1) Describe and explain three ways in which feces production enhances decomposition (4.5).

 
2) Explain in detail how interspecific density-dependence operates. Give an example of a density dependent interaction between two soil organisms (4).

 
3) What are the effects of nodulation by Rhizobia or infection by mycorrhiza on root exudation (2)?

 
4) Distinguish restoration from rehabilitation from replacement (3).

 
5) Herr Doctor Professor Frogschtomper has approached you about his model of litter decomposition that he hopes will predict decomposition of native plant material in any region in the world. Because he wants a simple model, he needs to identify the few factors that are most important in controlling the rate of mineralization of litter.

    a) Which three factors are most important? (3)

    b) What parameter in the following equation would be modified to reflect the effects of the factors (1):

6) In laboratory, we used most probable number procedures to estimate numbers of Monacrosporium cionopagum and enchytraeids in 'cages' with fine and coarse mesh. In what 2 ways is this cage experiment similar to and in what 2 ways is it different from litter bag experiments (4)?

 
7) List 5 major differences between bacterial and fungal life strategies (5).

 
8) In your research project you want to investigate aspects of the biology of a soil-borne fungus that attacks plant roots. You had heard in a class that the niche concept could be applied to understanding what biotic and abiotic factors affect the fungus in the soil.

    a) Pick one biotic and one abiotic factor that determine the organism's niche (1.5).

    b) Briefly, describe the general experimental approach you would use to determine how each of these factors affect the growth of
            your organism (2).

    c) Discuss at least two problems associated with applying the information obtained above to predict the biology of your organism
               in the soil (2)?

 
9) What kind of equation is almost always used to model food webs? Discuss one theoretical and one experimental problem in using food web models to describe soil communities (3).
 

10) What is the difference between qualitative and relative stability in soil food web models (2)?

 
11) Now that you've taken Soil Ecology, you've obtained a lucrative position as an environmental consultant. Your first job is to restore a site previously mined for heavy metals and now to be replanted with native vegetation. The site consists mainly of piles of mine tailings. Describe 4 major problems that must be overcome to successfully restore this site and briefly discuss how knowledge of soil biology may help to solve each problem (6).