1) Tundra Low variability due to marine env. Cold, dry, windy, low precipitation Climate: - Cold: due to HIGH spread of solar radiation AND albedo effect from snow and ice (reflects sunlight) Dry: due to polar cell region b/c by the time air reaches poles, the air has lost its moisture and is dry 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) Vegetation: - 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 season Animals: - 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 Vegetation: - Perennials 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) Animals: - 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 variability) Climate: - 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 fire) - 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 Migrate Impact on Primary Producers: - Short growing season, but longer periods of sunlight Permafrost 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: 1) 2) 3) 4) 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) Definitions 1) 2) 3) 4) 5) 6) 7) 8) 9) 10) 11) 12) 13) 14) 15) 16) 17) 18) 19) 20) 21) 22) 23) 24) 25) 26) 27) 28) 29) 30) 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 effect) 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 ecosystem 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 Biogeochemistry Where are biggest reservoirs/pools for each element on earth and in the terrestrial and marine environments? Carbon: Biggest Reservoirs on Earth: - In oceans as Sedimentary rocks (stored as carbonate and organic compounds) Marine: - Dissolved inorganic carbon (DIC) (ex/ dissolved Co2, bicarbonate and carbonates) Terrestrial: - Carbonate in rocks and soil Nitrogen: Biggest Reservoirs on Earth: - in the atmosphere (as N2) Marine: - limited in aquatic systems Terrestrial: - soil (tied up as recalcitrant soil OM), plant biomass is second Phosphorus: Biggest Reservoirs on Earth: - rock, soil, and sediments Marine: - sediments Terrestrial: - soil Sulfur: Biggest Reservoirs on Earth: - pyrite-rich igneous and sedimentary rocks Marine: - ocean (as SO2) Terrestrial: - pyrite-rich igneous and sedimentary rocks How does each element become available for biological processes? does this differ between the terrestrial & marine environment? Carbon: - 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 environment. Nitrogen: - 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. Phosphorus: - 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. Sulfur: - 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 storage? Carbon: - 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) Nitrogen: - N is released back into the environment through denitrification by bacteria Stored as N in soil, otherwise it is N2 in atmosphere Phosphorus: - Goes into environment through weather, leaching and erosion Gets stored as phosphates in rocks and sediments Sulfur: - 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? Carbon: More limiting in terrestrial env because carbon readily exchanges with the atmosphere but is supersaturated in water. Nitrogen: More limiting in aquatic env because in terrestrial env, nitrogen is tied up in soil OM Phosphorus: 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 Carbon: 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. Nitrogen: 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: 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: 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)
