山区县乡公路建设对沿线景观格局的影响研究——以昆明市东川区蒋家沟小流域为例

公路建设对区域的各种生态过程、灾害活动等影响引起广大学者的关注,目前对小尺度区域公路沿线景观格局的影响效应研究较少。利用3S技术对云南省昆明市东川区蒋家沟小流域内县乡级公路沿线三期影像的景观进行分类和制图,运用Fragstats3.3软件和景观指数计算方法,从斑块和景观两个层次上研究公路建设前后景观格局的变化。结果表明:(1)不同时期建设公路及全部公路沿线均出现坡耕地显著减少、梯田显著增加的趋势;在不同距离梯度上,针叶林、灌丛、坡耕地景观百分比不断降低,梯田、草地面积增加。(2)公路沿线景观格局动态变化则表现为:在斑块层次上,1973年前建设公路沿线景观形态更复杂,破碎化程度高,1973年后建设公路沿线阔叶林、针叶林斑块数量增加,破碎化趋势明显;在景观层次上,公路沿线景观多样性增加,景观内部连通性降低,整体景观格局破碎化加剧,但1973年前建设公路沿线空间连接性有所提升,1973年后建设公路沿线则表现出空间连接性下降的趋势,公路全线两侧150 m范围对景观水平指数的影响最大。

IMPACTS OF COUNTY ROAD CONSTRUCTION ON LANDSCAPE PATTERN ALONG THE ROADS IN MOUNTAINOUS AREA——A CASE STUDY IN JIANGJIA WATERSHED,DONGCHUAN DISTRICT,Kunmin CITY

At present, the effects of road construction on ecological processes and hazards of the region have aroused the interest of researchers, but little is known about the effects on landscape pattern in small-scale regions such as watersheds. In this paper, based on the aerial photograph in 1973, Landsat TM image in 1995 and QuickBird remote sensing image, we used Remote Sensing (RS), Global Positioning System (GPS) and Geographical Information System (GIS) technologies to carry out landscape classification and mapping along the roads constructed in the Jiangjiagou watershed, Dongchun District, Kunming City, Yunnan Province. Subsequently, we analyzed landscape pattern change before and after road construction at the landscape and patch levels using Fragstats 3.3 software. The results showed that:1) the area of slope farmlands decreased and that of terraced fields increased along the roads constructed in different periods, which were similar to the percentage change of slope farmlands and terraced fields along all roads and different distance gradients. In addition, the area of coniferous forests and shrubs decreased and that of grasslands increased within different distance gradients. 2) at the patch level, patch types along the road constructed before 1973 were mainly affected by human activities with complicated shapes and high fragmentation, but those along the road constructed after 1973 were affected by human and hazard activities with more vegetation patches and obvious fragmental trend. Moreover, at the landscape level, landscape diversity increased and landscape connectivity decreased with high fragmentation. In addition, the spatial connectivity increased along the road constructed before 1973, but it decreased along the road constructed after 1973. Landscape pattern along all roads was mostly affected by roads within a 150 m range.