Aboveground net primary productivity (ANPP) changes in response to temporal fluctuations in weather (Polley et al.2013) and soil nutrients (Harpole et al 2011). ANPP variations could potentially affect every ecosystem processes, thus detect changes in ANPP temporal stability has great importance in the design of strategies for grassland management and conservation. The whole research on grasslands ANPP stability has been focused on year-to-year basis, however test the seasonal stability could be very relevant for forage budget and the provision of ecosystem services. Changes in the factors controlling ANPP, such as nutrient and water addition, could cause contrasting responses in ANPP stability in different seasons of the year due to their specific climatic conditions. However, to date, there is no evidence from field experiments to reveal different seasonal stability responses.