Evaluation On Agricultural Ecological Security Of Zhifanggou Catchment In The Loess Hilly-Gully Region

Ecological security is an important component of national security and social stability. The situation of ecological security in watershed and region needs to be evaluated and put forward corresponding strategies for achieving ecological security. At present, the study of those mainly focused on individual and population, and there is little study on ecological security in watershed-scale.The objectives of this study were to: (1) discuss driving forces of situation changes for agro-ecological security in Zhifanggou catchment by analysis methods of multidisciplinary integration; (2)establish an assessment index system for agro-ecological security of catchment in the Loess Hilly-Gully region on the basis of"Pressure-State-Response"(PSR) model and method of Analytic Hierarchy Process (AHP); (3)assess the agro-ecological security in the catchment and analyze the pre-warning condition; (4)propose corresponding measures for achieving agro-ecological security of the catchment in the Loess Hilly-Gully region according to the investigation and monitoring data on eco-economic system evolution and development course of ecological security situation over 70 years.The detailed results are as following:(1)Eleven impact factors which affect changes of agro-ecological security state were chosen according to the analysis of agro-ecological security state in Zhifanggou catchment over 70 years. Meanwhile, driving forces of agro-ecological security change were discussed by the methods of Principal Components Analysis (PCA) and Path Analysis (PA) using investigation and monitoring data from 1985 to 2006. The results showed that natural condition is the basis for changing of agro-ecological security state, and socio-economic situations are main driving forces which could be classified into four types including economic development, the pressure of population, industrial restructuring of catchment, agricultural scientific and technological progress. Besides, the related policies of nation and region, correlation degree between agricultural industrial chain and resources affected it to some extent.(2)The evaluation index system of agro-ecological security in this region was established based on the analysis of driving forces, which includes ecological environment, socio-economy and integrative function, as well as 17 specific indexes by referring to the model of"Pressure-State-Response"(PSR) and method of Analytic Hierarchy Process (AHP). The indicator of"successional stages of community"revealed routine and major impact factors of vegetation community succession in Zhifanggou catchment. It could achieve the organic unity for forest and grass vegetation quantity and quality combined with ratio of forest and grass areas.(3)Weight of indicators was calculated based on methods of Delphi and Analytic Hierarchy Process (AHP). The quality value of ecological security was calculated by integrated weight value model, and then ecological security was evaluated by this value. The results showed that the Ecological Security Integrated Value (ESIV) had a trend of unsafe to safe. The catchment was in a relatively safe state in 1938 and a very unsafe state in 1958; as well as unsafe condition in 1975 and 1985, critically safe and relatively safe state in 1995 and 2005, respectively.(4)The black and yellow pre-warning methods were used to analyze the agro-ecological safety state in Zhifanggou catchment for past 70 years and predict security state of 2015. The results indicated that security condition lied in blue light region and did not need pre-warning in 1938. But it lied in black light region and needed pre-warning of deterioration velocity in 1958, and red light region and needed ill condition pre-warning in 1975 and 1985,and yellow light region in 1995. After these periods, it become much better and does not need pre-warning in 2005 and 2015.(5)Measures of maintenance of regional ecological security, which includes ecological security monitoring, assessment and pre-warning systems; strengthen coupling of industry and resources and promote the optimization and upgrading of industrial structure; explorement of water-saving farming techniques; supporting system of ecological safety laws and regulations; scientific and technological support for ecological security and financial security systems and so on, were integrated and discussed according to pre-warning and assessment results and predication of development indirection.