Soil fauna Flashcards
How do earthworm change the chemical and physical environment?
They are soil ecosystem engineers as they MODIFY SOIL STRUCTURE and interact with microbes through their FEEDING, BURROWING, and CASTING activities.
What is the role of earthworm in soil? What do they affect?
- Soil structure
- SOM dynamics
- Humification
- Mineralization
- Microbial activity
What are more concrete physical changes earthworm do to soil?
- Their casting increases micropores and mesopores
- Their burrowing increases macropores
Macropores=> increases infiltration of water, aeration
Micro and mesopores=> increases water-holding capacity of the soil
What are chemical changes earhtworms do to soil?
- Biochemical breakdown of OM
- Production of mucus, enzymes=> affect pH (??)
- Cast=> when decomposed=> releases nutrients
=> They also affect the microbial activity and population (control the population, but also favorises their proliferation through cast)
What is the role of earthworms in C and N?
- Decomposition of SOM
- Respiration=> CO2 production
- N mineralization=> Available nitrogen
What are the 3 different types of earthworms?
- Epigeic
- Anecic
- Endogeic
What are characteristics/ key functions of ENDOGEIC worms?
- Rich soil feeder
- TOPSOIL dweller
- horizontal burrows
- Small size
Function (principal)
- Participate a lot in SOIL AGGREGATE FORMATION
- Through excreted mucus
- Modified soil in casts
=> mainly SOIL STRUCTURE MAINTENANCE
Also other functions:
- Nutrient cycling
- Soil pore creation
What are characteristics/ key functions of EPIGEIC worms?
- Litter feeder
- Litter dweller
- no burrows
- Small size
Functions (principal):
DECOMPOSITION
- Breakdown of litter and OM
- Incorporation of litter into soil
- Stimulation of microbes
Other funtions
- Nutrient cycling
What are characteristics/ key functions of ANECIC worms?
- Litter + soil feeder
- Soil dweller
- Extensive vertical burrows
- Large size
Functions (principal):
Soil pore creation
- Deep vertical burrows
- Horizontal burrows
Other functions:
- Nutrient cycling
- Decomposition
What is epigeal and edaphic soil fauna?
Epigeal=> surface
Edaphic=> within
How are functional roles of soil fauna linked with microbes?
They regulate microbial processes
- Comminution: fragmentation of material (jump start microbial decomposition)
- Translocation: ovement of materials (can create “hot spots”)
- Inoculation: movement of microbes (alter microbial species composition and abundances)
- Predation: grazing on microbes (regulates population dynamics)
What are other important functions of soil fauna?
Bioturbatio :
- mixing and rearrangement of the soil
Cycle nutrients:
- With the help of microbes
- Excretion of nutrients
- Stimulate plant growth
Nutrient retention
- Organic form of nutrients and energy
Pest suppression (managed ecosystems)
- Consumption of herbivores
- Consumption of weeds
Parasitism
Vectors of disease
What are examples of microfauna?
- Protozoa
- Nematodes
- Rotifera
- Tardigrada
What are characteristics and functions of protozoa in soil?
- Single-celled
- Primarily bacterivorous but omnivory is common
Microbivorous
- Further mineralization via stimulation of microbes
- Retention of nutrients in biomass
What are characteristics and functions of nematodes?
- They form 90% of all multicellular animals in soil
- Can be free-living or parasitic
- Eat a wide range of foods (bacteria, fungus, plant, predators and omnivores)
- Increase mineralization
What are characteristics and functions of rotifera?
Aquatic animals but also terrestrials
Can survive long periods of desiccation, effective colonizers
Feed on microbes, protozoans, algea, dead OM
What are characteristics and functions of Tardigrada?
- Cosmopolitan species
- Water-dwelling
- Identification based on cuticles, claws, buccal apparuts
- Herbivores, carnivores, omnivores
- Survive harsh environmentak conditions such as drought (extreme dehydration), high and cold temperatures
- Freeze tolerant species => secrete cryoprotectants as sugars and polyols or certain proteins, which help keep cytoplasm in a liquid state
What is the size of mesofauna?
100 um- 2mm
What are examples of mesofauna?
- Collembola
- Soil mites, beetles, spiders
- Protura
- Diplurans
- Pseudoscorpions
- …
What are major functions of mesofauna?
- Regulations of bacterial, fungal and microfaunal populations
- Nutrient cycling
- transport of materials
- Alter litter decomposition rate
- Contribute to soil development
- Biocontrol agents
What are enchytraeidae?
- Part of oligoghaeta sub-class
- “pot worm”
- Small segmented white worms
- Ingest minerals and organic matter, but fungi and simple plant components are assimilated
Like acidic soils with lots of SOM
- Linked with INCREASED plant-N acquisition
What are collembola? ex?
- Spring tails (Hexapoda)
- Ubiquitous
- Ingest mineral and OM matter, but fungi and simple plant component are assimilated
- Likes acidic soil with lots of SOM
- Prey on many other soil fauna (nematodes) also plant roots (mycorrhizal and pathogenic fungi
- Often most common microarthropod in the rhizosphere
What are characteristics and functions of mites?
- Soil mites are arthropods related to the spiders
- Most abundant microarthropods in soils
- Tend to have higher resistance to water and temperature stress than collembola
- They also have unique gut microbiomes
Functions:
- Are active litter decomposers
- They also alter litter decomposition chemistry
What is the effect of tillage on mesofauna?
Coventional tillage=> less than zonal tillage
-> zonal tillage provides habitat for beneficial arthropods, conserving their abundances
What are approaches to organize catches?
- By function
- By body width
