Summary Applied Ecology
L1 Biocheochemistry
Biogeochemistry = study of mineral cycling and transfer, water cycling, and the relationship between
organisms and their environment; ecology, microbiology, geochemistry, hydrology
Important processes: biomass production (carbon fixation), decomposition, nutrient cycling
Redox reactions, aerobic/anaerobic processes
Carbon & energy flows:
- Photosynthesis: CO2 + H2O + light → CH2O + O2
- Respiration: aerobic or anaerobic
- Sedimentation & burial
- Exchange
- Extraction
- Combustion
Decomposition = metabolic breakdown of organic matter to simple organic or inorganic matter ->
generates energy
Mineralization = transition from organic-bound form to inorganic, water-soluble form by biological or
chemical process
Both depend on: temperature, nutrient concentration, organic compounds present,
alkalinity, salinity, phenolic compounds
Oxidation = giving away electrons, more positive charge
Reduction = gaining electrons, more negative charge
Electron acceptors: O2 > NO3 > Fe3+ > SO4-2
Electron donor: (usually) glucose
Gibbs free energy ΔG = - n * F * ΔE -> how easy reaction is to complete
ΔG < 0 exergonic, generates energy
ΔG > 0 endergonic, needs energy
Aerobic oxidation: produces acid
Anaerobic oxidation: uses acid
Oxygen saturation fluctuates over the day
In water: % compared to air, can be above 100
Lower water temp -> more dissolved oxygen
Wet peat meadows -> less CO2 emission
Peat = veen
Agriculture -> nitrogen deposition -> especially bad
for nutrient poor ecosystems
Nitrate = NO3
Nitrite = NO2
Nitrogen cycle:
- Nitrification = NH4 -> NO2 -> NO3
, - Nitrate reduction = NO3 -> NO2
- Denitrification = NO2 -> NO -> N2O -> N2
- Nitrogen fixation = N2 -> NH4
Higher temp -> faster denitrification
Low pH (acid) -> slower nitrification -> NH4 accumulation
NH3 (ammonia) build up -> acidification of the soil by microbial nitrification
Denitrification uses acid
Buffering = less strong effect of acidification,
ANC = acid neutralizing capacity = acid buffering
Carbonate = H2CO3, bicarbonate = HCO3
Nutrient states:
- Oligotrophic = water always clear, low productivity
- Mesotrophic = sometimes turbid, moderate productivity
- Eutrophic = almost always turbid, high productivity
- Polytrophic = very turbid, very high productivity, strong variation in oxygen concentration
- Ombrotrophic = rainwater source, acidic + low in nutrients
Eutrophication = enrichment of a system with nutrients from autotrophic growth, especially with
nitrogen and phosphorus
External eutrophication = influx of nutrients from outside the system
Internal eutrophication = increased release of nutrients from inside the system
Nutrient limitations:
- Ammonium/nitrate: most common, in peatlands/heathlands/grasslands.
o Often combined with P limitation
- Phosphate: lakes, tropical marine systems
- Inorganic carbon: soft water lakes, bogs
o Often combined with N limitation
- Fe: seagrass fields, algae/cyanobacteria in oceans
L3 Air pollution, acidification, eutrophication, and critical loads
Pressures on natural areas:
- Desiccation (= drying out)
- Eutrophication: freshwater, salt water
- Acidification (NO and SO2)
- Nitrogen deposition on land
-> all above sustainable conservation threshold in NL
, Acidification = reduction of acid buffering capacity, or reduction of ANC
Eutrophication = increased nutrient supply
+ toxicity = toxic effect of NH4 and NH3
Acid rain: NO + SO2 in air -> oxidation + dissolution -> NH4, SO4 and NO3 in rain
SO: fossil fuel combustion (industry, traffic)
NO: fossil fuel combustion (industry, traffic)
NH: manure (agriculture), sewage water treatment
S deposition strongly decreased the past decennia
Deposition increases with high of vegetation: higher plants -> more deposition
Origin nitrogen deposition in NL:
- Agriculture
- Influx from abroad
- Traffic
- Residential areas
- North Sea
- Industry
Nitrogen deposition -> problem worldwide
-> buffering
Cations = positively charged ion
CEC = cation exchange complex = clay + minerals in soil, cations are mobilized to leak to groundwater
Lower pH -> more reactive aluminium
More N -> higher grass biomass: dry weight + length -> decrease in species richness
Critical load = quantitative estimate of atmospheric deposition (flux, load), below which there is not
harmful effect on sensitive part of the ecosystem: safe threshold for acidity and N
Maximum no effect level = max safe concentration
Load vs level
Visible changes in:
- Plant development
- Species composition
- Biodiversity
Gap between science and policy ^: policy makers will still accept a higher level than science advises
L4 Climate-proof nature management