How do soil biota impact plant communities?

Question 1

Name abiotic characteristics of soil ecosystems

Answer 1

Moisture, temperature, solar radiation, light, space, allelopathy

Question 2

What are the two major pathways of soil feedback for soil biota to impact plant communities

Answer 2

Direct and indirect

Question 3

What is allelopathy?

Answer 3

The production of chemicals that are detrimental to neighbouring species

Question 4

Describe direct soil feedback of soil biota on plant communities

Answer 4

Occurs via root herbivores, pathogens, and symbionts

Question 5

Describe indirect soil feedback of soil biota on plant communities

Answer 5

Via the effect of the soil decomposer subsystem on the supply of nutrients

Question 6

What has an increase arbuscular mycorrhizal fungi diversity been shown to result in?

Answer 6

Increased plant diversity

Question 7

What is the role of mycorrhizal fungi?

Answer 7

Provide phosphorus for plant growth and increase direct nitrogen absorption in collaboration with nitrogen-fixing microbes

Question 8

Describe the relationship between a plant and mycorrhizal fungi

Answer 8

The fungi penetrates there root of the cell. The plant give the fungi carbon, the fungi extend into the soil, transferring nutrients from the soil to the place

Question 9

How do arbuscular mycorrhizal fungi lead to increased plant biodiversity?

Answer 9

They increase the survivorship of herbs, reducing the dominance of grasses. There is a more efficient exploitation of soil P reserves.

Question 10

Why do rare plants show a negative feedback that limits their growth and spread when invasive species show a positive feedback loop?

Answer 10

Invasive species accumulate pathogens more slowly. This enforces their dominance.

Question 11

How do plants modify the soil biota?

Answer 11

They change the quantity and quality of resources that enter the soil

Question 12

What are two resources that enter the soil that can affect the soil biota?

Answer 12

Root exudates and plant litter

Question 13

How can resources entering the soil affect the soil biota?

Answer 13

It can either stimulate or inhibit microbial activity and affect the soil nitrogen availability to plants

Question 14

Describe the carbon donor hypothesis

Answer 14

AM hyphae network interconnects species and carbon and nutrient supply is shared between herb species

Question 15

What did a 1998 study conclude about the diversity of AM fungi?

Answer 15

AM diversity enhanced plant diversity and productivity (ecosystem function) because high AM diversity increases external hyphae length.

Question 16

What did a 1993 study conclude about the degradation of Marram grass?

Answer 16

It degraded as it moves inland due to the build up of parasitic nematodes and soil-borne fungi

Question 17

What is the name of the marram grass genus suppressed by soil organisms and what species takes over?

Answer 17

Ammophila is suppressed and Festuca takes over

Question 18

What did a 2002 study find when studying rare and invasive species?

Answer 18

Rare plants showed -tive feedback in their own soil and invasive plants show +tive feedback in their own soil

Question 19

What did the same 2002 study conclude about soil organisms and their feedback effects?

Answer 19

That soil organisms and their feedback effects strongly influence the relative abundance within a community

Question 20

What do invasive species do to result in a positive feedback of growth?

Answer 20

Modify the soil biota in a way that modifies their growth

Question 21

What is DON?

Answer 21

Dissolved organic nitrogen

Question 22

What did a 1995 study conclude about how conifers have a competitive advantage in boreal forests?

Answer 22

Pine litter increases the ratio of DON to inorganic nitrogen. Pines take up DON by mycorrhizal associations.

Question 23

Before the 1995 study, what was thought about nutrients used by plants?

Answer 23

That plants only used inorganic forms of nutrients

Question 24

What was thought of the richness of polyphenols in pine litter?

Answer 24

Would inhibit the availability of inorganic nitrogen and enhance the production of DON.

Question 25

What have conifers (pines) adapted to and how?

Answer 25

Adapted to nitrogen limitation by monopolised the nitrogen economy

Question 26

What did Bowman et al (2004) study?

Answer 26

How slow-growing, phenol-rich herbs can coexist with fast-growing grasses in alpine meadows

Question 27

What did Bowman et al (2004) conclude?

Answer 27

Phenol-rich herb litter increases the soil microbial activity because they are a carbon source for microbes. Microbes uptake nitrogen, reducing the availability. Less N for grasses, reducing their dominance.

Question 28

How do herbaceous plants in alpine meadows enhance their persistence?

Answer 28

Modifying their environment