Influence Of Road Network On Regional Landscape Pattern And Eco-function

The development of road network is the vital factor to induce adjacent and regional landscape pattern change, to quantify its fragmentation effect not only is essential for Road Ecology, but also is significant for road and ecological management. Taking Jiangning District, Nanjing City as a case, with the support of remote sensing and GIS technology, referring to theoretical knowledge about road ecology and landscape ecology, and based on the spatiotemporal evolution characteristics of land use from1980to2010, the influence of road network on landscape pattern and eco-function was evaluated by comparing different characteristics of landscape pattern, ecosystem services value, ecosystem transformation and landscape ecological functions in the year of1980and2010. The main results were as follows:During1980to2010, a large area of cropland and woodland in Jiangning District was occupied and encroached by construction land. As a result, the area of construction land increased dramatically, from102.64km2in1980to472.46km2in2010, and increased by4.60times. The spatial pattern of road system of Jiangning District was analyzed using kernel density estimation (KDE) method. The landscape pattern disturbance effect of road network was discussed and found that patch density (PD) and splitting index (SPLIT) increased while largest patch (LPI) and aggregation index (AI) decreased after overlaying road network. Road construction had strong cutting effect on the integrity of original landscape and could lead to regional landscape fragmentation. But in terms of the change tendency of landscape disturbance index (LDI), road density and landscape fragmentation were not positively correlated relationship.Introducing ecosystem services value computing formula put forward by Costanza, eco-function deviation accumulation model was built to identify the eco-function deviation cumulative effect derived from road network. The ecosystem services value of Jiangning District lessened from2.922billion yuan in1980to2.582billion yuan in2010, and the decrement rate was11.62%. Along with the increase of road density, eco-function deviation cumulative index (FDCI) increased from0.016to0.639, with a gradual improvement in its variance. The analysis of road density and FDCI indicated that during the30years, with the expansion and extension of roads, the density of road network became higher and higher, human accessibility was promoted dramatically, the development of urbanization and industrialization also was driven significantly, and as a result, a large area of natural ecological system was occupied by construction land. Because of differences in ecosystem service value coefficients, the value supplied by construction land could not compensate for the losses, which lead to a decline in ecosystem service values and a reverse cumulative effect. The threshold analysis of ecosystem transformation indicated that road network density had a strong relationship with the transformation of some ecosystem. The transformation of woodland to sparse woodland was improved when road network density ranged from0.54-0.73km/km2; the road network density ranged from1.153-1.34km/km2triggered the transformation of woodland to high-covered grassland; the road network density ranged from0.627-0.725km/km2accelerated the transformation of shrub woodland to high-covered grassland.Road network theory was applied to research the effect of roads on forest landscape eco-function, the results showed that given the larger number of national and provincial roads, they took up much space in woodland, causing more severe impacts on the ecological functions of woodland ecosystem. However, due to highway with high isolation, the fragmentation degree of patch that cut through by it was higher, and its effect zone was wider than national and provincial roads’. Eventually, according to the landscape distribution characteristics of study area and the features of different road types, some advice on the layout of road network was proposed from the perspective of ecological protection.