Livestock and sewage waste increase nitrogen and can affect the biosphere (aquatic ecosystems). Additionally, trees are often cut down in order to make land available for livestock grazing. Deforestation can lead to an increase in soil erosion; oftentimes, this increase the amount of nutrients that end up in the water.

The interactive lab activity on the next page explores how deforestation affects a local pond ecosystem. The last experiment shows how nitrogen pollution, as a result of grazing, affects frogs that live in the pond.