GROUP 1:
Summary of pgs 81-95
Soil faunas are characterized by the degree of presence in the soil, in terms of amount and period of life
cycle spent in the soil. General classification most often used is base on size and how size relates to
habitats and function. Macro fauna are the ecosystem engineers as they move soil, mesofuana are the
little transformers, and micro fauna create the micro food web.
The Micro fauna : The free living protozoa of litter and soil being to 4 ecological groups : flagella, naked
amoebae, testacea, and ciliates. Flagellates are named for their flagella, one ore more and have
intensive feeding habits, mostly feeding on bacteria. Because of their feeding habits they play an
important nutrient recycling. Naked Amoebae feed phagotrophicly (engulfing) on bacteria, algae,
organic matter, and fungi and can explore small cavities that other microbes could not get to. Naked
amoebae also have a great diversity in soils. Testate Amoebae are less numerous but thrive in moist
forest systems. Ciliates have even lower numbers and enter cavities and pores and exploit bacterial food
sources. Their habitat is in moist soils, either seasonal or permanent. They can hide and reemerge
when conditions are favorable for growth and reproduction.
Reproduction: Mesofuana reproduce asexually by fission. Sexual reproduction are different by each
group. Flagelleates and amoebae can reproduce sexually by syngomy which is the fusion of two cells.
Ciliates reproduce by conjugation where a haploid “gametic” nuclei is exchanged. Fromt here they
through fission to make them genetically different from parents.
The direct count approach for counting protozoa is not very good because it cannot handle very
much material because they have to be individually counted. This affects the number of rare forms of
protozoa that are found. These protozoa can be found at depths up to 200 m deep in groundwater
environments.
Protozoa and other microfuana are a good indicator of the soil health as they are very sensitive changes
in the environment.
In the Meso fauna there are a few different groups. The Rotifera are aquatic organisms’. More than 90%
of them are wormlike and move by cilia and adhesive disc. They can form cysts to get through times of
stress. Because of their aquatic nature, they feed by creating water current and pull food to their
mouths. Nematodes are the most numerous in the soil. Their bodies are very well formed with cavities
for everybody function. Some are parthogenic and can reproduce without sex. They feed on roots, root
hairs and fungal hyphae. They have been used as indicators of overall ecological quality. They are very
sensitive to available soil water in the soil matrix. The tadigrada are the “water bears” and they are
bilateral with claws and four pairs of legs. They have “cryptobiosis” which basically allows them to
survive through anything. They live in the top 3 cm of soils in grasslands. They can be a sign of early
environmental stress.
Group 2 Soil Bio Reading Recap Pages 95-109
Tardigrada:
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Members of a group called Ecdysozoa, a group that includes nematodes and arthropods
Bilaterally symmetrical with four pairs of legs with claws on the distal ends
Are able to handle extreme environments such as be put into liquid nitrogen. This gives these
microorganisms a selective advantage in order to wait for better conditions to reproduce
Extremely resilient, able to survive after being in a dry state of suspended animation
Able to survive major environmental stresses
Primarily at the surface of grassland soils, can be found deeper in coniferous forests
Good indicators of environmental stress
Feed on nematodes
Found in association with lichens, mosses, liverworts and rosette angiosperms
Several ways to extract tardagrades by Baermann funnels, flotation and sieving through 44
micro meter sieve, or by sucrose flotation and centrifugation technique used for extracting
nematodes
Microarthropods:
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Significant impact on decomposition
Mites and collembolans are found in large numbers in soil; square meter of soil contains
hundreds of thousands of individuals representing thousands of species
Spiders, beetles, ants, and centipedes prey on microarthropods
Feed on fungi and nematodes, linking microfauna with mesofauna in food webs
Extraction efforts are not very efficient
Disturbances usually reduce numbers
Mites usually outnumber collembolans, both known as mesofauna
Significant reservoirs of biodiversity
Do not really impact soil structure
Temperate forest floors with if accumulation of organic matter support large numbers
Link microfauna and microbes to mesofauna in the food web
Unique in the way they are sampled
o To small and numerous to sample individually
o Small pieces of habitat are called and extracted in a lab
o Extractions are by Tullgren funnel, or flotation in solvents or saturated sugar solutions
followed by filtration
 Tullgren funnel best in high OM
 Flotation best in low organic, sandy soils
Collembola:
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Common name of springtails because of a lever on the bottom side of the abdomen that gives
them a jumping action
Equal to mites in abundance
Microscopes are needed to identify collembolans
Some collembolans protect plants from diseases such as Rhizoctonia solani in cotton
3 major groups
o Arthropleona
 Linear Collembola: great majority of species
 Poduromorpha
 Include important families like Hypogastruridae and Onychiuridae
whose species are dwellers in mineral soil layer
 The Poduridae family is a single darkly pigment species
 Podura aquatica natural habitat is in standing water
 Entomobryomorpha
 Furcula is well developed
 Primarily dwellers of surficial soil layers, in forest canopies or on tree
trunks
 Prey for spiders
 Symphypleona
 Spherical or globular collembolan
 Very small group, very uniform in habitats
 Dwellers in surficial litter layers, on vegetation, and in the canopies of
tropical humid forest
 Lacking eye and have short antenna
Collembolans are capable of rapid population growth in the right conditions
Occur throughout the upper soil profile and can number over 100,00 per square meter
They occur in aggregates, and are found in groups when soils are sampled
Have aggregation pheromones to bring sexes together
Main mode of reproduction utilizes spermatophores, but are also capable of parthogenic
reproduction
Continue to molt after reproduction, molt throughout life
Fungivores, feed on fungal hyphae and plant and animal remains, organic matter
Small impact on energy flow in ecosystems
Impact nitrogen mineralization, soil respiration, leaching of organic carbon, and plant growth
The major contribution of collembola on the decomposition process is from the grazing of fungal
hyphae
In agricultural fields populations increase rapidly after cultivation
Group 3
Pages 109-128
Acari (Mites)
o Oribatei
o Prostigmata
o Mesostigmata
o Astigmata
Oribatids
-400 million years ago
factors make these mites unique
o Most numerous of micro arthropods
o Possess juvenile polymorphism
o Reproduce relatively slow
o Sequester calcium by feeding on fungi
which range from 50,000-500000 per square meter
Population Growth of Oribatids
Oribatids Feeding Habits
Oribatids Impacts on the Ecosystem
o Grazes on microbial populations or fragments plant debris
mportant in the calcium dynamics of the soil
o Store and process a significant percentage of calcium in soil
Prostigmatic Mites
part of the diet of smaller Prostigmatic mites
o The family Tydeidae are important regulators of nematode populations in desert soils
o Grasshopper mites only feed on grasshopper eggs larvae
o Large red velvet mites are predators of termites and are abundant after desert rains
o Pestiforous chiggers are the larval stages of mites in the Trombiculide; the adults are predators of
collembolans and their eggs
igmata
Mesostigmatic Mites
Astigmatic Mites
Group 4
Summary of Mesofauna and Macrofauna pages 122-132
Pages 122-132 of the meso and macrofauna compared features of Mesotigmata, Astigmata, Acaridae,
Proturans, Diplura, Microcoryphia, Pseudoscorpionida, Symphyla and the use of Tullgren funnel to
effectively collect and sample insect populations. The first species that was discussed was the
Mesostigmata mites, which are mostly parasitic and predacious on invertebrates and vertebrates. The
larger of the Mesostigmata mites are the Prostigmata and may feed on small arthropods or eggs while
the smaller mites in the population may feed on nematodes. In one study it was found the 6/63 mites
collected did not feed on nematodes. Of the mites that did feed on nematodes, they were shown to
consume 3-8 nematodes per day. The Mesostigmata mite populations also seemed to increase in the
areas with high amounts of surface litter with other large litter inhabitants like Veigaiidae and
Macrochelidae.
Astigmatic mites are the least common, and they are free living and most commonly found in places that
are very moist and high in organic matter. The Astigmatic mites are commonly microbial feeders, but
some eat vegetable material, fungi, and algae. They can be a pest of stored grain, and seem to increase
in population following harvest, after rich manure applications, and following tillage incorporations
accompanied by fall rains. The astigmatic mite populations did not show increases in their population
following dry spring tillage. The Acaridae family of mites can also become pests and rapidly reproduce
under conditions of high nutrient availability.
Tullgren extractions can be used to collect small arthropods, small spiders, centipedes, small millipedes,
insect larva, and small adult insects. Social insects like ants termites require special sampling and
considerations, so the Tullgren funnel is not an appropriate measure for social insect sampling.
The second half of the reading focused on larger insects, some of which there seems to be little data on.
Proturans are small wingless insects with no antennae and eyes, and they seem to be associated with
roots and plant litter. There is uncertainty with the Proturan association with the plant roots, but it
seems that they may feed on the mycorrhizae.
Diplura are small elongate insects, with long antennae, two cerci, and can be euedaphic or nocturnal
crytozoans, which hide under rocks and bark in the day. They are found in low densities in tropical and
temperate soils. The Campodeidae family have fiiform cerci and are predators to arthropods and fungi
while the Japygidae family have modified cerci pinchers and are predators to mites and arthropods.
Some species that there seemed to be less known were the Microcoryphia who eat lichens and algae
and are eaten by spiders. The Pseudoscorpionida are predators of small arthropods, nematodes,
enchytraeids, and seem to like high humidity and leaf litter. Lastly Symphyla are small white eyeless,
elongated false centipedes that are omnivores and can become a pest who eat seedling roots.
The Macrofauna
Group 5
P132-144
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Pauropoda
o Members of the true eudaphic fauna
o Worldwide
o In forests they inhabit the lower litter layers, f layers, and mineral soils also occur in ag
soils
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o Fungus feeders but also may be predaceous
Enchytraeidae
o Family of terrestrial oligochaeta
o Small unpigmented worms aka “potworms”
o 600 species in 28 genera
 19 genera found in soils
 Rest are found in marine and freshwater
o Found in moist forest soils rich in organic matter
o Usually 10- 20 mm in length and similar to the earthworm
o Sexual reproduction
 Hermaphroditic
 Also asexual strategies of parthenogenesis and fragmentation
o Diet
 Ingest both mineral and organic particles in the soils
 Finely divided plant material, often enriched with fungal hyphae and bacteria
 Microbial tissues
 Lack the gut enzymes to digest more recalcitrant soil organic matter
o Mycorrhizal hyphae have been found in the fecal pellets from pine litter
o Strong likelihoon that they consume and further process larger fecal pellets and casting
of soil fauna such as collembolans and earthworms
o Can have a wide density range in different soils
o No relationship found for density with different
 Soil pH, temperature, precipitation
o Have significant effects on organic matter dynamic in soil and on soil physical structure
o Feeding on fungi and bacteria can increase activity and turnover and accelerate release
of nutrients from microbial biomass through selective grazing, but can also can decrease
them
 Thus the influence of enchytraeids on SOM dynamic is the net result of both
enhancement and inhabitation of microbial activity, depending on soil texture
and population densities of the animals
o Can enhance aggregates
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Macroarthropods are a group that includes larger insects, spiders, myriapods, and
others.
Body lengths range from 10mm to 15cm
Soil cores are used to collect specimens which belong to class of soil organisms
Macroarthropods can have a direct effect on soil structure (ex: termites and ants)
May be permanent or temporary residents of the soil
Numerous litter feeding species (millipedes in particular)
The diversity and number of macroarthropod species account for a major part of soil
organism diversity
Isopoda are a particular type of crustacean that occur under in many soil conditions
from drought to moist soil conditions
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Isopoda can feed on their own waste or waste dropped by other isopods
Isopods are well armed against water loss with a thick outer shell
Isopods prefer to consume a variety of leaf litters
Dan Lusty, Nick, Carson
Group 6 (145-159)
The reading from pages 145-159 contained discussion about:
Diplopoda (Millipedes)
Chilopoda (Centipedes)
Scorpionida (Scorpion)
Araneae (Spiders)
Opiliones (Harvestmen, Daddy longlegs)
Solifugae
Uropygi
Coleoptra (Beetles)
Diplopoda are major consumers of organic debris in temperate and tropical hardwood
forests. Millipedes are abundant in calcium rich areas. Millipedes can be important in calcium
cycling, since they are major consumers of leaf litter. They are able to process Ca that is
deposited on the forest floor.
Chilopoda are predators that are found throughout the world from deserts to forests.
There are five orders of Chilopoda and they are distinguished by the presence of forcipules,
which bears fangs that have poison ducts. All centipedes are predators that are fast runners,
commonly they capture small prey such as collembolans.
Scorpionida are inhabitants of warm, dry, tropical and temperate regions but have the
most diversity in deserts. Scorpions have many different prey and sometimes can be
cannibalistic. Some are mobile hunters while the others like to ambush prey. The sting of a
scorpion is about the same as a honeybee. Only a few species are deadly. Their impact on
ecosystems is unknown, although they may be dominant predators in desert ecosystems.
Aranea are the third group of chilopoda. They are solitary hunters. Spiders are found in
all environments except the truly polar arctic regions. Some of the smallest spiders could be
considered microarthropods. In a study in 2000, Lawrence and Wise found a “top-down” effect
of spiders on decomposition rates. Then spiders were removed from experimental areas of a
forest floor, collembolan populations increased. Subsequently, straw in litterbags decomposed
more rapidly in those areas. These results suggest that spider predation may reduce
collembolan populations enough to lower rates of litter disappearance on the forest floor.
Opiliones are among the largest arachnids in woodlands. They are found high in foliage,
soil surface and the smaller forms are found in litter layers.
Solifugae are desert arachnids with curved chelicerae. They are found in tropical and
temperate deserts worldwide. They do not have poison glands and are general predators.
Uropygi are arachnids that are some of the largest species. In N. America, they are
found from Florida to Arizona. When disturbed, the arachnid emits acetic acid, giving rise to
the name “vinegaroon”.
Coleoptera are the largest order of insects. Some species are predatory, phytophagous
or saprovores. They are abundant in tropical ecosystems. Rove beetles (Staphylinidae) are
attracted to decaying vegetation or carrion. Scarab beetles feed on plant roots and decaying
wood as larvae. Some species burrow under dung and create “tumble balls”, and deposit an
egg in it. Beetles bridge the gap between mesofauna and macrofauna. Beetles are important
agents in reduction of dung and animal carcasses, and in the early stages of wood
decomposition on the forest floor.
Hymenoptera- ants and ground dwelling wasps
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Formicidae- ants
o Most significant soil insect family
 Large influence on soil structure
o Live from arctic to tropics
 Communities have many species
 Also communities have many numbers of each specie
o “ecosystem engineers”
 predators of small invertebrates
 reduce abundance of other predators such as spiders and carabid
beetles
 influence soil structure
 move as much soil as earthworms
o especially important in deserts where earthworms are not
present
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Vespoidea- wasps
o Construct nest in soil
o Capture and paralyze prey to lay egg on and it is then entombed.
Diptera- Flies
 Participate in soil ecosystems involuntarily as pupae
 Larvae are important in decomposition of carrion
Isoptera- Termites
 One of the most important soil fauna for decomposition
 Great ability to digest wood
 Live in temperate, tropical and desert zones
 Some have possess a gut flora of protozoans which allows them to digest cellulose
 Others possess microbial symbionts instead which allows them to digest organic matter
Orthoptera
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Grasshoppers and Crickets
o Lay eggs on soil
Gastropoa- slugs and snails
 Feed on plant leaf litter
 Require moist conditions and high calcium levels
 A thousand species occur in North America
Oligochaeta- Earthworms
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Most important soil fauna
o Very important in soil structure and breakdown of organic matter
3,500 earthworm species have been defined
Occur worldwide where soil water and temperature are favorable for at least part of the year.
Mesofauna and Macrofauna Reading
Pages 159-171
Group 8
Meso/Micro Fauna Summary
Pages 171-185 in the reading of Meso Fauna-Micro Fauna found on the CSS 360 website
starts by discussing the biology and ecology of earthworms. Earthworms vary in size anywhere
from a few millimeters to over a meter in length in some rare cases. They consist of a tube-like
body shape that contains a pharynx and an esophagus, also with a gizzard that helps with
grinding of the organic matter they consume. In terms of reproduction, earthworms are
hermaphroditic, so they contain both male and female parts and produce a cocoon like
thickening around the body when developing embryos. Identifying earthworms requires
knowing the habitat, feeding, and morphological characteristics of different species. There are
three main categories, epigeic, endogeic, and anecic. These are then broken down into several
subcategories based on different sizes and feeding habits.
The next part of the reading discusses how much of an impact earthworms have on soil
processes. Earthworms can have a huge impact on soil including aeration and deep
incorporation of soil organic matter in the soil profile. They also have a large influence on soil
water drainage by vertical burrowing and creating more macropores for water flow.
Earthworms also secrete castings as they consume organic matter of a soil. These castings are
said to contain more plant available nutrients and can improve microbial activity of a soil. To
increase microbial activity, earthworms mix mineral soil and plant residues and inoculate them
with microbes. Epigeic species of earthworms generally stay near the soil surface and mix plant
residues in the A and O horizons, while Anecic species will secrete castings on the surface of
soils and burrow deep into the soil profile incorporating organic matter. Although earthworms
are generally known as helpful to a soil profile, they can be detrimental. They can increase
surface erosion, be an annoyance to gulf course with surface castings, promote the leaching of
nitrogen through the soil profile, and also increase the immobilization of organic carbon
through increased microbial activity.
There has been in interest of incorporating earthworms as a beneficial soil animal to
many areas including agricultural fields, and with waste materials. Because they greatly
increase the decomposition of organic matter, earthworms would be very beneficial to a waste
decomposing sight or a field with a slow rate of decomposition and decreased microbial
activity.
The reading also discusses the many methods of collecting earthworms from a soil
profile. These methods include digging a specific area of soil and quantitatively counting
earthworms; applying chemical irritants to the soil that brings earthworms to the surface;
“grunting” or vibrating of a wooden stake in the soil profile to bring them to the surface;
electrical extraction by using a metal rod and sending currents through the soil; and finally just
recording what castings were found on the soil surface will give a rough estimate of your
population of earthworms.
In all, earthworms are generally seen as beneficial to soil processes and are used by
environmental scientists to identify whether or not a soil is healthy. The more earthworms
present in a soil, the healthier the soil generally is. Scientists have done various studies on
castings of earthworms and their composition. They have noticed a large jump in microbial
activity where these castings are present in the soil.