon dioxide.

-inorganic carbon source

catabolism

the breakdown of complex molecules in living organisms to form simpler ones, together with the release of energy, destructive metabolism (energy generating metabolism)

-biogeochemistry

anabolism

the synthesis of complex molecules in living organisms from simpler ones together with the storage of energy, constructive metabolism (biomass building metabolism)

-food web ecology

ecosystem ecology

An interconnected set of living and non-living components existing in a defined set of boundaries and is scale independent

Primary controls (global scale) on ecosystem processes?

-solar radiation

-climate

1. What is climate? 2. What drives climate globally? 3. What drives climate locally?

1. average weather patterns over a long period of time that are associated with a specific locality

2.

-energy budget (solar inputs vs losses from Earth)

-atmospheric composition (CO2, clouds, aerosols)

-dynamics of water movement (hadley cells)

-Earth surface characteristics (mtns, aspect)

-Milankovitch cycles

3.

-spatial distribution of land, water, mountains

-Mountain Ranges (rainshadow effect)

-slope/aspect

-lakes

What is the difference between biogeochemistry, food web ecology, and ecosystem ecology?

biogeochemistry: biological interactions with chemical processes in ecosystems

food web ecology: the natural interconnection of food chains (food energy)

ecosystem ecology: An interconnected set of living and non-living components existing in a defined set of boundaries and is scale independent

Why were some of the earliest ecosystem ecologists limnologists?

lakes were a great tool for studying ecology because they had boundaries

-isolated units

-interconnection of organisms

1.What is a pool? 2.What is a flux? How do the units between each differ?

1. when a chemical has a high residence time in a certain area whether that's in the soil, organisms or atmosphere, the amounts are measured in mass.

2. the rate of change between pools, measured in mass per unit of time

What are the three tools that ecologists use to study ecosystems? Please give an example of each.

-observe: taking measurements, natural world

-experimentation: hold things constant (limnocoral experiment, experiment lakes with David Schindler)

-theoretical: relationship between things that matter most, mathematics (net eco-production, logistics)

How is the sun's energy partitioned once it enters the earth's atmosphere?

-absorbed/reflected by the surface (albedo)

-photosynthesis

-greenhouse gases absorbing it

-low clouds reflecting incoming radiation that cools Earth

-high clouds that absorb radiation that warm Earth

-earth's energy budget: balance between incoming/outgoing radiation determines energy availability to drive Earth's climate system

-atmospheric circulation: wind patterns and ocean patterns

How does solar energy create climate?

-transformation of solar energy into chemical energy through photosynthesis creates geographically distinct biomes

-the disproportioned distribution of photon particles drives a disproportioned distribution of water that determines how many photons turn into plant biomass and cause a variety of patterns in productivity on land and in the ocean.

-precipitation and temperature

Explain Milankovitch cycles and their combined effect on the earth's climate.

-eccentricity: the earth orbits the sun as an ellipse (shorten and lengthens), its a 100,000 yr cycle

-obliquity: how tilted the earth's axis, relative to the sun, is (41,00 yr cycle)

-procession of equinoxes: northern hemisphere is toward or away from the sun (19-23,000 yr cycle)

effect on climate: how much solar radiation (how many/intensity of photons) hitting the Earth

How does the atmospheric composition interact with solar radiation and radiation emitted from the earth's surface to affect climate?

-methane, oxygen, N2O, water vapor, CO2 absorb outgoing terrestrial radiation at different wavelengths and re-reflect it, trapping radiation on the way out. Vibrational frequency is different for each gas (energy)

-clouds either reflect or trap radiation

-atmospheric turbulences rising from Earth's surface:

-latent heat flux (stored): the heat that evaporates water at the surface is released to atmosphere as air parcels rise and cool and water vapor condenses forming clouds/precipitation

-sensible heat flux (direct): upward transfer of heat thats conducted from warm surface to air immediately above it and moved upward by convection of the atmosphere as thermals

What are greenhouse gases? Define 5 and explain their relative forcing effect.

-methane, oxygen, N2O, water vapor, CO2 absorb outgoing terrestrial radiation at different wavelengths and re-reflect it, trapping radiation on the way out. They have long mean residence times in the atmosphere. CO2, N2O, CH4 react slowly.

What has atmospheric CO2 composition been doing in the past 200 years? What are the major drivers of atmospheric CO2 concentration?

increasing dramatically and the major drives are the increase in human population with correlation to surplus in fossil fuel burning, industrial activities, animal husbandry, and fertilized and irrigated agriculture

What are the effects of greenhouse gas concentration on local and global climate?

Globally: surface and sea-surface temperatures will rise; increases energy transferred to tropical storms and pH levels in oceans. Glacial melting; ocean levels rise

Locally: extreme natural disasters like floods, droughts, warmer weather in colder areas, wildfires

What are Hadley cells? How do they affect the earth's climate?

-driven by expansion and uplift of equatorial air and subsidence of cool dense subtropical air.

-tropical air masses between equator and 30 degrees N/S.

-subtropical high pressure zones have clear skies, drives abundant evaporation.

-large amount of latent heat released as this moist tropical air rises, expands, cools and releases heat by condensation of water vapor.

Define how each of the following affect local climate: mountain ranges, large bodies of water, slope, and aspect.

mountain ranges: rainshadow effect (dry area on one side of mountain, the mountain blocks the passage of rain-producing systems and casts a shadow of dryness)

large bodies of water: Asian Monsoon (warm water hitting the Himalayas and going back out)

slope/aspect: south-facing (equator) receive more radiation

What are the main drivers of NPP on land (large scale patterns)?

-biochemistry of photosynthesis controls carbon input to ecosystems

-exchange of H2O for CO2 limits productivity (e.g. C3, C4, CAM)

What are the main drivers of NPP in the Ocean? In lake ecosystems?

-autochthonous production=NPP originating within the ecosystem boundary (controlled by temp, nutrients, and light)

-allochthonous production= NPP originating from outside the ecosystem boundary (controlled by watershed size, land use and precipitation)

How do light and stratification affect biomass distribution of algae and photosynthesis within lakes?

-wavelengths of light are reflected/absorbed at different depths (alters wavelength of light)

-stratification is caused by differences in densities and those differences are created by temperature differences

-less light limits the NPP

How can vegetation affect local climate? Explain

-it influences local climate through its effect on the surface energy budget, how much CO2 is being taken in and oxygen being released

-also the release of water vapor during photosynthesis, alters surface energy fluxes and leads to cloud formation

-low albedo, absorbing radiation

Name the major "pools" of carbon on the planet?

-intermediate and deep oceans

-lithosphere: fossil fuels and sedimentary rock deposits

-SOM

-atmosphere

-biosphere

What is the relative and absolute size of each major pool of carbon?

-ocean: 37, 100 Pg C

-Soil: 1500-2400 Pg C

-Fossil Fuel:

gas: 383-1135

oil: 173-264

coal:446-541

-atmosphere:589

-ocean floor:1750

-surface ocean:900

-permafrost: 1700

What are the primary sources of greenhouse gases to the atmosphere?

methane, oxygen, nitrous oxide, water vapor, carbon dioxide

Name three GHG and identify their major emitters.

carbon dioxide: industries, fossil fuels

nitrous oxide: agriculture, energy use, industries

methane: agriculture and waste management

Which terrestrial ecosystem has the largest NPP? Why? Where are the hotspots of NPP in the oceans? Why?

terrestrial ecosystem: tropical rainforests (enzymes catalyse reactions faster in warmer/wetter weather)

oceans: shallow areas (coral reefs) warm, well lit surface

What factors influence NPP?

solar energy input, temperature, moisture levels, CO2 levels, nutrient availability, and community interactions

Differentiate between C3, C4 and CAM photosynthesis. Identify in which habitats each metabolism dominates.

C3 (angiosperms): uses the enzyme RuBisCO to fix CO2 from the air and obtain 3-carbon organic molecule

-cool, wet climates

-produce more ATP

-more photorespiration

C4 (grasses): separate two reactions

-taking in CO2 and fixing CO2/sugar in two different cells

-mesophyll cells take in CO2, while bundle sheath cells fixes carbon into suagrs

-takes more energy to transport 4 carbons to each cell (less ATP produced) =less photorespiration

-located in hot, sunny climates

CAM (succulents): the stomata take in oxygen all along the surfaces of their leaves, open during the day to take in CO2 and release O2.

-located in xeric environments

What are mycorrhizae?

symbiotic relationships between plant roots and fungal hyphae, in which the plant acquires nutrients from the fungus in return for carbohydrates that are the major carbon source for the fungus.

-increases volume of soil exploited by plants

What controls local nutrient supply in terrestrial ecosystems?

N and P

What is the relationship between leaf N and NPP? Why?

N limits NPP because its the most abundant component of the atmosphere and nitrogen fixation takes a lot of energy and nitrogen fixation is naturally carried out by bacteria.

-25% of leaf N can be in Rubisco and 25% in other photosynthetic enzymes

-thus photosynthetic bottleneck is sensitive to light and CO2 and N availability

What is the relationship between CO2 uptake and H2O release? Explain? How do plants deal with this trade-off? Give examples.

-As plants take in CO2 through their stomata, it allows CO2 into mesophyll cells

-when stomata opens, water diffuses out (if diffusion gradient is higher on the outside then inside, CO2 will work its way into cell).

-if the leaf has a higher water density than the air, water will diffuse itself out

-Plants deal with this through C3, C4, CAM photosynthesis

How is NPP allocated within a single plant?

growth, maintenance and reproduction

How do environmental conditions alter the allocation within a plant? Give examples.

temperature, precipitation, seasonality and nutrient availability can reduce or increase the rate of photosynthesis can influence the total carbon gain of the plant and therefore the rate of plant growth. In turn, the lower plant growth rates will reduce overall net primary productivity.

Which elements limit primary productivity in most ecosystems? Are most ecosystems limited by one or multiple elements?

N and P, yes most ecosystems are limited by one or multiple elements

What are the main sources of N and P to terrestrial and aquatic ecosystems?

N:

deposition (rain, snow, dust)

biological fixation of atmospheric N

abiotic fixation of atmospheric N

lightning

P: enters ecosystems from human and animal waste, fertilizer and mineral (apatite), weathering/mining

What is meant by "reactive" N?

the compound forms of N that plants are able to use, supports growth

-ammonium, nitrate, nitrous oxide

What is meant by N-fixation? What are the three principal pathways for N-fixation?

-atmospheric nitrogen is converted into a compound to be used

three principal pathways:

1. conversion of N2 to NH4 takes a lot of energy

-breaks 3 bonds (requires abundant energy)

2. Nitrogenase (principle enzyme in N-fixing pathway doesn't work in the presence of O2)

-nitrogen fixation is carried out by bacteria

-Symbiotic N fixation (legumes, alder)

-heterotrophic N fixation (rhizosphere and carbon-rich environments)

-phototrophs (cyanobacteria)

3. Biological: Bacteria (and archaea)

-free living forms in soil, sediment, water

-within nodules on roots of vascular plants

-in lichens as symbiotic association with fungi

4. Human manipulation

Which organisms are responsible for N-fixation? Give several examples.

-cyanobacteria

-humans manipulation

-legumes/alders

-lichen

-grazers

What is the Haber-Bosch process? How was it invented and how is it used today?

-the industrial implementation of the reaction of nitrogen gas and hydrogen gas (main industrial procedure to produce ammonia)

-invented by Fritz Haber

-used today to make fertilizer by Carl Bosch

What ecosystems does human produced reactive N affect today?

Coastal zones (dead zones off the Gulf of Mexico)

What are the major pathways in the P cycle?

weathering and mining

Where are the primary reserves of P on the planet today?

United States, China, Morocco, South Africa, and Jordan

What is mass balance? How does it apply to ecosystem ecology?

-any system closed to all transfers of matter, the mass of the system must remain constant over time, as system mass can't change quantity if it is not added or removed

-it ensures that carbon fromerly locked up in biomass must go somewhere

List examples of nutrient inputs, nutrient recycling, and nutrient loss from ecosystems.

-inputs: fossil fuels released large quantities of nitrogen and sulfur oxides to the atmosphere, fertilizer use increased fluxes of N in aquatic ecosystems

-recycling: carbon and water

-loss: leaching of dissolved elements to groundwater

-gaseous losses of N influence the chemical and radiative properties of the atmosphere

In most ecosystems what is the principal source of nutrients to plants?

the sun or soil

What is one of the main drivers of riverine N export? Of N in surface waters and groundwaters?

the main driver is agriculture

How does the availability of N and P change overtime on a newly established ecosystem? Why?

older ecosystems have more P, then N

younger ecosystems have more N, then P

What are the common layers in a soil profile and characteristics of each?

O: (organic or humus) mostly organic matter such as decomposing leaves

A: (topsoil) mostly minerals from parent material with OM

E: (eluviated) leached of clay, minerals and OM

B: (Subsoil) rich in minerals that leached down from A or E

C: (parent material) the deposit at Earth's surface from which the soil developed

R: (bedrock) mass of rocks

the dominant properties of each soil layer

1. O:

-Oi: organic, slightly decomposed

-Oe: organic, moderately decomposed

-Oa: organic, highly decomposed

2. A: mineral, mixed with humus, dark colored

3. E: Horizon of max leaching of silicate clays, Fe, Al oxides,etc

4. B: Zone of Fe and Al accumulation

5. C: Zone of least weathering and accumulation; contains unweathered parent material

6. R: Bedrock

In what orders do soil orders develop?

Entisols to Inceptisols to Alfisols to Ultisols to Oxisols

What are the three simple aspects of decomposition? Define and provide an example for each.

-leaching: moves water-soluble compounds out of decomposing material

(physical process driven by water, snow melt)

-fragmentation: breaks apart litter to provide access to the microbes (driven by biology, increasing surface area due to breaking up leaves and plant matter)

-chemical alteration: the metabolism (anabolism and catabolism) of the organic matter once its small molecules sometimes mineralize, transform into microbials biomass. Driven by micro-organisms)

What are the major controls on the rate of decomposition.

1.Lignin and N content

2.climate

-evapotranspiration

-transpiration

-regional climate and plant biomass

3.substrate quality

-molecule size

-types of chemical bonds

-regularity of structure

-toxicity towards microbes

-nutrients concentration

Which two components of plant biomass can help predict decomposition rate?

lignin and N

Which organisms are primarily responsible for fragmentation? Provide examples.

-earthworms

-microbes

Which organisms are primarily responsible for chemical alteration? Provide examples.

-microbes (micro-organisms)

How do ecologists study decomposition?

-space for time substitutions provide natural experiments

-glacier fore-field (youngest/oldset soils)

-archipelago (Hawaii)

-Alpine sub-alpine boundary

SRP

soluble reactive phosphate

-measure of the phosphate form directly taken up by plant cells