Abstract:Longitudinal Range-Gorge Region (LRGR) of YUN Nan Province is characterized with its complex mountain ecosystem and the globally important biodiversity. However, this unique mountain ecosystem is experiencing extensively increased degradation largely due to the human activities, especially the road network development and associated land-use changes. To quantify the effects of road networks on the ecosystem at multi-scales in LRGR of YUN Nan Province, the spatial correlation and ANOVA analysis were conducted between road network density and ecosystem proportional index under different spatial scales varying from 2km×2km to 20km×20km. The independent effects of different grades of road networks and their interactive effects with those topographic factors (i.e. altitude, slop and aspect) on the ecosystem in LRGR were further explored. The results showed that the correlation between road network density and ecosystem distribution was mainly determined by the road networks grades with the tendency that correlation decreased with upgrading of the road networks, and the scaling effects of the road networks can be divided into 4 categories: rising, descending, mutation and unscaled. The interactive effects between the road networks and the topographic factors occurred at most scales, implicating that both of them affected the ecosystem distribution. The independent effects of high-grade road networks were more prominent than that of low-grade road networks. The independent effects of low-grade road networks (i.e. county road and trail) and their interactive effects with topographic factors were mostly notable with extremely similar changes of scaling-up, indicating that the effects of low-grade road networks were much extensively but largely mitigated by those topographic factors.