Theme 4 Flashcards
(46 cards)
What is soil biodiversity?
The variety of living organisms in the soil, including microbes (bacteria, fungi), microfauna (protozoa, nematodes), mesofauna (mites, springtails), and macrofauna (earthworms, ants).
Why is soil biodiversity important?
It supports nutrient cycling, soil structure, plant health and ecosystem resilience.
How does soil biodiversity contribute to nutrient cycling?
Microbes decompose organic matter, releasing essential nutrients like nitrogen and phosphorus.
How do soil organisms improve soil structure?
Earthworms and fungi create aggregates, increasing porosity and aeration.
What is the difference between species diversity and functional diversity?
Species diversity refers to the number of species, while functional diversity refers to the variety of ecological roles they perform.
Give an example of species diversity and functional diversity in soil.
Species Diversity: Counting bacterial and fungal species.
Functional Diversity: Different microbes specializing in nitrogen fixation, decomposition, etc.
What factors contribute to high soil biodiversity?
Soil structure, organic matter, moisture, temperature, oxygen, and soil heterogeneity.
How do different soil scales influence biodiversity?
Nano & microscales: microhabitats and chemical gradients.
Millimeter scale: Root exudates create hotspots.
Landscape scale: climate, vegetation, and soil type variations.
What are the methods for assessing soil biodiversity?
Microscopy, culture-based methods, DNA sequencing, enzyme activity assays, and fauna extraction (Berlese-Tullgren funnels).
What is microbial biomass estimation, and why is it important?
It measures the total microbial mass in soil using chloroform fumigation or ATP analysis, indicating soil health.
Name five ecosystem services provided by soil organisms
Nutrient cycling, soil formation, water regulation, carbon sequestration, and disease suppression.
What is the soil food web?
The network of trophic interactions among soil organisms, from primary producers to predators.
Name the four main levels of the soil food web.
Primary producers (plants, algae), decomposers (bacteria, fungi), consumers (protozoa, nematodes), and predators (beetles, ants).
What is the role of mycorrhizal fungi in soil ecosystems?
They form symbiotic relationships with plants, increasing nutrient and water uptake.
Name the five categories of soil organisms.
Microflora, macroflora, microfauna, mesofauna, macrofauna.
What are the metabolic strategies of soil organisms?
Autotrophs (photoautotrophs, chemoautotrophs) and heterotrophs (chemoheterotrophs).
Give examples of photoautotrophs and chemoautotrophs in soil.
Photoautotrophs: Cyanobacteria, algae.
Chemoautotrophs: Nitrifying bacteria (Nitrosomonas, Nitrobacter).
How do heterotrophs contribute to soil health?
They decompose organic matter, recycling nutrients.
What are the ecological roles of soil organisms?
Organic matter decomposition, nutrient cycling, soil structure formation, soil fertility maintenance.
How do soil organisms interact in predator-prey relationships?
Protozoa consume bacteria, nematodes feed on fungi, predatory arthropods hunt mesofauna.
What is the importance of nitrogen-fixing bacteria in soil?
Convert atmospheric nitrogen into forms usable by plants (e.g., Rhizobia).
Where are bacteria most abundant in soil?
In the rhizosphere, where plant roots release organic compounds.
How do fungi contribute to soil ecosystems?
Decomposition, soil aggregation, and forming mycorrhizal associations.
What is the role of actinomycetes in soil?
Decompose complex organic matter and produce antibiotics.
