EFFECTS OF IRRIGATION ON PRODUCTIVITIES OF DIFFERENT GRASSLANDS IN NORTHERN CHINA

摘要

Soil water is a major limiting factor to determine the grassland productivity in temperate grassland of China. Artificial irrigation is a useful way to increase the grassland productivity to improve the grassland service. However, the irrigation effects might be different among different grassland types including desert, typical, and meadow steppes across the Chines North Temperate grassland due to the variation in water limitation among them. To test it, three controlled water addition experiments were conducted in three steppe types including a desert, a typical, and meadow grassland, respectively. In each steppe, 18 plots with 1 m 2 were setup, and six treatments (i.e. added none, 20, 40, 60, 80, and 100 percent of annual mean annual precipitation) were supplied during growth season. We assessed the biomass production of each plot at the end of growth season. We found artificial irrigation had strong positive effects on grassland productivities of the three steppes. However, as expected, the effects of irrigation differed among the three different grassland types. The effect was stronger for typical steppe than for other two steppe types. In the meadow steppe, the grassland productivity did not increase anymore after the irrigation more than 40% of the local annual mean precipitation, possibly because the source limitation from water to nutrient. Further studies are still needed to test to improve the grassland management and service.