关键词: 道路网络, 生态影响, 景观, 澜沧江流域

Abstract: The existence and extension of road networks affect adjacent landscape patterns and processes.The direct or indirect influences of ecological process caused by roads can extend from population to landscape level. Road development is a primary mechanism of fragmentation, removing original land cover, creating edge habitat, altering landscape structure and function, and increasing access for humans.Nowadays road ecology becomes a newly-emerging field in the ecologic research. Studies of the road effects on population and ecosystems were carried out in the past few years. But large scale research beyond ecosystem level has just been initiated.As series of potential ecological effects are brought out by landscape fragmentation due to road construction, it is significant to quantify the fragmentation features for management of road and its surrounding ecosystem.Meanwhile the regional ecological security attracts more and more attention as the road network expands.This paper focuses on the Lancang River valley and analyzes the relationship between ecosystem fragmentation and road construction and planning using GIS and FragStat software. By scenario analysis, the paper got the landscape change with seven road construction scenarios. The results show that the first level roads affect the largest area, next is the second level while the third level roads affect the least. The sequence of affected patch number is first level road > second level road > third level road > expressway. For the different ecosystems, the effect shows similar tendency and the area order is forest > grassland > arable land > shrub land > paddy field > construction land and patch number is arable land > forest.Scenario analysis showed that in the Lancang River valley road network development results in the increase of patch complexity and landscape fragmentation, also the trend suggests that the third level roads have larger effect on fragmentation.The average patch area decreases while the patch number and fractal dimension increase with the actualization of road construction and planning.But the expressway affects little in general. The results suggest that expressways may affect the larger ecosystem area, but they have far less effect on regional landscape fragmentation. Soil eroded area sequence is first level road > second level road > expressway>third level road and the erosion intensity mainly exhibits middle level.

Key words: road networks, ecological effect, landscape, Lancang River valley