额济纳绿洲景观格局变化研究

以1990年与2002年2个时像TM/ETM遥感数据为数据源,结合野外实地调查,在遥感和地理信息系统技术的支持下,通过转换矩阵和景观多样性指数、优势度指数、均匀度指数、形状指数等景观指数,对比分析了额济纳绿洲12年来的景观格局变化.结果表明: 耕地、河岸林地、灌草林地和水域的面积分别减少66.68%、0.70%、21.70%和59.38%, 城镇用地、荒漠灌丛、荒漠草地和难利用土地分别增加了0.95%、36.34%、26.16%和31.03%;2002年额济纳绿洲景观缀块形状的破碎化和复杂性程度要高于1990年;额济纳绿洲具有从河岸林地和灌草林地向荒漠灌丛和荒漠草地演化的趋势.     

Oasis land-use change and its environmental impact in Jinta Oasis, arid northwestern China

Land use change resulted in land degradation is a focus of research on global environmental changes and plays a significant role in the stability and economic development of oases in arid regions of China. Jinta Oasis, a typical oasis of temperate arid zone in northwestern China, was investigated to assess land-use change dynamics during 1988–2003 with the aid of satellite remote sensing and GIS, and to explore the interaction between these changes and oasis environment. Six land-use types were identified, namely: cropland, forestland, grassland, water, urban or built-up land, and barren land. The results indicate that cropland, urban/built-up land, and barren land increase greatly by 30.03, 13.35, and 15.52 km², respectively; but grassland and forestland areas decrease rapidly by 58.06, and 1.76 km², respectively. These results also show that obvious widespread changes in land-use occur within the whole oasis over the study period and result in severe problems of environmental degradation (i.e. land desertification, decline of groundwater, and vegetation degeneracy).     

区域尺度地形因素对奇台绿洲土壤盐渍化空间分布的影响

在对土壤盐分实测分析的基础上,研究新疆天山北坡奇台绿洲盐碱土的分布特征同SRTM数据提取的地形信息的相关性,探讨了区域尺度基于地形因子的土壤盐碱化分异规律. 结果表明:研究区土壤盐化与碱化并存,主要盐分类型为硫酸钠盐和氯化钠盐. 盐分在垂直剖面上呈V型分布,硫酸盐具有明显的表聚性. 在区域尺度上,地形对当前盐碱土分布的空间格局起主要作用,低于680 m高程的缓坡区为积盐区,高于740 m高程的陡坡区为碱化区. 研究区的碱化是典型的脱盐碱化,盐化和碱化的演化趋势表现为明显的逆向特征,即盐分随着海拔高度的降低而增高,pH则随着海拔高度的降低而减少. 地形因素对表层(0～20 cm)和中层(＞20～60 cm)土壤盐分分布格局影响较大,随着深度的增加,相关性下降. 高程与大部分盐分指标呈极显著相关,其对盐渍化程度、各盐分离子空间分布格局的影响作用大于坡度.