Ecological Responses Along The Road Corridor In The Arid & Semi-Arid Regions Of Northwest China

Since the day when the motor vehicle came to the human society in a large volume, the road network has taken its opportunity to form the shape in a more sound manner, and gradually roads, as recognized as initiating factor for regional economic booming, has become an important facilities which can provide human being with mobile access to fulfill their day to day's exchange between places and people, economically and culturally. Therefore, the roads continuously enhance its scale and increase its density, finally overlaid on our land like fishing net; nevertheless, the roads never end its expansion and stretching in the voices of praise.During the three or four years for construction and a long term of life for operation of a road, it causes various scale ecological pressures on surrounding environment from a niche to a landscape, such as habitat occupation & shrinking, community fragmentation, water erosion, acoustic impacts, harmful waste, even the heavy metal releases etc.. However, all these impacts has not attracted sufficient attentions from the geographic and ecological circle for a pretty long time, especial much less studies have been done domestically. A recent study carried out in Netherlands indicates there are 17%~20% of the total national land being impacted by the roads network (R. Reijnenetal, 1995) in such country; in United States this ratio can even be as higher as 19%-22% of the total lands (Richard T.T. Forman, 2003) . In China, this figure has not been obtained so far, but the swift progress of the infrastructure development in China is eyeable, the mileage of expressway in China has reached almost 30,000 kms which raises China up to the 2nd position in the world only behind United States. In addition, if take account of the remaining Chinese classified highway, unclassified and unregistered roads spread in the vast countryside, this figure will never be a small one.Since the execution of the West Development Campaign Program in the northwest China, this region has to face a great deal of environmental challenges given its fragile ecological status qua. The Highway construction as a major ecologically affecting factor occupies many arable lands among the limited total amount, deprives the animal and plants of their habitats, causes many new erosion interfaces and spots etc., all these worsen the existing eco-condition in such an arid and semi-arid area, strengthen the ecologically irreversible feature. The roads construction aggravates the conflicts among the local resource development, eco-environment and population pressure, and then the road ecological issue become one of the most outstanding challenges. Given such background we selected five road sections all located in arid and semi-arid region in Gansu Province asthe studied areas in this dissertation. Through collection of the animal and plants data along the roads on field and utilization of the concerned statistics methods and Back-Propagation (BP) calculation methods of the Artificial Neural Network (ANN) under Matlab environment, we analyze the ecological responses, temporally and spatially, of those representative amphibian and reptile animals, growing plants and the soil lead content towards the road (traffic) on the side of the roads, as to indicate the ecological responses to the roads and its traffic in the ambient surroundings. Meanwhile we raise up some of the issues deserving the concerns in the road ecological management, and hopefully the study can form some references for the decision making in the harmony economic and social development activities in northwest China. This dissertation has been broken down into 5 chapters as detailed as below.The chapter one contains the brief introduction of the background for subject selection including description of the relationship between roads and ecology; the current situation of ecological effects due to the roads construction; and the status of the road network development in this arid & semi-arid region of northwest China, and also the study status of the road ecology both domestic...