施氮对退化天然草地主要物种地上生物量和重要值的影响

Effect of Nitrogen Fertilizer on Biomass and the Important Values of the Main Species in Degraded Grassland

在内蒙古太仆寺旗退化天然草地连续两年进行不同施氮水平的试验,结果表明:施用尿素可显著提高退化草地主要植物种群和草地群落的生产力。施用尿素50kg/hm2对羊草和冰草地上生物量的增加效果最为显著,重要值明显提高,羊草取代星毛委陵菜成为群落中的主要物种;施用尿素75kg/hm2,羊草和冰草出现效应递减现象,糙苏的地上生物量显著增加,重要值也有所上升;施用尿素100kg/hm2,星毛委陵菜的地上生物量显著增加,盖度增大。从改良草地的效果来看,研究地区退化草地的适宜施氮水平为尿素50kg/hm2。

A field trial was conducted on a natural grassland in Taibusi Banner, Inner Mongolia, for successive two years to understand the effect of nitrogen fertilizer rates on the biomass and the important values of the main species. The results showed that the biomass of community and populations of the main species was significantly increased by nitrogen fertilizer. The population biomass and the important value of Leymus chinensis and Agropyron cristatum were significantly increased at the 50kg urea/hm^2 , and the population of Leymus chinensis was dominant in community instead of the Potentilla acaulis. The population biomass and the important value of Phlomis tuberosa L. were significantly increased at 75kg urea/hm^2 and the Leymus chinensis still was the main species in community although there was trend of the biomass decreasing. The population biomass of Potentilla acaulis was significantly increased at the 100kg urea/hm^2. The results indicated that applying 50kg urea/hm^2 was the most profitable to improve the degraded grassland in that region.