Amphibian habitat network planning based on the graph theory: A case study of Pelophylax nigromaculata

Both biodiversity conservation and the construction of biological habitat networks are key components of territorial spatial planning in China. Improving the landscape functional connectivity of biological habitat networks plays a vital role in biodiversity conservation. Although biological habitat network planning is a hot topic in literature, there is still lack of operable technological and methodological support in practical planning. According to the graph theory, the following three different aspects of biodiversity conservation and ecological network construction should be addressed in territorial spatial planning. First, the importance of biological habitat patches should be evaluated to determine the priority of patch protection. Second, the best locations for adding new elements should be identified to increase landscape functional connectivity of biological habitat network. Third, the impacts of construction projects should be judged and the potential impact of new construction projects according to the reduction of landscape function connectivity should be evaluated. We applied such framework to the network planning of amphibian (Pelophylax nigromaculata) habitat in Xiong'an New Area. The results showed that graph theory approach effectively met the requirements of those three aspects. The identification of the five optimal locations of new habitats of P. nigromaculata improved the overall landscape functional connectivity of habitat network by 19%. Four optimal locations of cross passage were identified to reduce the impacts of G45 expressway by assessing its impacts on functional connectivity of the amphibian habitat network.