Ecological Carrying Capacity of Tibet China ——Variety of Ecological Footprints from 1978 to 2002

Ecological footprint's theory and method are used to calculate and analysisthe ecological carrying capacity in Tibet. The results indicate: Tibet ecological footprint (2.1hm^2) keeps higher than countrywide average level (1.5 hm^2), and lower than global average level(2.4 hm^2); the result show that Tibet pasture ecological footprint is the most different with otherarea, and woodland is the second; Tibet ecological footprint grows from 1. 25 hm^2 in 1978 to 2.09hm^2 in 2002, which states that life level is improving continuously; GDP (per RMB 10~4 Yuan)ecological footprint reduces from 61. 9 hm^2 in 1978 to 4. 54 hm^2 in 2002, which states resourcesutilized ratio is increasing continuously.

Huge Carbon Sequestration Potential in Global Forests

Forests play an important role in mitigating climate change by absorbing carbon from atmosphere. The global forests sequestrated 2.4±0.4 Pg C y^-1 from 1990 to 2007, while the quantitative assessment on the carbon sequestration potential （CSP） of global forests has much uncertainty. We collected and compiled a database of site above-ground biomass （AGB） of global mature forests, and obtained AGB carbon carrying capacity （CCC） of global forests by interpolating global mature forest site data. The results show that： （i） at a global scale, the AGB of mature forests decline mainly from tropical forests to boreal forests, and the maximum AGB occurs in middle latitude regions; （ii） temperature and precipitation are main factors influencing the AGB of mature forests; and （iii） the above-ground biomass CCC of global forests is about 586.2±49.3 Pg C, and with CSP of 313.4 Pg C. Therefore, achieving CCC of the existing forests by reducing human disturbance is an option for mitigating greenhouse gas emission.

Dynamic simulation of urban water metabolism under water environmental carrying capacity restrictions

A revised concept for urban water metabolism （UWM） is presented in this study to address the inadequacies in current research on UWM and the problems associated with the traditional urban water metabolic process. Feedback loops can be analyzed to increase the water environmental carrying capacity （WECC） of the new urban water metabolism system （UWMS） over that of a traditional UWMS. An analysis of the feedback loops of an UWMS was used to construct a system dynamics （SD） model for the system under a WECC restriction. Water metabolic processes were simulated for different scenarios using the Tongzhou District in Beijing as an example. The results for the newly developed UWM case showed that a water environment of Tongzhou District could support a population of 1.1926 × 106, an irrigation area of 375.521 km2, a livestock of 0.7732 × 106, and an industrial value added of ￥193.14 × 109 （i.e. about US$28.285 × 109） in 2020. A sensitivity analysis showed that the WECC could be improved to some extent by constructing new sewage treatment facilities or by expanding the current sewage treatment facilities, using reclaimed water and improving the water circulation system.