Soil biota and plant soil feedback

Question 1

Plant growth depends on

Answer 1

Pathogens: negative effect on growth
Mutualists: positive effect on growth
Abiotic factors: temperature, water content, nutrient availability, pH, soil type

Sum of effects: net soil biota effect (may be -, 0 or +)

Question 2

Soil biota effect

Answer 2

impact of soil organisms on plant growth

Question 3

Plant-soil feedback (PSF)

Answer 3

interaction between plant species and soil organisms

litter (leaf and root), exudates, uptake processes.

previous plant induced changes in soil properties affect subsequent plant growth. over time a plant species develops a specific composition of soil biota in the rhizosphere = conditioning. each plant species forms ists own soil biota community.

Question 4

Measuring effects of soil biota

Answer 4

Compare growth of a plant species in soil with and without soil biota.
Sterilised soil = control
sterilised soil plus small amount of normal soil (inoculation) = soil with soil biota (these regenerate and spread quickly)
- Compare growth in both soils
PSF = log (biomass ctrl/biomass normal soil)
PSF = 0 no effect
PSF < 0 negative effect
PSF > 0 positive soil biota effect

Question 5

Measuring effects of plant soil feedbacks

Answer 5

Home and away pairwise.
Home: soil from plants rhizosphere (correct soil)
Away: soil from another plants’ rhizosphere (wrong soil)
PSF = 0 no effect
PSF < 0 home soil worse
PSF > 0 home soil better

Question 6

Effect on rare species

Answer 6

Rare species are negatively affected by soil biota, abundant species are positively affected

Question 7

PSF and invasion biology

Answer 7

Invasive species often experience more negative PSF in their native ranges than in their introduced (non-native) ranges.
The longer a species is present the more negatively it is affected by soil biota.