Spatial distribution and spatial association of Stellera chamaejasme population in the different altitude in in degraded alpine grassland

Stellera chamaejasme L spread threatens productivity, conservation and ecological sustainability in wide range of meadows and grasslands on the Tibetan Plateau of China, it has become one of the most serious weeds threatening a widerange of grasslands, which were grazed heavily. In recent years, distribution of the Stellera chamaejasme have expanded and there formed severe degraded grassland in some high altitude area. Therefore, it is extremely important to understand their biologic characters of the population distribution that are in the different altitude. It is critical for revealing the cause and mechanism of population diffusion. The experiments were conducted in degraded alpine grassland in the upper reaches of Shiyang river, Gansu Province, China.