L16 - Soil biota impacting plant communities Flashcards
What are the abiotic factors structuring plant communities?
Moisture, temperature, solar radiation, competition for nutrients, light, water, and space, allelopathy, and dispersal
What are the two major pathways through which soil biota affect plant communities?
- Directly, via root herbivores, pathogens, and symbionts
- Indirectly, through the effect of soil decomposers on nutrient supply.
How do arbuscular mycorrhizal (AM) fungi affect plant diversity?
AM fungi reduce dominant grasses, increase sub-dominant herbs, and enhance overall plant diversity.
What is the “C donor hypothesis” in AM fungal interactions?
AM fungi create hyphal networks that interconnect plant species, facilitating the transfer of carbon and nutrients among them
How does AM fungal diversity impact ecosystems (Van der Heijden et al., 1998)?
- Enhanced AM fungal diversity increases plant productivity and diversity.
- It promotes more efficient use of soil phosphorus and enhances plant biomass.
Why does AM fungal diversity promote ecosystem function?
Increased fungal abundance and external hyphal length optimize nutrient use and improve plant growth and diversity
How do soil pathogens drive plant community succession (Van der Putten et al., 1993)?
Host-specific pathogens build up in stabilizing dunes, reducing the growth of dominant species (e.g., Ammophila), allowing other species (e.g., Festuca) to dominate.
How do rare plants and invasive plants differ in plant-soil feedbacks (Klironomos, 2002)?
- Rare plants exhibit negative feedback due to pathogen accumulation, limiting growth.
- Invasive plants show positive feedback by modifying soil biota to favor their own growth.
How do parasitic plants like Rhinanthus minor affect nutrient cycling?
- They infect roots of dominant grasses, causing root death.
- This enhances carbon leakage into the soil, stimulating microbial activity and nitrogen cycling
How do tannins in pine litter influence nitrogen cycling (Northup et al., 1995)?
- Tannins inhibit inorganic nitrogen mineralization.
- They increase dissolved organic nitrogen (DON), which pine trees can directly use via mycorrhizal associations.
What competitive advantage do pine trees gain from tannin production?
Pine trees monopolize nitrogen by favoring organic nitrogen forms, benefiting their growth in nitrogen-limited ecosystems.
How does Acomastylis affect nitrogen cycling in alpine communities (Bowman et al., 2004)?
Its phenolic-rich litter stimulates microbial uptake of nitrogen, reducing availability for competitors like fast-growing grasses (Deschampsia).
How do soil biota influence plant communities?
Through direct mechanisms like symbionts and pathogens and indirect mechanisms like altered nutrient cycling.
What role do plant-soil feedbacks play in ecosystems?
They are major drivers of plant community dynamics and ecosystem processes, with both positive and negative outcomes.
