Assessment of ecological risks of landscape along the Ming Great Wall in Beijing

In this study we evaluated the ecological risks of the landscapes along the Beijing Ming Great Wall, 3 km within each side of it. Firstly we built landscape ecological risk indices by using the data from Beijing Great Wall census and recent forest resource survey, then systematically sampled in each 2km×2km grid, and analyzed the data by spatial autocorrelation and analysis of semi-variance. Among the landscapes studied, shrub land had the highest coverage (26.58%) and also the highest ecological risk; Non-stumpage land had the highest degree of fragmentation and isolation and therefore suffered the highest disturbance and natural loss; agricultural land had the most complex shape. The spatial autocorrelation based on global Moran's I was 0.2725 and the nugget coefficient was 49.7%, suggesting that the ecological risk indices were spatially auto-correlated and scale-dependent; spatial autocorrelation generally decreased with the increase of research scale. Therefore, ecological risk was aggregated, with apparent high and low risk zones. The areas with high eco-risk were mainly in the more developed and well-known sections of the Great Wall including Badaling, Huanghuacheng, Mutianyu, Jinshanling, and Simatai. The ecological risk peaked at the border between southeast Huairou and Miyun and decreased gradually to the east and the west. The most of the study area was in medium to low ecological risks; however the percentage of area with high risk reached 21.09%, high enough for further attention. Our results would provide reference for environmental protection, policy development and conservation planning in the future.