近15年台兰河流域土地利用变化及其生态效应研究

Study on Land Use Change and Ecological Effect in Tailan River Watershed in Recent 15 years

利用1990、2000和2005年的TM影像数据，在GIS技术支持下，定量研究了近15年来台兰河流域的土地利用变化特征。结果表明：1990-2005年。台兰河流域耕地和沙地面积均明显增加，分别增加3．50万hm^2和2．05万hm^2，而草地和天然林地面积锐减，其中草地净减少6．00万hm^2，反映出流域有大面积拓荒的趋势。选择研究区5组自然条件相同而土地利用方式不同的代表性样区进行对比研究，结果发现不同土地利用方式对土壤有机质含量及总盐的影响主要发生在0～25cm土层中，剖面中土壤有机质含量及总盐自上而下明显降低。人工甘草地和盐碱地的土壤总盐远高于其他土地利用类型，土壤表层（0～20cm）有机质含量在几种土地利用类型之间的比较是：经济林〉耕地〉人工甘草地〉改良沙地〉盐碱地。随耕种年限的增加耕地总盐含量降低，有机质含量增加。

TM remote data in 1990, 2000 and 2005 were used to explore land use type changes from 1990 to 2005 in Tailan River watershed using GIS. The results indicated that the areas of cropland and sandy land increased by 3.50×10^4 hm^2 and 2.05 × 10^4 hm^2 respectively while grassland area decreased by 1.43 × 10^4 hm^2, suggesting the great reclamation over the past years. Five sites with similar natural conditions but different land uses were selected for comparing soil properties, soil organic matter （SOM） and total salt decreased sharply with soil depth, and the effects of land use type on SOM and total salt occurred mainly within 0 - 25 cm depth. The total salt of croped glycyrrhiza land and saline-alkali land were greatly higher than those of the other land use types. SOM contents in topsoils of land use types followed an order of economic forest 〉 farmland 〉 croped glycyrrhiza land 〉 ameliorated sandy land 〉 saline-alkali land. In addition, total salt decreased while SOM increased with the years of farming.