围封对内蒙古锡林河流域羊草草原主要构成植物个体、枯落物及群落热值的影响

2010年8月,对中国科学院内蒙古草原生态系统定位站1979、1999和2004年围封的羊草样地进行取样,测定植物个体、枯落物及群落的热值,探讨不同围封时间对羊草草原主要构成植物、枯落物、群落热值及单位面积能量积累量的影响.结果表明:围封对羊草草原主要植物个体、枯落物、群落热值及单位面积能量积累量均具有显著影响.1979和1999年围封的羊草草原单位面积能量积累量显著高于2004年围封,2004年围封群落和枯落物的热值均显著高于1979和1999年围封,而1979和1999年之间无显著差异.在不同围封时间下,同种植物的热值差异显著,而不同种植物的热值则表现出一定差异;群落热值高低取决于构成植物,而单位面积能量积累量主要由草地的生物产量决定,二者的变化趋势均为短期内有一定波动,长期围封之后基本维持在一个较稳定的水平,最终达到生态能量平衡.

Effects of enclosure on the caloric values of main plant species, litters, and communities in Leymus chinensis steppe in Xilin River Basin, Inner Mongolia

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.