Ecology 3 Flashcards
GPP and NPP
Gross primary production – total biomass of C compounds made by producers (also total E stored in producer’s body in form of C compounds)
Net primary production – portion of GPP than can be transferred to further trophic levels (GPP minus the biomass lost due to respiration of the plant – amount of biomass available to consumers)
Carbon cycle sink and flux examples
Sink/pool (methods of C storage): fossils (fuel – coal, oil, natural gas, limestone), consumer, dead consumer, producer, aquatic ecosystems (dissolved CO2 and hydrogen carbonate ions (HCO-))
Flux (processes that transfer C from one sink into another): photosynthesis, CR, feeding, death, decomposition, incomplete decomposition, combustion (of fossil fuels), respiration, fossilization (e.g. shells into limestone)
Outline the carbon cycle (mentioning sinks and fluxes)
- Photosynthesis uses CO2 from the atmosphere to produce C-compounds and oxygen
- Autotrophs fix CO2 from the atmosphere to from C-compounds
- Cell respiration releases CO2 (oxidation of C-compounds) – BOTH AEROBIC AND ANAEROBIC
- Saprotrophs/detritivores release CO2 by decomposing dead organic matter (return nutrients to the soil)
- Partial decomposition of organic matter can lead to formation of fossilized organic matter and peat
- Combustion of C-compounds releases CO2
- CO2 dissolved in aquatic ecosystems (forms carbonic acid) – used by reef-building corals
- Decomposition of shells/aquatic exoskeletons forms limestone
Energy flow in an ecosystem
Light E captured by autotrophs and converted to chemical E by photosynthesis – chemical E passed to consumers along the food chain – at each transfer, 90% of E is lost as heat (CR) – some E made available to decomposers when organism die – E cannot be recycled as nutrients are
Energy flow through a food chain
Light E converted to chemical by photosynthesis – chem E flows through the chain by feeding – E released from C compounds by respiration and a portion is lost as heat – heat not recyclable as it is lost from food chains (heat cannot be converted to other forms of E) – E losses between trophic levels limits the length of food chains
Transfer of E vs transfer of inorganic nutrients in ecosystems
E is lost between trophic levels (must be resupplied) while nutrients are recycled
How does carbon enter and exit ecosystems (form and processes)
When does an ecosystem act as a C sink and when as a C source?
In the form of CO2 through photosynthesis and CR
If photosynthesis > CR, there is a net uptake of C – the ecosystem is acting as a C sink (growing forests and waterlogged habitats) where anaerobic and acidic conditions prevent dead organic matter decomposition – so C compounds accumulate
If CR > photosynthesis, there is net release of C compounds – the ecosystem is acting as a C source (fires in forests cause release of CO2 by combustion)
What is incomplete decomposition – origin of coal and gas/oil
Happens in anoxic environment, less E, CO2 and H2O released, slower process - produces fossil fuels
Coal has plant origin, gas and oil animal origin
What does the Keeling Curve show?
annual fluctuations (C increases between October and May and fall from May to October) and long-term trend upwards (largely due to burning of fossil duels and other anthropogenic factors such as deforestation)
Features of a stable ecosystem:
- Steady E supply (the Sun)
- Nutrients recycling to replenish nutrients in the abiotic environment
- Stable climate within the range of tolerance – can be disturbed by things like tectonic plate movements, earthquakes, formation of new mountains and trenches – global warming/ice age
- High genetic variability of species, especially keystone species
Keystone species
organisms that have a disproportionately large effect on their natural environment relative to their abundance – when their population declines or disappears, there are very few or no species that can fulfill their role, ecosystem degrades and sometimes completely collapse – Croatia (Dinaridi): wild boar, European lynx and wild horses (reintroduced), beech tree
Tipping point – explain on the example of the Amazon rainforest (comment on reforestation)
point of no return reached when too large a disturbance happens in any of the features that make a stable ecosystem, once the ecosystem can no longer reset the change
Amazon rainforest deforestation: if a tipping point is reached, there will be positive feedback mechanism in place, forests area will turn into a grassland: deforestation -> les transpiration -> higher T, lower rainfall, less wind -> climate change, forest fire (drier biomass) -> conversion to grassland -> less transpiration, etc.
Reforestation can aid the ecosystem in recovering only if the appropriate trees are planted – often palm trees replacing trees that have a rich oxygen production
Ecosystem resistance vs resilience
Resistance – ability to remain unchanged despite disturbances
Resilience – ability to rebound from change/disturbance – lost at the tipping point
Mesocosm
model ecosystem used for ecological research, has potential to be self-sustainable if nutrients are recycled and energy supplied – autotrophs and saprotrophs mandatory (consumers and detritivores not)
How does agriculture threaten stability of ecosystems?
Intensive agriculture not sustainable:
Tillage – loosened soil prone to leaching and erosion, mechanical tillage requires E (high carbon footprint)
Nutrient depletion of soils –planting the same crops few times a year, removing nutrients by not letting the plants decompose on that same soil – fertilizer used but nutrients in fertilizers are taken from another ecosystem and the production of fertilizers is not environment-friendly (increases C footprint, from non-renewable sources)
Monoculture – encourages pests and weed growth, pesticides and herbicides applied, resistance, pollution, C footprint
Eutrophication – caused by what? Natural vs anthropogenic
Eutrophication is the enrichment of aquatic ecosystems with nutrients, resulting of leaching (minerals that should be in the soil, go deeper into the soil or into the water – erosion due to intense agriculture)
It causes increased primary production, thus algal bloom (cyanobacteria attempt to get closer to the sunlight so they disrupt the penetration of light to lower levels), and massive decomposition, which demands greater oxygen supply, causing anoxic water (result: fish and other aerobic organisms die)
Natural eutrophication is a natural phenomenon that leads to the “ageing of lakes” – partial decomposition occurs due to a lack of O2, this creates sediment so shallower lakes – process is gradual and slow (over centuries)
Anthropogenic eutrophication – minerals (PO43-) carried by wastewaters which leach into the lake, consequences are the same as in natural eutrophication but happen much faster (over decades)
What is plastic pollution? Differentiate between different types of plastics and their effect on the ecosystem
Non-biodegradable human production
Macroplastics – usually not digested but create problems in the environment (for animals, turtles..)
Microplastics – gets ingested, carried over the food web – xenoestrogens (have the same effect as estrogen) decreasing male fertility)
Nanoplastics – might create problems on a cellular level, can get through the plasma membrane, increases inflammation, acts as a toxin
Bioaccumulation vs biomagnification
Bioaccumulation – ingested not digestible, hydrophobic, deposited in the adipose tissue, increases as the organism ages
Biomagnification – top predators consume all existing toxins and microplastics in the chain – toxins accumulate in fat tissues of organisms (bioaccumulation), other organisms feed on them, toxins not excreted so their concentration increases as trophic level increases
Ecological succession definition, examples of primary and secondary succession, disturbance and climax
Primary succession – colonization of areas that were not previously inhabited
