Tropical forests are sometimes cut down so that humans can use the trees for wood and other products. Then, the cleared land is made into a pasture so that cattle can be raised for human consumption. When forest land becomes pasture, the soil changes. The soil changes again once the land is abandoned. The scientists wanted to know if new forests in pastures released greenhouse gases. Topics: Active Forest Management, Agriculture, Atmosphere, Cattle, Deforestation, Forest Succession, Green House Effect, Nitrogen Cycle.