The Response Of Relationship Between Biodiversity And Productivity To The Change Of Precipitation In Steppe Of Duolun Of Inner Mongolia

The relationship between productivity of ecosystem and biodiversity was studied under the change of precipitation. The experiments were carried out in the Duolun restoration ecological station of IB CAS, the grassland of which belongs to the Inner Mongolia typical grassland. Three precipitation grades(150% precipitation,100% precipitation, and 50% precipitation) were simulated through manual control, under which five biodiversity level (1,2,4,8,14) were set up. And the species were sampled by unequal probabilities. Measure the biomasses. The results obtained are as follow: 1. Under the condition of 50% precipitation, the curve of the equation which express the relationship between productivity of ecosystem and biodiversity is U-shaped, but its trend is ambiguous. The productivity decrease with the increase of number of species, but it was increased when the species'number was 14.Under the condition of 100% precipitation and 150% precipitation, the curve of the equation is U-shaped too. 2. The precipitation has a major influence on the relationship between biodiversity and productivity. As the precipitation increases the pattern of relationship between biodiversity and productivity turn to visible U-shaped from negative correlation. The productivity increase quickly as water condition improved when the species'number is 14. 3. The relationship between productivity and soil nutrient is negative. The productivity increases with the decrease of soil nutrient. The soil nutrient is influenced mainly by consume of plant growth. The aboveground biomass and the consumption of nutrient have the same trend. Higher aboveground biomass means more soil nutrients consumption, so C content and N content of soil decrease accordingly. 4. At the same precipitation, the lower species have stronger sampling effect, and the higher species have stronger complementing effect. Sampling effect and complementing effect are equivalent when the number of species is moderate. Complementing effect enhance with the increase of precipitation, which is obvious especially when the number of species is higher.