Interactions - Decomposers/Detritivores Flashcards
How do these differ from carnivores?
They have no control on the abundance of their resource consumed, depending on resource rates of other forces driving death.
What are the two types of saprotroph?
Decomposers
Detritivores
Saprophyte
An organism living on dead or decaying organic matter.
Immobilization
The process where nitrate/ammonium are taken up by soil organisms thus becoming unavailable to crops
Decomposition
Gradual disintegration of dead OM by physical/biological agencies
Where may dead organic matter derive frmo?
Shedding, leaf litter, faeces, death of an organism…
Rhizosphere
The region goverend by interactions between plants and organisms now in close association with the roots
Phyllosphere
Aboveground plant prts colonized by mcorbial communities
What supports the phyllosphere?
Exudation of plant tissue soluble sugars supports bacterial growth
What is the first step in decomposition process?
Prokaryotic colonization and autolysis by enzymes in the dead tissue, breaking down macromolecules into soluble forms.
How do bacteria break down material?
Leach soluble materials like AA and sugars, where then ‘enzyme reliant material’ is digested by specialised organisms
R Selection
These have high growth rates, exploiting less crowded ecological niches, and produce many offspring
Examples of enzyme-reliant material?
Lignin, Chitin, Celullose and Keratin
What is early decomposition dominated by?
Aerobic conditions, prokaryotes utilising O2 for sugar breakdown with CO2 byproducts
What follows prokaryotic sugar decomposition?
Fermenntation breakdown sugars with alcohol formation, usually lowering pH of soils due to acid production
Examples of anoxic habitats?
Waterlogged soils, estuaries and lake sediments.
Example of resource change with decomposition?
Pectins and hemicellulose by beta-glucosidase, then cellulose by endocellulases, whilst lignin constnat throughout by laccase
How are fungi and Bacteria measured?
Levels of ergosterol and phospholipid fatty acids.
How do decomposers change over time?
First eight months of leaf litter decomposition by varying fungi, with complete decomp dependent on bacteria and archae and fungi
How is rate of decomposition regulated by organisms?
Early slowed by microbivores due to recruiting faster than decomposers, then sensecent hyphae cropping later faciltiates decomposition
Classes of organisms?
Microfauna
Mesofauna
Megafauna
Function of fauna proceeding degradation?
Shred remains, potential of soil structure development with detritus re-distribution.
What is an example of plant biochemistry variablity among ecosystems?
Decomposition occurs quicker closer to parent trees
What is rate of decomposition dependent on most?
Quality of litter, like magnesium, tannin and water saturation capacty(tannins being toxic, magnesiums essential and water adsorption controlling fauna.
What are the most prominent organic compounds of dead leaf?
Cellulose and Lignin, of which animal herbivores typically cannot degrade
How may animals facilitate cellulose breakdown?
Symbiotic bacterial communities within the stomach
Importance of coprophagous detritivores?
Increase decomposition rate and thus nutrient release into soil.
