| Yellow River delta (YRD) is one of the biggest deltas that there is a large area of wetland in the world. Thanks to soil (sands) sediment carried by the Yellow River, there was averagely the newly formed land 21.3 km~2 in YRD. During the development of petroleum industry and urban expansion, wetlands were degraded due to population growth, irrational land use and so on. Roads, appeared as major artificial corridors, have been proved to result in habitat loss and environmental decay. However, the important ecological effects were ignored. So, in this paper, based on fields survey, the characteristics and Evolution rules of the road system in the Yellow River delta, and also the ecological effect, such as plant's habitat and Species nearly the road, soil heavy metal pollution and landscape patterns were study on micro and macro scale by various methods, and the results as flowed(1) Based on analysis results of the fields survey, the semi-automatic road extraction model adapt to Coastal Plain , including morphology detection, pattern recognition and Logical Reasoning was put forward, and the yearly road network database in the YRD from 1984 to 2006 were built by the model. The results from morphological characteristics and spatial topological analysis of the road network showed that, the expansion characteristics were different for road types. The driving force of the expansion for provincial roads and county roads was resident trip demands, while to meet the need of petroleum industry development was the most important reason for expansion oilfleld highways, and the construction of highway mainly affected by the national industrial distribution and traffic distribution. And for the result of network and barycenter analyses, the processes of network development can be divided into three stages: network divergent expanding, loops of network decreasing slowly, and network mutual connecting. The spatial form of road network development mode was from 'expanding around one axis-two cores', 'four cores confronting in two banks', to 'network connecting with multicores'.(2) Based on the analysis results of soils near the road, and combining with regional background information, a MLP artificial neural network was constructed, which could deduce heavy metals content of soil in road verges from regional background information. Heavy metals content of Soil within 50m road verges in the YRD were simulated grid by grid with 2.5m resolution, and the results showed that, this model provided a better simulation of the spatial distribution heavy metal content of soil, and the simulation results had high accuracy. The heavy metal content of soil in road verges were higher than the background values of those in Shandong province slightly, but not exceed national environmental quality standard for soils except the slight pollution of Cd. Affected by the Cd pollution, for the soil in 50m of road verges in the YRD, there are 80.69% soil are light pollution and 15.49% are almost non-pollution, and the left are non-pollution. The results indicated that though Road in study area played an important role in heavy metal accumulation, but did not bring broad and notable environment contamination yet. For different types of road, the concentrations of the tested metals were in order of Express Way (R_g)> Provincial Road (R_s)> Rural Road (R_x), except Pb. The concentrations of heavy metals besides road verge reach to peak value in 30m, and the distribution was impacted mainly by the factors such as wind direction, soil properties and vegetation cover. But the different change pattern was observed in individual metal elements because of their different diffusion mechanism.(3) The herbaceous communities beside road verges were firstly obtained based on field investigations and Twinspan classifications. The gradient change law of these plant communities and mainly environmental driving factors then were studied by using diversity analysis and DCCA ordination methods. The results showed, herbaceous plant of road verges in modern YRD are belonged to 20 families, 41 genera and 48 species, which account for 51.3%, 34.5% and 25.5% of angiosperm in YRD separately. Results of areal types analysis shows that, the plant of road verges are eurychoric, and the temperate type was dominant, while the tropical type was supplementary. Vegetation in road verges can be divided into 4 formations and 11 associations, and the constructive species in most adjacent area of road verges were mesophytes and xerophytes while hygrophyte distribute a little farer. Mainly constructive species are Suaeda glauca, Phragmites australis, Aeluropus sinensis and Setaria viridis. The plant community distribution patterns in road verges are affected by salt gradient in land-sea scale and by water gradient, nutrient gradient and microclimate in local scale. The species turnover rate in the community was exhibited a unimodal pattern and distributed symmetrically with the road. And turnover rate of provincial road was significantly greater than that of rural road. Distance from road verges, distance from seashore and road type are the mainly determinant factors. As a typical artificial corridor, roads disturbance the habitat of hygrophyte. Especially in strip within 10m of road verges, mesophytes and xerophytes invasion are observed. It is one of the most important factors which conducted wetland degraded.(4) Classification system of landscape in road margins was constructed based on field investigation, which include 1 landscape class, 3 subclass and 12 series. Multi temporal remote sensing image then used to identify landscape with 1km of mainly road verges. And dynamic evolution characteristics of landscape with different road types, different buffers and different units were analyzed by several landscape pattern indices. The result showed, dynamic evolution laws of landscape in road verges is impacted by development process of road network, function of roads, and regional development policies. The nearer of road verges was, the more serious of disturbance by human being was. The development and utilization by human decreased landscape diversity, increased landscape fragmentation, caused wetland vanishing, and regularized the boundary of landscape. Different landscape appeared different spatial pattern. Tidal flat,grass and shrub,reed field and salt field were largest in area, dry land and settlement area were largest in patch number, meantime tidal flat and reed field were highest in aggregation degree. Fractal dimension of natural wet landscape was higher than that of agricultural and artificial landscape. Combining with the study results of micro ecology process, so it can be considered that the micro ecology effect of road is not strong enough to changes the landscape pattern at landscape scale, and the main reason caused landscape changes were the persistent negative entropy input to road margin by human. hydro-ecological processes, geographical processes, biological processes and urbanization process was the dominate ecological processes impact the dynamic evolution of road verges.
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