不同道路类型对澜沧江流域景观的生态影响

生境破碎化引发一系列潜在的生态效应,定量表达道路建设造成破碎化特征对于道路生态系统管理具有重要意义。针对澜沧江流域,利用GIS和FragStat软件,通过情景分析,分析了不同级别道路建设对景观的影响。结果表明:澜沧江流域一级路所影响面积最大,三级路最小,而影响的斑块数目则为一级路>二级路>三级路>高速路;生态系统影响面积为林地>草地>旱地>灌丛>水田>建设用地,斑块数目以旱地最高,其次为林地。情景分析表明,随着道路的建设和规划方案的实施,影响域内斑块平均面积减少,斑块数目、平均分维数增加,但总体上,高速路建设对生境破碎化的贡献率较小。土壤侵蚀分布结果表明,侵蚀面积为一级路>二级路>高速路>三级路。

Ecological effects of different road classes on landscape in the Lancang River valley

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.