基于分形理论的车尔臣河流域中下游土地利用动态变化

The land use change of the middle and lower reaches of Qerchen River based on Fractal Theory

土地利用变化是全球变化的重要内容和主要表现之一,该研究已成为全球变化研究的前沿和热点问题。土地利用变化一方面与自然环境演变相关,另一方面与人类活动的不断增强密切相关。文中以车尔臣河流域中下游为例,在遥感和地理信息系统的支持下,通过对1970年、1990年、2000年和2005年遥感图像的解译,获取研究区四个时期土地利用类型数据和属性数据,应用土地利用空间形态分形模型,计算四个时期各主要地类的分形维数和稳定性指数。研究表明:从综合分形维数和稳定性指数来看,且末5大类土地利用类型的形态结构复杂性基本都经历了由简单到复杂到再简单的过程,稳定性则由稳定到不稳定再稍稳定的演变过程,唯独水域的稳定性一直处于下降的趋势;从土地类型的时空变化来看,2000年各地类的复杂性由前期的简单变为复杂,土地利用斑块形态趋于不规则、空间上呈扩张趋势,稳定性最低,也是整个研究区土地利用复杂性和稳定性的一个转折点。此后,在各种人为及自然驱动力的作用下,除水域外其他各土地利用斑块形状复杂程度逐步降低,土地形态变得简单、规则,在空间上成缩小趋势,其稳定性逐渐增强,而水域的空间复杂性却在增强,稳定性下降。

Researches on LUCC（Land use/cover change） now are the frontier problem for discussion in the researches of the global environmental change.LUCC is a major part and also a main cause of global environmental changes,and it has emerged recently as an important focus for land change studies.In the paper,Qerchen oasis,which is the representative strip oasis and along with Qerchen River was selected as a typical area for this case study.A combination of remote sensing（RS）,geographical information system（GIS） and fractal theory was used to evaluate the spatial pattern of land use in Qerchen during the period from 1970 to 2005.Specifically,land use classification information was extracted from Landsat images of Qerchen in 1970,1990,2000 and 2005 under the support of RS and GIS and then used to generate a spatial database of land use.The result showed that from the universal fractal dimensions and stability indexes（SK） we can see that five different land use types in each landscape type were calculated for different periods and went through a process of from simple to complex and from stability to unstability,the fractal dimensions of water tended to decrease.From the spatio-temporal changes of the various types of land,it was obvious that from the year 2000 the each types of land went to the tendency of changing from simplcity to complexity.During that time period,the land use patch shape became more complex and more irregular,and the minimum stability was observed and it was important corner of whole study areas land use staybility and complexity.From this time,under the driving force of nature and human activicies,apart from the water area other land use shapes compliity was going to decrease.Land shapes changes was simple and regular,and in space it came in to small size,farther more the complexity of water area was going to increase,the stability decreased.