禁牧政策对宁夏盐池县农业生态系统服务影响的能值分析

农牧交错区农业可持续发展问题一直是我国区域农业研究的重要课题,以典型北方农牧交错区宁夏盐池县为例,利用农业生态系统能值分析框架,评估盐池县1991—2016年农业生态系统正反服务,揭示禁牧政策对农业可持续发展的影响。研究结果表明:(1) 1991—2016年盐池县农业投入能值和农业生态系统正反服务能值一直处于增长的趋势,禁牧政策实施以后增长速度高于禁牧之前,其中农业投入能值的增加主要是由于经济反馈能值投入的增加。(2)根据Pearson相关性分析,盐池县农业生态系统服务和反服务在0.01水平(双侧)呈显著的强正相关,农业生态系统服务和反服务具有相同的变化趋势。(3)生态环境的改善、经济反馈能值和农业灌溉面积的增加,可以增强北方农牧交错区农业抵御气候波动的能力。(4)盐池县农业可持续性高于全国和典型农区的平均水平,禁牧政策实施之前盐池县农业可持续性表现出稳定的下降趋势,而禁牧政策实施以后其可持续性表现为上升的趋势,禁牧政策的实施已初步实现农业生产的生态经济效益。

Emergy analysis of the crop ecosystem services of Yanchi County in Ningxia

The sustainable development of agriculture in the agro-pastoral ecotone has always been an important topic of regional agricultural research in China. In this paper, Yanchi County in Ningxia was taken as a typical case area of the agro-pastoral transitional zone in north China; a ecosystem services and dis-services of the crop ecosystem in Yanchi County from 1991 to 2016 were evaluated by using the framework of emergy analysis of an agricultural ecosystem, to try to reveal the effects of a grazing-prohibition policy on sustainable development of crops. The results showed that:(1) From 1991 to 2016, the emergy input, ecosystem services and dis-services of the cropping ecosystem in Yanchi County increased. After the implementation of the grazing-prohibition policy, the growth rate increased. The increase of emergy input in cropping was mainly due to the increase of purchased emergy input. (2) According to the Pearson correlation analysis, there was a significant positive correlation between the ecosystem services and anti-services at the 0.01 level (bilateral), and changes in agricultural ecosystem services and dis-services had the same trend. (3) The implementation of the grazing-prohibition policy promoted an improvement in the ecological environment, the increase in the purchased emergy input of the social economic system, and the increase in irrigated area, which can enhance the ability of the semi-arid northern agro-pastoral ecotone to withstand climate fluctuations. (4) The sustainability of crops in Yanchi County was higher than the national average and that of typical agricultural areas, and its sustainability showed a steady downward trend before the implementation of the grazing-prohibition policy, whereas an upward trend was observed after the implementation of this policy. The implementation of the grazing-prohibition policy has led to preliminary ecological and economic benefits for agricultural production.