【作者】 杨云贵；

【导师】 常庆瑞；

【作者基本信息】 西北农林科技大学 ， 土壤学， 2006， 博士

【摘要】 陕北农牧交错带生态环境脆弱,经济基础薄弱,粮食不能自给,粮食供需之间的矛盾成为困扰区域经济发展的重大问题。随着人口不断增长,土地压力逐渐增大,造成土地荒漠化严重,成为沙尘暴发生的主要沙源地区之一。因此,利用1986年8月、1992年7月和94年7月、1999年8月、10月和2002年8月及2000年8月的TM遥感影像,在地理信息系统技术的支持下,分析陕北农牧交错带近15年来土地利用/覆盖及荒漠化的动态变化过程与驱动机制。以Arc GIS为基础平台,完成土地资源专题图的数字化,建立空间数据库,通过层次分析法,评价研究区土地资源。采用逐步订正法估算作物生产潜力,运用迈阿密模型对草地自然生产力进行估算,从而计算出区域土地极限生产力,并估算区域最大人口承载量;用近50年的历史资料,分析区域人口发展规模与消费水平,预测研究区土地生产力发展水平,预测到2030年适宜的人口承载量。结果表明:1.从1986到2000年,研究区耕地面积减少了3599.29 km2,以旱地减少为主,减少的面积主要转化为草地、盐碱地和沙地。林地和牧草地面积分别增加1320.74 km2和785.90 km2,主要以退耕还林和沙地治理后,由耕地和沙地转化而来。城镇和农村居民建设用地增加了195.19 km2,布局上以原城区为基础上向外扩展。水体整体变化不大,但河流水面萎缩69.80 km2;滩涂和水库面积分别增加99.67 km2和9.80km2。旱地大面积盐渍化引起盐碱地面积急剧增加,特别是在监测初期到监测中期,平均以32.67km2/a的速度增加,6年内增加了196.07 km2,并且呈现景观破碎化。2.区域土地荒漠状况较为严重,荒漠化面积占到全区土地总面积的l/3,15年来沙地面积增加了463.06 km2,荒漠化的范围逐渐扩大,景观结构上破碎化程度加剧。但荒漠化程度明显下降,严重荒漠化土地面积减少了1214.74 km2。3.陕北农牧交错带土地利用/覆盖及荒漠化变化是由自然、人文和社会经济因素共同影响所导致的。气候因素是驱动土地利用/覆盖及荒漠化变化的重要自然因素;政策制度的导向、人口压力及社会经济活动直接影响土地利用/土地覆盖变化的时空分异,驱动了土地利用覆盖格局的变化。特别是人口数量的增加及不合理的土地利用,是导致土地荒漠化的主要因子。4.陕北农牧交错带土地资源综合质量评价结果显示该区的土地质量总体不高。一、二级地极少,只有238 km2,仅占研究区总面积的0.7%;三级地4143 km2,占11.5%;四级地9572 km2,占30.4%;五级地9254 km2。,占25.6%;六级地8105 km2,占22.4 %;七级地3372 km2,占9.3%。区域土地总面积为35759.43 km2,耕地8264.33 km2:人均占有粮食量仅为285 kg/人.年。全区牧草地面积占土地总面积的39.6%,草地生产力更多还原

【Abstract】 It is a problem that affects the economy of interlaced area of agriculture and pasture in northern Shaanxi that fragile ecosystem, weak economy foundation, and short food supply. The increase in population and then land pressure caused land desertification, this zone had changed into main source place of dust storm. Therefore, the land use/cover and desertification change of this zone in the past 15 years had been investigated through three sets of remote sensing data of TM acquired in August, 1986, July, 1992 and July, 1994, and August, October, 1999 and August, 2002 and August, 2000. Based on the RS and GIS, research attempted to monitor the land use/cover and desertification process and spatial heterogeneity dynamic change, work out the driving mechanism from 1986 to 2000 in this region. The spatial database was built, and then land quality evaluation based on the software—Arc GIS; the land ultimate production potentiality and carrying capacity were estimated; forecasts the land production level and suitable carrying capacity in 2005, 2015, and 2030 according to the population development and consumption standard by using 50 year’s historical data. The results show that:1. From 1986 to 2000, the total area of crop land was decreasing 3599.29km2, which was caused by rain fed land decreasing mainly, the decreasing area had mainly converted to wasteland, salina land and sand land. The area of forest land and grassland have increased 1320.74km2 and 785.90km2 respectively, the increasing area come from crop land and sand land, that was the result of returning cropland to grassland or woodland and sand land rehabilitated. With the rapid development of city base and economic of the study area, the scale of urban and country area had highly enlarged 195.19km2 from 1986 to 2000, which expanded outward based on the primary city. The body of water had hardly changed through monitoring, but the river showed shrinking by 69.80km2 in the past nearly 15 years, on the contrary, beach and reservoir area with the great augment, each increased by 99.67km2 and 9.80km2 from 1986 to 2000. The large scale of rainfed land became salina land, which brought about the increasing of its areas sharply. In particularly, during the beginning to更多还原