Axel studied experimental plots in a tropical rain forest and in a temperate grassland, and found th

Axel studied experimental plots in a tropical rain forest and in a temperate grassland, and found that when he fumigated decomposers, killing them, plant growth suffered more in the tropical forest than in the grassland. What is an explanation for this?
   A. Grasslands have greater rainfall.    
   B. Grassland soils hold more nutrients    
   C. Grasslands lack vines.    
   D. Grasslands have more efficient recycling of nutrients.    
   E. Grasslands lack epiphytes.

If global warming were to reduce rainfall from 100 cm annually to 20 cm annually in an area of taiga at 30 degrees north latitude, what kind of ecosystem would replace the taiga?
   A. Grassland.    
   B. Deciduous forest.    
   C. Desert.    
   D. Arctic tundra.    
   E. Savanna

Dirk is a politician who is trying to understand the greenhouse effect. Which of the following explanations is most accurate?
   A. Atmospheric gases block heat radiation from the earth.    
   B. Tropical rain forest destruction mimics the destruction of a greenhouse.    
   C. Ozone is generated by automobile pollution.    
   D. CFCs produce holes in the ozone layer.    
   E. Global warming results in melting of glaciers.