The Physiological-Ecological Responses And Its Stability Of Mixture Grassland Of Medicago And Bromus Inermis

The research was conducted at Tongliao,Inner Mongolia Autonomous Region, which was a typical part of the Agro-pastoral Transitional zone of North China, for three plant-growing seasons between 2003 to 2005. It mainly studied on physiological-ecological characteristics of mixture grasslands composed of different Medicago varia Martin and Bromus inermis, the influence of fertilization and clipping on these characteristics, and the interspecies competition in mixture communities. The purpose of this research was to discuss deeply into the mixture grassland's physiological-ecological characteristics, study and choose the optimal combination of Medicago varia Martin and Bromus inermis and the optimal fertilization and clipping measure to maintain the stability of the mixture community. The results showed that:1. The yield component of Medicago varia Martin showed a tendency to increase in mixture grassland along with the increase of cutting times and sward growth years, while that of Bromus inermis decreased by degrees. The mixture community composed of Medicago and Bromus inermis was an unstable community. Only when it got a fitting artificial controlling ccould it relatively maintain the stability of its components. N and K application increased Bromus inermis'component and decreased that of Medicago , but the effect of P application was opposite to this.2. Mix-sowing decreased the Medicago's height and growth rate in spring and autumn ,but raised those of Bromus inermis, which was more obvious in the third year after the mixture grasslands were established. The yield of mixture grassland was lower than that of corresponding single Medicago grassland(averagely by 22%). The time when mixture grassland reached its highest biomass was later than that of single grassland.3. The net accumulation of grassland biomass mainly occurred in its early growth period (20 th May to 9 th July). The absolute growth rate (AGR) and relative growth rate (RGR) of parti-colored flower'Medicago varia Martin in both single grassland and mixture grassland were higher than those of Medicago sativa .cv. Aohan. For the same Medicago variety, the fast biomass accumulation periods were uniform in single...