soil food web Flashcards
what can be contained in a handful of healthy soil
billions of individual bacteria, several km of fungal hyphae, up to 100,000 protists, up to 500 beneficial nematodes, micro-arthropods(mites and springtails)
what are soil organisms
a multitude of different species found in the soil that range in size, where they live in the soil (habitat), and what they do in the soil (their function)
they are related through the soil food web
what is the definition of the soil food web
a complex community of organisms living all or part of their lives within the soil, which interact through the transfer of energy, nutrients, and carbon between species within the ecosystem
the soil food web describes how these different organisms interact, specifically how nutrients, energy, and carbon are exchanged
what is a trophic level
a group of organisms within an ecosystem that occupy the same level in the food web
what is in the first trophic level
photosynthesizers
what do photosynthesizers do
they capture carbon from the atmosphere and energy from the sun
what is in the second trophic level
decomposers, mutualists, pathogens, parasites, root feeders
whats in the third trophic level
shredders, predators, grazers
whats in the fourth trophic level
higher-level predators
whats in the fifth and higher trophic levels
higher-level predators
what fuels the food web and what captures the energy
photosynthesis and primary producers (such as plants, algae, moss) use the suns energy to fix CO2 from the atmosphere
where do organisms higher on the trophic levels get their energy and carbon from
by consuming the organic compounds found in primary producers, waste by-products, and other organisms in the food web
what happens as different organisms comprising the soil food web consume other organisms
energy is exchanged between trophic levels and nutrients are exchanged between organisms or released into the inorganic environment (soil solution or the atmosphere)
what depends on the activity of the soil food web
nutrient cycling and thus plant growth
within the food web, organisms can be categorized on the basis of…
Where they get there source of carbon (heterotrophs or autotrophs)
Where they get there source of energy (phototrophs or chemotrophic)
what are autotrophs
organisms that obtain their cellular carbon from CO2
what are heterotrophs
organisms that obtain their carbon from pre-formed organic compounds and are incapable of using inorganic compounds as sole sources of energy
what are phototrophs
organisms that obtain their energy from the sun
what are chemotrophs
organisms that get their energy from biochemical oxidation of inorganic elements such as N, S, and from organic energy sources such as carbohydrates, lipids, and proteins
what is an example of a chemoheterotrophs
all animals, fungi, actinobacteria, and most bacterial
what is an example of photoheterotrophs
a few algae
what is an example of chemoautotrophs
ammonia oxidizers, sulfur oxidizers
what is bacteria
single-cell organisms, prokaryotic, can be both auto and heterotrophic, most abundant group of soil microorganisms
what role do bacteria play on the soil
important for: nutrient cycling, soil organic matter formation, remediation of contaminated soils, and a variety of symbiotic interactions with plants and other soil microbes
what is fungi
heterotrophic organisms, ranging from microscopic single-cell yeast to multicellular filamentous organisms
what is the function of fungi
primarily responsible for decomposition of complex macromolecules (ex. lignin) comprising organic matter
fungi are generally more abundant than bacteria in forest soils (due to lignin)
what are the benefits of fungi
help to cycle nutrients and carbon, and form soil organic matter
form filamentous hyphae, which is good for foraging for food and is important for stabilizing soil aggregates
can also have a symbiotic relationship with plants ex. myerrhizal
how can fungi be bad
can be pathogenic and cause diseases in planta, animals, and humans
produces spores prolifically, therefore, can be easily dispersed in the environment (many are airborne)
soil type, pH, water content, and temperature affect the presence of soil-borne plant pathogenic fungi
what are protists
single-cell eukaryotes, many are predatiors-consume other microorganisms, some cause plant disease,
what is clubroot and how can we reduce the spread
it is a soil-born disease caused by a protist pathogen affection canola in Canada
to reduce we can make sure to clean equipment when moving field and have a diverse crop rotation
what are algae and cyanobacteria
photosynthetic organisms that can fix C via photosynthesis, therefore, they must be at or near the soil surface.
some cyanobacteria can also fix atmospheric N2
together they are important colonizers in early soil formation and they can add both organic C and N to parent materials (ie. primary producers)
