Final Study Guide - Soil Biology Flashcards
What is an ecosystem?
A community of living organisms that interact among themselves and with their physical environment (topography, air, water), interacting as a system
What biotic and abiotic factors drive soil biodiversity?
Abiotic (affects the most): Soil pH, organic carbon quantity and quality, soil moisture availability
Biotic: Plant species identity, predation and viral lysis
Discuss the different scales at which spatial heterogeneity in biotic and abiotic factors drives biodiversity (i.e. vertical, horizontal (small and large/landscape scale), temporal)
Biodiversity can change throughout soil horizons, different topography, and even at different times of the year
Discuss how global patterns of above and below ground biodiversity differ from each other
Higher above and below ground biodiversity near the tropics
Decrease in above ground diversity toward the poles but below ground also has high diversity close to the poles
What is a food web?
What kind of information does it give about the movement of energy in an ecosystem?
Shows the transfer of energy within an ecosystem
What is a trophic level?
An organism’s position within a food chain/food web
What are the basic trophic levels in all food webs?
Primary producers, primary consumers, secondary consumers, sometimes tertiary consumers
What are the fundamental soil ecosystem processes regulated by food web interactions?
Nutrient cycling, decomposition, plant growth, soil formation
What is the structure of an ecosystem? What is the function?
The structure is related to species diversity. The more complex the structure, the greater the species diversity The functions of ecosystems are related to the flow of energy and cycling of materials through structural components of the ecosystem
What are the most common ways of studying soil ecosystem structure (classifying soil biodiversity)?
Studying size, morphology, and taxonomical relatedness
Why do we prefer to classify soil biota by its size?
Reflects their functional roles in the ecosystem
What are the basic morphological characteristics of viruses?
What are the composed of and what cover do they have?
How big are they?
Acellular structures composed of a central nucleic acid core (DNA, RNA) with a protein or lipid cover. Size: 0.01-1 μm long
What are the possible ecological roles of soil viruses?
They contribute to nutrient turnover because they kill bacteria
Main morphological features of archaea
Unicellular or multicellular?
Eukaryotic or prokaryotic?
Low or high variety of cell shapes?
Unicellular, prokaryotic, and high variety of cell shapes
What are some examples of environments where archaea can be found? Are archaea always extremophiles? How do archaea contribute to the C and N cycle?
Hot and acid environments, hydrothermal vents, etc.
They are not always extremophiles
They can contribute to the C/N cycles as methanogens, sulfur oxidizers, and ammonia oxidizers
What are the basic morphological feature of bacteria?
Unicellular or multicellular?
Eukaryotic or prokaryotic?
Low or high variety of cell shapes?
Unicellular, prokaryotic, and high variety of cell shapes
Most numerous and diverse, smallest
What are some important roles of bacteria in soils?
There are many, list them all
Photoautotrophs, lithoautotrophs, lithoheterotrophs, weathering minerals and nutrient cycling, decomposition, production of bioactive compounds
Photoautotrophs
What do they do?
Release O2, fix N, pioneer accumulation of C/N
Week 7 Soil Biology 2 p10
Lithoautotrophs
Important regulators of the N cycle
Lithoheterotrophs
N fixing bacteria
What are the basic morphological features of fungi? What type of ecological roles they play in soils?
Unicellular, multicellular, or both?
Eukaryotic or prokaryotic?
Uni- or multicellular, eukaryotic
Saprotrophic fungi (decomposition)
Symbionts (live in close interaction with plants)
What are microbial grazers? What are some examples of microbial grazers and why are they important in soils?
Feed on the primary decomposers (bacteria, fungi, actinomycetes)
Examples are springtails (collembula), ants, termites, worms. Can stimulate the growth of microbial populations depending on grazing pressure
What are the different groups of microfauna?
What size are they?
Nematodes, rotifers, tardigrades
(2μm-100μm) micrometer, millionth of a meter
What are the different groups of mesofauna? What are their main ecological roles?
Protura, diplura, pseudoscorpions, symphylids, pauropoda, enchytraeidae, collembola, acari (mites)
Ecological functions: detritivores, microbial grazers, predators
2mm-100μm
