生态足迹模型及其改进模型在耕地评价中的应用

耕地是一种公众资源,承载着保证粮食安全、满足工业化和城市化用地需求,以及生态建设退耕还林还草要求等功能。运用传统生态足迹模型及区域能值足迹模型、耕地能值足迹模型两种能值改进模型,从时间序列上(1978～2007年)对新疆耕地资源利用进行了评价,并分析了3种模型的优缺点。结果表明:1978～2007年间,新疆人均耕地生态足迹不断上升,而人均生态承载力呈无规律变化,但变化幅度较小;新疆耕地生态可持续发展指数不断下降。耕地能值足迹模型显示,新疆耕地可持续发展指数由1978年的5.63下降到2007年的0.60,新疆耕地利用逐步由可持续状态(1978～2000年)恶化为不可持续状态(2001～2007年)。3种模型的对比研究表明:区域能值足迹模型不适合对耕地利用进行评价,只能从总体上分析一个区域的可持续状况;耕地能值足迹模型评价效果最好,能更客观地反映出耕地利用的可持续状态及其变化,在一定程度上克服了传统生态足迹模型的不足和缺陷。

Application of traditional ecological footprint and its derivatives in evaluating utilization of croplands

Cropland is a public resource with important functions such as ensuring food security, offsetting the demands of industrialization and urbanization and balancing ecological requirements by returning farmlands to forests and grasslands. Based on emergy theory analysis, two modified ecological footprint accounting models regional emergetic ecological footprint (REMF) and cropland emergetic ecological footprint (EMEF)] and the traditional ecological footprint model were used to evaluate utilization of croplands in Xinjiang. The merits and demerits of the three models were also determined. The study shows rising ecological footprint of cropland for per-capita in Xinjiang in 1978~2007. Per-capita ecological capacity in the study area is stable, indicating a marked decline in sustainable ecological development index (ESI) in the region. EMEF also shows an unsustainable use of croplands in Xinjiang for 2001~2007, following a sustainable use in 1978~2000, with ESI dropping from 5.63 in 1978 to 0.60 in 2007. Comparative studies of the three methods show that the regional emergy ecological footprint model (which is only a general analysis of regional sustainability) is not suitable for evaluating use of croplands. Cropland emergy ecological footprint model is the best as it takes into account of sustainability of croplands and to some extent overcomes the shortcomings of traditional ecological footprint model.