Question

Imagine that you have been working in the plant community on the Scottish moor. After

many field observations, you have demonstrated that plots with more diverse plant

communities tend to be more highly productive.

You want to test a niche complementarity model, to see if the niche complementarity

model describes the reason for the positive relationship between plant diversity and

production. To test this model, you plant several plots of each of the following

treatments:

Treatment 1: 10 plant species from 2 functional groups

Treatment 2: 10 plant species from 5 functional groups

Treatment 3: 5 plant species from 2 functional groups

Treatment 4: 5 plant species from 5 functional groups

You measure the total plant biomass produced in each of the plots.

If the niche complementarity model is true, what relationship would you expect to see

between functional group richness and productivity for a given number of species? You

can describe the relationship or sketch a graph. Briefly explain why you would expect to

see this relationship.

Answer 1

Niche complementarity model states co-existing species can overlap in fundamental niches, if they use different forms of resources. Now, functional groups are non-phylogenetic collection of species which share an ecological characteristic and play an equivalent role in the community. These are the sets of species showing either similar responses to the environment or similar effects on ecosystem processes.

If niche complementarity model is true, the we will find that higher the fuctional group richess, higher will be the productivity for a given number of species. This is because high functional richness will provide more different options available to species for their survival activities. And hence, according to complementarity model, different species, in this case, will co-exist using different resouces available in different functional groups. Due to this, productivity will be more for a given number of species.