基于能值理论的盐城市农业生态系统动态分析

Dynamic Analysis on Agri-ecological System of Yancheng City Based on Emergy Theory

农业生态系统是人类生存的最基本系统,对其结构和功能进行分析是解决农业生态环境问题的关键。应用能值分析理论与方法,对盐城市1995—2010年的农业生态系统能值结构进行了动态分析,采用净能值产出率、能值投入率、环境承载力、能值密度、人均能值用量及可持续性指数对该地区的能值结构进行了详细研究。结果表明:系统能值总投入呈上升趋势,在能值投入中,风能资源投入逐渐增加,但总体比重不高,劳力能值投入受乡镇企业发展和进城务工因素影响逐年下降,以劳力和畜力等有机辅助能为主的传统农业正逐渐被以农机、化肥等工业辅助能为主的现代农业所替代。系统能值总产出呈上升趋势,农业产业结构由以种植业、畜牧业为主向高附加值的畜牧业、水产业的多样化方向转化。系统能值可持续发展指标为0.97,是典型的消费型生态系统,产出的能值是消耗较多的资源获得。系统对于环境的压力较大,可持续性较低,应进一步调整农业产业结构,依靠科学技术,大力发展绿色和生态农业,保护环境资源,实现盐城城市农业生态系统的可持续发展。

Agro-ecosystem is the most basic system for human beings survival, while the analysis on the structure and function of the system is the key to solve the problems of agro-ecological environment. Based on the theories and methodologies of emergy, the emergy structure in agro-ecosystem about Yancheng City from 1995 to 2010 was studied. Some indicators of emergy were selected such as emergy input ratio, net emergy yield ratio, emergy environmental carrying capacity, emergy density, emergy per capita, emergy sustainable indices were assessed. The results showed that the agro-ecosystem gross input values of research area dis- played the increasing trend. The wind resource input values added gradually but with low ratio. Because of the development of towns＇ industrial and young rural people working in cities, the manpower resource input values decreased gradually. The agro ecosystem gross input values of research area also showed the increas- ing trend. Traditional agriculture which is composed mainly by organic emergy such as manpower and live- stock is being substituted for modern agriculture gradually, which is composed mainly by agricultural ma- chinery, chemical fertilizer and industrial assistant emergy. Diversity of agriculture mode is also increasing with higher additional-value aquaculture industry. The sustainable development index of system emergy was 0.97, the system was a typical consumption-based ecological system, output emergy was obtained by consu- ming more resources. The system has a low sustainability and creates a large pressure on environment. It is necessary to adjust agricultural structure, adopt science and technology, develop environmental-friendly and ecological agriculture and obtain the object to keep sustainable development.