Background The key state-owned forest region in Northeast China is one of "Two Screen and Three Zones" as the subject, to ensure the ecological safety of the Northeast China. For comprehensively, systematically, scientifically, and quantitatively evaluating the ecological benefits of the region's Natural Forest Protection, dividing the ecoregions is indispensable.

Method First, we chosen the map of the Natural Forest Protection, eco-geological system of China, Chinese vegetation regionalization, China's soil erosion region and China's administrative division as the data sources. Then, we selected hydrothermal conditions, vegetation types, soil erosion types and intensities as three levels of regionalization indicators. Finally, we applied the geographic information system(GIS) space analysis to obtain the ecoregions.

Results Based on the climate there are 3 Class I areas of cool moist, mid-temperate moist, and mid-temperate semi-moist. Based on the Class I and vegetation type, there are 4 Class Ⅱ areas:cool moist coniferous forest, mid-temperate moist mixed broadleaf-conifer forest, mid-temperate moist rangeland, and mid-temperate semi-moist rangeland. Based on the Class Ⅱ and soil erosion type and intensity, there are 12 Class Ⅲ areas:Ⅰ-A-a-1 cool moist deciduous conifers non-erosive area, Ⅰ-A-a-2 cool moist deciduous coniferous slight wind erosive area, Ⅰ-A-a-6 cool moist deciduous coniferous high water erosive area, Ⅱ-A-b-1 mid-temperate moist mixed broadleaf-conifer forest non-erosive area, Ⅱ-A-b-3 mid-temperate moist mixed broadleaf-conifer forest slight water erosive area, Ⅱ-A-b-4 mid-temperate moist mixed broadleaf-conifer forest mild water erosive area, Ⅱ-A-b-5 mid-temperate moist mixed broadleaf-conifer forest moderate water erosive area, Ⅱ-A-b-6 mid-temperate moist mixed broadleaf-conifer forest high water erosive area, Ⅱ-A-c-6 mid-temperate moist rangeland high water erosive area, Ⅱ-B-c-1 mid-temperate semi-moist rangeland non-erosive area, Ⅱ-B-c-2 mid-temperate semi-moist rangeland slight wind erosive area, and Ⅱ-B-c-3 mid-temperate semi-moist rangeland slight water erosive area

Conclusions Based on multiple indicators, the key state-owned forest region Natural Forest Protection in Northeast China is characterized, ecoregions intuitively reflects the actual geographical regional rules. Meanwhile, we may use regionalization characteristics to verify the results of ecological benefit assessment, thus this work lays the foundation for ecological benefits monitoring and evaluation of the region's Natural Forest Protection.