Uploaded by yip88ryan


1) Tundra
Low variability due to marine env.
Cold, dry, windy, low precipitation
Cold: due to HIGH spread of solar radiation AND albedo effect from snow and ice (reflects
Dry: due to polar cell region b/c by the time air reaches poles, the air has lost its moisture and is
Precipitation: Evaporation is greater than precipitation
Freeze-thaw cycle causes polygons and solifluction
2 types of tundra ecosystem: polar grassland (100% plant cover, near lake or valleys) and polar
desert (dry soil, low plant cover)
Waxy leaves and fewer and smaller leaves- to reduce SA and decrease water, heat loss
Hairy stem/leaves- traps heat
Low growing and CLUSTERED- more wind protection
Shallow/No root systems- permafrost; can grow on rocks (higher albedo)
Perennials- short growing season, grow and reproduce in same year, roots survive during winter
(nutrients go into roots during winter)
Fast short-term growth (slow long-term growth)- photosynthesizes 24 hours a day in growing
Fur- thick layer w/ fat underneath
Reduced SA:Volume- ex/ hares curl up in ball
Herbivores- consume ANYTHING (lichens, plants, moss)
Carnivores- consume terrestrial and aquatic animals
Camouflage- changing coat colour (winter vs summer) (ex/ arctic fox)
Hibernation- reduce metabolism (during winter)
Migrate- if cant hibernate they migrate
Impact on Primary Producers:
Permafrost (frozen soil for most of year)
Short growing season
Nutrient poor soil
Results: low productivity
2) Alpine
Cold, Windy, high elevation, No tree growth
Well-developed root systems (can store carbs during winter while dormant)
Vegetative Reproduction
Waxy Leaves, small leaves- prevent loss of water (some succulents, can store high solute
concentration without freezing)
Clustered, low growth
Higher species diversity than Tundra
High rate of endemism (unique species found here)
Similar adaptations to tundra animals
Additional: Split, rough hooves to climb rocky ledges (ex/ bighorn sheep)
Impact on Primary Producers:
High winds= soil erosion
High winds and solar radiation = high evaporation of water
Results: low productivity
3) Boreal forest (Taiga)
Biggest terrestrial biome on Earth
Cold, low precipitation, continental climate (coldest temperature can be colder than tundra, more
Variable temp: More fluctuations in temperatures (-20 to 18)
Precipitation: Precipitation greater than evaporation (not as dry or cold as tundra)
Continental Climate- higher extremes
Vegetation (Primary Producers):
Dominated by closed-crown coniferous forests (lower biodiversity than temperate forest, BUT
higher than tundra) (growth season too short for investment in deciduous leaves)
Needle-shaped leaves, waxy, thick coat- prevent water loss
Reduce SA- reduces evaporative loss
Remain year round- to extend photosynthetic period
Difficult to consume- have tannins and thick cuticle
Conical shape- reduces snow buildup and wind damage + maximize sunlight exposure
Shallow root system
Photosynthesize at low temps
FIRES- recycles nutrients back into soil (adaptations include resin sealed cones, germinates after
INSECT OUTBREAKS (2nd type of disturbance in boreal forests)
Animals (Consumers):
Fire and insect outbreak allows animals to come (black fire beetles, lay egg on recently burned
trees; warblers, feed on insects
Fur- thick layer (ex/ bison)
Herbivores- consume lichen
Camouflage- change coat colour
Snowshoes- ability to move on top of snow (ex/ lynx)
Hibernation- reduce metabolism
Impact on Primary Producers:
Short growing season, but longer periods of sunlight
Nutrient poor soil, shallow and acidic (waterlogged summer)
Higher standing biomass (compared to tundra and alpines)
Results: low productivity
4) Peatlands
Wet, acidic, nutrient poor
Found in Boreal and Tundra regions
Peat: accumulation of partially decayed OM; defined as having soils with over 30% OM with deposits 3040cm deep
Composed of two layers:
1) Acrotelm: top, aerobic layer
2) Catotelm: lower, anaerobic layer, also acidic
Peat functions as an important Carbon Sink (30% of all soil carbon); it also takes 1000 years to form and
can be used for fossil fuel source (b/c carbon rich)(rate of decomposition very slow)
4 ways of form Peatlands:
Paludification (swamping) of dry land
Primary Succession of dry, mineral soil
Terrestrialization of Lakes (gradually filling lake with sediment)
Forms in dried lake basins (lakes become evaporated or drained)
Types of Peatlands (NOT marshes and swamps):
1) Bogs- receive water ONLY from the atmosphere, thus hydrologically isolated (ombrotrophic);
Precipitation > evapotranspiration; ACIDIC; ground layer dominated by moss; Low levels of N
and P (3 types of bogs; oceanic eccentric, continental, northern)
2) Fens- fed by mineral-rich surface or groundwater (minerotrophic); more nutrients than bogs but
still poor; Neutral to alkaline (not acidic); sedges and cotton grass are abundant
Vegetation (Primary Producers):
Carnivorous plants (obtain nutrient by digesting insects) (ex/ venus flytrap and pitcher plants)
Plants associated with mycorrhizal fungi (symbiotic relationship)
Habitat Manipulators (manipulates environments to keep it stable for themselves)
5) Grasslands
Temperate Grasslands:
Cold winters and warm to hot summers
Limited nutrient
Mainly defined as having less than 10% tree and shrub cover (mostly grass)
Results: moderate productivity
Types of Grasslands:
1) Tallgrass prairie: highest rainfall, tallest plants; better productivity
2) Shortgrass prairie: lowest rainfall, shortest plants; also least productive, too dry for crops
Control Factors:
Climate, fire and grazing (regulates grasslands)
Climate has dry periods of water stress most of the years
Short vegetation= high solar radiation and strong winds = higher evaporation and water stress
Fire is good and natural; occurs in dormant season and leads of increase grass growth (removes
dead biomass which block light)
Grazers increase rate of nutrient cycling (excretes N that is sequesters in plants); some grasses
will grow faster when grazed (process called overcompensation)
Element cycling: transport and transformation of chemicals within and ecosystems
Gaseous Cycles: main reservoirs are the atmosphere and ocean (ex/ N, O)
Sedimentary Cycles: main reservoir is the lithosphere (ex/ P)
Hybrid Cycles: main reservoir is atmosphere, ocean and lithosphere (ex/ S, C)
Oxygenic Photosynthesis: photosynthetic pathway for modern plants and microbes; uses water
and CO2 to get energy and produces oxygen as a byproduct
Anoxygenic Photosynthesis: earliest type of photosynthesis by bacterial groups; uses hydrogen
sulfide instead of water to get energy
Chemosynthesis: reaction require oxygen to oxidize compounds to get energy
Oxic Respiration: reaction in aerobic organisms used to obtain energy
Anaerobic Respiration: reaction using molecule other than oxygen to obtain energy
Photoautotrophs: use inorganic C (CO2) as C source and sunlight as energy source
Chemoautotrophs: use inorganic C (Co2) as C source, and reduced inorganic compounds as
energy source
Nitrogen Fixation: process that converts biologically unavailable N (N2) into bioavailable form
(NH4 or NO3)
Nitrification: conversion of ammonium to nitrate (NH4 -> NO3)
Denitrification: conversion of nitrates into N2
Biomagnify: accumulation of contaminants with an increase in trophic level
Control: a change in a factor causing a change of flow in an ecosystem
Negative Feedback: an output the counters the original input (dampening or correcting the
Positive Feedback: an output that reinforces the original input (reinforcing effect)
Heterogeneity : the variation in biotic and abiotic components in an ecosystem
Structural Heterogeneity: complexity and variability of a property of an ecosystem over space
and time (includes both spatial and temporal heterogeneity)
Spatial Heterogeneity: different values of an ecosystem component in different places within an
Temporal Heterogeneity: different values of an ecosystem component time
Diel Cycles: cycles that occur over a 24 hour period
Resistance: a measure of the capacity of a system to WITHSTAND a disturbance
Resilience: a measure of the capacity of a system to RECOVER from disturbance
Succession: the gradual change in biological communities in an ecosystem following a
disturbance or creation of new geological substrate
Primary Succession: succession that occurs on NEWLY EXPOSED geological substrate
Secondary Succession: succession that occurs after the destruction of biological community but
NOT the destruction of soil
Immobilization: ammonia or nitrate  organic N
Mineralization: organic N  ammonia
Where are biggest reservoirs/pools for each element on earth and in the terrestrial and marine
Biggest Reservoirs on Earth:
In oceans as Sedimentary rocks (stored as carbonate and organic compounds)
Dissolved inorganic carbon (DIC) (ex/ dissolved Co2, bicarbonate and carbonates)
Carbonate in rocks and soil
Biggest Reservoirs on Earth:
in the atmosphere (as N2)
limited in aquatic systems
soil (tied up as recalcitrant soil OM), plant biomass is second
Biggest Reservoirs on Earth:
rock, soil, and sediments
Biggest Reservoirs on Earth:
pyrite-rich igneous and sedimentary rocks
ocean (as SO2)
pyrite-rich igneous and sedimentary rocks
How does each element become available for biological processes? does this differ between the
terrestrial & marine environment?
Photosynthesis incorporates CO2 into organisms
Producers and consumers return CO2 to the atmosphere or water through respiration
Residual carbon gets sequestered in living tissues and dead OM
More CO2 in the marine env. Compared to terrestrial env. So more photosynthesis happens in
marine env. Storage pool in terrestrial environments are much larger for carbon than in marine
environments because carbon is cycled within the ecosystem at a higher rate in terrestrial
Nitrogen fixation must occur to convert atmospheric N2 into nitrates or ammonia
Then immobilization occurs to convert nitrates and ammonia into organic N
Available pool of nitrogen is small and cycled rapidly in terrestrial env. But Nitrogen is also limits
primary productivity (PP) in marine env.
Only soluble reactive phosphorus is bioavailable and needs to be released through the
weathering of rocks, soil and sediments
In terrestrial env, lots of P is unavailable for uptake, only soluble P can move to plant roots via
diffusion. Increase root growth or having symbiotic relationships help with this. In marine env, lots
of P is in sediments and is also unavailable for uptake. To release this P, resuspension needs to
occur, otherwise P must be in dissolved form.
Soluble form of S (So4) can be taken up by plants
Sulfur bacteria’s oxidize organic compounds to release S in a bioavailable form (use H2S as an
electron source in photosynthesis, which release elemental S which is oxidized into SO4)
How does each element get put back into the environment? what form does it take for long-term
Respiration helps return C back into the atmosphere or water as Co2
Combustion and burning of fossil fuels release Co2 into the atmosphere
Takes form of carbonates in rocks and soil for long-term storage (inorganic); takes form of
residual C which is sequestered in biota like trees for long-term storage (organic)
N is released back into the environment through denitrification by bacteria
Stored as N in soil, otherwise it is N2 in atmosphere
Goes into environment through weather, leaching and erosion
Gets stored as phosphates in rocks and sediments
Moves to terrestrial env naturally through weathering and volcanic activity (does not stay long
in atmosphere)
Stored as FeS2 in igneous and sedimentary rocks (long term)
Which elements are more limiting in different environments? why?
More limiting in terrestrial env because carbon readily exchanges with the atmosphere but is
supersaturated in water.
More limiting in aquatic env because in terrestrial env, nitrogen is tied up in soil OM
Limiting in both env, but more limiting in marine env, because P is trapped in sediments
How do humans affect these cycles? **you'll definitely want to know this one
Human activities massively affect the carbon cycle by causing Co2 levels to rapidly rise in the
atmosphere, which will eventually enter the terrestrial and ocean environments. Activities include
burning fossil fuels, clearing land and burning vegetation, and making cement from carbonate rocks.
Humans affect the nitrogen cycle by harnessing N2 from atmosphere and fixing it into fertilizers
which eventually runoff into aquatic environments. This causes a higher amount of ammonia and
nitrates to be put into the ecosystem.
Phosphorus cycle is affected because humans break down phosphorus through processes like
mining which releases much more phosphorus into the ecosystem than it naturally would through
weathering. Humans also put phosphorus into fertilizers which eventually cycle into the aquatic
environments through run-off and excretion. This also causes algal blooms.
Sulfur cycle is affected through human fossil fuel combustion. Sulfur enters the atmosphere as
hydrogen sulfide (H2S) and interacts with water to form sulfuric acid. This causes more sulfur to be
released into the ecosystem.
Mercury and metals:
Humans have caused more mercury to enter the environment mostly due to burning of fossil fuels.
Bacteria are able to convert industrial and natural Hg into methyl-Hg which is the bioavailable form
of mercury. This has a negative impact to the ecosystem as mercury levels biomagnify in the
environment. This has an effect on humans and apex predators.
Move, stick, and change Model
Move: elements move WITHIN and BETWEEN ecosystems due to…
Physical gradients: erosion of soil which transports elements downstream
Chemical gradients: diffusion of CO2 from areas of net respiration in soil to atmosphere
Biological vectors: salmon migrating upstream from ocean to lakes; bioaccumulation of toxin
through foodweb
Stick: elements temporarily held in a reservoir (sequestered)
Important for limiting losses from systems
Residence time measures how long an element stays within an ecosystem component
Change: transformation of elements from one state to another
Determines whether a chemical MOVES or STICKS
Includes phase changes (ice to snow); biologically mediated (sulfate reduced by bacteria to
hydrogen sulfide)