Answer to Question 1
Answer: Forests are integral to the hydrologic cycle in that by reducing forests and replacing them with grasses, the amount of water transpired is greatly reduced. This may cause precipitation to be reduced.
Answer to Question 2
Answer: The exchanges of carbon between the biosphere, atmosphere, hydrosphere and lithosphere is the carbon cycle. This cycle is being modified by the increased use of fossil fuels since the late 1700s, causing an increase in carbon released into the atmosphere.