基于牧场生产力的内蒙古典型草原载畜率研究

Research on stocking rates based on the productivity of typical steppe in Inner Mongolia

基于长期放牧控制实验平台,研究了内蒙古典型草原群落在两种降水年型(平水年和丰水年)和两种地形系统(平地和坡地)条件下的初级生产力和次级生产力对不同载畜率(0、1.5、3.0、4.5、6.0、7.5、9.0羊单位/hm^2)的响应。结果表明:随着载畜率的增加,地上现存生物量逐渐降低。两种降水年型不同地形条件下,载畜率为3.0和4.5羊单位/hm^2处理均获得较高的地上净初级生产力,平均比对照区增加了30.87%,而重度放牧(SR=7.5、9.0羊单位/hm^2)处理则降低了13.53%。羊公顷增重随载畜率的增加逐渐升高,载畜率为3.0和4.5羊单位/hm^2处理的平均只羊增重均高于其他处理。综合分析初级和次级生产力的变化趋势可知,本试验条件下内蒙古典型草原牧场的最适载畜率为3.0~4.5羊单位/hm^2。

Based on the ongoing Sino - German grazing experiment, which was established in June 2004, the impacts of stocking rates on aboveground net primary productivity （ANPP） and secondary productivity were studied in the typical steppe region of Inner Mongolia grassland. The study was carried out in the two different precipitation years （i. e. , normal and abundance）, and the experimental treatments included two topographical systems （i. e. , flat and slope） and seven levels of stocking rates （i. e. , 0, 1.5, 3.0, 4.5, 6.0, 7.5, 9.0 sheep hm^-2）. The results showed that, with increasing stocking rate （SR）, the remained aboveground biomass decreased significantly. Under conditions of the two precipitation years and two topographical systems, the relatively higher ANPP were observed at the stocking rates of 3.0 and 4.5 sheep hm^-2, and was averagely 30.87% higher than that in the control plot （SR = 0 sheep hm-2）. However, the high stocking rates （SR = 7.5, 9.0 sheep hm^-2） resulted in the averagely 13.53% lower ANPP than the control plot. With increasing stocking rate, the sheep weight gain per hectare increased significantly. The treatments with 3.0 and 4.5 sheep hm^-2 exhibited higher mean weight gain per sheep than other grazing treatments, respectively. Hence, the preferable stocking rate would be on the scale of 3.0 to 4.5 sheep hm^-2 in the typical steppe region of Inner Mongolia grassland, when both primary and secondary productivity were taken into account.