Projections of the responses and feedbacks of terrestrial ecosystems to global climatic change need better understanding of soil carbon (C) storage and cycling. Grasslands account for approximately 30-40% of the Earth's surface and play an important role in regulating global C cycling. Located in arid and semiarid regions, the temperate steppe in northern China is predicted to be sensitive to climatic change (Christensen et al. 2004). Changes in plant growth in the temperate steppe in response to atmospheric and climatic change could substantially impact soil C storage and cycling, consequently influence ecosystem and regional C cycling. Soil organic carbon primarily comes from aboveground (litter decomposition) and belowground (root exudate, root decomposition) C input from plants. However, the relative roles of these two C input pathways in regulating different components of soil organic C pools and cycling are still not clear. Thus, a field experiment has been established in the temperate steppe in Inner Mongolia, northern China since 2005. This field experiment mainly solves two scientific problems: 1. Whether the various carbons input approach differentially influence grassland ecosystem and soil carbon pool; 2. How the process of different carbon input approach involved in regional carbon cycle.
The Latin square design was used in the experiment. Thirty-six 3 × 4 m plots are arranged into 6 rows and 6 columns. The distance between any two plots is 1 m. One plot in each row is assigned to one of the six treatments: 1) Control, 2) Litter removal, 3) Plant removal, 4) Litter and plant removal, 5) Double litter, and 6) Double litter and plant removal. Each treatment had six repetitions (Nadelhoffer et al. 2004). Litter was managed in the end of October each year, and a net was covered on plots to fixed litter.