The study looked at how different types of forests in subtropical China affect the amount of easily decomposable carbon in the soil. They collected soil samples from three types of forests and found that the topsoil in one type had more of this carbon compared to the others. This means that converting forests from one type to another can reduce the amount of easily decomposable carbon in the soil. Additionally, they found that the reduction of carbon was higher in the rainy season compared to the dry season.