To test how predicted increases in rainfall variability might affect a temperate

Question

To test how predicted increases in rainfall variability might affect a temperate grassland ecosystem, researchers set up the following experiment: over a 4-year period, control plots received normal rainfall. Experimental plots received the same overall amount of precipitation, but delivered in fewer rain events separated by longer dry spells. They measured aboveground biomass (an index of NPP; P = 0.039) and plant species diversity (P = 0.05):

1) These data suggest that increasing rainfall variability in this system will lead to __________ productivity and __________ diversity.

            a) no change in either

b) no change in; higher

c) lower; no change in

d) lower; higher

2) Relative to controls, experimental plots presumably experienced __________.

a) reduced soil water content between rain events

b) increased leaching of nutrients during rain events

c) both A and B

d) reduced sunlight due to clouds during rain events

3) Observed changes in average NPP were likely due to __________.        

a) a trade-off between CO2 uptake and water loss rates

b) a trade-off between root (belowground) and shoot (aboveground) biomass

c) increased herbivory in response to reduced allocation to anti-herbivore defenses

d) All of the above

4) Relative to controls, experimental plots presumably experienced __________.

a) reduced competition from the dominant species

b) reduced predation from the dominant species

c) increased competition from a keystone species

d) increased predation from a keystone species

5) Observed changes in plant species diversity were likely due to __________.

a) a trade-off between growth rate and stress tolerance

b) high nutrient availability due to increased plant mortality and decomposition rates

c) both A and B

d) warmer temperatures between rain events

1.8 1.6 1.4 1.2 1.0 700- o 600 a 500 o 400 300 200 Control Experimental Control Experimental plotsplots plotsplots

Explanation / Answer

1 d is the answer , as predicted by the graph whenever thee is increase in rainfall variability the lower productivity but higher variability

2 both a and b because rainwall doesnot means that the water will reach to the plants , there might be leaching also i.e loss of water

3 all of the above are the contributoring reasons

4 increased competion because of availability of water and leaching effect. the nutrients were lost so the competititon increases

5 c is the correct answer

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