RESUMO
In August 2010, a sampling work was conducted in the plots of the Leymus chinensis steppe, which were fenced in 1979, 1999, and 2004, respectively, in Inner Mongolia Grassland Ecosystem Research Station (IMGERS), aimed to approach the effects of different time periods of enclosure on the caloric values of main plant species, litters, and commnities, and on the total energy storage per unit area. Enclosure had significant effects on the caloric values of the main plant species, litters, and communities, and on the total energy storage per unit area. The total energy storage per unit area in the plots fenced in 1979 and 1999 was significantly higher than that in the plot fenced in 2004, while the caloric values of the litters and communities were in adverse. No significant differences were observed between the plots fenced in 1979 and 1999, respectively. The caloric value of the same plant species varied significantly with the time period of enclosure, and that of different plant species presently definite differences. The caloric value of communities depended on the plant species in the communities, while the total energy storage per unit area depended on the biomass production of the steppe. Both the caloric value of communities and the total energy storage per unit area presented the same variation trend of fluctuation in a short term, but maintained at a stable level over a long period of enclosure, and ecologically reached enrgy balance finally.
