**5. Conclusions**

Ancient environmental preference is rooted in the primary perception of nature and living practice when selecting a residential location. As the most popular method of site selection for ancient peoples, geomantic analysis was applied to find an auspicious environment based on constructing the closed space circled by the mountains and river, which illustrated that environmental utilization was focused on optimizing the overall layout of the living space from early times. As a matter of fact, it is only one aspect of the complicated environmental preference. The ecological meanings behind ancients' behavior of site selection deserve universal attention. The methodologies of the edge e ffect and ecological network are helpful for further recognizing the ancient site selection pattern.

Many ancient sites are distributed in the ecological transition zone, with an obvious edge e ffect. By the analysis of edge e ffect at di fferent scales, it has been shown that the edge intensity grows linearly between neighboring scales as the edge width increases. The e ffective scales were found at a medium and high level to separate the preferred locations of archaeological sites from the surrounding environment and the ancient city from other archaeological sites. The separability of edge e ffect shown up in the medium level under the ecologically balanced pattern in the ecosystem with various ecological types and an equilibrium constitution, while the optimal separability in the largest scale is useful to extract the high-value anomaly of edge e ffect to recognize the mountain-domain (or the forest-domain) environmental preference, especially after ecological fragmentation during urbanization with the transition from forest-domain ecology to settlement-domain ecology. Therefore, the edge effect can be used to reflect the site selection patterns. Its high-value region can be considered as possible locations with more chances of exchanging resources and energy with the neighbor ecological units to provide the basic material basis of ancient life. From the perspective of the ecological network, it is possible for a complex ecological structure to form a stable environment. This is reflected in the less frequent transfer of ecological constitutions in the network and changes of the edge e ffect in the ecologically balanced ecosystem. Significant variations of the edge e ffect are related to the simple network structure of the mountain-domain ecosystem. As for the centrality of patches in the ecological network, the river and forest patches have the highest centrality importance and play the vital roles in the regional environment. They also constitute the main part in the closed space in geomancy. That is an important reason why a geomantic environment was preferred by the ancients. In addition, the ancient sites are located in or next to the high-centrality terrain for accessing su fficient raw materials for ancient life. Of course, the site selection patterns are localized in a similar environment in the middle and lower reaches of the Yangtze River and may be widely applicable. They are also helpful to discover the unknown location of ancient cities. In practice, one suspected site was found through an analysis in the geomantic environment of closed space and its ecological characteristics, though more archaeological details are needed to confirm this speculation. However, a comprehensive analysis of the geomantic environment and ecological structure has been proved e ffective for research on ancient site selection and exploring undiscovered sites. The results were validated by the spatial analysis in ArcGIS and the field investigation.

In short, we have attempted to discuss the ecological significance of ancient site-selection patterns with the background of fast urban development. However, it is not enough to explain the individual behavior pattern and the rich meanings of sociology and culturology under environmental preference. Further work will be conducted to take archaeological sites as important carriers to extract more scientific information in order to reveal the inner connection between humans and the environment from multi-disciplinary perspectives. If traditional cultural perceptions can be integrated into a scientific system of ecological landscapes, it would contribute more to the conservation of archaeological sites and the study of ancient cultures.

**Author Contributions:** Methodology and writing, J.Z.; conceptualization, Y.N. and Y.Z.; data curation, L.Y.; investigation and validation, Y.S.; formal analysis, F.L.; software, W.S. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded and supported by the National Natural Science Foundation of China (NSFC), gran<sup>t</sup> number 41801134 and "Remote sensing and geophysical comprehensive in archaeological research of China classical archaeological site" (No. 2015BAK01B01).

**Acknowledgments:** The SRTM DEM data set was provided by the International Scientific and Technical Data Mirror Site, Computer Network Information Center, the Chinese Academy of Sciences, http://www.gscloud.cn. The soil classification map is provided by Cold and Arid Regions Sciences Data Center at Lanzhou (http: //westdc.westgis.ac.cn). Thanks are given to Chao X., a researcher at the Ningbo Municipal Institute of Cultural Relics and Archaeology, for providing help with the field investigation and data about archaeological sites in this study, as well as some suggestions on historical and archaeological study.

**Conflicts of Interest:** The authors declare no conflicts of interest.
