Habitat networks have a vital function in inhibiting habitat fragmentation and biodiversity conservation due to the connectivity among habitat patches. However, in previous studies, habitat networks optimization have been carried on mainly from the perspective of landscape structural connectivity rather than that of landscape functional connectivity; while the latter has more ecological significance. The objective of this paper was, from the functional connectivity perspective, to optimize habitat networks by an approach combined by methods of graph theory and probability of moving between patches theory. Through this approach, a screening threshold and a recovering threshold were calculated and applied to identify corridors as well as newly-added patches and their corresponding corridors, which have significantly functional connectivity features, from the existing Little Egret habitat networks. The Su-Xi-Chang area, the core of the Yangtze River Delta Region of China was selected as the study cite. The Little Egret (Egretta garzetta) was chosen as a regionally representative species.
The results show that: a) the optimized habitat networks possess a higher density and clearer aggregation centers, while the optimized arterial habitat networks effectively simulate the species' long-distance migration direction; b) the optimized networks and arterial habitat networks, which were consisted by the patches and corridors with significantly functional connectivity features, were both the optimization scheme for the current networks, based on the result that the network connectivity indexes α, β, γ for them were greater than the current networks. The optimized arterial networks was recommended due to the almost same network connectivity indexes and less habitat nodes and migration corridors, compared with those of the optimized habitat networks. The arterial habitat networks can be used in conservation plan making and its easier implementation especially in rapidly urbanizing areas. The designed method of this paper also provides a new approach for migration corridors and stepping stones priority ranking and is easily implement in the aspect of land resources management for biodiversity conservation. Lastly, some shortcomings of method design was well as future research have been discussed.