生态脆弱区耕地集约利用变化的能值分析

Emergy Analysis of Intensive Cropland Use Change in Ecological Fragile Area

为了进一步分析生态脆弱区农地集约利用变化对区域农业经济和生态环境的影响,利用综合研究方法定量表征农业投入、产出、产投比的研究显得十分必要。以处于典型农牧交错区的宁夏盐池县为案例区,利用能值分析的计算方法探讨了研究区实施生态退耕后的2001—2008年耕地劳动力和农资投入、产出、产投比的动态变化特征。结果表明:随着种植面积的变化,单位面积劳动力投入总体呈下降趋势,而农资投入呈波动上升趋势;单位面积产出大幅度波动,而产投比呈波动下降趋势;产投比的波动方向受劳动力投入、农资投入和降水量的制约明显。研究结果显示,生态退耕后,单纯注重增加农资投入、扩大种植面积,而忽视高素质劳动力的投入以及因地制宜利用气候条件,可能是耕地产投比波动下降的原因;同时,研究区农资投入强度的增加,使农业面源污染风险加大。

In order to study the effect of intensive cropland use change on regional agricultural economy,ecological and environmental conditions in ecological fragile area,it is necessary to use comprehensive method to quantify agricultural inputs,outputs,and the ratio of output to input.Yanchi County in Ningxia was selected as a case area,which is located in typical farming-pastoral ecotone,and emergy analysis was used to study the changes of labor input,agricultural material input,cropland output,and the ratio of output to input of the cropland during 2001 to 2008.It was found that the labor input per unit area showed a fluctuating downward trend,but the agricultural material input per unit area increased in volatility with the change of cropland area;output per unit area fluctuated and the ratio of output to input decreased fluctuately,which was affected by labor input,agricultural material input,and precipitation.The results suggested that simply focusing on increasing agricultural investment and expansion of cropland area,while neglecting educated labor input and local ecological conditions after ecological restoration,might affect cropland productivity and resulted in increase of agricultural non-point source pollution risks.