中文摘要：

以滇西南中低山盆谷区的芒市为例,在探讨土地利用变化合理度的概念和内涵并构建土地利用变化合理度的评价指标、测算方法和分级标准体系基础上,定量地分析评价了芒市近8 a来退耕还林工程驱动下各个地类变化的合理度和总体土地利用变化的合理度,为推进山区土地资源的可持续利用和退耕还林工程的科学实施提供基础依据。评价结果表明,全市近8 a所有地类转化的总面积为77 602.80 hm2,转化的合理度（RD值）只有48.98%,属于＂中度不合理＂级。总体上,芒市近8 a来退耕还林工程驱动下的土地利用变化,既有合理的部分,如部分陡坡耕地的生态退耕、荒山造林和封山育林等,但其不合理性亦非常突出,主要体现在生态退耕地中约96%属于＂不该退＂的宜耕地。此外,在实施退耕还林工程的同时,却又出现较为突出的毁林开垦现象。这些问题的突出存在,使芒市近8 a土地利用变化的合理性程度很低。

英文摘要：

In present study on land use/land cover change（LUCC）,rationality analysis and evaluation of land use change has not been taken seriously.In particular,there is hardly any study on the theory and method system for evaluating rationality of land use change.By taking Luxi City as an example,which is located in the middle and low mountainous basin and valley area in southwest Yunnan,this paper has discussed the concept and connotation of rational degree of land use change and constructed the evaluation target,estimation method,and grading standard system for studying rational degree of land use change.Then,based on these,it has quantitatively analyzed and evaluated the rational degree of the change in every land use type and rational degree of the overall land use change driven by the nearly-eight-year Program of Converting Farmland to Forest in Luxi City.It aims to provide basic foundation for promoting the sustainable use of land resources in mountainous areas and scientific implementation of the Program of Converting Farmland to Forest.The evaluation results reveal the following facts： 1） During recent eight years,the whole city witnessed land use type changes in a total area of 77602.80 hm2.Rational degree（RD value） of the change was only 48.98% while the irrational degree（ID value） was 51.02%,making the change at the ＂moderately rational＂ level.2） Among all land use types,farmland,forest and waste grassland had the largest changes.Farmland was mainly changed into forest,garden plot and waste grassland,a result driven by the Program of Converting Farmland to Forest.During recent eight years,the whole city had 19661.07 hm2 of farmland converted to ecological uses.Of which,18886.09 hm2 were the farmland suitable for cultivation（farmland that ＂should not have been converted＂） and only 774.98 hm2 were the farmland not suitable for cultivation（farmland that ＂should be converted＂）.The nearly-eight-year Program of Converting Farmland to Forest（grassland） had a rational degree of