Analysis of Emergy Dynamice in Beijing Urban Ecosystem

The changes in the emergy structure of Beijing urban ecosystem were analyzed with Emergy method from 1990 to 2001,some indicators of emergy were selected such as per capita emergy,the density of emergy,the potential of ecological functions,the basic carrying capacity of population,the self-supporting rate of emergy,and so on,and the dynamics of emergy of the city were assessed.The research result shown that Beijing urban ecosystem developed up to a higher level,but the city also faced great challenges from ecological and environmental pressures and it was an urgent task to strengthen the capacity building of sustainability for the city development.Some key areas for this capacity building also were presented.