Question

(6) A land manager wants to know whether she will maximize the total biomass in a restored grassland by increasing the species diversity of native grasses. To test this, she grows each grass species (A, B, C, D) by itself at a constant density. She also grows an equal mix of all 4 species at the same density. Each of the 5 treatments is repeated in 3 replicate plots. At the end of the growing season, she weighs the total biomass of each plot. Results are shown below: Total Biomass Replicate Species A Species B Species C Species D All 4 Species #180 #2 60 #3 100 40 80 60 15 10 40 50 60 80 60 70 (A) Does increasing species diversity have a positive effect on total biomass? Show the calculations that (B) Do these data suggest that your answer to part A is a result ofa "sampling effect" or is it more likely (C) Explain the difference between these two mechanisms ("sampling effec" versus "niche you did to get this answer an example of "niche complementarity complementarity"). (10 pts.) Show the comparison you made to get this answer

Answer 1

A)Answer

The effect of plant richness on plant biomass was significantly positive.

B) Answer

The data shows an example of complementary niche, in which the tendency for co-exsisting species occupy a similar position along one niche dimension .

C) ANSWER

Sampling effect :

More diversities communities have a greater Probability of containing and becoming dominated by a highly productive species.

Niche complementary:

Ecological differences between species lead to more complete untilisation Of available resources in more diverse communities.

Eg: rodents feeding on different sized seeds

Different rooting depths by plants, different degrees of shade tolerance.