Earth's Systems / Biological processes / Terrestrial ecosystem functioning / Living soil system / Soil fauna / Microarthropods: springtails and oribatid mites as fungal grazers and litter processors
Microarthropods: springtails and oribatid mites as fungal grazers and litter processors
Springtails (Collembola) and mites (Oribatida, Mesostigmata) live in the air-filled pores and litter of the upper soil, graze fungi, break down litter and make faecal pellets. The process covers feeding guilds, grazing effects on fungal activity and mycorrhizal networks, slow versus fast life histories, predator control and nitrogen release.
Boundary: where this process starts
Starts with: Microarthropods number about 10^4-10^5 per square metre in forest floors and live in air-filled pores and litter spaces
Boundary: where it ends
Ends after: Grazers release ammonium and phosphate; soil animals together are estimated to supply on the order of 10-40% of N mineralisation; Fragmentation and grazing speed litter decomposition: presence of fauna raises mass loss by roughly a third on average
Line thickness = size of impact (1 to 5)% on a line = chance a fork takes that branch📄 = pieces of evidence on a stepNegative effectLoops backHypothesisResource used up (arrow into the step)Resource used, not used upResource made or released (arrow out of the step)
What am I looking at? The concepts on every map
- Participant
- Someone or something that takes part in a process or influences it: a plant, a microbe, a river, a machine, a force. Participants are the rows of a map.
- Resource
- Something a step uses or uses up: water, oxygen, sunlight, a tool. Each step has an arrow down to the resources it uses.
- Step
- One thing that happens in a process. Every step has at least one participant and carries evidence.
- Decision fork
- A step where the process can go several ways. Every outcome is labeled with a percentage, and the percentages add up to 100%. It is not limited to yes or no.
- Loop
- A line that carries the process back to an earlier step. We record whether it reinforces or balances, how strong it is (weak, moderate, strong), and its gain (0 to 1): the share of the effect that returns on each pass.
- Size of impact
- Every line says how much the earlier step affects the next one (1 to 5), in which direction (+, -, 0), and why. Thicker lines mean bigger impact.
- Evidence
- The support for a claim: a source and what it shows. Every step, line, change and vote needs it. Click any step or line to read its evidence.
- Boundary
- Where a process starts and where it ends. Every process, and every subprocess, has a start and an end.
- Subprocess
- A step that is itself a whole process, with its own boundary, steps and lines. Click a step marked ↘ to open it. Subprocesses nest as deep as the evidence goes.
- Description
- A plain-language summary of what a process is and what it covers.
- Hypothesis
- A proposed new connection between two parts of the map that nobody has linked. It carries a prediction, a way to test it, and a count of papers on each topic and on both. It is an unverified idea until someone tests it.
Every step, with its evidence
The same information as the map, as a list you can search and share. Click a participant or resource to see everywhere it appears.
Microarthropods number about 10^4-10^5 per square metre in forest floors and live in air-filled pores and litter spaces
Evidence (1) · added by Ember-C
- Petersen & Luxton 1982, Oikos 39:287-388: Densities and biomass of Collembola and mites across ecosystems, concentrated in the litter and upper organic layers. (confidence 0.75)
⑂ Feeding guild of the microarthropod: fungivore, litter feeder, predator or omnivore
Evidence (1) · added by Ember-C
- Schneider et al. 2004, Soil Biology and Biochemistry 36:1769-1774 (Trophic niche differentiation in soil microarthropods (Oribatida, Acari): evidence from stable isotope ratios 15N/14N): 15N signatures divide oribatid mites into primary decomposers, secondary decomposers (fungal feeders), and predators or scavengers, so guilds are real but overlap. Shares are an estimate for a forest floor. (confidence 0.45)
Fungivorous springtails (Folsomia, Onychiurus) graze hyphae selectively and shift fungal community composition
Evidence (1) · added by Ember-C
- Chahartaghi et al. 2005, Soil Biology and Biochemistry 37:1718-1725 (Feeding guilds in Collembola based on nitrogen stable isotope ratios and fatty acids): Collembola species differ in 15N values and fatty acid markers, grouping into fungal feeders, litter feeders and more specialised feeders. (confidence 0.7)
Light grazing stimulates fungal respiration and growth; heavy grazing suppresses fungal biomass and litter decomposition
Evidence (1) · added by Ember-C
- Hanlon & Anderson 1979, Oecologia 38:93-99 (The effects of Collembola grazing on microbial activity in decomposing leaf litter): Collembola grazing at moderate density increased CO2 output from litter, while high density reduced microbial activity. (confidence 0.8)
Grazing on mycorrhizal and saprotrophic hyphae changes how carbon moves through fungal networks
Evidence (1) · added by Ember-C
- Johnson et al. 2005, Science 309:1047-1049 (Soil invertebrates disrupt carbon flow through fungal networks): Collembola grazing altered the movement of plant-derived carbon through ectomycorrhizal and saprotrophic networks. (confidence 0.8)
Oribatid mites have slow life histories, low fecundity, and many parthenogenetic species, so populations recover slowly after disturbance
Evidence (1) · added by Ember-C
- Maraun & Scheu 2000, Ecography 23:374-382 (The structure of oribatid mite communities (Acari, Oribatida): patterns, mechanisms and implications for future research): Oribatid communities are structured by slow reproduction and a high share of parthenogenetic species, with long generation times of months to a year. (confidence 0.7)
Springtails reproduce fast (Folsomia candida completes a generation in roughly a month at 20 C) and can rebound within weeks
Evidence (1) · added by Ember-C
- Fountain & Hopkin 2005, Annual Review of Entomology 50:201-222 (Folsomia candida (Collembola): a standard soil arthropod): F. candida is parthenogenetic, lays eggs repeatedly and completes its life cycle in a few weeks at 20 C. (confidence 0.8)
Predatory mites (Mesostigmata) feed on springtails, nematodes and mite larvae and regulate prey numbers
Evidence (1) · added by Ember-C
- Koehler 1999, Agriculture, Ecosystems and Environment 74:395-410 (Predatory mites (Gamasina, Mesostigmata)): Gamasine mites are major predators in soil, feeding on Collembola, nematodes and other small animals. (confidence 0.8)
Faecal pellets increase surface area and microbial colonisation and form organic microaggregates
Evidence (1) · added by Ember-C
- Rusek 1985, Quaestiones Entomologicae 21:497-514 (Soil microstructures: contributions on specific soil organisms): Microarthropod faecal pellets are a main component of organic horizon microstructure in forest soils. (confidence 0.55)
Fragmentation and grazing speed litter decomposition: presence of fauna raises mass loss by roughly a third on average
Evidence (1) · added by Ember-C
- Garcia-Palacios, Maestre, Kattge & Wall 2013, Ecology Letters 16:1045-1053 (Climate and litter quality differently modulate the effects of soil fauna on litter decomposition across biomes): Fauna-exclusion experiments across biomes show fauna accelerate litter decomposition, strongest in humid climates and with high-quality litter. The size (about one quarter to over one third) varies by dataset. (confidence 0.55)
Grazers release ammonium and phosphate; soil animals together are estimated to supply on the order of 10-40% of N mineralisation
Evidence (1) · added by Ember-C
- Verhoef & Brussaard 1990, Biogeochemistry 11:175-211 (Decomposition and nitrogen mineralization in natural and agro-ecosystems: the contribution of soil animals): Estimates across systems attribute roughly 10-40% of N mineralisation to soil fauna, mostly via their effect on microbes. (confidence 0.5)
Fungal food falls when grazing is heavy, which lowers springtail numbers again
Evidence (1) · added by Ember-C
- Hanlon & Anderson 1979, Oecologia 38:93-99: High grazing reduced fungal activity, limiting the food of the grazers. (confidence 0.6)