Regional ecological risk assessment of multi-ecosystems under the disturbance of regional pole-axis system: a case study of the Tongjiang–Fuyuan region, China

In this study, the regional pole-axis system (urban/town areas and multi-level roads) where human production and living activities are concentrated was recognized as the main regional ecological risk source space; in contrast, multi-type ecosystems, such as wetland/waterbody and forestland and cropland with significant ecosystem service provisioning function, were identified as the main regional ecological risk receptor spaces. Based on this regional ecological risk source/receptor space division scheme, related ecological risk source/receptor indicators were chosen to characterize the spatial heterogeneities of human activities and ecological capital distribution within the study area. Among them, the Defense Meteorological Program Operational Line-Scan System (DMSP/OLS) nighttime light intensity and normalized density of multi-level roads data were employed as regional ecological risk source indicators, whereas the ecosystem service value of multi-ecosystems was employed as a regional ecological risk receptor indicator. Then, combined with regional eco-environmental vulnerability indexes, a regional ecological risk assessment framework was established and practiced in the Tongjiang–Fuyuan region, a wetland-concentrated area of the Sanjiang Plain. The results showed that (1) the DMSP/OLS nighttime light intensity data matched the distribution of regional urban/town areas and farms well, and it was reasonable to employ this dataset to represent the scope of regional production–living land space; (2) regional ecological space, such as wetlands and forestlands, had a higher ecological risk grade; (3) because of their higher human disturbance severity and ecological vulnerability level, regional settlement points (county seats and farms) had the highest ecological risk, whereas agricultural land space, occupying the largest area of the region, had the lowest ecological risk level; and finally, (4) in terms of proportion, the low, medium, high, and very high risk grades accounted for 71.66%, 17.13%, 8.43%, and 2.78% of the study area, respectively. Based on the results, a series of approaches, which can be adopted to promote regional sustainable development of the Tongjiang–Fuyuan region, were discussed, such as spatial governance of wetlands by establishing nature reserves, coordination of economic exploitation activities within forestlands, setup of a spatial expansion boundary of urban/town/farm areas, and tradeoffs between production and ecology functions of croplands.