Researchers studied carbon dioxide exchange in a degraded grassland and a maize cropland in China from 2003 to 2009. The cropland lost carbon overall, while the grassland released carbon consistently. Sunlight and vegetation health influenced carbon exchange, with more rain leading to more carbon uptake. Drought affected the grassland early in the growing season and the cropland later on. Overall, the amount of rain and timing of droughts play a big role in how these ecosystems release or absorb carbon.